Project description:Alternative polyadenylation (APA) is a regulatory mechanism that controls gene expression level and function through the usage of different transcription termination sites, but how APA is regulated to influence epidermal tissue differentiation remains under-characterized. Leveraging 3’READS+, we identified prevalent APA in keratinocytes. We further identified a high-confidence list of genes that alters their usages of polyadenylation site (PAS) during keratinocyte differentiation. To begin to understand the mechanisms that modulates PAS selection within a given gene, we identified that the expression of the Cleavage and Polyadenylation Specificity Factor (CPSF) complex is down regulated during keratinocyte differentiation. Suppression of CPSF using RNAi or CRISPRi strongly impaired epidermal regeneration with upregulation of terminal differentiation marker gene expression. Mechanistically, we identified that CPSF suppression decreased the usage of the GRHL3 proximal PAS and upregulated full-length GRHL3 mRNA production. Knockdown of GRHL3 in the context of CPSFi partially restored differentiation marker gene expression. We also found CPSF interacts with RNA-binding proteins to control PAS usage. Thus, our data suggest a model where CPSF binding preference and PAS choices regulate epidermal terminal differentiation.
Project description:The M3 muscarinic acetylcholine receptor (CHRM3) is predominantly expressed in the basal epidermal layer where it mediates the effects of the auto/paracrine cytotransmitter acetylcholine. Patients with the autoimmune blistering disease pemphigus develop autoantibodies to CHRM3 and show alterations in keratinocyte adhesion, proliferation and differentiation, suggesting that CHRM3 controls these cellular functions. Chrm3 mice display altered epidermal morphology resembling that seen in patients with pemphigus vulgaris. Here, we characterized the cellular and molecular mechanisms whereby CHRM3 controls epidermal structure and function. We used single cell (sc)RNA-seq to evaluate keratinocyte heterogeneity and identify differentially expressed genes in specific subpopulations of epidermal cells in Chrm3 KO neonatal mice.
Project description:Numerous long non-coding RNAs (lncRNAs) were shown to have functional impact on cellular processes, such as human epidermal homeostasis, but for only a few the mode of action has been elucidated. Here, we report that lncRNA LINC00941 controls keratinocyte differentiation on a global level through association with the MTA2/NuRD complex, one of the major chromatin remodelers in cells. LINC00941 was found to interact with NuRD-associated MTA2, suppressing the expression of the transcription factor EGR3, a regulator of epidermal differentiation. Both LINC00941 and the MTA2/NuRD complex are enriched in non-differentiated keratinocytes and repress the expression of differentiation genes through epigenetic silencing of EGR3, consequentially preventing premature differentiation of human progenitor cells.
Project description:Progenitor cells at the basal layer of skin epidermis play an essential role in maintaining tissue homeostasis and enhancing wound repair in skin. The proliferation, differentiation, and cell death of epidermal progenitor cells have to be delicately regulated, as deregulation of this process can lead to many skin diseases, including skin cancers. However, the underlying molecular mechanisms involved in skin homeostasis remain poorly defined. In this study, with quantitative proteomics approach, we identified an important interaction between KDF1 (Keratinocyte Differentiation Factor 1) and IKKα (IκB kinase α) in differentiating skin keratinocytes. Ablation of either KDF1 or IKKα in mice leads to similar but striking abnormalities in skin development, particularly in skin epidermal differentiation. With biochemical and mouse genetics approach, we further demonstrate that the interaction of IKKα and KDF1 is essential for epidermal differentiation. To probe deeper into the mechanisms, we find that KDF1 associates with a deubiquitinating protease, USP7 (Ubiquitin Specific Peptidase 7), and KDF1 can regulate skin differentiation through deubiquitination and stabilization of IKKα. Taken together, our study unravels an important molecular mechanism underlying skin tissue homeostasis and epidermal differentiation.
Project description:Disrupted differentiation is a hallmark of numerous diseases, which in epidermis alone impact >25% of the population. In a search for dominant mediators of differentiation, we defined a requirement for the ZNF750 nuclear protein in terminal epidermal differentiation. ZNF750 controlled genes mutated in numerous human skin diseases, including FLG, LOR, LCE3B, ALOXE3, and SPINK5. ZNF750 potently induced progenitor differentiation via an evolutionarily conserved C2H2 zinc finger motif. The epidermal master regulator, p63, bound the ZNF750 promoter and was necessary for its induction. ZNF750 restored differentiation to p63-deficient tissue, suggesting it acts downstream of p63. A search for functionally important ZNF750 targets via analysis of ZNF750-regulated genes identified KLF4, a transcription factor that activates late epidermal differentiation genes. ZNF750 binds the Klf4 promoter and controls its expression. ZNF750 thus provides a direct link between a tissue-specifying factor, p63, and an effector of terminal differentiation, Klf4, and represents a potential future target for disorders of this process. Gene expression analysis: To establish a differentiation signature for primary human keratinocytes, with ZNF750-depleted, and Klf4-depleted, total RNA was isolated in biologic duplicate from cells in different conditions and hybridized to Affymetrix HG-U133 2.0 Plus arrays.