Jesus Torres-Vazquez - Academia.edu (original) (raw)

Papers by Jesus Torres-Vazquez

Research paper thumbnail of Dual role for shn in Dpp signaling

Decapentaplegic (Dpp), a homolog of vertebrate bone morphogenic protein 2/4, is crucial for embry... more Decapentaplegic (Dpp), a homolog of vertebrate bone morphogenic protein 2/4, is crucial for embryonic patterning and cell fate specification in Drosophila. Dpp signaling triggers nuclear accumulation of the Smads Mad and Medea, which affect gene expression through two distinct mechanisms: direct activation of target genes and relief of repression by the nuclear protein Brinker (Brk). The zinc-finger transcription factor Schnurri (Shn) has been implicated as a co-factor for Mad, based on its DNAbinding ability and evidence of signaling dependent interactions between the two proteins. A key question is whether Shn contributes to both repression of brk as well as to activation of target genes. We find that during embryogenesis, brk expression is derepressed in shn mutants. However, while Mad is essential for Dpp-mediated repression of brk, the requirement for shn is stage specific. Analysis of brk; shn double mutants reveals that upregulation of brk does not account for all aspects of ...

Research paper thumbnail of The transcription factor Schnurri plays a dual role in mediating Dpp signaling during embryogenesis

Development, 2001

Decapentaplegic (Dpp), a homolog of vertebrate bone morphogenic protein 2/4, is crucial for embry... more Decapentaplegic (Dpp), a homolog of vertebrate bone morphogenic protein 2/4, is crucial for embryonic patterning and cell fate specification in Drosophila. Dpp signaling triggers nuclear accumulation of the Smads Mad and Medea, which affect gene expression through two distinct mechanisms: direct activation of target genes and relief of repression by the nuclear protein Brinker (Brk). The zinc-finger transcription factor Schnurri (Shn) has been implicated as a co-factor for Mad, based on its DNA-binding ability and evidence of signaling dependent interactions between the two proteins. A key question is whether Shn contributes to both repression of brk as well as to activation of target genes. We find that during embryogenesis, brk expression is derepressed in shn mutants. However, while Mad is essential for Dpp-mediated repression of brk, the requirement for shn is stage specific. Analysis of brk; shn double mutants reveals that upregulation of brk does not account for all aspects of...

Research paper thumbnail of GIPC proteins negatively modulate Plexind1 signaling during vascular development

eLife, 2019

Semaphorins (SEMAs) and their Plexin (PLXN) receptors are central regulators of metazoan cellular... more Semaphorins (SEMAs) and their Plexin (PLXN) receptors are central regulators of metazoan cellular communication. SEMA-PLXND1 signaling plays important roles in cardiovascular, nervous, and immune system development, and cancer biology. However, little is known about the molecular mechanisms that modulate SEMA-PLXND1 signaling. As PLXND1 associates with GIPC family endocytic adaptors, we evaluated the requirement for the molecular determinants of their association and PLXND1’s vascular role. Zebrafish that endogenously express a Plxnd1 receptor with a predicted impairment in GIPC binding exhibit low penetrance angiogenesis deficits and antiangiogenic drug hypersensitivity. Moreover, gipc mutant fish show angiogenic impairments that are ameliorated by reducing Plxnd1 signaling. Finally, GIPC depletion potentiates SEMA-PLXND1 signaling in cultured endothelial cells. These findings expand the vascular roles of GIPCs beyond those of the Vascular Endothelial Growth Factor (VEGF)-dependent...

Research paper thumbnail of Structure analyses reveal a regulated oligomerization mechanism of the PlexinD1/GIPC/myosin VI complex

eLife, 2017

The GIPC family adaptor proteins mediate endocytosis by tethering cargo proteins to the myosin VI... more The GIPC family adaptor proteins mediate endocytosis by tethering cargo proteins to the myosin VI motor. The structural mechanisms for the GIPC/cargo and GIPC/myosin VI interactions remained unclear. PlexinD1, a transmembrane receptor that regulates neuronal and cardiovascular development, is a cargo of GIPCs. GIPC-mediated endocytic trafficking regulates PlexinD1 signaling. Here, we unravel the mechanisms of the interactions among PlexinD1, GIPCs and myosin VI by a series of crystal structures of these proteins in apo or bound states. GIPC1 forms a domain-swapped dimer in an autoinhibited conformation that hinders binding of both PlexinD1 and myosin VI. PlexinD1 binding to GIPC1 releases the autoinhibition, promoting its interaction with myosin VI. GIPCs and myosin VI interact through two distinct interfaces and form an open-ended alternating array. Our data support that this alternating array underlies the oligomerization of the GIPC/Myosin VI complexes in solution and cells.

Research paper thumbnail of Reck enables cerebrovascular development by promoting canonical Wnt signaling

Development (Cambridge, England), Jan 10, 2015

The cerebral vasculature provides the massive blood supply that the brain needs to grow and survi... more The cerebral vasculature provides the massive blood supply that the brain needs to grow and survive. By acquiring distinctive cellular and molecular characteristics it becomes the Blood Brain Barrier (BBB), a selectively permeable and protective interface between the brain and the peripheral circulation that maintains the extra-cellular milieu permissive for neuronal activity. Accordingly, there is great interest in uncovering the mechanisms that modulate the formation and differentiation of the brain vasculature. By performing a forward genetic screen in zebrafish we isolated no food for thought (nft(y72)), a recessive late-lethal mutant that lacks most of the intra-cerebral Central Arteries (CtAs), but not other brain blood vessels. We found that the cerebral vascularization deficit of nft(y72) is caused by an inactivating lesion in reck (reversion-inducing-cysteine-rich protein with Kazal motifs or ST15; Suppressor of Tumorigenicity 15 protein), which encodes a membrane-anchored ...

Research paper thumbnail of Origin, Specification, and Plasticity of the Great Vessels of the Heart

Current Biology, 2015

The pharyngeal arch arteries (PAAs) are a series of paired embryonic blood vessels that give rise... more The pharyngeal arch arteries (PAAs) are a series of paired embryonic blood vessels that give rise to several major arteries that connect directly to the heart. During development, the PAAs emerge from nkx2.5-expressing mesodermal cells and connect the dorsal head vasculature to the outflow tract of the heart. Despite their central role in establishing the circulatory system, the embryonic origins of the PAA progenitors are only coarsely defined, and the factors that specify them and their regenerative potential are unclear. Using fate mapping and mutant analysis, we find that PAA progenitors are derived from the tcf21 and nkx2.5 double-positive head mesoderm and require these two transcription factors for their specification and survival. Unexpectedly, cell ablation shows that the tcf21+; nkx2.5+ PAA progenitors are not required for PAA formation. We find that this compensation is due to the replacement of ablated tcf21+; nkx2.5+ PAA cells by endothelial cells from the dorsal head vasculature. Together, these studies assign the embryonic origin of the great vessel progenitors to the interface between the pharyngeal and cardiac mesoderm, identify the transcription factor code required for their specification, and reveal an unexpected plasticity in the formation of the great vessels.

Research paper thumbnail of In parallelinterconnectivity of the dorsal longitudinal anastomotic vessels requires both VEGF signaling and circulatory flow

Journal of Cell Science, 2012

Blood vessels deliver oxygen, nutrients, hormones and immunity factors throughout the body. To pe... more Blood vessels deliver oxygen, nutrients, hormones and immunity factors throughout the body. To perform these vital functions, vascular cords branch, lumenize and interconnect. Yet, little is known about the cellular, molecular and physiological mechanisms that control how circulatory networks form and interconnect. Specifically, how circulatory networks merge by interconnecting in parallel along their boundaries remains unexplored. To examine this process we studied the formation and functional maturation of the plexus that forms between the Dorsal Longitudinal Anastomotic Vessels (DLAVs) in the zebrafish. We find that the migration and proliferation of endothelial cells within the DLAVs and their Segmental (Se) vessel precursors drives DLAV plexus formation. Remarkably, the presence of Se vessels containing only endothelial cells of the arterial lineage is sufficient for DLAV plexus morphogenesis, suggesting that endothelial cells from the venous lineage make a dispensable or null ...

Research paper thumbnail of Semaphorin-PlexinD1 Signaling Limits Angiogenic Potential via the VEGF Decoy Receptor sFlt1

Developmental Cell, 2011

Sprouting angiogenesis expands the embryonic vasculature enabling survival and homeostasis. Yet h... more Sprouting angiogenesis expands the embryonic vasculature enabling survival and homeostasis. Yet how the angiogenic capacity to form sprouts is allocated among endothelial cells (ECs) to guarantee the reproducible anatomy of stereotypical vascular beds remains unclear. Here we show that Sema-PlxnD1 signaling, previously implicated in sprout guidance, represses angiogenic potential to ensure the proper abundance and stereotypical distribution of the trunk's segmental arteries (SeAs). We find that Sema-PlxnD1 signaling exerts this effect by antagonizing the proangiogenic activity of vascular endothelial growth factor (VEGF). Specifically, Sema-PlxnD1 signaling ensures the proper endothelial abundance of soluble flt1 (sflt1), an alternatively spliced form of the VEGF receptor Flt1 encoding a potent secreted decoy. Hence, Sema-PlxnD1 signaling regulates distinct but related aspects of angiogenesis: the spatial allocation of angiogenic capacity within a primary vessel and sprout guidance.

Research paper thumbnail of Semaphorin-Plexin Signaling Guides Patterning of the Developing Vasculature

Developmental Cell, 2004

none and Comoglio, 2000). We show here that the endothelial receptor PlexinD1 plays a similar rol... more none and Comoglio, 2000). We show here that the endothelial receptor PlexinD1 plays a similar role during vas-NICHD National Institutes of Health cular patterning. In the developing trunk, angiogenic intersegmental vessels extend near somite boundaries Bethesda, Maryland 20892 2 Cardiovascular Division (Isogai et al., 2001; Childs et al., 2002). Loss of plxnD1 function via morpholino injection or in zebrafish out of University of Pennsylvania Philadelphia, Pennsylvania 19104 bounds (obd) mutants (Childs et al., 2002) causes dramatic mispatterning of these vessels, which are no 3 Department of Biochemistry and Molecular Biology and Smooth Muscle Research Group longer restricted to growth near intersomitic boundaries. Somites flanking intersegmental vessels express sema-University of Calgary Calgary, Alberta T2N 4N1 phorins (Roos et al., 1999; Yee et al., 1999), and reducing the function of these semaphorins causes similar inter-Canada 4 Cardiovascular Research Center segmental vessel patterning defects. Conversely, semaphorin overexpression inhibits the growth of interseg-Massachusetts General Hospital Charlestown, Massachusetts 02129 mental vessels in a plxnD1-dependent manner. These results indicate that the establishment of anatomical pattern in the developing vasculature is directed in part by cues and mechanisms similar to those used to pattern Summary the developing nervous system (Tessier-Lavigne and Goodman, 1996), including semaphorin-plexin sig-Major vessels of the vertebrate circulatory system disnaling. play evolutionarily conserved and reproducible anatomy, but the cues guiding this stereotypic patterning remain obscure. In the nervous system, axonal path-Results and Discussion ways are shaped by repulsive cues provided by ligands of the semaphorin family that are sensed by migrating Plexin D1 Is Expressed neuronal growth cones through plexin receptors. We in the Embryonic Vasculature show that proper blood vessel pathfinding requires We identified murine plexinD1 (plxnD1) in the EST datathe endothelial receptor PlexinD1 and semaphorin sigbase by sequence homology to other members of the nals, and we identify mutations in plexinD1 in the zeplexin family. Expression analysis revealed that plxnD1, brafish vascular patterning mutant out of bounds. unlike other members of the extended family, is not These results reveal the fundamental conservation of primarily expressed by neurons. Rather, expression is repulsive patterning mechanisms between axonal mirestricted to endothelial cells (Cheng et al., 2001; Tagration in the central nervous system and vascular magnone et al., 1999; van der Zwaag et al., 2002). We endothelium during angiogenesis. reasoned that plxnD1 might function to guide the patterning of developing blood vessels, in a manner analo-Introduction gous to the role of other plexins in axonal patterning in the nervous system (Tamagnone and Comoglio, 2000). The vertebrate circulatory system is crucial for the de-To explore this possibility, we isolated a full-lengthlivery and exchange of gases, hormones, metabolic zebrafish plxnD1 ortholog (see Experimental Procewastes, and immunity factors. Although key players in dures and Supplemental Data, section 1 [http://www. vascular endothelial cell specification and differentiation developmentalcell.com/cgi/content/full/7/1/117/DC1]). have been identified, we have limited understanding of Zebrafish plxnD1 is expressed throughout the vasculathe molecular mechanisms responsible for the remarkture in blood vessel endothelial cells and their angioblast able regularity in pattern of larger blood vessels within precursors (Figures 1B, 1D, 1F, and 1H), mirroring the and across species (Weinstein, 1999). In the nervous endothelial-specific expression pattern of the fli1 gene system, axonal pathways are established by repulsive (Figures 1A, 1C, 1E, and 1G; Brown et al., 2000). plxnD1 and attractive signals from surrounding tissues, sensed transcripts are evident in angioblast precursors prior to by migrating neuronal growth cones through specific trunk vessel assembly (Figure 1B) and in the newly formed trunk dorsal aorta and posterior cardinal vein

Research paper thumbnail of Neurovascular development in the embryonic zebrafish hindbrain

Developmental Biology, 2011

The brain is made of billions of highly metabolically active neurons whose activities provide the... more The brain is made of billions of highly metabolically active neurons whose activities provide the seat for cognitive, affective, sensory and motor functions. The cerebral vasculature meets the brain's unusually high demand for oxygen and glucose by providing it with the largest blood supply of any organ. Accordingly, disorders of the cerebral vasculature, such as congenital vascular malformations, stroke and tumors, compromise neuronal function and survival and often have crippling or fatal consequences. Yet, the assembly of the cerebral vasculature is a process that remains poorly understood. Here we exploit the physical and optical accessibility of the zebrafish embryo to characterize cerebral vascular development within the embryonic hindbrain. We find that this process is primarily driven by endothelial cell migration and follows a two-step sequence. First, perineural vessels with stereotypical anatomies are formed along the ventro-lateral surface of the neuroectoderm. Second, angiogenic sprouts derived from a subset of perineural vessels migrate into the hindbrain to form the intraneural vasculature. We find that these angiogenic sprouts reproducibly penetrate into the hindbrain via the rhombomere centers, where differentiated neurons reside, and that specific rhombomeres are invariably vascularized first. While the anatomy of intraneural vessels is variable from animal to animal, some aspects of the connectivity of perineural and intraneural vessels occur reproducibly within particular hindbrain locales. Using a chemical inhibitor of VEGF signaling we determine stage-specific requirements for this pathway in the formation of the hindbrain vasculature. Finally, we show that a subset of hindbrain vessels is aligned and/or in very close proximity to stereotypical neuron clusters and axon tracts. Using endothelium-deficient cloche mutants we show that the endothelium is dispensable for the organization and maintenance of these stereotypical neuron clusters and axon tracts in the early hindbrain. However, the cerebellum's upper rhombic lip and the optic tectum are abnormal in clo. Overall, this study provides a detailed, multi-stage characterization of early zebrafish hindbrain neurovascular development with cellular resolution up to the third day of age. This work thus serves as a useful reference for the neurovascular characterization of mutants, morphants and drug-treated embryos.

Research paper thumbnail of Beyond guidance: A novel role for Sema–PlxnD1 signaling in vascular development

Developmental Biology, 2011

Research paper thumbnail of Diverse functions for the semaphorin receptor PlexinD1 in development and disease

Developmental Biology, 2011

Plexins are a family of single pass transmembrane proteins that serve as cell surface receptors f... more Plexins are a family of single pass transmembrane proteins that serve as cell surface receptors for Semaphorins during the embryonic development of animals. Semaphorin-Plexin signaling is critical for many cellular aspects of organogenesis, including cell migration, proliferation and survival. Until recently, little was known about the function of PlexinD1, the sole member of the vertebrate-specific PlexinD (PlxnD1) subfamily. Here we review novel findings about PlxnD1's roles in the development of the cardiovascular, nervous and immune systems and salivary gland branching morphogenesis and discuss new insights concerning the molecular mechanisms of PlxnD1 activity.

Research paper thumbnail of The Zinc Finger Protein Schnurri Acts as a Smad Partner in Mediating the Transcriptional Response to Decapentaplegic

Developmental Biology, 2000

In Drosophila, a BMP-related ligand Decapentaplegic (Dpp) is essential for cell fate specificatio... more In Drosophila, a BMP-related ligand Decapentaplegic (Dpp) is essential for cell fate specification during embryogenesis and in imaginal disc development. Dpp signaling culminates in the phosphorylation and nuclear translocation of Mothers against dpp (Mad), a receptor-specific Smad that can bind DNA and regulate the transcription of Dpp-responsive genes. Genetic analysis has implicated Schnurri (Shn), a zinc finger protein that shares homology with mammalian transcription factors, in the Dpp signal transduction pathway. However, a direct role for Shn in regulating the transcriptional response to Dpp has not been demonstrated. In this study we show that Shn acts as a DNA-binding Mad cofactor in the nuclear response to Dpp. Shn can bind DNA in a sequence-specific manner and recognizes sites within a well-characterized Dpp-responsive promoter element, the B enhancer of the Ultrabithorax (Ubx) gene. The Shn-binding sites are relevant for in vivo expression, since mutations in these sites affect the ability of the enhancer to respond to Dpp. Furthermore we find that Shn and Mad can interact directly through discrete domains. To examine the relative contribution of the two proteins in the regulation of endogenous Dpp target genes we developed a cell culture assay and show that Shn and Mad act synergistically to induce transcription. Our results suggest that cooperative interactions between these two transcription factors could play an important role in the regulation of Dpp target genes. This is the first evidence that Dpp/BMP signaling in flies requires the direct interaction of Mad with a partner transcription factor.

Research paper thumbnail of schnurri Is Required for dpp-Dependent Patterning of the Drosophila Wing

Developmental Biology, 2000

The BMP-related ligand Decapentaplegic (Dpp) has a well-characterized role in pattern formation d... more The BMP-related ligand Decapentaplegic (Dpp) has a well-characterized role in pattern formation during Drosophila embryogenesis and in larval development. Previous work has shown that transcription of Dpp-responsive genes requires the activity of the BMP-specific Smad, Mothers against dpp (Mad). In this study we investigated the role of the zinc finger transcription factor Schnurri (Shn) in mediating the nuclear response to Dpp during adult patterning. Using clonal analysis, we show that wing imaginal disc cells mutant for shn fail to transcribe the genes spalt, optomotor blind, vestigial, and Dad, that are known to be induced by dpp signaling. shn clones also ectopically express brinker, a gene that is downregulated in response to dpp, thus implicating Shn in both activation and repression of Dpp target genes. We demonstrate that loss of shn activity affects anterior-posterior patterning and cell proliferation in the wing blade, in a manner that reflects the graded requirement for Dpp in these processes. Furthermore, we find that shn is expressed in the pupal wing and plays a distinct role in mediating dpp-dependent vein differentiation at this stage. The absence of shn activity results in defects that are similar in nature and severity to those caused by elimination of Mad, suggesting that Shn has an essential role in dpp signal transduction in the developing wing. Our data are consistent with a model in which Shn acts as a cofactor for Mad.

Research paper thumbnail of A phylogenetically conserved cis-regulatory module in theMsx2promoter is sufficient for BMP-dependent transcription in murine andDrosophilaembryos

Development, 2004

To understand the actions of morphogens, it is crucial to determine how they elicit different tra... more To understand the actions of morphogens, it is crucial to determine how they elicit different transcriptional responses in different cell types. Here,we identify a BMP-responsive enhancer of Msx2, an immediate early target of bone morphogenetic protein (BMP) signaling. We show that the BMP-responsive region of Msx2 consists of a core element, required generally for BMP-dependent expression, and ancillary elements that mediate signaling in diverse developmental settings. Analysis of the core element identified two classes of functional sites: GCCG sequences related to the consensus binding site of Mad/Smad-related BMP signal transducers; and a single TTAATT sequence, matching the consensus site for Antennapedia superclass homeodomain proteins. Chromatin immunoprecipitation and mutagenesis experiments indicate that the GCCG sites are direct targets of BMP restricted Smads. Intriguingly, however, these sites are not sufficient for BMP responsiveness in mouse embryos; the TTAATT sequenc...

Research paper thumbnail of Development of functional hindbrain oculomotor circuitry independent of both vascularization and neuronal activity in larval zebrafish

Current neurobiology, 2016

We investigated the contribution of blood vessel formation and neuronal excitability to the devel... more We investigated the contribution of blood vessel formation and neuronal excitability to the development of functional neural circuitry in larval zebrafish by analyzing oculomotor performance in response to visual and vestibular stimuli. To address the dependence of neuronal function on the presence of blood vessels, we compared wild type embryos to reck and cloche mutants that lacked intracerebral blood vessels. To test how neuronal excitability impacts neuronal development and intracerebral vascularization, we blocked neural activity using Tetraodotoxin (TTX) and Tricaine. In reck mutants, we found both slow phase horizontal tracking and fast phase resets with only a slightly reduced amplitude and bandwidth. Spontaneous saccades, eye position holding and vestibular gravitoinertial induced eye rotation were also present. All of these behaviors except for visual tracking were observed in cloche mutants that lacked any head vasculature. Thus, numerous oculomotor neuronal circuits span...

Research paper thumbnail of Genetic determinants of hyaloid and retinal vasculature in zebrafish-0

<b>Copyright information:</b>Taken from "Genetic determinants of hyaloid and ret... more <b>Copyright information:</b>Taken from "Genetic determinants of hyaloid and retinal vasculature in zebrafish"http://www.biomedcentral.com/1471-213X/7/114BMC Developmental Biology 2007;7():114-114.Published online 15 Oct 2007PMCID:PMC2169232.nner vessels covering the entire inner surface of the retina. Example of disparity in branch number between left (5) and right (8) eyes. Transverse view of the blood vessels (green: Fli1-EGFP) overlaying the inner limiting membrane of the adult retina (blue: DAPI nuclear staining). Inset shows the same vessels overlying GCL nuclei in a flatmount preparation. At peripheral retinal regions, neighbouring vessels anastomose (inset), and elongated filopodia sprout from the capillaries suggesting active angiogenic remodelling. The diameter of vessels is thicker proximal to the optic disc and thinner peripherally. Numbers refer to the thickness of the vessel and the angle of measurement in reference to horizontal plane. Flatmount adult retinas immuno-labelled with retinal vasculature markers. collagen IV (red) stains the basal membrane of blood vessels. smooth muscle actin (SMA) stains vascular pericytes (green). Factor VIII labels endothelial cells (red). Cone photoreceptors label green as analysis was performed in transgenic line [67]. Glial fibrillary acidic protein (GFAP) stains retinal vessels in adult zebrafish and a population of cells throughout the retina. GFAP (red), DAPI (blue) and fli1-EGFP (green). Flat-mounted retina, and Transverse view of the peripheral retina. Müller endfeet (asterisks) directly contact the endothelial cells (yellow co-staining). : FITC channel turned off to highlight the GFAP reactivity of retinal vessels. .

Research paper thumbnail of Aminoacyl-Transfer RNA Synthetase Deficiency Promotes Angiogenesis via the Unfolded Protein Response Pathway

Arteriosclerosis, Thrombosis, and Vascular Biology, 2016

Objective— Understanding the mechanisms regulating normal and pathological angiogenesis is of gre... more Objective— Understanding the mechanisms regulating normal and pathological angiogenesis is of great scientific and clinical interest. In this report, we show that mutations in 2 different aminoacyl-transfer RNA synthetases, threonyl tRNA synthetase (tars y58 ) or isoleucyl tRNA synthetase (iars y68 ) , lead to similar increased branching angiogenesis in developing zebrafish. Approach and Results— The unfolded protein response pathway is activated by aminoacyl-transfer RNA synthetase deficiencies, and we show that unfolded protein response genes atf4, atf6 , and xbp1 , as well as the key proangiogenic ligand vascular endothelial growth factor (vegfaa) , are all upregulated in tars y58 and iars y68 mutants. Finally, we show that the protein kinase RNA-like endoplasmic reticulum kinase–activating transcription factor 4 arm of the unfolded protein response pathway is necessary for both the elevated vegfaa levels and increased angiogenesis observed in tars y58 mutants. Conclusions— Our r...

Research paper thumbnail of Making Waves in Madison: The 6th International Meeting on Zebrafish Development and Genetics

Research paper thumbnail of The role of Hath6, a novel shear stress-responsive transcription factor, in endothelial differentiation and function modulation

Journal of Cell Science, 2014

The key regulators of endothelial differentiation induced by shear stress (SS) are mostly unclear... more The key regulators of endothelial differentiation induced by shear stress (SS) are mostly unclear. Human atonal homolog 6 (Hath6) was identified as an endothelial-selective and SS-responsive transcription factor. In this study, we sought to elucidate the role of Hath6 in the endothelial specification of embryonic stem cells. In a stepwise human embryonic stem cell-endothelial cell (hESC-EC) induction system, Hath6 was upregulated synchronously with endothelial determination. Subsequently, gain-of-function and loss-of-function studies of Hath6 were performed using the hESC-EC induction model and endothelial cell lines. The overexpression of Hath6, which mimics SS treatment, resulted in an increased CD45−CD31+KDR+ population, a higher tubular-structure-formation capacity, and increased endothelial-specific gene expression. In contrast, the knockdown of the Hath6 gene markedly decreased endothelial differentiation. Hath6 also facilitates the maturation of ECs in terms of endothelial ge...

Research paper thumbnail of Dual role for shn in Dpp signaling

Decapentaplegic (Dpp), a homolog of vertebrate bone morphogenic protein 2/4, is crucial for embry... more Decapentaplegic (Dpp), a homolog of vertebrate bone morphogenic protein 2/4, is crucial for embryonic patterning and cell fate specification in Drosophila. Dpp signaling triggers nuclear accumulation of the Smads Mad and Medea, which affect gene expression through two distinct mechanisms: direct activation of target genes and relief of repression by the nuclear protein Brinker (Brk). The zinc-finger transcription factor Schnurri (Shn) has been implicated as a co-factor for Mad, based on its DNAbinding ability and evidence of signaling dependent interactions between the two proteins. A key question is whether Shn contributes to both repression of brk as well as to activation of target genes. We find that during embryogenesis, brk expression is derepressed in shn mutants. However, while Mad is essential for Dpp-mediated repression of brk, the requirement for shn is stage specific. Analysis of brk; shn double mutants reveals that upregulation of brk does not account for all aspects of ...

Research paper thumbnail of The transcription factor Schnurri plays a dual role in mediating Dpp signaling during embryogenesis

Development, 2001

Decapentaplegic (Dpp), a homolog of vertebrate bone morphogenic protein 2/4, is crucial for embry... more Decapentaplegic (Dpp), a homolog of vertebrate bone morphogenic protein 2/4, is crucial for embryonic patterning and cell fate specification in Drosophila. Dpp signaling triggers nuclear accumulation of the Smads Mad and Medea, which affect gene expression through two distinct mechanisms: direct activation of target genes and relief of repression by the nuclear protein Brinker (Brk). The zinc-finger transcription factor Schnurri (Shn) has been implicated as a co-factor for Mad, based on its DNA-binding ability and evidence of signaling dependent interactions between the two proteins. A key question is whether Shn contributes to both repression of brk as well as to activation of target genes. We find that during embryogenesis, brk expression is derepressed in shn mutants. However, while Mad is essential for Dpp-mediated repression of brk, the requirement for shn is stage specific. Analysis of brk; shn double mutants reveals that upregulation of brk does not account for all aspects of...

Research paper thumbnail of GIPC proteins negatively modulate Plexind1 signaling during vascular development

eLife, 2019

Semaphorins (SEMAs) and their Plexin (PLXN) receptors are central regulators of metazoan cellular... more Semaphorins (SEMAs) and their Plexin (PLXN) receptors are central regulators of metazoan cellular communication. SEMA-PLXND1 signaling plays important roles in cardiovascular, nervous, and immune system development, and cancer biology. However, little is known about the molecular mechanisms that modulate SEMA-PLXND1 signaling. As PLXND1 associates with GIPC family endocytic adaptors, we evaluated the requirement for the molecular determinants of their association and PLXND1’s vascular role. Zebrafish that endogenously express a Plxnd1 receptor with a predicted impairment in GIPC binding exhibit low penetrance angiogenesis deficits and antiangiogenic drug hypersensitivity. Moreover, gipc mutant fish show angiogenic impairments that are ameliorated by reducing Plxnd1 signaling. Finally, GIPC depletion potentiates SEMA-PLXND1 signaling in cultured endothelial cells. These findings expand the vascular roles of GIPCs beyond those of the Vascular Endothelial Growth Factor (VEGF)-dependent...

Research paper thumbnail of Structure analyses reveal a regulated oligomerization mechanism of the PlexinD1/GIPC/myosin VI complex

eLife, 2017

The GIPC family adaptor proteins mediate endocytosis by tethering cargo proteins to the myosin VI... more The GIPC family adaptor proteins mediate endocytosis by tethering cargo proteins to the myosin VI motor. The structural mechanisms for the GIPC/cargo and GIPC/myosin VI interactions remained unclear. PlexinD1, a transmembrane receptor that regulates neuronal and cardiovascular development, is a cargo of GIPCs. GIPC-mediated endocytic trafficking regulates PlexinD1 signaling. Here, we unravel the mechanisms of the interactions among PlexinD1, GIPCs and myosin VI by a series of crystal structures of these proteins in apo or bound states. GIPC1 forms a domain-swapped dimer in an autoinhibited conformation that hinders binding of both PlexinD1 and myosin VI. PlexinD1 binding to GIPC1 releases the autoinhibition, promoting its interaction with myosin VI. GIPCs and myosin VI interact through two distinct interfaces and form an open-ended alternating array. Our data support that this alternating array underlies the oligomerization of the GIPC/Myosin VI complexes in solution and cells.

Research paper thumbnail of Reck enables cerebrovascular development by promoting canonical Wnt signaling

Development (Cambridge, England), Jan 10, 2015

The cerebral vasculature provides the massive blood supply that the brain needs to grow and survi... more The cerebral vasculature provides the massive blood supply that the brain needs to grow and survive. By acquiring distinctive cellular and molecular characteristics it becomes the Blood Brain Barrier (BBB), a selectively permeable and protective interface between the brain and the peripheral circulation that maintains the extra-cellular milieu permissive for neuronal activity. Accordingly, there is great interest in uncovering the mechanisms that modulate the formation and differentiation of the brain vasculature. By performing a forward genetic screen in zebrafish we isolated no food for thought (nft(y72)), a recessive late-lethal mutant that lacks most of the intra-cerebral Central Arteries (CtAs), but not other brain blood vessels. We found that the cerebral vascularization deficit of nft(y72) is caused by an inactivating lesion in reck (reversion-inducing-cysteine-rich protein with Kazal motifs or ST15; Suppressor of Tumorigenicity 15 protein), which encodes a membrane-anchored ...

Research paper thumbnail of Origin, Specification, and Plasticity of the Great Vessels of the Heart

Current Biology, 2015

The pharyngeal arch arteries (PAAs) are a series of paired embryonic blood vessels that give rise... more The pharyngeal arch arteries (PAAs) are a series of paired embryonic blood vessels that give rise to several major arteries that connect directly to the heart. During development, the PAAs emerge from nkx2.5-expressing mesodermal cells and connect the dorsal head vasculature to the outflow tract of the heart. Despite their central role in establishing the circulatory system, the embryonic origins of the PAA progenitors are only coarsely defined, and the factors that specify them and their regenerative potential are unclear. Using fate mapping and mutant analysis, we find that PAA progenitors are derived from the tcf21 and nkx2.5 double-positive head mesoderm and require these two transcription factors for their specification and survival. Unexpectedly, cell ablation shows that the tcf21+; nkx2.5+ PAA progenitors are not required for PAA formation. We find that this compensation is due to the replacement of ablated tcf21+; nkx2.5+ PAA cells by endothelial cells from the dorsal head vasculature. Together, these studies assign the embryonic origin of the great vessel progenitors to the interface between the pharyngeal and cardiac mesoderm, identify the transcription factor code required for their specification, and reveal an unexpected plasticity in the formation of the great vessels.

Research paper thumbnail of In parallelinterconnectivity of the dorsal longitudinal anastomotic vessels requires both VEGF signaling and circulatory flow

Journal of Cell Science, 2012

Blood vessels deliver oxygen, nutrients, hormones and immunity factors throughout the body. To pe... more Blood vessels deliver oxygen, nutrients, hormones and immunity factors throughout the body. To perform these vital functions, vascular cords branch, lumenize and interconnect. Yet, little is known about the cellular, molecular and physiological mechanisms that control how circulatory networks form and interconnect. Specifically, how circulatory networks merge by interconnecting in parallel along their boundaries remains unexplored. To examine this process we studied the formation and functional maturation of the plexus that forms between the Dorsal Longitudinal Anastomotic Vessels (DLAVs) in the zebrafish. We find that the migration and proliferation of endothelial cells within the DLAVs and their Segmental (Se) vessel precursors drives DLAV plexus formation. Remarkably, the presence of Se vessels containing only endothelial cells of the arterial lineage is sufficient for DLAV plexus morphogenesis, suggesting that endothelial cells from the venous lineage make a dispensable or null ...

Research paper thumbnail of Semaphorin-PlexinD1 Signaling Limits Angiogenic Potential via the VEGF Decoy Receptor sFlt1

Developmental Cell, 2011

Sprouting angiogenesis expands the embryonic vasculature enabling survival and homeostasis. Yet h... more Sprouting angiogenesis expands the embryonic vasculature enabling survival and homeostasis. Yet how the angiogenic capacity to form sprouts is allocated among endothelial cells (ECs) to guarantee the reproducible anatomy of stereotypical vascular beds remains unclear. Here we show that Sema-PlxnD1 signaling, previously implicated in sprout guidance, represses angiogenic potential to ensure the proper abundance and stereotypical distribution of the trunk's segmental arteries (SeAs). We find that Sema-PlxnD1 signaling exerts this effect by antagonizing the proangiogenic activity of vascular endothelial growth factor (VEGF). Specifically, Sema-PlxnD1 signaling ensures the proper endothelial abundance of soluble flt1 (sflt1), an alternatively spliced form of the VEGF receptor Flt1 encoding a potent secreted decoy. Hence, Sema-PlxnD1 signaling regulates distinct but related aspects of angiogenesis: the spatial allocation of angiogenic capacity within a primary vessel and sprout guidance.

Research paper thumbnail of Semaphorin-Plexin Signaling Guides Patterning of the Developing Vasculature

Developmental Cell, 2004

none and Comoglio, 2000). We show here that the endothelial receptor PlexinD1 plays a similar rol... more none and Comoglio, 2000). We show here that the endothelial receptor PlexinD1 plays a similar role during vas-NICHD National Institutes of Health cular patterning. In the developing trunk, angiogenic intersegmental vessels extend near somite boundaries Bethesda, Maryland 20892 2 Cardiovascular Division (Isogai et al., 2001; Childs et al., 2002). Loss of plxnD1 function via morpholino injection or in zebrafish out of University of Pennsylvania Philadelphia, Pennsylvania 19104 bounds (obd) mutants (Childs et al., 2002) causes dramatic mispatterning of these vessels, which are no 3 Department of Biochemistry and Molecular Biology and Smooth Muscle Research Group longer restricted to growth near intersomitic boundaries. Somites flanking intersegmental vessels express sema-University of Calgary Calgary, Alberta T2N 4N1 phorins (Roos et al., 1999; Yee et al., 1999), and reducing the function of these semaphorins causes similar inter-Canada 4 Cardiovascular Research Center segmental vessel patterning defects. Conversely, semaphorin overexpression inhibits the growth of interseg-Massachusetts General Hospital Charlestown, Massachusetts 02129 mental vessels in a plxnD1-dependent manner. These results indicate that the establishment of anatomical pattern in the developing vasculature is directed in part by cues and mechanisms similar to those used to pattern Summary the developing nervous system (Tessier-Lavigne and Goodman, 1996), including semaphorin-plexin sig-Major vessels of the vertebrate circulatory system disnaling. play evolutionarily conserved and reproducible anatomy, but the cues guiding this stereotypic patterning remain obscure. In the nervous system, axonal path-Results and Discussion ways are shaped by repulsive cues provided by ligands of the semaphorin family that are sensed by migrating Plexin D1 Is Expressed neuronal growth cones through plexin receptors. We in the Embryonic Vasculature show that proper blood vessel pathfinding requires We identified murine plexinD1 (plxnD1) in the EST datathe endothelial receptor PlexinD1 and semaphorin sigbase by sequence homology to other members of the nals, and we identify mutations in plexinD1 in the zeplexin family. Expression analysis revealed that plxnD1, brafish vascular patterning mutant out of bounds. unlike other members of the extended family, is not These results reveal the fundamental conservation of primarily expressed by neurons. Rather, expression is repulsive patterning mechanisms between axonal mirestricted to endothelial cells (Cheng et al., 2001; Tagration in the central nervous system and vascular magnone et al., 1999; van der Zwaag et al., 2002). We endothelium during angiogenesis. reasoned that plxnD1 might function to guide the patterning of developing blood vessels, in a manner analo-Introduction gous to the role of other plexins in axonal patterning in the nervous system (Tamagnone and Comoglio, 2000). The vertebrate circulatory system is crucial for the de-To explore this possibility, we isolated a full-lengthlivery and exchange of gases, hormones, metabolic zebrafish plxnD1 ortholog (see Experimental Procewastes, and immunity factors. Although key players in dures and Supplemental Data, section 1 [http://www. vascular endothelial cell specification and differentiation developmentalcell.com/cgi/content/full/7/1/117/DC1]). have been identified, we have limited understanding of Zebrafish plxnD1 is expressed throughout the vasculathe molecular mechanisms responsible for the remarkture in blood vessel endothelial cells and their angioblast able regularity in pattern of larger blood vessels within precursors (Figures 1B, 1D, 1F, and 1H), mirroring the and across species (Weinstein, 1999). In the nervous endothelial-specific expression pattern of the fli1 gene system, axonal pathways are established by repulsive (Figures 1A, 1C, 1E, and 1G; Brown et al., 2000). plxnD1 and attractive signals from surrounding tissues, sensed transcripts are evident in angioblast precursors prior to by migrating neuronal growth cones through specific trunk vessel assembly (Figure 1B) and in the newly formed trunk dorsal aorta and posterior cardinal vein

Research paper thumbnail of Neurovascular development in the embryonic zebrafish hindbrain

Developmental Biology, 2011

The brain is made of billions of highly metabolically active neurons whose activities provide the... more The brain is made of billions of highly metabolically active neurons whose activities provide the seat for cognitive, affective, sensory and motor functions. The cerebral vasculature meets the brain's unusually high demand for oxygen and glucose by providing it with the largest blood supply of any organ. Accordingly, disorders of the cerebral vasculature, such as congenital vascular malformations, stroke and tumors, compromise neuronal function and survival and often have crippling or fatal consequences. Yet, the assembly of the cerebral vasculature is a process that remains poorly understood. Here we exploit the physical and optical accessibility of the zebrafish embryo to characterize cerebral vascular development within the embryonic hindbrain. We find that this process is primarily driven by endothelial cell migration and follows a two-step sequence. First, perineural vessels with stereotypical anatomies are formed along the ventro-lateral surface of the neuroectoderm. Second, angiogenic sprouts derived from a subset of perineural vessels migrate into the hindbrain to form the intraneural vasculature. We find that these angiogenic sprouts reproducibly penetrate into the hindbrain via the rhombomere centers, where differentiated neurons reside, and that specific rhombomeres are invariably vascularized first. While the anatomy of intraneural vessels is variable from animal to animal, some aspects of the connectivity of perineural and intraneural vessels occur reproducibly within particular hindbrain locales. Using a chemical inhibitor of VEGF signaling we determine stage-specific requirements for this pathway in the formation of the hindbrain vasculature. Finally, we show that a subset of hindbrain vessels is aligned and/or in very close proximity to stereotypical neuron clusters and axon tracts. Using endothelium-deficient cloche mutants we show that the endothelium is dispensable for the organization and maintenance of these stereotypical neuron clusters and axon tracts in the early hindbrain. However, the cerebellum's upper rhombic lip and the optic tectum are abnormal in clo. Overall, this study provides a detailed, multi-stage characterization of early zebrafish hindbrain neurovascular development with cellular resolution up to the third day of age. This work thus serves as a useful reference for the neurovascular characterization of mutants, morphants and drug-treated embryos.

Research paper thumbnail of Beyond guidance: A novel role for Sema–PlxnD1 signaling in vascular development

Developmental Biology, 2011

Research paper thumbnail of Diverse functions for the semaphorin receptor PlexinD1 in development and disease

Developmental Biology, 2011

Plexins are a family of single pass transmembrane proteins that serve as cell surface receptors f... more Plexins are a family of single pass transmembrane proteins that serve as cell surface receptors for Semaphorins during the embryonic development of animals. Semaphorin-Plexin signaling is critical for many cellular aspects of organogenesis, including cell migration, proliferation and survival. Until recently, little was known about the function of PlexinD1, the sole member of the vertebrate-specific PlexinD (PlxnD1) subfamily. Here we review novel findings about PlxnD1's roles in the development of the cardiovascular, nervous and immune systems and salivary gland branching morphogenesis and discuss new insights concerning the molecular mechanisms of PlxnD1 activity.

Research paper thumbnail of The Zinc Finger Protein Schnurri Acts as a Smad Partner in Mediating the Transcriptional Response to Decapentaplegic

Developmental Biology, 2000

In Drosophila, a BMP-related ligand Decapentaplegic (Dpp) is essential for cell fate specificatio... more In Drosophila, a BMP-related ligand Decapentaplegic (Dpp) is essential for cell fate specification during embryogenesis and in imaginal disc development. Dpp signaling culminates in the phosphorylation and nuclear translocation of Mothers against dpp (Mad), a receptor-specific Smad that can bind DNA and regulate the transcription of Dpp-responsive genes. Genetic analysis has implicated Schnurri (Shn), a zinc finger protein that shares homology with mammalian transcription factors, in the Dpp signal transduction pathway. However, a direct role for Shn in regulating the transcriptional response to Dpp has not been demonstrated. In this study we show that Shn acts as a DNA-binding Mad cofactor in the nuclear response to Dpp. Shn can bind DNA in a sequence-specific manner and recognizes sites within a well-characterized Dpp-responsive promoter element, the B enhancer of the Ultrabithorax (Ubx) gene. The Shn-binding sites are relevant for in vivo expression, since mutations in these sites affect the ability of the enhancer to respond to Dpp. Furthermore we find that Shn and Mad can interact directly through discrete domains. To examine the relative contribution of the two proteins in the regulation of endogenous Dpp target genes we developed a cell culture assay and show that Shn and Mad act synergistically to induce transcription. Our results suggest that cooperative interactions between these two transcription factors could play an important role in the regulation of Dpp target genes. This is the first evidence that Dpp/BMP signaling in flies requires the direct interaction of Mad with a partner transcription factor.

Research paper thumbnail of schnurri Is Required for dpp-Dependent Patterning of the Drosophila Wing

Developmental Biology, 2000

The BMP-related ligand Decapentaplegic (Dpp) has a well-characterized role in pattern formation d... more The BMP-related ligand Decapentaplegic (Dpp) has a well-characterized role in pattern formation during Drosophila embryogenesis and in larval development. Previous work has shown that transcription of Dpp-responsive genes requires the activity of the BMP-specific Smad, Mothers against dpp (Mad). In this study we investigated the role of the zinc finger transcription factor Schnurri (Shn) in mediating the nuclear response to Dpp during adult patterning. Using clonal analysis, we show that wing imaginal disc cells mutant for shn fail to transcribe the genes spalt, optomotor blind, vestigial, and Dad, that are known to be induced by dpp signaling. shn clones also ectopically express brinker, a gene that is downregulated in response to dpp, thus implicating Shn in both activation and repression of Dpp target genes. We demonstrate that loss of shn activity affects anterior-posterior patterning and cell proliferation in the wing blade, in a manner that reflects the graded requirement for Dpp in these processes. Furthermore, we find that shn is expressed in the pupal wing and plays a distinct role in mediating dpp-dependent vein differentiation at this stage. The absence of shn activity results in defects that are similar in nature and severity to those caused by elimination of Mad, suggesting that Shn has an essential role in dpp signal transduction in the developing wing. Our data are consistent with a model in which Shn acts as a cofactor for Mad.

Research paper thumbnail of A phylogenetically conserved cis-regulatory module in theMsx2promoter is sufficient for BMP-dependent transcription in murine andDrosophilaembryos

Development, 2004

To understand the actions of morphogens, it is crucial to determine how they elicit different tra... more To understand the actions of morphogens, it is crucial to determine how they elicit different transcriptional responses in different cell types. Here,we identify a BMP-responsive enhancer of Msx2, an immediate early target of bone morphogenetic protein (BMP) signaling. We show that the BMP-responsive region of Msx2 consists of a core element, required generally for BMP-dependent expression, and ancillary elements that mediate signaling in diverse developmental settings. Analysis of the core element identified two classes of functional sites: GCCG sequences related to the consensus binding site of Mad/Smad-related BMP signal transducers; and a single TTAATT sequence, matching the consensus site for Antennapedia superclass homeodomain proteins. Chromatin immunoprecipitation and mutagenesis experiments indicate that the GCCG sites are direct targets of BMP restricted Smads. Intriguingly, however, these sites are not sufficient for BMP responsiveness in mouse embryos; the TTAATT sequenc...

Research paper thumbnail of Development of functional hindbrain oculomotor circuitry independent of both vascularization and neuronal activity in larval zebrafish

Current neurobiology, 2016

We investigated the contribution of blood vessel formation and neuronal excitability to the devel... more We investigated the contribution of blood vessel formation and neuronal excitability to the development of functional neural circuitry in larval zebrafish by analyzing oculomotor performance in response to visual and vestibular stimuli. To address the dependence of neuronal function on the presence of blood vessels, we compared wild type embryos to reck and cloche mutants that lacked intracerebral blood vessels. To test how neuronal excitability impacts neuronal development and intracerebral vascularization, we blocked neural activity using Tetraodotoxin (TTX) and Tricaine. In reck mutants, we found both slow phase horizontal tracking and fast phase resets with only a slightly reduced amplitude and bandwidth. Spontaneous saccades, eye position holding and vestibular gravitoinertial induced eye rotation were also present. All of these behaviors except for visual tracking were observed in cloche mutants that lacked any head vasculature. Thus, numerous oculomotor neuronal circuits span...

Research paper thumbnail of Genetic determinants of hyaloid and retinal vasculature in zebrafish-0

<b>Copyright information:</b>Taken from "Genetic determinants of hyaloid and ret... more <b>Copyright information:</b>Taken from "Genetic determinants of hyaloid and retinal vasculature in zebrafish"http://www.biomedcentral.com/1471-213X/7/114BMC Developmental Biology 2007;7():114-114.Published online 15 Oct 2007PMCID:PMC2169232.nner vessels covering the entire inner surface of the retina. Example of disparity in branch number between left (5) and right (8) eyes. Transverse view of the blood vessels (green: Fli1-EGFP) overlaying the inner limiting membrane of the adult retina (blue: DAPI nuclear staining). Inset shows the same vessels overlying GCL nuclei in a flatmount preparation. At peripheral retinal regions, neighbouring vessels anastomose (inset), and elongated filopodia sprout from the capillaries suggesting active angiogenic remodelling. The diameter of vessels is thicker proximal to the optic disc and thinner peripherally. Numbers refer to the thickness of the vessel and the angle of measurement in reference to horizontal plane. Flatmount adult retinas immuno-labelled with retinal vasculature markers. collagen IV (red) stains the basal membrane of blood vessels. smooth muscle actin (SMA) stains vascular pericytes (green). Factor VIII labels endothelial cells (red). Cone photoreceptors label green as analysis was performed in transgenic line [67]. Glial fibrillary acidic protein (GFAP) stains retinal vessels in adult zebrafish and a population of cells throughout the retina. GFAP (red), DAPI (blue) and fli1-EGFP (green). Flat-mounted retina, and Transverse view of the peripheral retina. Müller endfeet (asterisks) directly contact the endothelial cells (yellow co-staining). : FITC channel turned off to highlight the GFAP reactivity of retinal vessels. .

Research paper thumbnail of Aminoacyl-Transfer RNA Synthetase Deficiency Promotes Angiogenesis via the Unfolded Protein Response Pathway

Arteriosclerosis, Thrombosis, and Vascular Biology, 2016

Objective— Understanding the mechanisms regulating normal and pathological angiogenesis is of gre... more Objective— Understanding the mechanisms regulating normal and pathological angiogenesis is of great scientific and clinical interest. In this report, we show that mutations in 2 different aminoacyl-transfer RNA synthetases, threonyl tRNA synthetase (tars y58 ) or isoleucyl tRNA synthetase (iars y68 ) , lead to similar increased branching angiogenesis in developing zebrafish. Approach and Results— The unfolded protein response pathway is activated by aminoacyl-transfer RNA synthetase deficiencies, and we show that unfolded protein response genes atf4, atf6 , and xbp1 , as well as the key proangiogenic ligand vascular endothelial growth factor (vegfaa) , are all upregulated in tars y58 and iars y68 mutants. Finally, we show that the protein kinase RNA-like endoplasmic reticulum kinase–activating transcription factor 4 arm of the unfolded protein response pathway is necessary for both the elevated vegfaa levels and increased angiogenesis observed in tars y58 mutants. Conclusions— Our r...

Research paper thumbnail of Making Waves in Madison: The 6th International Meeting on Zebrafish Development and Genetics

Research paper thumbnail of The role of Hath6, a novel shear stress-responsive transcription factor, in endothelial differentiation and function modulation

Journal of Cell Science, 2014

The key regulators of endothelial differentiation induced by shear stress (SS) are mostly unclear... more The key regulators of endothelial differentiation induced by shear stress (SS) are mostly unclear. Human atonal homolog 6 (Hath6) was identified as an endothelial-selective and SS-responsive transcription factor. In this study, we sought to elucidate the role of Hath6 in the endothelial specification of embryonic stem cells. In a stepwise human embryonic stem cell-endothelial cell (hESC-EC) induction system, Hath6 was upregulated synchronously with endothelial determination. Subsequently, gain-of-function and loss-of-function studies of Hath6 were performed using the hESC-EC induction model and endothelial cell lines. The overexpression of Hath6, which mimics SS treatment, resulted in an increased CD45−CD31+KDR+ population, a higher tubular-structure-formation capacity, and increased endothelial-specific gene expression. In contrast, the knockdown of the Hath6 gene markedly decreased endothelial differentiation. Hath6 also facilitates the maturation of ECs in terms of endothelial ge...