Project description:Microglia are the resident immune cells of the central nervous system (CNS). They govern the immunogenicity of the retina, which is considered to be part of the CNS; however, it is not known how microglia develop in the eye. Here, we studied human-induced pluripotent stem cells (hiPSCs) that had been expanded into a self-formed ectodermal autonomous multi-zone (SEAM) of cells that partially mimics human eye development. Our results indicated that microglia-like cells, which have characteristics of yolk-sac-like linage cells, naturally develop in 2D eye-like SEAM organoids, which lack any vascular components. These cells are unique in that they are paired box protein 6 (PAX6)-positive, yet they possess some characteristics of mesoderm. Collectively, the data support the notion of the existence of an isolated, locally developing immune system in the eye, which is independent of the body's vasculature and general immune system.
Project description:Glutathione (GSH) is a critical endogenous antioxidant that protects against intracellular oxidative stress. As such, pathological alterations in GSH levels are linked to a myriad of diseases including cancer, neurodegeneration and cataract. The rate limiting step in GSH biosynthesis is catalyzed by the glutamate cysteine ligase catalytic subunit (GCLC). The high expression of GCLC in the lens supports the synthesis of millimolar concentrations of GSH in this tissue. Herein, we describe the morphological consequences of deleting (knocking out) Gclc from surface ectoderm-derived ocular tissues (using the Le-Cre transgene; Gclc KO) which includes an overt microphthalmia phenotype and severely disrupted formation of multiple ocular structures (i.e., cornea, iris, lens, retina). Controlling for the Le-Cre transgene revealed that the deletion of Gclc significantly exacerbated the microphthalmia phenotype in Le-Cre hemizygous mice and resulted in dysregulated gene expression that was unique to only the lenses of KO mice. We further characterized the impaired lens development by conducting an RNA-seq experiment on KO and Gclc control (CON) mouse lens at the day of birth. RNA-sequencing revealed significant differences between Gclc knockout (KO) and Gclc control (CON) lenses, including down-regulation of crystallins and lens fiber cell identity genes, and up-regulation of lens epithelial cell identity genes. In addition, genes related to the immune system (e.g., immune system process, inflammatory response, neutrophil chemotaxis) were upregulated, and genes related to eye/lens development were downregulated. TRANSFAC analysis of differentially expressed genes (DEGs) in the lens of Gclc KO mice implicated PAX6 as a key upstream regulator of Gclc KO sensitive genes. This was further supported by a strong positive correlation between the transcriptomes of the lenses of Gclc KO and Pax6 KO mice. Strikingly, the dysregulation of PAX6-regulated genes in Gclc KO mice was observed despite no change in the ocular localization of PAX6 or decrease in the expression of PAX6 in the lens. In vitro experiments demonstrated that suppression of intracellular GSH concentrations resulted in impairment of PAX6 transactivation activity. Taken together, the present results elucidate a novel mechanism wherein intracellular GSH concentrations may modulate PAX6 activity.
Project description:The paired box gene 6 (PAX6) is an essential transcription factor for eye formation. Genetic alterations in PAX6 can lead to various ocular malformations including aniridia. The purpose of this study was to identify genetic defects as the underlying cause of familial coloboma of iris in a large Chinese family. After linkage analysis was carried out in this family, all exons of PAX6 in the proband were sequenced by the Sanger sequencing technique. Then the genome of the proband was evaluated by a microarray-based comparative genomic hybridization (aCGH). Quantitative real-time PCR was applied to verify the abnormal aCGH findings. All patients presented bilateral partial coloboma of iris, severe congenital nystagmus, hyperpresbyopia and congenital posterior polar cataracts. Two-point linkage analysis in the autosomal dominant family showed loss of heterozygosity at the D11S914 locus. There was no pathogenic mutation in the exons of PAX6. The aCGH analysis revealed a 681 kb heterozygous deletion on chromosome 11p13. Quantitative real-time PCR verified the deletion in the patients and further confirmed this deletion cosegregation with the coloboma of iris phenotype in the family. The 681 kb large deletion of chromosome 11p13 downstream of PAX6 is the genetic cause of the familial coloboma of ocular in this large Chinese family. aCGH should be applied if there is a negative result for the mutation detection of PAX6 in patients with aniridia. One Case sample and one control sample
Project description:The paired box gene 6 (PAX6) is an essential transcription factor for eye formation. Genetic alterations in PAX6 can lead to various ocular malformations including aniridia. The purpose of this study was to identify genetic defects as the underlying cause of familial coloboma of iris in a large Chinese family. After linkage analysis was carried out in this family, all exons of PAX6 in the proband were sequenced by the Sanger sequencing technique. Then the genome of the proband was evaluated by a microarray-based comparative genomic hybridization (aCGH). Quantitative real-time PCR was applied to verify the abnormal aCGH findings. All patients presented bilateral partial coloboma of iris, severe congenital nystagmus, hyperpresbyopia and congenital posterior polar cataracts. Two-point linkage analysis in the autosomal dominant family showed loss of heterozygosity at the D11S914 locus. There was no pathogenic mutation in the exons of PAX6. The aCGH analysis revealed a 681 kb heterozygous deletion on chromosome 11p13. Quantitative real-time PCR verified the deletion in the patients and further confirmed this deletion cosegregation with the coloboma of iris phenotype in the family. The 681 kb large deletion of chromosome 11p13 downstream of PAX6 is the genetic cause of the familial coloboma of ocular in this large Chinese family. aCGH should be applied if there is a negative result for the mutation detection of PAX6 in patients with aniridia.