The influence of sex and age on the lens injury response
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ABSTRACT: The purpose of this study was to investigate/characterize age- and sex-dependent changes in transcriptomic profile in a mouse model of cataract surgery that mimics human cataract surgery. This surgery involves the removal of lens fiber cells (LFC) leaving behind the lens capsule and associated lens epithelial cells (LEC). The lens capsule and associated remnant LECs were harvested either following cataract surgery (0 hour) or 24 hours later. Fiber cells were collected at the time of surgery, equivalent to 0 hour, and analyzed separately from epithelial cells. For samples from LEC, each biological replicate is a pool of 5 lens capsules from 5 independent mice. For samples from LFC, each biological replicate is a pool of 2 fiber cell masses from two independent mice. Mice were either 24 months old (Aged), or 3 months old (Young).
Project description:This study investigates the response of human lens epithelial cells to mechanical injury. Human geriatric lenses obtained from cadaver eyes from donated to an eye bank for research were subject to in-vitro capsulotomy mimicking the injury sustained during cataract surgery. The anterior capsule was dissected using a curvilinear capsulorhexis technique, and central lens epithelial cells attached to the patch of anterior capsule (Rhexis) were immediately stabilized in RNAlater. The fiber cells were then removed, and the cortical fibers were immediately stabilized in RNA later. The remaining equatorial lens epithelial cells attached to the capsular bag from one eye were stabilized in RNA later immediately while the equatorial lens epithelial cells from the other eye were cultured for 24 hours then stabilized in RNAlater.
Project description:Although majority of the genes linked to pediatric cataract exhibit lens fiber cell-enriched expression, our understanding of gene regulation in these cells is limited to function of just eight transcription factors and largely in the context of crystallins. Here, we identify small Maf transcription factors MafG and MafK as regulators of several non-crystallin human cataract genes in fiber cells and establish their significance to cataract. We applied a bioinformatics tool for cataract gene discovery iSyTE to identify MafG and its co-regulators in the lens, and generated various null-allelic combinations of MafG:MafK mouse mutants for phenotypic and molecular analysis. By age 4-months, MafG-/-:MafK+/- mutants exhibit lens defects that progressively develop into cataract. High-resolution phenotypic characterization of MafG-/-:MafK+/- lens reveals severe defects in fiber cells, while microarrays-based expression profiling identifies 97 differentially regulated genes (DRGs). Integrative analysis of MafG-/-:MafK+/- lens-DRGs with 1) binding-motifs and genomic targets of small Mafs and their regulatory partners, 2) iSyTE lens-expression data, and 3) interactions between DRGs in the String database, unravels a detailed small Maf regulatory network in the lens, several nodes of which are linked to human cataract. This analysis prioritizes 36 highly promising candidates from the original 97 DRGs. Significantly, 8/36 (22%) DRGs are associated with cataracts in human (GSTO1, MGST1, SC4MOL, UCHL1) or mouse (Aldh3a1, Crygf, Hspb1, Pcbd1), suggesting a multifactorial etiology that includes elevation of oxidative stress. These data identify MafG and MafK as new cataract-associated candidates and define their function in regulating largely non-crystallin genes linked to mouse and human cataract. Microarray comparision of lenses from mixed background (129Sv/J, C57BL/6J, and ICR) control (MafG+/-:MafK+/-; no-cataract) and compound (MafG-/-:MafK+/-; cataract) mouse mutants
Project description:Differential expression of HSF4 in null newborn mouse and wildtype lenses was examined to identify putative downstream targets of HSF4. To examine roles of Brg1 in mouse lens development, a dnBrg1 transgenic construct was expressed using the lens-specific aA-crystallin promoter in postmitotic lens fiber cells. Morphological studies revealed abnormal lens fiber cell differentiation in transgenic lenses resulting in cataract. Electron microscopic studies showed abnormal lens suture formation and incomplete karyolysis (denucleation) of lens fiber cells. To identify genes regulated by Brg1, RNA expression profiling was performed in E15.5 embryonic wild type and dnBrg1 transgenic lenses. In addition, comparisons between differentially expressed genes in dnBrg1 transgenic, Pax6 heterozygous, and Hsf4 homozygous lenses identified multiple genes co-regulated by Brg1, Hsf4 and Pax6. Among them DNase IIb, a key enzyme required for lens fiber cell denucleation, was found downregulated in each of the Pax6, Brg1 and Hsf4 model systems. Lens-specific deletion of Brg1 using conditional gene targeting demonstrated that Brg1 was required for lens fiber cell differentiation and indirectly for retinal development but was not essential for lens lineage formation. Keywords: Differential mRNA Expression Three biological replicate experiments were performed with HSF null and wildtype lenses.
Project description:The epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) has been proposed as a major cause of posterior capsule opacification (PCO) after cataract surgery. Molecular mechanism of PCO progression is still unclear. Using a microarray-based approach, herein we studied the changes in gene expression pattern during rat PCO formation in vivo as a model.
Project description:Ocular lens development entails epithelial to fiber cell differentiation, defects in which cause congenital cataract. We report the first single-cell multiomic atlas of lens development, leveraging snRNA-seq, snATAC-seq, and CUT&RUN-seq to discover novel mechanisms of cell fate determination and cataract-linked regulatory networks. A comprehensive profile of cis- and trans-regulatory interactions, including for the cataract-linked transcription factor MAF, is established across a temporal trajectory of fiber cell differentiation. Further, we divulge a conserved epigenetic paradigm of cellular differentiation, defined by progressive loss of H3K27 methylation writer Polycomb repressive complex 2 (PRC2). PRC2 localizes to heterochromatin domains across master-regulator transcription factor gene bodies, suggesting it safeguards epithelial cell fate. Moreover, we demonstrate that FGF hyper-stimulation in vivo leads to MAF network activation and the emergence of novel lens cell states. Collectively, these data depict a comprehensive portrait of lens fiber cell differentiation, while defining regulatory effectors of cell identity and cataract formation.
Project description:Ocular lens development entails epithelial to fiber cell differentiation, defects in which cause congenital cataract. We report the first single-cell multiomic atlas of lens development, leveraging snRNA-seq, snATAC-seq, and CUT&RUN-seq to discover novel mechanisms of cell fate determination and cataract-linked regulatory networks. A comprehensive profile of cis- and trans-regulatory interactions, including for the cataract-linked transcription factor MAF, is established across a temporal trajectory of fiber cell differentiation. Further, we divulge a conserved epigenetic paradigm of cellular differentiation, defined by progressive loss of H3K27 methylation writer Polycomb repressive complex 2 (PRC2). PRC2 localizes to heterochromatin domains across master-regulator transcription factor gene bodies, suggesting it safeguards epithelial cell fate. Moreover, we demonstrate that FGF hyper-stimulation in vivo leads to MAF network activation and the emergence of novel lens cell states. Collectively, these data depict a comprehensive portrait of lens fiber cell differentiation, while defining regulatory effectors of cell identity and cataract formation.
Project description:Ocular lens development entails epithelial to fiber cell differentiation, defects in which cause congenital cataract. We report the first single-cell multiomic atlas of lens development, leveraging snRNA-seq, snATAC-seq, and CUT&RUN-seq to discover novel mechanisms of cell fate determination and cataract-linked regulatory networks. A comprehensive profile of cis- and trans-regulatory interactions, including for the cataract-linked transcription factor MAF, is established across a temporal trajectory of fiber cell differentiation. Further, we divulge a conserved epigenetic paradigm of cellular differentiation, defined by progressive loss of H3K27 methylation writer Polycomb repressive complex 2 (PRC2). PRC2 localizes to heterochromatin domains across master-regulator transcription factor gene bodies, suggesting it safeguards epithelial cell fate. Moreover, we demonstrate that FGF hyper-stimulation in vivo leads to MAF network activation and the emergence of novel lens cell states. Collectively, these data depict a comprehensive portrait of lens fiber cell differentiation, while defining regulatory effectors of cell identity and cataract formation.
Project description:Early changes in the transcriptome associated with lens wounding in an ex vivo post-cataract surgery chicken model. Here we report the changes in the transcriptome that occur 1hr vs. time 0 post-cataract surgery wounding. Our data provide a molecular framework for understanding the early gene changes associated with the injury response of the lens.
Project description:Although majority of the genes linked to pediatric cataract exhibit lens fiber cell-enriched expression, our understanding of gene regulation in these cells is limited to function of just eight transcription factors and largely in the context of crystallins. Here, we identify small Maf transcription factors MafG and MafK as regulators of several non-crystallin human cataract genes in fiber cells and establish their significance to cataract. We applied a bioinformatics tool for cataract gene discovery iSyTE to identify MafG and its co-regulators in the lens, and generated various null-allelic combinations of MafG:MafK mouse mutants for phenotypic and molecular analysis. By age 4-months, MafG-/-:MafK+/- mutants exhibit lens defects that progressively develop into cataract. High-resolution phenotypic characterization of MafG-/-:MafK+/- lens reveals severe defects in fiber cells, while microarrays-based expression profiling identifies 97 differentially regulated genes (DRGs). Integrative analysis of MafG-/-:MafK+/- lens-DRGs with 1) binding-motifs and genomic targets of small Mafs and their regulatory partners, 2) iSyTE lens-expression data, and 3) interactions between DRGs in the String database, unravels a detailed small Maf regulatory network in the lens, several nodes of which are linked to human cataract. This analysis prioritizes 36 highly promising candidates from the original 97 DRGs. Significantly, 8/36 (22%) DRGs are associated with cataracts in human (GSTO1, MGST1, SC4MOL, UCHL1) or mouse (Aldh3a1, Crygf, Hspb1, Pcbd1), suggesting a multifactorial etiology that includes elevation of oxidative stress. These data identify MafG and MafK as new cataract-associated candidates and define their function in regulating largely non-crystallin genes linked to mouse and human cataract.
Project description:Genome-wide approach to identify the cell-autonomous role of Brg1 in lens fiber cell terminal differentiation. To examine roles of Brg1 in mouse lens development, a dnBrg1 transgenic construct was expressed using the lens-specific alphaA-crystallin promoter in postmitotic lens fiber cells. Morphological studies revealed abnormal lens fiber cell differentiation in transgenic lenses resulting in cataract. Electron microscopic studies showed abnormal lens suture formation and incomplete karyolysis (denucleation) of lens fiber cells. To identify genes regulated by Brg1, RNA expression profiling was performed in E15.5 embryonic wild type and dnBrg1 transgenic lenses. In addition, comparisons between differentially expressed genes in dnBrg1 transgenic, Pax6 heterozygous, and Hsf4 homozygous lenses identified multiple genes co-regulated by Brg1, Hsf4 and Pax6. Among them DNase IIbeta, a key enzyme required for lens fiber cell denucleation, was found downregulated in each of the Pax6, Brg1 and Hsf4 model systems. Lens-specific deletion of Brg1 using conditional gene targeting demonstrated that Brg1 was required for lens fiber cell differentiation and indirectly for retinal development but was not essential for lens lineage formation. Wild type and dnBrg1 transgenic lenses, 4 biological replicates each