maike sander - Academia.edu (original) (raw)
Papers by maike sander
1Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashvil... more 1Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee, USA. 2Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University, Nashville, Tennessee, USA. 3Departments of Pediatrics and Cellular and Molecular Medicine, Pediatric Diabetes Research Center, University of California at San Diego, La Jolla, California, USA. 4University of Washington, Division of Metabolism, Endocrinology, and Nutrition, Departments of Medicine and Pharmacology, and the Pacific Northwest Diabetes Research Institute, Seattle, Washington, USA. 5VA Tennessee Valley Healthcare System, Nashville, Tennessee, USA.
V1 interneurons are inhibitory neurons that play an essential role in vertebrate locomotion. The ... more V1 interneurons are inhibitory neurons that play an essential role in vertebrate locomotion. The molecular mechanisms underlying their genesis remain, however, largely undefined. Here, we show that the transcription factor Prdm12 is selectively expressed in p1 progenitors of the hindbrain and spinal cord in the frog embryo, and that a similar restricted expression profile is observed in the nerve cord of other vertebrates as well as of the cephalochordate amphioxus. Using frog, chick and mice, we analyzed the regulation of Prdm12 and found that its expression in the caudal neural tube is dependent on retinoic acid and Pax6, and that it is restricted to p1 progenitors, due to the repressive action of Dbx1 and Nkx6-1/2 expressed in the adjacent p0 and p2 domains. Functional studies in the frog, including genomewide identification of its targets byRNA-seq andChIP-Seq, reveal that vertebrate Prdm12 proteins act as a general determinant of V1 cell fate, at least in part, by directly repr...
Highlights d Genetic studies show Pdx1 and Sox9 cooperatively specify the pancreatic lineage d Pd... more Highlights d Genetic studies show Pdx1 and Sox9 cooperatively specify the pancreatic lineage d Pdx1+Sox9 co-occupy regulatory sequences of pancreatic and intestinal genes d Pdx1+Sox9 cooperatively repress intestinal cell fate determinants such as Cdx2 d Pdx1+Sox9 are necessary and sufficient to repress the intestinal fate choice
Ruiyu Xie,1 Logan J. Everett,2 Hee-Woong Lim,2 Nisha A. Patel,1 Jonathan Schug,2 Evert Kroon,3 Ol... more Ruiyu Xie,1 Logan J. Everett,2 Hee-Woong Lim,2 Nisha A. Patel,1 Jonathan Schug,2 Evert Kroon,3 Olivia G. Kelly,3 Allen Wang,1 Kevin A. D’Amour,3 Allan J. Robins,3 Kyoung-Jae Won,2 Klaus H. Kaestner,2 and Maike Sander1,* 1Department of Pediatrics and Cellular & Molecular Medicine, University of California San Diego, La Jolla, CA 92093-0695, USA 2Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA 3ViaCyte Inc., 3550 General Atomics Court, San Diego, CA 92121, USA *Correspondence: masander@ucsd.edu http://dx.doi.org/10.1016/j.stem.2012.11.023
Nature Communications
Developmental progression depends on temporally defined changes in gene expression mediated by tr... more Developmental progression depends on temporally defined changes in gene expression mediated by transient exposure of lineage intermediates to signals in the progenitor niche. To determine whether cell-intrinsic epigenetic mechanisms contribute to signal-induced transcriptional responses, here we manipulate the signalling environment and activity of the histone demethylase LSD1 during differentiation of hESC-gut tube intermediates into pancreatic endocrine cells. We identify a transient requirement for LSD1 in endocrine cell differentiation spanning a short time-window early in pancreas development, a phenotype we reproduced in mice. Examination of enhancer and transcriptome landscapes revealed that LSD1 silences transiently active retinoic acid (RA)-induced enhancers and their target genes. Furthermore, prolonged RA exposure phenocopies LSD1 inhibition, suggesting that LSD1 regulates endocrine cell differentiation by limiting the duration of RA signalling. Our findings identify LSD1...
Nature Communications
FOXA pioneer transcription factors (TFs) associate with primed enhancers in endodermal organ prec... more FOXA pioneer transcription factors (TFs) associate with primed enhancers in endodermal organ precursors. Using a human stem cell model of pancreas differentiation, we here discover that only a subset of pancreatic enhancers is FOXA-primed, whereas the majority is unprimed and engages FOXA upon lineage induction. Primed enhancers are enriched for signal-dependent TF motifs and harbor abundant and strong FOXA motifs. Unprimed enhancers harbor fewer, more degenerate FOXA motifs, and FOXA recruitment to unprimed but not primed enhancers requires pancreatic TFs. Strengthening FOXA motifs at an unprimed enhancer near NKX6.1 renders FOXA recruitment pancreatic TF-independent, induces priming, and broadens the NKX6.1 expression domain. We make analogous observations about FOXA binding during hepatic and lung development. Our findings suggest a dual role for FOXA in endodermal organ development: first, FOXA facilitates signal-dependent lineage initiation via enhancer priming, and second, FOX...
Working with Stem Cells, 2016
The ability to produce human pancreatic cells in vitro would open new possibilities for developin... more The ability to produce human pancreatic cells in vitro would open new possibilities for developing improved therapies through cell transplantation, disease modeling, and drug screening. Of particular medical importance are the insulinproducing beta cells of the pancreas, which are lost or dysfunctional in diabetes. Furthermore, an in vitro model of human exocrine cells could help devise new therapies for pancreatic exocrine disease, most notably pancreatic cancer. In the past decade much progress has been made in developing protocols to generate multipotent pancreatic progenitor cells from human pluripotent stem cells (hPSCs) that are capable of differentiating into both endocrine and exocrine cells. The sole approach that has proven successful is to reproduce essential steps of in vivo development in vitro through directed step-wise differentiation of hPSCs. The directed differentiation entails sequential exposure of hPSCs to different signaling factors, thereby moving cells through several developmental intermediates towards the pancreatic fate. Upon implantation into mice, hPSC-derived pancreatic progenitor cells spontaneously differentiate into endocrine and exocrine cells. Here, we describe a detailed protocol for the generation of pancreatic progenitor cells from hPSCs. We provide methods for the directed differentiation as well as the characterization of pancreatic progenitor cells and lineage intermediates by immunofl uorescence staining and fl ow cytometry. With recently developed protocols, these pancreatic progenitor cells can be further differentiated in vitro into beta-like cells that functionally resemble immature human beta cells.
The Journal of clinical investigation, Jan 3, 2017
The recognition of β cell dedifferentiation in type 2 diabetes raises the translational relevance... more The recognition of β cell dedifferentiation in type 2 diabetes raises the translational relevance of mechanisms that direct and maintain β cell identity. LIM domain-binding protein 1 (LDB1) nucleates multimeric transcriptional complexes and establishes promoter-enhancer looping, thereby directing fate assignment and maturation of progenitor populations. Many terminally differentiated endocrine cell types, however, remain enriched for LDB1, but its role is unknown. Here, we have demonstrated a requirement for LDB1 in maintaining the terminally differentiated status of pancreatic β cells. Inducible ablation of LDB1 in mature β cells impaired insulin secretion and glucose homeostasis. Transcriptomic analysis of LDB1-depleted β cells revealed the collapse of the terminally differentiated gene program, indicated by a loss of β cell identity genes and induction of the endocrine progenitor factor neurogenin 3 (NEUROG3). Lineage tracing confirmed that LDB1-depleted, insulin-negative β cells...
Development (Cambridge, England), 2015
V1 interneurons are inhibitory neurons that play an essential role in vertebrate locomotion. The ... more V1 interneurons are inhibitory neurons that play an essential role in vertebrate locomotion. The molecular mechanisms underlying their genesis remain, however, largely undefined. Here, we show that the transcription factor Prdm12 is selectively expressed in p1 progenitors of the hindbrain and spinal cord in the frog embryo, and that a similar restricted expression profile is observed in the nerve cord of other vertebrates as well as of the cephalochordate amphioxus. Using frog, chick and mice, we analyzed the regulation of Prdm12 and found that its expression in the caudal neural tube is dependent on retinoic acid and Pax6, and that it is restricted to p1 progenitors, due to the repressive action of Dbx1 and Nkx6-1/2 expressed in the adjacent p0 and p2 domains. Functional studies in the frog, including genome-wide identification of its targets by RNA-seq and ChIP-Seq, reveal that vertebrate Prdm12 proteins act as a general determinant of V1 cell fate, at least in part, by directly r...
Wiley interdisciplinary reviews. Systems biology and medicine, 2015
The development of the pancreas and determination of endocrine cell fate are controlled by a high... more The development of the pancreas and determination of endocrine cell fate are controlled by a highly complex interplay of signaling events and transcriptional networks. It is now known that an interconnected epigenetic program is also required to drive these processes. Recent studies using genome-wide approaches have implicated epigenetic regulators, such as DNA and histone-modifying enzymes and noncoding RNAs, to play critical roles in pancreas development and the maintenance of cell identity and function. Furthermore, genome-wide analyses have implicated epigenetic changes as a casual factor in the pathogenesis of diabetes. In the future, genomic approaches to further our understanding of the role of epigenetics in endocrine cell development and function will be useful for devising strategies to produce or manipulate β-cells for therapies of diabetes. WIREs Syst Biol Med 2015, 7:1-11. doi: 10.1002/wsbm.1287 For further resources related to this article, please visit the WIREs websi...
PLoS ONE, 2014
Although astrocytes are the most abundant cell type in the central nervous system (CNS), little i... more Although astrocytes are the most abundant cell type in the central nervous system (CNS), little is known about their molecular specification and differentiation. It has previously been reported that transcription factor Nkx6.1 is expressed in neuroepithelial cells that give rise to astrocyte precursors in the ventral spinal cord. In the present study, we systematically investigated the function of Nkx6.1 in astrocyte development using both conventional and conditional Nkx6.1 mutant mice. At early postnatal stages, Nkx6.1 was expressed in a subpopulation of astrocytes in the ventral spinal cord. In the conventional Nkx6.1KO spinal cord, the initial specification of astrocyte progenitors was affected by the mutation, and subsequent migration and differentiation were disrupted in newborn mice. In addition, the development of VA2 subtype astrocytes was also inhibited in the white matter. Further studies with Nkx6.1 conditional mutants revealed significantly delayed differentiation and disorganized arrangement of fibrous astrocytes in the ventral white matter. Together, our studies indicate that Nkx6.1 plays a vital role in astrocyte specification and differentiation in the ventral spinal cord.
Cell Reports, 2013
Recently, loss of beta-cell-specific traits has been proposed as an early cause of beta cell fail... more Recently, loss of beta-cell-specific traits has been proposed as an early cause of beta cell failure in diabetes. However, the molecular mechanisms that underlie the loss of beta cell features remain unclear. Here, we identify an Nkx6.1-controlled gene regulatory network as essential for maintaining the functional and molecular traits of mature beta cells. Conditional Nkx6.1 inactivation in adult mice caused rapid-onset diabetes and hypoinsulinemia. Genomewide analysis of Nkx6.1-regulated genes and functional assays further revealed a critical role for Nkx6.1 in the control of insulin biosynthesis, insulin secretion, and beta cell proliferation. Over time, Nkx6.1-deficient beta cells acquired molecular characteristics of delta cells, revealing a molecular link between impaired beta cell functional properties and loss of cell identity. Given that Nkx6.1 levels are reduced in human type 2 diabetic beta cells, our study lends support to the concept that loss of beta cell features could contribute to the pathogenesis of diabetes.
Proceedings of the National Academy of Sciences, 2013
The study of hematopoietic colony-forming units using semisolid culture media has greatly advance... more The study of hematopoietic colony-forming units using semisolid culture media has greatly advanced the knowledge of hematopoiesis. Here we report that similar methods can be used to study pancreatic colony-forming units. We have developed two pancreatic colony assays that enable quantitative and functional analyses of progenitor-like cells isolated from dissociated adult (2-4 mo old) murine pancreas. We find that a methylcellulose-based semisolid medium containing Matrigel allows growth of duct-like "Ring/ Dense" colonies from a rare (∼1%) population of total pancreatic single cells. With the addition of roof plate-specific spondin 1, a wingless-int agonist, Ring/Dense colony-forming cells can be expanded more than 100,000-fold when serially dissociated and replated in the presence of Matrigel. When cells grown in Matrigel are then transferred to a Matrigel-free semisolid medium with a unique laminin-based hydrogel, some cells grow and differentiate into another type of colony, which we name "Endocrine/Acinar." These Endocrine/Acinar colonies are comprised mostly of endocrine-and acinar-like cells, as ascertained by RNA expression analysis, immunohistochemistry, and electron microscopy. Most Endocrine/Acinar colonies contain beta-like cells that secrete insulin/C-peptide in response to D-glucose and theophylline. These results demonstrate robust self-renewal and differentiation of adult Ring/Dense colony-forming units in vitro and suggest an approach to producing beta-like cells for cell replacement of type 1 diabetes. The methods described, which include microfluidic expression analysis of single cells and colonies, should also advance study of pancreas development and pancreatic progenitor cells. extracellular matrix proteins | Sry-related HMG box (Sox) 9 | Promonin 1 (CD133) | neurogenin 3 | dickkopf1 (Dkk1)
Molecular Endocrinology, 2011
Journal of the American Society of Nephrology, 2014
The balanced self-renewal and differentiation of nephron progenitors are critical for kidney deve... more The balanced self-renewal and differentiation of nephron progenitors are critical for kidney development and controlled, in part, by the transcription factor Six2, which antagonizes canonical Wnt signalingmediated differentiation. A nuclear factor, Sall1, is expressed in Six2-positive progenitors as well as differentiating nascent nephrons, and it is essential for kidney formation. However, the molecular functions and targets of Sall1, especially the functions and targets in the nephron progenitors, remain unknown. Here, we report that Sall1 deletion in Six2-positive nephron progenitors results in severe progenitor depletion and apoptosis of the differentiating nephrons in mice. Analysis of mice with an inducible Sall1 deletion revealed that Sall1 activates genes expressed in progenitors while repressing genes expressed in differentiating nephrons. Sall1 and Six2 co-occupied many progenitor-related gene loci, and Sall1 bound to Six2 biochemically. In contrast, Sall1 did not bind to the Wnt4 locus suppressed by Six2. Sall1-mediated repression was also independent of its binding to DNA. Thus, Sall1 maintains nephron progenitors and their derivatives by a unique mechanism, which partly overlaps but is distinct from that of Six2: Sall1 activates progenitor-related genes in Six2-positive nephron progenitors and represses gene expression in Six2-negative differentiating nascent nephrons.
Development, 2005
In diabetic individuals, the imbalance in glucose homeostasis is caused by loss or dysfunction of... more In diabetic individuals, the imbalance in glucose homeostasis is caused by loss or dysfunction of insulin-secreting β-cells of the pancreatic islets. As successful generation of insulin-producing cells in vitro could constitute a cure for diabetes, recent studies have explored the molecular program that underlies β-cell formation. From these studies, the homeodomain transcription factor NKX6.1 has proven to be a key player. In Nkx6.1 mutants, β-cell numbers are selectively reduced, while other islet cell types develop normally. However, the molecular events downstream of NKX6.1, as well as the molecular pathways that ensure residualβ-cell formation in the absence of NKX6.1 are largely unknown. Here, we show that the Nkx6.1 paralog, Nkx6.2, is expressed during pancreas development and partially compensates for NKX6.1 function. Surprisingly, our analysis of Nkx6 compound mutant mice revealed a previously unrecognized requirement for NKX6 activity in α-cell formation. This finding sugg...
Development, 2012
In the pancreas, Notch signaling is thought to prevent cell differentiation, thereby maintaining ... more In the pancreas, Notch signaling is thought to prevent cell differentiation, thereby maintaining progenitors in an undifferentiated state. Here, we show that Notch renders progenitors competent to differentiate into ductal and endocrine cells by inducing activators of cell differentiation. Notch signaling promotes the expression of Sox9, which cell-autonomously activates the pro-endocrine gene Ngn3. However, at high Notch activity endocrine differentiation is blocked, as Notch also induces expression of the Ngn3 repressor Hes1. At the transition from high to intermediate Notch activity, only Sox9, but not Hes1, is maintained, thus de-repressing Ngn3 and initiating endocrine differentiation. In the absence of Sox9 activity, endocrine and ductal cells fail to differentiate, resulting in polycystic ducts devoid of primary cilia. Although Sox9 is required for Ngn3 induction, endocrine differentiation necessitates subsequent Sox9 downregulation and evasion from Notch activity via cell-au...
1Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashvil... more 1Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee, USA. 2Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University, Nashville, Tennessee, USA. 3Departments of Pediatrics and Cellular and Molecular Medicine, Pediatric Diabetes Research Center, University of California at San Diego, La Jolla, California, USA. 4University of Washington, Division of Metabolism, Endocrinology, and Nutrition, Departments of Medicine and Pharmacology, and the Pacific Northwest Diabetes Research Institute, Seattle, Washington, USA. 5VA Tennessee Valley Healthcare System, Nashville, Tennessee, USA.
V1 interneurons are inhibitory neurons that play an essential role in vertebrate locomotion. The ... more V1 interneurons are inhibitory neurons that play an essential role in vertebrate locomotion. The molecular mechanisms underlying their genesis remain, however, largely undefined. Here, we show that the transcription factor Prdm12 is selectively expressed in p1 progenitors of the hindbrain and spinal cord in the frog embryo, and that a similar restricted expression profile is observed in the nerve cord of other vertebrates as well as of the cephalochordate amphioxus. Using frog, chick and mice, we analyzed the regulation of Prdm12 and found that its expression in the caudal neural tube is dependent on retinoic acid and Pax6, and that it is restricted to p1 progenitors, due to the repressive action of Dbx1 and Nkx6-1/2 expressed in the adjacent p0 and p2 domains. Functional studies in the frog, including genomewide identification of its targets byRNA-seq andChIP-Seq, reveal that vertebrate Prdm12 proteins act as a general determinant of V1 cell fate, at least in part, by directly repr...
Highlights d Genetic studies show Pdx1 and Sox9 cooperatively specify the pancreatic lineage d Pd... more Highlights d Genetic studies show Pdx1 and Sox9 cooperatively specify the pancreatic lineage d Pdx1+Sox9 co-occupy regulatory sequences of pancreatic and intestinal genes d Pdx1+Sox9 cooperatively repress intestinal cell fate determinants such as Cdx2 d Pdx1+Sox9 are necessary and sufficient to repress the intestinal fate choice
Ruiyu Xie,1 Logan J. Everett,2 Hee-Woong Lim,2 Nisha A. Patel,1 Jonathan Schug,2 Evert Kroon,3 Ol... more Ruiyu Xie,1 Logan J. Everett,2 Hee-Woong Lim,2 Nisha A. Patel,1 Jonathan Schug,2 Evert Kroon,3 Olivia G. Kelly,3 Allen Wang,1 Kevin A. D’Amour,3 Allan J. Robins,3 Kyoung-Jae Won,2 Klaus H. Kaestner,2 and Maike Sander1,* 1Department of Pediatrics and Cellular & Molecular Medicine, University of California San Diego, La Jolla, CA 92093-0695, USA 2Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA 3ViaCyte Inc., 3550 General Atomics Court, San Diego, CA 92121, USA *Correspondence: masander@ucsd.edu http://dx.doi.org/10.1016/j.stem.2012.11.023
Nature Communications
Developmental progression depends on temporally defined changes in gene expression mediated by tr... more Developmental progression depends on temporally defined changes in gene expression mediated by transient exposure of lineage intermediates to signals in the progenitor niche. To determine whether cell-intrinsic epigenetic mechanisms contribute to signal-induced transcriptional responses, here we manipulate the signalling environment and activity of the histone demethylase LSD1 during differentiation of hESC-gut tube intermediates into pancreatic endocrine cells. We identify a transient requirement for LSD1 in endocrine cell differentiation spanning a short time-window early in pancreas development, a phenotype we reproduced in mice. Examination of enhancer and transcriptome landscapes revealed that LSD1 silences transiently active retinoic acid (RA)-induced enhancers and their target genes. Furthermore, prolonged RA exposure phenocopies LSD1 inhibition, suggesting that LSD1 regulates endocrine cell differentiation by limiting the duration of RA signalling. Our findings identify LSD1...
Nature Communications
FOXA pioneer transcription factors (TFs) associate with primed enhancers in endodermal organ prec... more FOXA pioneer transcription factors (TFs) associate with primed enhancers in endodermal organ precursors. Using a human stem cell model of pancreas differentiation, we here discover that only a subset of pancreatic enhancers is FOXA-primed, whereas the majority is unprimed and engages FOXA upon lineage induction. Primed enhancers are enriched for signal-dependent TF motifs and harbor abundant and strong FOXA motifs. Unprimed enhancers harbor fewer, more degenerate FOXA motifs, and FOXA recruitment to unprimed but not primed enhancers requires pancreatic TFs. Strengthening FOXA motifs at an unprimed enhancer near NKX6.1 renders FOXA recruitment pancreatic TF-independent, induces priming, and broadens the NKX6.1 expression domain. We make analogous observations about FOXA binding during hepatic and lung development. Our findings suggest a dual role for FOXA in endodermal organ development: first, FOXA facilitates signal-dependent lineage initiation via enhancer priming, and second, FOX...
Working with Stem Cells, 2016
The ability to produce human pancreatic cells in vitro would open new possibilities for developin... more The ability to produce human pancreatic cells in vitro would open new possibilities for developing improved therapies through cell transplantation, disease modeling, and drug screening. Of particular medical importance are the insulinproducing beta cells of the pancreas, which are lost or dysfunctional in diabetes. Furthermore, an in vitro model of human exocrine cells could help devise new therapies for pancreatic exocrine disease, most notably pancreatic cancer. In the past decade much progress has been made in developing protocols to generate multipotent pancreatic progenitor cells from human pluripotent stem cells (hPSCs) that are capable of differentiating into both endocrine and exocrine cells. The sole approach that has proven successful is to reproduce essential steps of in vivo development in vitro through directed step-wise differentiation of hPSCs. The directed differentiation entails sequential exposure of hPSCs to different signaling factors, thereby moving cells through several developmental intermediates towards the pancreatic fate. Upon implantation into mice, hPSC-derived pancreatic progenitor cells spontaneously differentiate into endocrine and exocrine cells. Here, we describe a detailed protocol for the generation of pancreatic progenitor cells from hPSCs. We provide methods for the directed differentiation as well as the characterization of pancreatic progenitor cells and lineage intermediates by immunofl uorescence staining and fl ow cytometry. With recently developed protocols, these pancreatic progenitor cells can be further differentiated in vitro into beta-like cells that functionally resemble immature human beta cells.
The Journal of clinical investigation, Jan 3, 2017
The recognition of β cell dedifferentiation in type 2 diabetes raises the translational relevance... more The recognition of β cell dedifferentiation in type 2 diabetes raises the translational relevance of mechanisms that direct and maintain β cell identity. LIM domain-binding protein 1 (LDB1) nucleates multimeric transcriptional complexes and establishes promoter-enhancer looping, thereby directing fate assignment and maturation of progenitor populations. Many terminally differentiated endocrine cell types, however, remain enriched for LDB1, but its role is unknown. Here, we have demonstrated a requirement for LDB1 in maintaining the terminally differentiated status of pancreatic β cells. Inducible ablation of LDB1 in mature β cells impaired insulin secretion and glucose homeostasis. Transcriptomic analysis of LDB1-depleted β cells revealed the collapse of the terminally differentiated gene program, indicated by a loss of β cell identity genes and induction of the endocrine progenitor factor neurogenin 3 (NEUROG3). Lineage tracing confirmed that LDB1-depleted, insulin-negative β cells...
Development (Cambridge, England), 2015
V1 interneurons are inhibitory neurons that play an essential role in vertebrate locomotion. The ... more V1 interneurons are inhibitory neurons that play an essential role in vertebrate locomotion. The molecular mechanisms underlying their genesis remain, however, largely undefined. Here, we show that the transcription factor Prdm12 is selectively expressed in p1 progenitors of the hindbrain and spinal cord in the frog embryo, and that a similar restricted expression profile is observed in the nerve cord of other vertebrates as well as of the cephalochordate amphioxus. Using frog, chick and mice, we analyzed the regulation of Prdm12 and found that its expression in the caudal neural tube is dependent on retinoic acid and Pax6, and that it is restricted to p1 progenitors, due to the repressive action of Dbx1 and Nkx6-1/2 expressed in the adjacent p0 and p2 domains. Functional studies in the frog, including genome-wide identification of its targets by RNA-seq and ChIP-Seq, reveal that vertebrate Prdm12 proteins act as a general determinant of V1 cell fate, at least in part, by directly r...
Wiley interdisciplinary reviews. Systems biology and medicine, 2015
The development of the pancreas and determination of endocrine cell fate are controlled by a high... more The development of the pancreas and determination of endocrine cell fate are controlled by a highly complex interplay of signaling events and transcriptional networks. It is now known that an interconnected epigenetic program is also required to drive these processes. Recent studies using genome-wide approaches have implicated epigenetic regulators, such as DNA and histone-modifying enzymes and noncoding RNAs, to play critical roles in pancreas development and the maintenance of cell identity and function. Furthermore, genome-wide analyses have implicated epigenetic changes as a casual factor in the pathogenesis of diabetes. In the future, genomic approaches to further our understanding of the role of epigenetics in endocrine cell development and function will be useful for devising strategies to produce or manipulate β-cells for therapies of diabetes. WIREs Syst Biol Med 2015, 7:1-11. doi: 10.1002/wsbm.1287 For further resources related to this article, please visit the WIREs websi...
PLoS ONE, 2014
Although astrocytes are the most abundant cell type in the central nervous system (CNS), little i... more Although astrocytes are the most abundant cell type in the central nervous system (CNS), little is known about their molecular specification and differentiation. It has previously been reported that transcription factor Nkx6.1 is expressed in neuroepithelial cells that give rise to astrocyte precursors in the ventral spinal cord. In the present study, we systematically investigated the function of Nkx6.1 in astrocyte development using both conventional and conditional Nkx6.1 mutant mice. At early postnatal stages, Nkx6.1 was expressed in a subpopulation of astrocytes in the ventral spinal cord. In the conventional Nkx6.1KO spinal cord, the initial specification of astrocyte progenitors was affected by the mutation, and subsequent migration and differentiation were disrupted in newborn mice. In addition, the development of VA2 subtype astrocytes was also inhibited in the white matter. Further studies with Nkx6.1 conditional mutants revealed significantly delayed differentiation and disorganized arrangement of fibrous astrocytes in the ventral white matter. Together, our studies indicate that Nkx6.1 plays a vital role in astrocyte specification and differentiation in the ventral spinal cord.
Cell Reports, 2013
Recently, loss of beta-cell-specific traits has been proposed as an early cause of beta cell fail... more Recently, loss of beta-cell-specific traits has been proposed as an early cause of beta cell failure in diabetes. However, the molecular mechanisms that underlie the loss of beta cell features remain unclear. Here, we identify an Nkx6.1-controlled gene regulatory network as essential for maintaining the functional and molecular traits of mature beta cells. Conditional Nkx6.1 inactivation in adult mice caused rapid-onset diabetes and hypoinsulinemia. Genomewide analysis of Nkx6.1-regulated genes and functional assays further revealed a critical role for Nkx6.1 in the control of insulin biosynthesis, insulin secretion, and beta cell proliferation. Over time, Nkx6.1-deficient beta cells acquired molecular characteristics of delta cells, revealing a molecular link between impaired beta cell functional properties and loss of cell identity. Given that Nkx6.1 levels are reduced in human type 2 diabetic beta cells, our study lends support to the concept that loss of beta cell features could contribute to the pathogenesis of diabetes.
Proceedings of the National Academy of Sciences, 2013
The study of hematopoietic colony-forming units using semisolid culture media has greatly advance... more The study of hematopoietic colony-forming units using semisolid culture media has greatly advanced the knowledge of hematopoiesis. Here we report that similar methods can be used to study pancreatic colony-forming units. We have developed two pancreatic colony assays that enable quantitative and functional analyses of progenitor-like cells isolated from dissociated adult (2-4 mo old) murine pancreas. We find that a methylcellulose-based semisolid medium containing Matrigel allows growth of duct-like "Ring/ Dense" colonies from a rare (∼1%) population of total pancreatic single cells. With the addition of roof plate-specific spondin 1, a wingless-int agonist, Ring/Dense colony-forming cells can be expanded more than 100,000-fold when serially dissociated and replated in the presence of Matrigel. When cells grown in Matrigel are then transferred to a Matrigel-free semisolid medium with a unique laminin-based hydrogel, some cells grow and differentiate into another type of colony, which we name "Endocrine/Acinar." These Endocrine/Acinar colonies are comprised mostly of endocrine-and acinar-like cells, as ascertained by RNA expression analysis, immunohistochemistry, and electron microscopy. Most Endocrine/Acinar colonies contain beta-like cells that secrete insulin/C-peptide in response to D-glucose and theophylline. These results demonstrate robust self-renewal and differentiation of adult Ring/Dense colony-forming units in vitro and suggest an approach to producing beta-like cells for cell replacement of type 1 diabetes. The methods described, which include microfluidic expression analysis of single cells and colonies, should also advance study of pancreas development and pancreatic progenitor cells. extracellular matrix proteins | Sry-related HMG box (Sox) 9 | Promonin 1 (CD133) | neurogenin 3 | dickkopf1 (Dkk1)
Molecular Endocrinology, 2011
Journal of the American Society of Nephrology, 2014
The balanced self-renewal and differentiation of nephron progenitors are critical for kidney deve... more The balanced self-renewal and differentiation of nephron progenitors are critical for kidney development and controlled, in part, by the transcription factor Six2, which antagonizes canonical Wnt signalingmediated differentiation. A nuclear factor, Sall1, is expressed in Six2-positive progenitors as well as differentiating nascent nephrons, and it is essential for kidney formation. However, the molecular functions and targets of Sall1, especially the functions and targets in the nephron progenitors, remain unknown. Here, we report that Sall1 deletion in Six2-positive nephron progenitors results in severe progenitor depletion and apoptosis of the differentiating nephrons in mice. Analysis of mice with an inducible Sall1 deletion revealed that Sall1 activates genes expressed in progenitors while repressing genes expressed in differentiating nephrons. Sall1 and Six2 co-occupied many progenitor-related gene loci, and Sall1 bound to Six2 biochemically. In contrast, Sall1 did not bind to the Wnt4 locus suppressed by Six2. Sall1-mediated repression was also independent of its binding to DNA. Thus, Sall1 maintains nephron progenitors and their derivatives by a unique mechanism, which partly overlaps but is distinct from that of Six2: Sall1 activates progenitor-related genes in Six2-positive nephron progenitors and represses gene expression in Six2-negative differentiating nascent nephrons.
Development, 2005
In diabetic individuals, the imbalance in glucose homeostasis is caused by loss or dysfunction of... more In diabetic individuals, the imbalance in glucose homeostasis is caused by loss or dysfunction of insulin-secreting β-cells of the pancreatic islets. As successful generation of insulin-producing cells in vitro could constitute a cure for diabetes, recent studies have explored the molecular program that underlies β-cell formation. From these studies, the homeodomain transcription factor NKX6.1 has proven to be a key player. In Nkx6.1 mutants, β-cell numbers are selectively reduced, while other islet cell types develop normally. However, the molecular events downstream of NKX6.1, as well as the molecular pathways that ensure residualβ-cell formation in the absence of NKX6.1 are largely unknown. Here, we show that the Nkx6.1 paralog, Nkx6.2, is expressed during pancreas development and partially compensates for NKX6.1 function. Surprisingly, our analysis of Nkx6 compound mutant mice revealed a previously unrecognized requirement for NKX6 activity in α-cell formation. This finding sugg...
Development, 2012
In the pancreas, Notch signaling is thought to prevent cell differentiation, thereby maintaining ... more In the pancreas, Notch signaling is thought to prevent cell differentiation, thereby maintaining progenitors in an undifferentiated state. Here, we show that Notch renders progenitors competent to differentiate into ductal and endocrine cells by inducing activators of cell differentiation. Notch signaling promotes the expression of Sox9, which cell-autonomously activates the pro-endocrine gene Ngn3. However, at high Notch activity endocrine differentiation is blocked, as Notch also induces expression of the Ngn3 repressor Hes1. At the transition from high to intermediate Notch activity, only Sox9, but not Hes1, is maintained, thus de-repressing Ngn3 and initiating endocrine differentiation. In the absence of Sox9 activity, endocrine and ductal cells fail to differentiate, resulting in polycystic ducts devoid of primary cilia. Although Sox9 is required for Ngn3 induction, endocrine differentiation necessitates subsequent Sox9 downregulation and evasion from Notch activity via cell-au...