IFNa is a key regulator of the dialogue between pancreatic 0 cells and the immune system in early type 1 diabetes (T1D). IFNa up-regulates HLA class I expression in human 0 cells, fostering... Show moreIFNa is a key regulator of the dialogue between pancreatic 0 cells and the immune system in early type 1 diabetes (T1D). IFNa up-regulates HLA class I expression in human 0 cells, fostering autoantigen presentation to the immune system. We observed by bulk and single-cell RNA sequencing that exposure of human induced pluripotentderived islet-like cells to IFNa induces expression of HLA class I and of other genes involved in antigen presentation, including the transcriptional activator NLRC5. We next evaluated the global role of NLRC5 in human insulinproducing EndoC-0H1 and human islet cells by RNA sequencing and targeted gene/protein determination. NLRC5 regulates expression of HLA class I, antigen presentation-related genes, and chemokines. NLRC5 also mediates the effects of IFNa on alternative splicing, a generator of 0 cell neoantigens, suggesting that it is a central player of the effects of IFNa on 0 cells that contribute to trigger and amplify autoimmunity in T1D. Show less
Alvelos, M.I.; Bruggemann, M.; Sutandy, F.X.R.; Juan-Mateu, J.; Colli, M.L.; Busch, A.; ... ; Castela, A. 2021
In pancreatic beta-cells, the expression of the splicing factor SRSF6 is regulated by GLIS3, a transcription factor encoded by a diabetes susceptibility gene. SRSF6 down-regulation promotes beta... Show moreIn pancreatic beta-cells, the expression of the splicing factor SRSF6 is regulated by GLIS3, a transcription factor encoded by a diabetes susceptibility gene. SRSF6 down-regulation promotes beta-cell demise through splicing dysregulation of central genes for beta-cells function and survival, but how RNAs are targeted by SRSF6 remains poorly understood. Here, we define the SRSF6 binding landscape in the human pancreatic beta-cell line EndoC-beta H1 by integrating individual-nucleotide resolution UV cross-linking and immuno-precipitation (iCLIP) under basal conditions with RNA sequencing after SRSF6 knockdown. We detect thousands of SRSF6 bindings sites in coding sequences. Motif analyses suggest that SRSF6 specifically recognizes a purine-rich consensus motif consisting of GAA triplets and that the number of contiguous GAA triplets correlates with increasing binding site strength. The SRSF6 positioning determines the splicing fate. In line with its role in beta-cell function, we identify SRSF6 binding sites on regulated exons in several diabetes susceptibility genes. In a proof-of-principle, the splicing of the susceptibility gene LMO7 is modulated by antisense oligonucleotides. Our present study unveils the splicing regulatory landscape of SRSF6 in immortalized human pancreatic beta-cells. Show less
