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RFX6 maintains gene expression and function of adult human islet a cells

Version 2 2023-12-28, 16:45
Version 1 2023-12-08, 18:52
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posted on 2023-12-28, 16:45 authored by Vy M. N. Coykendall, Mollie F. Qian, Krissie Tellez, Austin Bautista, Romina J. Bevacqua, Xueying Gu, Yan Hang, Martin Neukam, Weichen Zhao, Charles Chang, Patrick E. MacDonald, Seung K. Kim

ABSTRACT

Mutations in the gene encoding the transcription factor RFX6 are associated with human diabetes mellitus. Within pancreatic islets, RFX6 expression is most abundant in islet a cells, and a cell RFX6 expression is altered in diabetes. However, the roles of RFX6 in regulating gene expression, glucagon output and other crucial human adult a cell functions are not yet understood. We developed a method for selective genetic targeting of human a cells and assessed RFX6-dependent a cell function. RFX6 suppression with RNA interference led to impaired a cell exocytosis and dysregulated glucagon secretion in vitro and in vivo. By contrast, these phenotypes were not observed with RFX6 suppression across all islet cells. Transcriptomics in a cells revealed RFX6-dependent expression of genes governing nutrient sensing, hormone processing, and secretion, with some of these exclusively expressed in human a cells. Mapping of RFX6 DNA-binding sites in primary human islet cells identified a subset of direct RFX6 target genes. Together, these data unveil RFX6-dependent genetic targets and mechanisms crucial for regulating adult human a cell function.


ARTICLE HIGHLIGHTS

· RFX6 is expressed in all islet endocrine cell types and is dysregulated in multiple forms of diabetes, but its function has not yet been delineated in a cells.

· We used specific targeting of shRNA-mediated suppression of RFX6 in primary human a cells to unveil glucagon secretion phenotypes.

· RFX6 is required in adult human a cells to maintain gene regulation and hallmark functions, including regulated glucagon secretion.

· RNA-sequencing and CUT&RUN studies reveal distinct RFX6 genetic targets in adult human a and b cells.

Funding

Human Islet Research Network SCR_014393 U01-DK-123594 U01-DK-123716 UC4-DK-112217 UC4-DK-112232

Human Pancreas Analysis Program x SCR_016202

JDRF x 3-PDF-2018-584-A-N

National Science Foundation DGF-114747

NIH x 1S10OD021763 5T32GM007790 P30 DK116074 R01 DK107507 R01 DK108817 R01DK126482 S10OD025212 U01 DK123743 UC4 DK098085

History