Chromatin remodeling complexes are required for many distinct nuclear processes such as transcription, DNA replication, and DNA repair. However, the contribution of these complexes to the development of complex tissues within an organism is poorly characterized. Imitation switch (ISWI) proteins are among the most evolutionarily conserved ATP-dependent chromatin remodeling factors and are represented by yeast Isw1/Isw2, and their vertebrate counterparts Snf2h (Smarca5) and Snf2l (Smarca1). In this study, we focused on the role of the Snf2h gene during the development of the mammalian retina. We show that Snf2h is expressed in both retinal progenitors and post-mitotic retinal cells. Using Snf2h conditional knockout mice (Snf2h cKO), we found that when Snf2h is deleted, the laminar structure of the adult retina is not retained, the overall thickness of the retina is significantly reduced compared with controls, and the outer nuclear layer (ONL) is completely missing. The depletion of Snf2h did not influence the ability of retinal progenitors to generate all the differentiated retinal cell types. Instead, the Snf2h function is critical for the proliferation of retinal progenitor cells. Cells lacking Snf2h have a defective S-phase, leading to the entire cell division process impairments. Although all retinal cell types appear to be specified in the absence of the Snf2h function, cell-cycle defects and concomitantly increased apoptosis in Snf2h cKO result in abnormal retina lamination, complete destruction of the photoreceptor layer, and consequently, a physiologically non-functional retina.

• MeSH
• adenosintrifosfatasy * metabolismus   MeSH
• buněčné jádro metabolismus   MeSH
• chromatin * metabolismus   MeSH
• chromozomální proteiny, nehistonové * metabolismus   MeSH
• myši knockoutované MeSH
• myši MeSH
• proliferace buněk MeSH
• restrukturace chromatinu * MeSH
• retina MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

The vertebrate eye is derived from the neuroepithelium, surface ectoderm, and extracellular mesenchyme. The neuroepithelium forms an optic cup in which the spatial separation of three domains is established, namely, the region of multipotent retinal progenitor cells (RPCs), the ciliary margin zone (CMZ)-which possesses both a neurogenic and nonneurogenic potential-and the optic disk (OD), the interface between the optic stalk and the neuroretina. Here, we show by genetic ablation in the developing optic cup that Meis1 and Meis2 homeobox genes function redundantly to maintain the retinal progenitor pool while they simultaneously suppress the expression of genes characteristic of CMZ and OD fates. Furthermore, we demonstrate that Meis transcription factors bind regulatory regions of RPC-, CMZ-, and OD-specific genes, thus providing a mechanistic insight into the Meis-dependent gene regulatory network. Our work uncovers the essential role of Meis1 and Meis2 as regulators of cell fate competence, which organize spatial territories in the vertebrate eye.

• MeSH
• buněčná diferenciace genetika   MeSH
• genový knockdown MeSH
• homeodoménové proteiny genetika   metabolismus   MeSH
• kmenové buňky cytologie   metabolismus   MeSH
• obratlovci MeSH
• retina cytologie   metabolismus   MeSH
• transkripční faktory genetika   metabolismus   MeSH
• vývojová regulace genové exprese MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Genome duplication leads to an emergence of gene paralogs that are essentially free to undergo the process of neofunctionalization, subfunctionalization or degeneration (gene loss). Onecut1 (Oc1) and Onecut2 (Oc2) transcription factors, encoded by paralogous genes in mammals, are expressed in precursors of horizontal cells (HCs), retinal ganglion cells and cone photoreceptors. Previous studies have shown that ablation of either Oc1 or Oc2 gene in the mouse retina results in a decreased number of HCs, while simultaneous deletion of Oc1 and Oc2 leads to a complete loss of HCs. Here we study the genetic redundancy between Oc1 and Oc2 paralogs and focus on how the dose of Onecut transcription factors influences abundance of individual retinal cell types and overall retina physiology. Our data show that reducing the number of functional Oc alleles in the developing retina leads to a gradual decrease in the number of HCs, progressive thinning of the outer plexiform layer and diminished electrophysiology responses. Taken together, these observations indicate that in the context of HC population, the alleles of Oc1/Oc2 paralogous genes are mutually interchangeable, function additively to support proper retinal function and their molecular evolution does not follow one of the typical routes after gene duplication.

• MeSH
• alely MeSH
• amakrinní buňky metabolismus   patologie   MeSH
• bipolární buňky sítnice metabolismus   patologie   MeSH
• čípky retiny metabolismus   patologie   MeSH
• ependymální buňky metabolismus   patologie   MeSH
• genetické lokusy MeSH
• genotyp MeSH
• hepatocytární jaderný faktor 6 genetika   metabolismus   MeSH
• homeodoménové proteiny genetika   metabolismus   MeSH
• myši transgenní MeSH
• myši MeSH
• oči růst a vývoj   patologie   MeSH
• retina cytologie   patologie   fyziologie   MeSH
• retinální gangliové buňky cytologie   metabolismus   MeSH
• transkripční faktory genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Lens induction is a classical developmental model allowing investigation of cell specification, spatiotemporal control of gene expression, as well as how transcription factors are integrated into highly complex gene regulatory networks (GRNs). Pax6 represents a key node in the gene regulatory network governing mammalian lens induction. Meis1 and Meis2 homeoproteins are considered as essential upstream regulators of Pax6 during lens morphogenesis based on their interaction with the ectoderm enhancer (EE) located upstream of Pax6 transcription start site. Despite this generally accepted regulatory pathway, Meis1-, Meis2- and EE-deficient mice have surprisingly mild eye phenotypes at placodal stage of lens development. Here, we show that simultaneous deletion of Meis1 and Meis2 in presumptive lens ectoderm results in arrested lens development in the pre-placodal stage, and neither lens placode nor lens is formed. We found that in the presumptive lens ectoderm of Meis1/Meis2 deficient embryos Pax6 expression is absent. We demonstrate using chromatin immunoprecipitation (ChIP) that in addition to EE, Meis homeoproteins bind to a remote, ultraconserved SIMO enhancer of Pax6. We further show, using in vivo gene reporter analyses, that the lens-specific activity of SIMO enhancer is dependent on the presence of three Meis binding sites, phylogenetically conserved from man to zebrafish. Genetic ablation of EE and SIMO enhancers demostrates their requirement for lens induction and uncovers an apparent redundancy at early stages of lens development. These findings identify a genetic requirement for Meis1 and Meis2 during the early steps of mammalian eye development. Moreover, they reveal an apparent robustness in the gene regulatory mechanism whereby two independent "shadow enhancers" maintain critical levels of a dosage-sensitive gene, Pax6, during lens induction.

• MeSH
• dánio pruhované genetika   MeSH
• ektoderm růst a vývoj   patologie   MeSH
• genové regulační sítě genetika   MeSH
• homeodoménové proteiny genetika   metabolismus   MeSH
• lidé MeSH
• myši MeSH
• nádorové proteiny genetika   metabolismus   MeSH
• oči růst a vývoj   metabolismus   patologie   MeSH
• oční čočka růst a vývoj   metabolismus   patologie   MeSH
• transkripční faktor PAX6 genetika   metabolismus   MeSH
• vazebná místa MeSH
• vývojová regulace genové exprese MeSH
• zesilovače transkripce genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Lecithin:retinol acyltransferase (LRAT) is the major enzyme responsible for retinol esterification in the mammalian body. LRAT exhibits specific activity in the cells with active retinol metabolism where it converts retinols into retinyl esters, which represents the major storage form of retinol. Besides hepatic stellate cells in the liver, LRAT appears to have a key physiologic role in several other tissues. In this study, we generated a transgenic reporter mouse expressing green fluorescence protein (EGFP) under the control of region containing -1166 bps from promoter upstream from the putative transcriptional start site and 262 bps downstream of this start. Transgenic reporter mice exhibited specific expression in eyes and testes. In eyes, expression of EGFP-reporter is found in lens and lens epithelium and fibers from embryo to adulthood. In testes, LRAT-EGFP reporter is expressed both in Sertoli and in spermatocytes marking initiation of spermatogenesis in prepubertal mice. Our data show that the examined LRAT regulatory region is sufficient to achieve strong and selective expression in the eye and testes but not in liver and other organs.

• MeSH
• acyltransferasy genetika   MeSH
• epitel metabolismus   MeSH
• genetická transkripce genetika   MeSH
• genotyp MeSH
• meióza genetika   MeSH
• myši transgenní MeSH
• myši MeSH
• oční čočka metabolismus   MeSH
• promotorové oblasti (genetika) genetika   MeSH
• regulace genové exprese enzymů genetika   MeSH
• Sertoliho buňky metabolismus   MeSH
• spermatocyty ultrastruktura   MeSH
• spermatogeneze MeSH
• testis metabolismus   MeSH
• vitamin A metabolismus   MeSH
• vývojová regulace genové exprese genetika   MeSH
• zelené fluorescenční proteiny MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Wnt/β-catenin signaling plays an essential role in the retinal pigment epithelium (RPE) determination. Since activity of Pax6 (together with Pax2) is also required for the RPE determination, we investigated a possible genetic interaction between Pax6 and Wnt/β-catenin signaling pathway by analyzing Pax6, β-catenin, and Pax6/β-catenin conditional knockout mice. Although Pax6 inactivation alone had no impact on initial specification determined by the expression of Mitf and Otx2, melanin pigmentation was reduced in the RPE. This suggests that along with Mitf and Otx2, Pax6 is required for the full differentiation of RPE. Reporter gene assays in vitro suggest that hypopigmentation is at least in part due to the direct regulation of genes encoding enzymes involved in melanin synthesis by Pax6, Mitf, and β-catenin. The RPE of a β-catenin/Pax6 double mutant was differentiated into the neural retina; however, the tissue was thinner than that of the conditional β-catenin mutant due to reduced proliferation. Together, our data demonstrate that Pax6 is required for the RPE differentiation by regulating pigmentation and accountable for hyperproliferation in the transdifferentiated RPE. In this context, Pax6 appears to function as a pleiotropic regulator, directing development of ocular tissues in concert with the signaling pathway and, at the same time, regulating expression of structural component of the eye, such as shielding pigment.

• MeSH
• beta-katenin genetika   metabolismus   MeSH
• homeodoménové proteiny genetika   metabolismus   MeSH
• myši transgenní MeSH
• myši MeSH
• oční proteiny genetika   metabolismus   MeSH
• represorové proteiny genetika   metabolismus   MeSH
• retina cytologie   metabolismus   MeSH
• retinální pigmentový epitel metabolismus   MeSH
• signální dráha Wnt * MeSH
• transdiferenciace buněk MeSH
• transkripční faktory paired box genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Genetic studies of the last decades strongly indicated that generation of particular retinal cell types is governed by gene regulatory networks of transcription factors and their target genes. The paired and homeodomain transcription factor Pax6 plays a pivotal role in retinal development as its inactivation in the retinal progenitor cell population leads to abolished differentiation of all retinal cell types. However, until now, only a few transcription factors operating downstream of Pax6 responsible for generation of individual retinal cell types have been identified. In this study, we identified two transcription factors of the Onecut family, Onecut1 and Onecut2, as Pax6 downstream-acting factors. Onecut1 and Onecut2 were previously shown to be expressed in developing horizontal cells, retinal ganglion cells and cone photoreceptors; however, their role in differentiation of these cell types is poorly understood. In this study, we show that the horizontal cell genesis is severely disturbed in Onecut-deficient retinae. In single Onecut1 and Onecut2 mutants, the number of horizontal cells is dramatically reduced while horizontal cells are completely missing in the Onecut1/Onecut2 compound mutant. Analysis of genes involved in the horizontal cell genesis such as Foxn4, Ptf1a, Prox1 and Lim1 showed that although horizontal cells are initially formed, they are not maintained in Onecut-deficient retinae. Taken together, this study suggests the model in which Pax6 regulates the maintenance of horizontal cells through the activation of Onecut1 and Onecut2 transcription factors.

• MeSH
• čípky retiny metabolismus   MeSH
• fenotyp MeSH
• hepatocytární jaderný faktor 6 metabolismus   MeSH
• homeodoménové proteiny metabolismus   MeSH
• hybridizace in situ MeSH
• kmenové buňky cytologie   MeSH
• molekulární sekvence - údaje MeSH
• mutace MeSH
• myši transgenní MeSH
• myši MeSH
• oční proteiny metabolismus   MeSH
• represorové proteiny metabolismus   MeSH
• retina embryologie   metabolismus   MeSH
• sekvence nukleotidů MeSH
• sekvenční homologie nukleových kyselin MeSH
• transkripční faktory paired box metabolismus   MeSH
• transkripční faktory metabolismus   MeSH
• vazebná místa MeSH
• vývojová regulace genové exprese MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The Wnt/β-catenin signaling pathway controls many processes during development, including cell proliferation, cell differentiation and tissue homeostasis, and its aberrant regulation has been linked to various pathologies. In this study we investigated the effect of ectopic activation of Wnt/β-catenin signaling during lens fiber cell differentiation. To activate Wnt/β-catenin signaling in lens fiber cells, the transgenic mouse referred to as αA-CLEF was generated, in which the transactivation domain of β-catenin was fused to the DNA-binding protein LEF1, and expression of the transgene was controlled by αA-crystallin promoter. Constitutive activation of Wnt/β-catenin signaling in lens fiber cells of αA-CLEF mice resulted in abnormal and delayed fiber cell differentiation. Moreover, adult αA-CLEF mice developed cataract, microphthalmia and manifested downregulated levels of γ-crystallins in lenses. We provide evidence of aberrant expression of cell cycle regulators in embryonic lenses of αA-CLEF transgenic mice resulting in the delay in cell cycle exit and in the shift of fiber cell differentiation to the central fiber cell compartment. Our results indicate that precise regulation of the Wnt/β-catenin signaling activity during later stages of lens development is essential for proper lens fiber cell differentiation and lens transparency.

• MeSH
• beta-katenin genetika   metabolismus   MeSH
• buněčná diferenciace genetika   MeSH
• buněčný cyklus genetika   MeSH
• DNA vazebné proteiny genetika   metabolismus   MeSH
• epitelové buňky metabolismus   MeSH
• katarakta genetika   metabolismus   MeSH
• krystaliny genetika   metabolismus   MeSH
• lidé MeSH
• mikroftalmie genetika   metabolismus   MeSH
• myši inbrední C57BL MeSH
• myši transgenní genetika   metabolismus   MeSH
• myši MeSH
• oční čočka metabolismus   MeSH
• promotorové oblasti (genetika) genetika   MeSH
• signální dráha Wnt genetika   MeSH
• signální transdukce genetika   MeSH
• transkripční faktor LEF-1 MeSH
• vývojová regulace genové exprese MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• Publikační typ
• abstrakty MeSH

• MeSH
• finanční podpora výzkumu jako téma MeSH
• Publikační typ
• abstrakty MeSH