Enrique Martin Blanco - Academia.edu (original) (raw)

Papers by Enrique Martin Blanco

Journal of Cell Science, 1998

Neuronal differentiation may be induced by different mechanisms. In PC12 cells, differentiation c... more Neuronal differentiation may be induced by different mechanisms. In PC12 cells, differentiation can be achieved after stimulation by nerve growth factor through the sustained activation and nuclear translocation of MAPKs. A peptide covering the homeodomain of Drosophila Antennapedia translocates through the cell membrane in primary neurons in culture and reaches their nuclei. This process accelerates neurite elongation. We have examined whether the capacity for neuronal induction is a general characteristic of homeodomains, and whether differentiation proceeds through the same pathway as that induced by growth factors or represents a distinct cellular response. We show here that Engrailed homeodomain is internalized by UR61 cells, a PC12 cell derivative, and that it promotes and sustains neurite outgrowth. This event appears to proceed independently of MAPKs activation, suggesting that either parallel signal transduction pathways are under the control of homeoproteins or that they a...

Current Biology, 2022

During development, multicellular organisms undergo stereotypical patterns of tissue growth in sp... more During development, multicellular organisms undergo stereotypical patterns of tissue growth in space and time. How developmental growth is orchestrated remains unclear, largely due to the difficulty of observing and quantitating this process in a living organism. Drosophila histoblast nests are small clusters of progenitor epithelial cells that undergo extensive growth to give rise to the adult abdominal epidermis and are amenable to live imaging. Our quantitative analysis of histoblast proliferation and tissue mechanics reveals that tissue growth is driven by cell divisions initiated through basal extracellular matrix degradation by matrix metalloproteases secreted by the neighboring larval epidermal cells. Laser ablations and computational simulations show that tissue mechanical tension does not decrease as the histoblasts fill the abdominal epidermal surface. During tissue growth, the histoblasts display oscillatory cell division rates until growth termination occurs through the rapid emergence of G0/G1 arrested cells, rather than a gradual increase in cell-cycle time as observed in other systems such as the Drosophila wing and mouse postnatal epidermis. Different developing tissues can therefore achieve their final size using distinct growth termination strategies. Thus, adult abdominal epidermal development is characterized by changes in the tissue microenvironment and a rapid exit from the cell cycle.

Development, 2001

puckered (puc) encodes a VH1-like phosphatase that down-regulates Jun kinase (JNK) activity durin... more puckered (puc) encodes a VH1-like phosphatase that down-regulates Jun kinase (JNK) activity during dorsal closure of the Drosophila embryo. We report a role for puc in follicle cell morphogenesis during oogenesis. puc mRNA accumulates preferentially in the centripetally migrating follicle cells and cells of the elongating dorsal appendages. Proper levels of Puc activity in the follicle cells are critical for the production of a normal egg: either reduced or increased Puc activity result in incomplete nurse cell dumping and aberrant dorsal appendages. Phenotypes associated with puc mutant follicle cells include altered DE-cadherin expression in the follicle cells and a failure of nurse cell dumping to coordinate with dorsal appendage elongation, leading to the formation of cup-shaped egg chambers. The JNK pathway target A251-lacZ showed cell-type-specific differences in its regulation by puc and by the small GTPase DRac1. puc mutant cells displayed region-specific ectopic expression ...

Computer Optimized Microscopy, 2019

This chapter provides an ImageJ/Fiji automated macro approach to remove the vitelline membrane au... more This chapter provides an ImageJ/Fiji automated macro approach to remove the vitelline membrane autofluorescence in live Drosophila embryo movies acquired in a 4D (3D plus time) fashion. The procedure consists in a segmentation pipeline that can cope with different relative intensities of the vitelline membrane autofluorescence, followed by a developed algorithm that adjusts the extracted outline selection to the shape deformations that naturally occur during Drosophila embryo development. Finally, the fitted selection is used to clear the external glowing halo that, otherwise, would obscure the visualization of the internal embryo labeling upon projection or 3D rendering.

During development, organs must form with precise shapes and sizes. Organ morphology is not alway... more During development, organs must form with precise shapes and sizes. Organ morphology is not always obtained through growth; a classic counterexample is condensation of the nervous system duringDrosophilaembryogenesis. The mechanics underlying such condensation remain poorly understood. Here, we combinein totolive-imaging, biophysical and genetic perturbations, and atomic force microscopy to characterize the condensation of theDrosophilaventral nerve cord (VNC) during embryonic development at both subcellular and tissue scales. This analysis reveals that condensation is not a unidirectional continuous process, but instead occurs through oscillatory contractions alternating from anterior and posterior ends. The VNC mechanical properties spatially and temporally vary during its condensation, and forces along its longitudinal axis are spatially heterogeneous, with larger ones exerted between neuromeres. We demonstrate that the process of VNC condensation is dependent on the coordinated ...

Morphogenesis shapes pattern and size during development. The initiation and propagation of morph... more Morphogenesis shapes pattern and size during development. The initiation and propagation of morphogenetic processes is led by the integrated activation of signaling cascades. Much is known about regulatory control of signaling cascades in cell culture systems. However, how this regulatory elements act when cells need to behave coordinately is still unknown territory. The morphogenetic process of dorsal closure proceeds through changes in cell shape and polarity under the control of JNK signaling. Amongst other regulatory elements, Puckered, a Drosophila MAPK phosphatase, is involved in a negative feedback loop that controls JNK signaling activity. puckered is expressed in many other tissues, could influence other developmental events and might regulate different signaling cascades. The negative regulatory control of signal transduction pathways could be a general mechanism regulating differentiation and morphogenesis.

Frontiers in Cell and Developmental Biology, 2021

Morphogenesis in early embryos demands the coordinated distribution of cells and tissues to their... more Morphogenesis in early embryos demands the coordinated distribution of cells and tissues to their final destination in a spatio-temporal controlled way. Spatial and scalar differences in adhesion and contractility are essential for these morphogenetic movements, while the role that membrane remodeling may play remains less clear. To evaluate how membrane turnover modulates tissue arrangements we studied the role of endocytosis in zebrafish epiboly. Experimental analyses and modeling have shown that the expansion of the blastoderm relies on an asymmetry of mechanical tension in the yolk cell generated as a result of actomyosin-dependent contraction and membrane removal. Here we show that the GTPase Rab5ab is essential for the endocytosis and the removal of the external yolk cell syncytial layer (E-YSL) membrane. Interfering in its expression exclusively in the yolk resulted in the reduction of yolk cell actomyosin contractility, the disruption of cortical and internal flows, a disequ...

Development, 1998

In this work, we analyse the blistered function in wing vein development by studying genetic mosa... more In this work, we analyse the blistered function in wing vein development by studying genetic mosaics of mutant cells, genetic interactions with other genes affecting vein development and blistered expression in several mutant backgrounds. blistered encodes for a nuclear protein homologous to the mammalian Serum Response Factor and is expressed in presumptive intervein cells of third larval instar and pupal wing discs. Clones of blistered mutant cells proliferate normally but tend to grow along veins and always differentiate as vein tissue. These observations indicate that vein-determined wing cells show a particular behaviour that is responsible for their allocation to vein regions. We observe strong genetic interactions between blistered, veinlet and genes of the Ras signaling cascade. During disc proliferation, blistered expression is under the control of the Ras signal transduction pathway, but its expression is independent of veinlet. During the pupal period, blistered and veinl...

For developmental processes we know most of the gene networks controlling specific cell responses... more For developmental processes we know most of the gene networks controlling specific cell responses. We still have to determine how these networks cooperate and how signals become integrated. The JNK pathway is one of the key elements modulating cellular responses during development. Yet, we still know little on how the core components of the pathway interact with additional regulators or how this network modulates cellular responses in the whole organism in homeostasis or during tissue morphogenesis. We have performed a promoter analysis searching for potential regulatory sequences of puc and identified different specific enhancers directing gene expression in different tissues and at different developmental times. Remarkably, some of these domains respond to the JNK activity, but not all. Altogether, these analyses show that puc expression regulation is very complex and that JNK activities participate in non-previously known processes during the development of Drosophila.

Development, 1999

The Drosophila EGF receptor (DER) is required for the specification of diverse cell fates through... more The Drosophila EGF receptor (DER) is required for the specification of diverse cell fates throughout development. We have examined how the activation of DER controls the development of vein and intervein cells in the Drosophila wing. The data presented here indicate that two distinct events are involved in the determination and differentiation of wing cells. (1) The establishment of a positive feedback amplification loop, which drives DER signaling in larval stages. At this time, rhomboid (rho), in combination with vein, initiates and amplifies the activity of DER in vein cells. (2) The late downregulation of DER activity. At this point, the inactivation of MAPK in vein cells is necessary for the maintenance of the expression of decapentaplegic (dpp) and becomes essential for vein differentiation. Together, these temporal and spatial changes in the activity of DER constitute an autoregulatory network that controls the definition of vein and intervein cell types.

SummaryDuring development, multicellular organisms undergo stereotypical patterns of tissue growt... more SummaryDuring development, multicellular organisms undergo stereotypical patterns of tissue growth to yield organs of highly reproducible sizes and shapes. How this process is orchestrated remains unclear. Analysis of the temporal dynamics of tissue growth in the Drosophila abdomen reveals that cell cycle times are spatially correlated and that growth termination occurs through the rapid emergence of a population of arrested cells rather than a gradual slowing down of cell cycle time. Reduction in apical tension associated with tissue crowding has been proposed as a developmental growth termination mechanism. Surprisingly, we find that growth arrest in the abdomen occurs while apical tension increases, showing that in this tissue a reduction in tension does not underlie the mechanism of growth arrest. However, remodeling of the extracellular matrix is necessary for tissue expansion. Thus, changes in the tissue microenvironment, and a rapid exit from proliferation, control the format...

Journal of Visualized Experiments, 2020

Within multicellular organisms, mature tissues and organs display high degrees of order in the sp... more Within multicellular organisms, mature tissues and organs display high degrees of order in the spatial arrangements of their constituent cells. A remarkable example is given by sensory epithelia, where cells of the same or distinct identities are brought together via cell-cell adhesion showing highly organized planar patterns. Cells align to one another in the same direction and display equivalent polarity over large distances. This organization of the mature epithelia is established over the course of morphogenesis. To understand how the planar arrangement of the mature epithelia is achieved, it is crucial to track cell orientation and growth dynamics with high spatiotemporal fidelity during development in vivo. Robust analytical tools are also essential to identify and characterize local-to-global transitions. The Drosophila pupa is an ideal system to evaluate oriented cell shape changes underlying epithelial morphogenesis. The pupal developing epithelium constitutes the external surface of the immobile body, allowing long-term imaging of intact animals. The protocol described here is designed to image and analyze cell behaviors at both global and local levels in the pupal abdominal epidermis as it grows. The methodology described can be easily adapted to the imaging of cell behaviors at other developmental stages, tissues, subcellular structures, or model organisms.

Mechanisms of Development, 2017

Los tipos de cláusulas de complemento en o'dam (tepehuano del sureste) ABSTRACT: In contrast to t... more Los tipos de cláusulas de complemento en o'dam (tepehuano del sureste) ABSTRACT: In contrast to the majority of Uto-Aztecan languages, O'dam (Uto-Aztecan, Tepiman), also known as Southeastern Tepehuan does not use nominalization as a general way to encode clause embedding. What it uses instead is finite clauses, marked by subordination markers. For this reason, this paper provides an analysis of completive clauses in O'dam based on a corpus of forty-five hours of naturally recorded speech. O'dam has a large number of features that distinguish different dependent relationships including: subordinator, aspect, second position clitics, inherent control, negation, and focus. Thus, this study analyzes these morphosyntactic characteristics along with the semantic classes to identify the type of dependent clause we are facing.

Seminars in cell & developmental biology, Jan 20, 2017

Neurons allocated to sense organs respond rapidly to mechanical signals dictating behavioral resp... more Neurons allocated to sense organs respond rapidly to mechanical signals dictating behavioral responses at the organism level. The receptors that transduce these signals, and underlie these senses, are mechanically gated channels. Research on mechanosensation over the past decade, employing in many cases Drosophila as a model, has focused in typifying these receptors and in exploring the different ways, depending on context, in which these mechanosensors are modulated. In this review, we discuss first what we have learned from Drosophila on these mechanisms and we describe the different mechanosensory organs present in the Drosophila larvae and adult. Secondly, we focus on the progress obtained by studying the fly on the characterization of the mechanosensory crosstalk underlying complex behaviors like motor coordination. Finally, turning to a cellular level, we summarize what is known on the mechanical properties and sensing capabilities of neural cells and how they may affect neura...

ABSTRACTPrecise tissue remodeling during development is essential for shaping embryos and for opt... more ABSTRACTPrecise tissue remodeling during development is essential for shaping embryos and for optimal organ function. Epiboly is an early gastrulation event by which the blastoderm expands around the yolk to engulf it. Three different layers are involved, an epithelial layer (the enveloping layer, EVL), the embryo proper, constituted by the deep cells (DCs), and the yolk cell. Although teleost epiboly has been studied for many years, a clear understanding of its mechanics was still missing. Here we present new information on the cellular, molecular and mechanical elements involved in epiboly that, together with some other recent data and upon comparison with previous biomechanical models, lets conclude that the expansion of the epithelia is passive and driven by cortical contraction and membrane removal in the adjacent layer, the External Yolk Syncytial Layer (E-YSL). The isotropic actomyosin contraction of the E-YSL generates an anisotropic stress pattern and a directional net move...

ABSTRACTThe Central Nervous System (CNS) organogenesis is a complex process that obeys precise ar... more ABSTRACTThe Central Nervous System (CNS) organogenesis is a complex process that obeys precise architectural rules. Yet, both the mechanisms dictating CNS structural organization, and the impact that this may have on its functionality remain unknown. Analyzing the Drosophila embryo Ventral Nerve Cord (VNC) morphogenesis, we found that tight control of JNK signaling levels is essential for its stereotyped architectural organization. The JNK pathway is active in a specific subset of pioneer neurons, where it, autonomously, regulates the expression of cell adhesion molecules, the integrity of axons and dendrites, and motoneurons electrophysiological properties. Interfering during early embryogenesis in the activity of JNK signaling in these cells, it affects their pioneer functions and leads to cumulative scaffolding defects during the establishment of axonal networks. This global architectural disarray associates to the failure of the VNC condensation and the coordination of the embry...

SummaryMorphogenetic processes demand the coordinated allocation of cells and tissues to their fi... more SummaryMorphogenetic processes demand the coordinated allocation of cells and tissues to their final destination in a spatio-temporal controlled way. Identifying how these morphogenetic movements are directed and implemented is essential for understanding morphogenesis. Topographical and scalar differences in adhesion and contractility within and between cells are essential, yet, the role that membrane remodeling may play remains less clear. To clarify how surface turnover and dynamics may modulate tissue arrangements we studied epiboly in the zebrafish. During epiboly the blastoderm expands as a result of an asymmetry of mechanical tension along the embryo surface. In this scenario, we found that the membrane removal by macropinocytosis of the external yolk cell syncytial layer (E-YSL) ahead of the blastoderm is key for epiboly progression In early zebrafish embryos, the activity of the GTPase Rab5ab was essential for endocytosis, and interference in its expression exclusively in t...

SUMMARYDespite a cumulative body of knowledge describing short-range cell interactions in morphog... more SUMMARYDespite a cumulative body of knowledge describing short-range cell interactions in morphogenetic processes, relatively little is known on the mechanism involved in the long-range spatial and temporal coordination of cells to build functional and structurally organized tissues. In particular, the attainment of a functionally optimized epithelia must require directional cues to instruct cell movements and cell orientations throughout the tissue field. In Drosophila, the adult epidermis of the abdominal segments is created de novo by the replacement of obsolete larval epidermal cells (LECs) by histoblasts (imaginal founder cells). As these proliferate, expand and fuse, they uniformly organize orienting on the surface along the antero-posterior axis. We found that the coordinated, axially oriented changes in shape of histoblasts respond to a dynamic, yet stereotyped redesign of the epithelial field mediated by the Dachsous/Fat/Four-jointed (Ds/Ft/Fj) pathway. The establishment an...