Project description:MicroRNA expression in the mouse eye.MicroRNAs (miRNAs) are key regulators of biological processes. To define miRNA function in the eye, it is essential to determine a high-resolution profile of their spatial and temporal distribution. In this report, we present the first comprehensive survey of miRNA expression in ocular tissues, using both microarray and RNA in situ hybridization (ISH) procedures. We initially determined the expression profiles of miRNAs in the retina, lens, cornea and retinal pigment epithelium of the adult mouse eye by microarray. Each tissue exhibited notably distinct miRNA enrichment patterns and cluster analysis identified groups of miRNAs that showed predominant expression in specific ocular tissues or combinations of them. Next, we performed RNA ISH for over 220 miRNAs, including those showing the highest expression levels by microarray, and generated a high-resolution expression atlas of miRNAs in the developing and adult wild-type mouse eye, which is accessible in the form of a publicly available web database. We found that 122 miRNAs displayed restricted expression domains in the eye at different developmental stages, with the majority of them expressed in one or more cell layers of the neural retina . This analysis revealed miRNAs with differential expression in ocular tissues and provided a detailed atlas of their tissue-specific distribution during development of the murine eye. The combination of the two approaches offers a valuable resource to decipher the contributions of specific miRNAs and miRNA clusters to the development of distinct ocular structures. microRNA profiling of ocular tissues from mouse. In particular we analysed the cornea, lens, Retina Pigment Epithelium (RPE) and retina and compared them against RNA extracted from the entire eye. The purpose of this experiment was to understand which microRNAs are present nd/or show differential expression in the various structures of the eye (cornea, lens, RPE, retina). The samples numbered 1 & 2 (i.e. CORNEA1, CORNEA2 etc ) are biological replicates, prepared from tissues dissecyed from different groups of wild-type animals. RNA extracted from the entire eye (EYE) served as the unique reference sample. For each tissue to be analysed we performed the following hybridizations: - 2 slides for lens (LENS1, LENS2) vs entire eye (EYE) - 2 slides for RPE (RPE1, RPE2) vs entire eye (EYE) - 2 slides for retina (RETINA1, RETINA2) vs entire eye (EYE) - 2 slides for cornea (CORNEA1, CORNEA2) vs entire eye (EYE) - 1 slide for entire eye (EYE) vs entire eye (EYE)

Project description:Methylation at cytosines (mCG) is a well-known regulator of gene expression but its requirements for cellular differentiation have yet to be fully elucidated. A well-studied cellular differentiation model system is the eye lens, consisting of a single anterior layer of epithelial cells that migrate laterally and differentiate into a core of fiber cells. Here, we explore the genome-wide relationships between mCG methylation, chromatin accessibility and gene expression during differentiation of eye lens epithelial cells into fiber cells. Whole genome bisulfite sequencing identified 7621 genomic loci exhibiting significant differences in mCG levels between lens epithelial and fiber cells. Changes in mCG levels were inversely correlated with the differentiation state-specific expression of 1285 genes preferentially expressed in either lens fiber or lens epithelial cells (Pearson correlation r = -0.37, p < 1x10-42). mCG levels were inversely correlated with chromatin accessibility determined by Assay for transposase-accessible sequencing (ATAC-seq) (Pearson correlation r = -0.86, p < 1x10-300). Many of the genes exhibiting altered regions of DNA methylation, chromatin accessibility and gene expression levels in fiber cells relative to epithelial cells are associated with lens fiber cell structure, homeostasis and transparency. These include lens crystallins (CRYBA4, CRYBB1, CRYGN, CRYBB2), lens beaded filament proteins (BFSP1, BFSP2), transcription factors (HSF4, SOX2, HIF1A), and Notch signaling pathway members (NOTCH1, NOTCH2, HEY1, HES5). Analysis of regions exhibiting cell-type specific alterations in DNA methylation revealed an overrepresentation of consensus sequences of multiple transcription factors known to play key roles in lens cell differentiation including HIF1A, SOX2, and the MAF family of transcription factors. Collectively, these results link DNA methylation with control of chromatin accessibility and gene expression changes required for eye lens differentiation. The results also point to a role for DNA methylation in the regulation of transcription factors previously identified to be important for lens cell differentiation.

Project description:Background: During eye lens development the fetal vasculature regresses leaving the lens without a direct oxygen source. Both embryonically and throughout adult life, the lens contains a decreasing oxygen gradient from the surface to the core that parallels the natural differentiation of immature surface epithelial cells into mature core transparent fiber cells. These properties of the lens suggest a potential role for hypoxia in the regulation of genes required for mature lens structure and function. Since HIF1α is a master regulator of the hypoxic response, these lens properties also implicate HIF1α as a potential requirement for lens formation and homeostasis. Here, we employed a multiomics approach combining CUT&RUN, RNAseq and ATACseq analysis to establish the genomic complement of lens HIF1α binding sites, genes activated or repressed by HIF1α and the chromatin states of HIF1α-regulated genes. Results: CUT&RUN analysis revealed 8,375 HIF1α-DNA binding complexes in the chick lens genome. 1,190 HIF1α-DNA binding complexes were significantly clustered within chromatin accessible regions (χ2 test p < 1x10-55) identified by ATACseq. Formation of the identified HIF1α-DNA complexes paralleled the activation or repression of 526 genes, 116 of which contained HIF1α binding sites within 10kB of the transcription start sites. Some of the identified HIF1α genes have previously established lens functions while others have novel functions never before examined in the lens. GO and pathway analysis of these genes implicate HIF1α in the control of a wide-variety of cellular pathways potentially critical for lens formation, structure and function including glycolysis, cell cycle regulation, chromatin remodeling, Notch and Wnt signaling, differentiation, development, and transparency. Conclusions: These data establish the first functional map of genomic HIF1α-DNA complexes in the eye lens. They identify HIF1α as an important regulator of a wide-variety of genes previously shown to be critical for lens formation and function and they reveal a requirement for HIF1α in the regulation of a wide-variety of genes not yet examined for lens function. They support a requirement for HIF1α in lens development, structure and function and they provide a basis for understanding the potential roles and requirements for HIF1α in the development, structure and function of more complex tissues.

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Transcriptomic profiling investigating altered cellular pathways upon QKI depletion in mouse eye lens tissue, mouse neural stem cell-derived lens progenitor-like cells (NLPCs), and human lens epithelial cell line (HLE-B3).

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