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1.
Nature ; 574(7777): 249-253, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31578523

RESUMO

The integrity of the mammalian epidermis depends on a balance of proliferation and differentiation in the resident population of stem cells1. The kinase RIPK4 and the transcription factor IRF6 are mutated in severe developmental syndromes in humans, and mice lacking these genes display epidermal hyperproliferation and soft-tissue fusions that result in neonatal lethality2-5. Our understanding of how these genes control epidermal differentiation is incomplete. Here we show that the role of RIPK4 in mouse development requires its kinase activity; that RIPK4 and IRF6 expressed in the epidermis regulate the same biological processes; and that the phosphorylation of IRF6 at Ser413 and Ser424 primes IRF6 for activation. Using RNA sequencing (RNA-seq), histone chromatin immunoprecipitation followed by sequencing (ChIP-seq) and assay for transposase-accessible chromatin using sequencing (ATAC-seq) of skin in wild-type and IRF6-deficient mouse embryos, we define the transcriptional programs that are regulated by IRF6 during epidermal differentiation. IRF6 was enriched at bivalent promoters, and IRF6 deficiency caused defective expression of genes that are involved in the metabolism of lipids and the formation of tight junctions. Accordingly, the lipid composition of the stratum corneum of Irf6-/- skin was abnormal, culminating in a severe defect in the function of the epidermal barrier. Collectively, our results explain how RIPK4 and IRF6 function to ensure the integrity of the epidermis and provide mechanistic insights into why developmental syndromes that are characterized by orofacial, skin and genital abnormalities result when this axis goes awry.


Assuntos
Diferenciação Celular , Células Epidérmicas/citologia , Epiderme/fisiologia , Fatores Reguladores de Interferon/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais , Anormalidades Múltiplas/genética , Animais , Fenda Labial/genética , Fissura Palatina/genética , Cistos/genética , Embrião de Mamíferos/citologia , Embrião de Mamíferos/embriologia , Embrião de Mamíferos/metabolismo , Células Epidérmicas/metabolismo , Epiderme/embriologia , Anormalidades do Olho/genética , Feminino , Dedos/anormalidades , Regulação da Expressão Gênica , Fatores Reguladores de Interferon/deficiência , Fatores Reguladores de Interferon/genética , Joelho/anormalidades , Articulação do Joelho/anormalidades , Lábio/anormalidades , Metabolismo dos Lipídeos/genética , Deformidades Congênitas das Extremidades Inferiores/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fosforilação , Fosfosserina/metabolismo , Proteínas Serina-Treonina Quinases/genética , Sindactilia/genética , Anormalidades Urogenitais/genética
2.
Nat Commun ; 10(1): 4042, 2019 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-31492871

RESUMO

Tissue injury induces changes in cellular identity, but the underlying molecular mechanisms remain obscure. Here, we show that upon damage in a mouse model, epidermal cells at the wound edge convert to an embryonic-like state, altering particularly the cytoskeletal/extracellular matrix (ECM) components and differentiation program. We show that SOX11 and its closest relative SOX4 dictate embryonic epidermal state, regulating genes involved in epidermal development as well as cytoskeletal/ECM organization. Correspondingly, postnatal induction of SOX11 represses epidermal terminal differentiation while deficiency of Sox11 and Sox4 accelerates differentiation and dramatically impairs cell motility and re-epithelialization. Amongst the embryonic genes reactivated at the wound edge, we identify fascin actin-bundling protein 1 (FSCN1) as a critical direct target of SOX11 and SOX4 regulating cell migration. Our study identifies the reactivated embryonic gene program during wound repair and demonstrates that SOX11 and SOX4 play a central role in this process.


Assuntos
Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Fatores de Transcrição SOXC/genética , Cicatrização/genética , Ferimentos e Lesões/genética , Animais , Diferenciação Celular/genética , Movimento Celular/genética , Citoesqueleto/metabolismo , Células Epidérmicas/citologia , Células Epidérmicas/metabolismo , Epiderme/embriologia , Epiderme/metabolismo , Matriz Extracelular , Camundongos , Proteínas dos Microfilamentos/genética , Proteínas dos Microfilamentos/metabolismo , Receptores Odorantes/genética , Receptores Odorantes/metabolismo , Fatores de Transcrição SOXC/metabolismo , Ferimentos e Lesões/embriologia
3.
Nat Commun ; 10(1): 3049, 2019 07 11.
Artigo em Inglês | MEDLINE | ID: mdl-31296872

RESUMO

The transcription factor p63 is a master regulator of ectoderm development. Although previous studies show that p63 triggers epidermal differentiation in vitro, the roles of p63 in developing embryos remain poorly understood. Here, we use zebrafish embryos to analyze in vivo how p63 regulates gene expression during development. We generate tp63-knock-out mutants that recapitulate human phenotypes and show down-regulated epidermal gene expression. Following p63-binding dynamics, we find two distinct functions clearly separated in space and time. During early development, p63 binds enhancers associated to neural genes, limiting Sox3 binding and reducing neural gene expression. Indeed, we show that p63 and Sox3 are co-expressed in the neural plate border. On the other hand, p63 acts as a pioneer factor by binding non-accessible chromatin at epidermal enhancers, promoting their opening and epidermal gene expression in later developmental stages. Therefore, our results suggest that p63 regulates cell fate decisions during vertebrate ectoderm specification.


Assuntos
Ectoderma/embriologia , Desenvolvimento Embrionário/genética , Regulação da Expressão Gênica no Desenvolvimento , Placa Neural/embriologia , Fosfoproteínas/metabolismo , Transativadores/metabolismo , Proteínas de Peixe-Zebra/metabolismo , Animais , Animais Geneticamente Modificados , Sistemas CRISPR-Cas/genética , Diferenciação Celular/genética , Cromatina/metabolismo , Regulação para Baixo , Ectoderma/metabolismo , Embrião não Mamífero , Elementos Facilitadores Genéticos/genética , Epiderme/embriologia , Epiderme/metabolismo , Técnicas de Inativação de Genes , Modelos Animais , Placa Neural/metabolismo , Fosfoproteínas/genética , Ligação Proteica/genética , Fatores de Transcrição SOXB1/genética , Fatores de Transcrição SOXB1/metabolismo , Transativadores/genética , Peixe-Zebra/embriologia , Proteínas de Peixe-Zebra/genética
4.
Elife ; 82019 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-31187731

RESUMO

The control of cell fate through oriented cell division is imperative for proper organ development. Basal epidermal progenitor cells divide parallel or perpendicular to the basement membrane to self-renew or produce differentiated stratified layers, but the mechanisms regulating the choice between division orientations are unknown. Using time-lapse imaging to follow divisions and fates of basal progenitors, we find that mouse embryos defective for the planar cell polarity (PCP) gene, Vangl2, exhibit increased perpendicular divisions and hyperthickened epidermis. Surprisingly, this is not due to defective Vangl2 function in the epidermis, but to changes in cell geometry and packing that arise from the open neural tube characteristic of PCP mutants. Through regional variations in epidermal deformation and physical manipulations, we show that local tissue architecture, rather than cortical PCP cues, regulates the decision between symmetric and stratifying divisions, allowing flexibility for basal cells to adapt to the needs of the developing tissue.


Assuntos
Epiderme/embriologia , Epitélio/anatomia & histologia , Mamíferos/embriologia , Fuso Acromático/metabolismo , Células-Tronco/citologia , Animais , Divisão Celular , Linhagem da Célula , Polaridade Celular , Forma Celular , Embrião de Mamíferos/metabolismo , Células Epidérmicas/citologia , Camundongos Endogâmicos C57BL , Mutação/genética , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Tubo Neural/patologia
5.
Nature ; 569(7757): 497-502, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31092920

RESUMO

Cell competition-the sensing and elimination of less fit 'loser' cells by neighbouring 'winner' cells-was first described in Drosophila. Although cell competition has been proposed as a selection mechanism to optimize tissue and organ development, its evolutionary generality remains unclear. Here, by using live imaging, lineage tracing, single-cell transcriptomics and genetics, we identify two cell competition mechanisms that sequentially shape and maintain the architecture of stratified tissue during skin development in mice. In the single-layered epithelium of the early embryonic epidermis, winner progenitors kill and subsequently clear neighbouring loser cells by engulfment. Later, as the tissue begins to stratify, the basal layer instead expels losers through upward flux of differentiating progeny. This cell competition switch is physiologically relevant: when it is perturbed, so too is barrier formation. Our findings show that cell competition is a selective force that optimizes vertebrate tissue function, and illuminate how a tissue dynamically adjusts cell competition strategies to preserve fitness as its architectural complexity increases during morphogenesis.


Assuntos
Comunicação Celular , Células Epidérmicas/citologia , Epiderme/embriologia , Morfogênese , Animais , Apoptose , Células Clonais/citologia , Drosophila melanogaster/citologia , Drosophila melanogaster/embriologia , Células Epidérmicas/metabolismo , Feminino , Masculino , Camundongos , Fagocitose , Análise de Célula Única
6.
Dev Biol ; 450(2): 115-131, 2019 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-30935896

RESUMO

Desmoplakin (Dsp) is a unique and critical desmosomal protein, that is integral to epidermal development. However, it is unclear whether this protein is required specifically for epidermal morphogenesis. Using morpholinos or Crispr/Cas9 mutagenesis we decreased the function of Dsp in frog embryos to better understand its role during epidermal development. Dsp morphant and mutant embryos had developmental defects such as epidermal fragility that mimicked what has been reported in mammals. Most importantly, we also uncovered a novel function for Dsp in the morphogenesis of the epidermis in X. laevis. In particular, Dsp is required during the process of radial intercalation where basally located cells move into the outer epidermal layer. Once inserted these newly intercalated cells expand their apical surface and then they differentiate into specific epidermal cell types. Decreased levels of Dsp resulted in the failure of the radially intercalating cells to expand their apical surface, thereby reducing the number of differentiated multiciliated and secretory cells. Such defects correlate with changes in E-cadherin levels and actin and microtubule localization which could explain the defects in apical expansion. A mutated form of Dsp that maintains cell-cell adhesion but eliminates the connections to the cytoskeleton results in the same epidermal morphogenesis defect. These results suggest a specific role for Dsp in the apical expansion of cells during radial intercalation. We have developed a novel system, in the frog, to demonstrate for the first time that desmosomes not only protect against mechanical stress but are also critical for epidermal morphogenesis.


Assuntos
Adesão Celular , Comunicação Celular , Desmoplaquinas/metabolismo , Embrião não Mamífero/embriologia , Epiderme/embriologia , Morfogênese , Proteínas de Xenopus/metabolismo , Animais , Desmoplaquinas/genética , Embrião não Mamífero/citologia , Proteínas de Xenopus/genética , Xenopus laevis
7.
Elife ; 82019 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-30995201

RESUMO

Epithelial fusion establishes continuity between the separated flanks of epithelial sheets. Despite its importance in creating resilient barriers, the mechanisms that ensure stable continuity and preserve morphological and molecular symmetry upon fusion remain unclear. Using the segmented embryonic epidermis whose flanks fuse during Drosophila dorsal closure, we demonstrate that epidermal flanks modulate cell numbers and geometry of their fusing fronts to achieve fusion fidelity. While fusing flanks become more matched for both parameters before fusion, differences persisting at fusion are corrected by modulating fusing front width within each segment to ensure alignment of segment boundaries. We show that fusing cell interfaces are remodelled from en-face contacts at fusion to an interlocking arrangement after fusion, and demonstrate that changes in interface length and geometry are dependent on the spatiotemporal regulation of cytoskeletal tension and Bazooka/Par3. Our work uncovers genetically constrained and mechanically triggered adaptive mechanisms contributing to fusion fidelity and epithelial continuity.


Assuntos
Proteínas de Drosophila/metabolismo , Drosophila/embriologia , Embrião não Mamífero , Desenvolvimento Embrionário , Epiderme/embriologia , Células Epiteliais/fisiologia , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Fenômenos Mecânicos , Animais
8.
Dev Growth Differ ; 61(4): 276-282, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30968390

RESUMO

Skin development is tightly temporally coordinated with its sensory innervation, which consists of the peripheral branches of the dorsal root ganglion (DRG) axons. Various studies suggest that the skin produces a long-range attractant for the sensory axons. However, the exact identity of the guidance cue(s) remains unclear. To reveal the detailed molecular mechanism that controls DRG axon guidance and targeting, manipulation of specific skin layers at specific time points are required. To test a variety of attractants that can be expressed in specific skin layers at specific timepoints, we combined in utero electroporation with the Tol2 transposon system to induce long-term transgene expression in the developing mouse skin, including in the highly proliferative epidermal stem cells (basal layer) and their descendants (spinous and granular layer cells). The plasmid solution was injected as close to the hindpaw plantar surface as possible. Immediately, electric pulses were passed through the embryo to transduce the plasmid DNA into hindpaw skin cells. Balancing outcome measurements including: embryo survival, transfection efficiency, and the efficiency of transgene integration into host cells, we found that IUE was best performed on E13.5, and using an electroporation voltage of 34V. After immunostaining embryonic and early postnatal skin tissue sections for keratinocyte and sensory axon markers, we observe the growth of axons into skin epidermal layers including areas expressing EGFP. Therefore, this method is useful for studying the interaction between axon growth and epidermal cell division/differentiation.


Assuntos
Epiderme/inervação , Epiderme/metabolismo , Neurônios/metabolismo , Pele/inervação , Pele/metabolismo , Transgenes/genética , Animais , Axônios/metabolismo , Células Epidérmicas/citologia , Células Epidérmicas/metabolismo , Epiderme/embriologia , Epiderme/crescimento & desenvolvimento , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/citologia , Gravidez , Pele/embriologia , Pele/crescimento & desenvolvimento
9.
Dev Biol ; 448(2): 173-182, 2019 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-30059669

RESUMO

Tadpole larvae of the ascidian, Halocynthia roretzi, show morphological left-right asymmetry in the brain structures and the orientation of tail bending within the vitelline membrane. Neurula embryos rotate along the anterior-posterior axis in a counterclockwise direction, and then this rotation stops when the left side of the embryo is oriented downwards. Contact of the left-side epidermis with the vitelline membrane promotes nodal gene expression in the left-side epidermis. This is a novel mechanism in which rotation of whole embryos provides the initial cue for breaking left-right symmetry. Here we show that epidermal monocilia, which appear at the neurula rotation stage, generate the driving force for rotation. A ciliary protein, Arl13b, fused with Venus YFP was used for live imaging of ciliary movements. Although overexpression of wild-type Arl13b fusion protein resulted in aberrant movements of the cilia and abrogation of neurula rotation, mutant Arl13b fusion protein, in which the GTPase and coiled-coil domains were removed, did not affect the normal ciliary movements and neurula rotation. Epidermis cilia moved in a wavy and serpentine way like sperm flagella but not in a rotational way or beating way with effective stroke and recovery stroke. They moved very slowly, at 1/7 Hz, consistent with the low angular velocity of neurula rotation (ca. 43°/min). The tips of most cilia pointed in the opposite direction of embryonic rotation. Similar motility was also observed in Ciona robusta embryos. When embryos were treated with a dynein inhibitor, Ciliobrevin D, both ciliary movements and neurula rotation were abrogated, showing that ciliary movements drive neurula rotation in Halocynthia. The drug also inhibited Ciona neurula rotation. Our observations suggest that the driving force of rotation is generated using the vitelline membrane as a substrate but not by making a water current around the embryo. It is of evolutionary interest that ascidians use ciliary movements to break embryonic left-right symmetry, like in many vertebrates. Meanwhile, ascidian embryos rotate as a whole, similar to embryos of non-vertebrate deuterostomes, such as echinoderm, hemichordate, and amphioxus, while swimming.


Assuntos
Padronização Corporal , Cílios/fisiologia , Embrião de Mamíferos/metabolismo , Epiderme/embriologia , Movimento , Rotação , Urocordados/embriologia , Animais , Dineínas/metabolismo , Proteínas Recombinantes de Fusão/metabolismo
10.
PLoS Biol ; 16(10): e3000027, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30379844

RESUMO

Extensive apoptosis is often seen in patterning mutants, suggesting that tissues can detect and eliminate potentially harmful mis-specified cells. Here, we show that the pattern of apoptosis in the embryonic epidermis of Drosophila is not a response to fate mis-specification but can instead be explained by the limiting availability of prosurvival signaling molecules released from locations determined by patterning information. In wild-type embryos, the segmentation cascade elicits the segmental production of several epidermal growth factor receptor (EGFR) ligands, including the transforming growth factor Spitz (TGFα), and the neuregulin, Vein. This leads to an undulating pattern of signaling activity, which prevents expression of the proapoptotic gene head involution defective (hid) throughout the epidermis. In segmentation mutants, where specific peaks of EGFR ligands fail to form, gaps in signaling activity appear, leading to coincident hid up-regulation and subsequent cell death. These data provide a mechanistic understanding of how cell survival, and thus appropriate tissue size, is made contingent on correct patterning.


Assuntos
Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriologia , Drosophila melanogaster/metabolismo , Receptores ErbB/metabolismo , Receptores de Peptídeos de Invertebrados/metabolismo , Animais , Animais Geneticamente Modificados , Apoptose/genética , Apoptose/fisiologia , Padronização Corporal/genética , Padronização Corporal/fisiologia , Sobrevivência Celular/genética , Sobrevivência Celular/fisiologia , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Fator de Crescimento Epidérmico/genética , Fator de Crescimento Epidérmico/metabolismo , Epiderme/embriologia , Epiderme/metabolismo , Receptores ErbB/genética , Feminino , Genes de Insetos , Ligantes , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Mutação , Neurregulinas/genética , Neurregulinas/metabolismo , Neuropeptídeos/genética , Neuropeptídeos/metabolismo , Receptores de Peptídeos de Invertebrados/genética , Transdução de Sinais
11.
Dev Cell ; 46(3): 344-359.e4, 2018 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-30032992

RESUMO

As animals mature from embryonic to adult stages, the skin grows and acquires specialized appendages, like hairs, feathers, and scales. How cutaneous blood vessels and sensory axons adapt to these dramatic changes is poorly understood. By characterizing skin maturation in zebrafish, we discovered that sensory axons are delivered to the adult epidermis in organized nerves patterned by features in bony scales. These nerves associate with blood vessels and osteoblasts above scales. Osteoblasts create paths in scales that independently guide nerves and blood vessels during both development and regeneration. By preventing scale regeneration and examining mutants lacking scales, we found that scales recruit, organize, and polarize axons and blood vessels to evenly distribute them in the skin. These studies uncover mechanisms for achieving comprehensive innervation and vascularization of the adult skin and suggest that scales coordinate a metamorphosis-like transformation of the skin with sensory axon and vascular remodeling.


Assuntos
Axônios/metabolismo , Epiderme/embriologia , Pele/irrigação sanguínea , Pele/inervação , Animais , Axônios/ultraestrutura , Cabelo/embriologia , Pele/ultraestrutura , Remodelação Vascular/fisiologia , Peixe-Zebra/crescimento & desenvolvimento
12.
G3 (Bethesda) ; 8(7): 2277-2290, 2018 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-29720391

RESUMO

The cytoskeleton is the basic machinery that drives many morphogenetic events. Elongation of the C. elegans embryo from a spheroid into a long, thin larva initially results from actomyosin contractility, mainly in the lateral epidermal seam cells, while the corresponding dorsal and ventral epidermal cells play a more passive role. This is followed by a later elongation phase involving muscle contraction. Early elongation is mediated by parallel genetic pathways involving LET-502/Rho kinase and MEL-11/MYPT myosin phosphatase in one pathway and FEM-2/PP2c phosphatase and PAK-1/p21 activated kinase in another. While the LET-502/MEL-11 pathway appears to act primarily in the lateral epidermis, here we show that FEM-2 can mediate early elongation when expressed in the dorsal and ventral epidermis. We also investigated the early elongation function of FHOD-1, a member of the formin family of actin nucleators and bundlers. Previous work showed that FHOD-1 acts in the LET-502/MEL-11 branch of the early elongation pathway as well as in muscle for sarcomere organization. Consistent with this, we found that lateral epidermal cell-specific expression of FHOD-1 is sufficient for elongation, and FHOD-1 effects on elongation appear to be independent of its role in muscle. Also, we found that fhod-1 encodes long and short isoforms that differ in the presence of a predicted coiled-coil domain. Based on tissue-specific expression constructions and an isoform-specific CRISPR allele, the two FHOD-1 isoforms show partially specialized epidermal or muscle function. Although fhod-1 shows only impenetrant elongation phenotypes, we were unable to detect redundancy with other C. elegans formin genes.


Assuntos
Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/embriologia , Caenorhabditis elegans/genética , Regulação da Expressão Gênica no Desenvolvimento , Proteínas dos Microfilamentos/genética , Morfogênese/genética , Fosfoproteínas Fosfatases/genética , Processamento Alternativo , Animais , Animais Geneticamente Modificados , Embrião não Mamífero , Epiderme/embriologia , Epiderme/metabolismo , Especificidade de Órgãos/genética , Fenótipo
13.
G3 (Bethesda) ; 8(7): 2361-2387, 2018 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-29776969

RESUMO

Cell sheet morphogenesis characterizes key developmental transitions and homeostasis, in vertebrates and throughout phylogeny, including gastrulation, neural tube formation and wound healing. Dorsal closure, a process during Drosophila embryogenesis, has emerged as a model for cell sheet morphogenesis. ∼140 genes are currently known to affect dorsal closure and new genes are identified each year. Many of these genes were identified in screens that resulted in arrested development. Dorsal closure is remarkably robust and many questions regarding the molecular mechanisms involved in this complex biological process remain. Thus, it is important to identify all genes that contribute to the kinematics and dynamics of closure. Here, we used a set of large deletions (deficiencies), which collectively remove 98.5% of the genes on the right arm of Drosophila melanogaster's 2nd chromosome to identify "dorsal closure deficiencies". Through two crosses, we unambiguously identified embryos homozygous for each deficiency and time-lapse imaged them for the duration of closure. Images were analyzed for defects in cell shapes and tissue movements. Embryos homozygous for 47 deficiencies have notable, diverse defects in closure, demonstrating that a number of discrete processes comprise closure and are susceptible to mutational disruption. Further analysis of these deficiencies will lead to the identification of at least 30 novel "dorsal closure genes". We expect that many of these novel genes will identify links to pathways and structures already known to coordinate various aspects of closure. We also expect to identify new processes and pathways that contribute to closure.


Assuntos
Mapeamento Cromossômico , Cromossomos de Insetos , Proteínas de Drosophila/genética , Drosophila/embriologia , Drosophila/genética , Morfogênese/genética , Animais , Caderinas , Cruzamentos Genéticos , Desenvolvimento Embrionário/genética , Epiderme/embriologia , Epiderme/metabolismo , Testes Genéticos , Fenótipo , Deleção de Sequência , Imagem com Lapso de Tempo
14.
J Cell Sci ; 131(11)2018 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-29748380

RESUMO

Hemidesmosomes are epithelial-specific attachment structures that maintain tissue integrity and resist tension. Despite their importance, how hemidesmosomes are regulated at the post-transcriptional level is poorly understood. Caenorhabditiselegans hemidesmosomes (CeHDs) have a similar structure and composition to their mammalian counterparts, making C. elegans an ideal model for studying hemidesmosomes. Here, we focus on the transcription regulator CCAR-1, identified in a previous genetic screen searching for enhancers of mutations in the conserved hemidesmosome component VAB-10A (known as plectin in mammals). Loss of CCAR-1 function in a vab-10(e698) background results in CeHD disruption and muscle detachment from the epidermis. CCAR-1 regulates CeHD biogenesis, not by controlling the transcription of CeHD-related genes, but by affecting the alternative splicing of unc-52 (known as perlecan or HSPG2 in mammals), the predicted basement extracellular matrix (ECM) ligand of CeHDs. CCAR-1 physically interacts with HRP-2 (hnRNPR in mammals), a splicing factor known to mediate unc-52 alternative splicing to control the proportions of different UNC-52 isoforms and stabilize CeHDs. Our discovery underlines the importance of post-transcriptional regulation in hemidesmosome reorganization. It also uncovers previously unappreciated roles of CCAR-1 in alternative splicing and hemidesmosome biogenesis, shedding new light on the mechanisms through which mammalian CCAR1 functions in tumorigenesis.


Assuntos
Processamento Alternativo , Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/metabolismo , Hemidesmossomos/metabolismo , Proteínas de Membrana/metabolismo , Proteoglicanas/metabolismo , Animais , Caenorhabditis elegans/embriologia , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Epiderme/embriologia , Epiderme/metabolismo , Hemidesmossomos/genética , Ribonucleoproteínas Nucleares Heterogêneas Grupo A-B/genética , Ribonucleoproteínas Nucleares Heterogêneas Grupo A-B/metabolismo , Proteínas de Membrana/genética , Músculos/embriologia , Músculos/metabolismo , Ligação Proteica , Proteoglicanas/genética
15.
Eur J Cell Biol ; 97(4): 243-256, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29573831

RESUMO

Tissues and organs undergo extensive remodelling to reach their final morphology and physiological activity. The genetic programs underlying tissue formation are well studied, but less is known about how this formation is influenced by extrinsic forces derived from other concomitant morphogenetic events. Here we address this question in Drosophila melanogaster. We analyse tissue organisation in the embryonic epidermis at stage 10 by computational tissue segmentation methods to provide a quantitative description of packing. We find that the epidermis adopts different organisations along the dorso-ventral axis that correlate with differences in cell density. We analyse the contribution of three morphogenetic events that take place right before or concomitant to this period of embryogenesis, neuroblast delamination, asynchronous postblastoderm cell divisions and germ band extension, and we find that they all exert an influence on the packing of the epidermis. We previously described that the apical determinant Crumbs accumulates differentially in the epidermis along the dorso-ventral axis. Here we find that this differential accumulation of Crumbs correlates with the differential tissue packing. Perturbation of the three mentioned morphogenetic events also modulate Crumbs differential accumulation, suggesting that Crb could act as a read-out of tissue organisation. We also previously showed that Crb plays a role in regulating cell architecture. Now we find that it is also required for proper packing of the embryonic epidermis. In summary, here we uncover an intimate relationship between morphogenetic events and cell packing within a tissue that is dependent on surrounding cell density. Furthermore we find that this morphogenetically-regulated tissue packing modulates the key cell polarity protein Crumbs, which in turn is required for tissue packing, suggesting that it may participate in the molecular mechanism/s underlying the described tissue organisation.


Assuntos
Drosophila melanogaster/embriologia , Epiderme/embriologia , Morfogênese , Animais , Divisão Celular , Linhagem da Célula , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Células Epidérmicas , Epiderme/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo
16.
Int J Mol Sci ; 19(3)2018 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-29495602

RESUMO

Development and homeostasis of the epidermis are governed by a complex network of sequence-specific transcription factors and epigenetic modifiers cooperatively regulating the subtle balance of progenitor cell self-renewal and terminal differentiation. To investigate the role of histone H2A deubiquitinase 2A-DUB/Mysm1 in the skin, we systematically analyzed expression, developmental functions, and potential interactions of this epigenetic regulator using Mysm1-deficient mice and skin-derived epidermal cells. Morphologically, skin of newborn and young adult Mysm1-deficient mice was atrophic with reduced thickness and cellularity of epidermis, dermis, and subcutis, in context with altered barrier function. Skin atrophy correlated with reduced proliferation rates in Mysm1-/- epidermis and hair follicles, and increased apoptosis compared with wild-type controls, along with increases in DNA-damage marker γH2AX. In accordance with diminished α6-Integrinhigh+CD34⁺ epidermal stem cells, reduced colony formation of Mysm1-/- epidermal progenitors was detectable in vitro. On the molecular level, we identified p53 as potential mediator of the defective Mysm1-deficient epidermal compartment, resulting in increased pro-apoptotic and anti-proliferative gene expression. In Mysm1-/-p53-/- double-deficient mice, significant recovery of skin atrophy was observed. Functional properties of Mysm1-/- developing epidermis were assessed by quantifying the transepidermal water loss. In summary, this investigation uncovers a role for 2A-DUB/Mysm1 in suppression of p53-mediated inhibitory programs during epidermal development.


Assuntos
Endopeptidases/metabolismo , Epiderme/embriologia , Epiderme/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Animais , Apoptose/genética , Atrofia , Endopeptidases/genética , Epiderme/patologia , Expressão Gênica , Genótipo , Imuno-Histoquímica , Camundongos , Camundongos Knockout , Células-Tronco/metabolismo , Proteína Supressora de Tumor p53/genética
17.
J Cell Biol ; 217(3): 1079-1095, 2018 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-29358210

RESUMO

In epithelia, cells adhere to each other in a dynamic fashion, allowing the cells to change their shape and move along each other during morphogenesis. The regulation of adhesion occurs at the belt-shaped adherens junction, the zonula adherens (ZA). Formation of the ZA depends on components of the Par-atypical PKC (Par-aPKC) complex of polarity regulators. We have identified the Lin11, Isl-1, Mec-3 (LIM) protein Smallish (Smash), the orthologue of vertebrate LMO7, as a binding partner of Bazooka/Par-3 (Baz), a core component of the Par-aPKC complex. Smash also binds to Canoe/Afadin and the tyrosine kinase Src42A and localizes to the ZA in a planar polarized fashion. Animals lacking Smash show loss of planar cell polarity (PCP) in the embryonic epidermis and reduced cell bond tension, leading to severe defects during embryonic morphogenesis of epithelial tissues and organs. Overexpression of Smash causes apical constriction of epithelial cells. We propose that Smash is a key regulator of morphogenesis coordinating PCP and actomyosin contractility at the ZA.


Assuntos
Junções Aderentes/metabolismo , Proteínas de Drosophila/metabolismo , Epiderme/embriologia , Células Epiteliais/metabolismo , Morfogênese/fisiologia , Junções Aderentes/genética , Animais , Proteínas de Drosophila/genética , Drosophila melanogaster
18.
Zoology (Jena) ; 126: 36-45, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29373166

RESUMO

The lingual nail as the cornified layer of the orthokeratinized epithelium in birds is responsible for the collection of solid food by pecking. The aim of the present study is to determine the manner of orthokeratinized epithelium development and assess the degree of readiness of the epithelium to fulfill its mechanical function at hatching. Three developmental phases are distinguished, i.e. embryonic, transformation and pre-hatching stage. In the embryonic stage lasting until day 13 of incubation the epithelium is composed of several layers of undifferentiated cells. During the transformation stage, from day 14 to 20 of incubation, the epithelium becomes differentiated to form three layers. A characteristic feature is the formation of osmophilic granules in the superficial layer, referred to as periderm granules. Until the pre-hatching stage the fibrous cytoskeleton of epithelial cells and an impermeable epithelial barrier are gradually developed. In the pre-hatching stage, a cornified lingual nail is formed, while the periderm is exfoliated. At hatching the orthokeratinized epithelium and lingual nail are fully developed and ready to perform feeding activities. The presence of periderm, similarly as in the epidermis, indicates the ectodermal derivation of the oral cavity epithelium. Moreover, occurrence of osmophilic granules may be considered as evidence for the phylogenetic affinity of birds and reptiles.


Assuntos
Patos/embriologia , Língua/embriologia , Animais , Embrião não Mamífero/ultraestrutura , Desenvolvimento Embrionário , Epiderme/embriologia , Queratinas/metabolismo , Microscopia , Microscopia Eletrônica de Varredura
20.
Artigo em Inglês | MEDLINE | ID: mdl-28246184

RESUMO

Epithelia exist in the animal body since the onset of embryonic development; they generate tissue barriers and specify organs and glands. Through epithelial-mesenchymal transitions (EMTs), epithelia generate mesenchymal cells that form new tissues and promote healing or disease manifestation when epithelial homeostasis is challenged physiologically or pathologically. Transforming growth factor-ßs (TGF-ßs), activins, bone morphogenetic proteins (BMPs), and growth and differentiation factors (GDFs) have been implicated in the regulation of epithelial differentiation. These TGF-ß family ligands are expressed and secreted at sites where the epithelium interacts with the mesenchyme and provide paracrine queues from the mesenchyme to the neighboring epithelium, helping the specification of differentiated epithelial cell types within an organ. TGF-ß ligands signal via Smads and cooperating kinase pathways and control the expression or activities of key transcription factors that promote either epithelial differentiation or mesenchymal transitions. In this review, we discuss evidence that illustrates how TGF-ß family ligands contribute to epithelial differentiation and induce mesenchymal transitions, by focusing on the embryonic ectoderm and tissues that form the external mammalian body lining.


Assuntos
Transição Epitelial-Mesenquimal , Epitélio/embriologia , Transdução de Sinais/fisiologia , Fator de Crescimento Transformador beta/fisiologia , Animais , Diferenciação Celular , Epiderme/embriologia , Plumas/embriologia , Folículo Piloso/embriologia , Humanos , Mesoderma/citologia , Crista Neural/citologia , Dente/embriologia
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