Transcriptional Regulation of X-Box-Binding Protein One (XBP1) by Hepatocyte Nuclear Factor 4α (HNF4α) is Vital to Beta-Cell Function.
Research output: Contribution to journal › Article
The transcription factor, X-box Binding Protein-One (XBP1), controls the development and maintenance of the endoplasmic reticulum (ER) in multiple secretory cell lineages. We show here that Hepatocyte Nuclear Factor 4-alpha (HNF4α) directly induces XBP1 expression. Mutations in HNF4α cause Mature-Onset Diabetes of the Young I (MODYI), a subset of diabetes characterized by diminished GSIS. In mouse models, cell lines, and ex vivo islets, using dominant negative and human-disease-allele point mutants or knockout and knockdown models, we show that disruption of HNF4α caused decreased expression of XBP1 and reduced cellular ER networks. GSIS depends on ER Ca2+ signaling; we show that diminished XBP1 and/or HNF4α in β-cells led to impaired ER Ca2+ homeostasis. Restoring XBP1 expression was sufficient to completely rescue GSIS in HNF4α-deficient β-cells. Our findings uncover a transcriptional relationship between HNF4α and Xbp1 with potentially broader implications about MODYI and the importance of transcription factor signaling in the regulation of secretion.
|Research areas and keywords||
Subject classification (UKÄ) – MANDATORY
|Journal||Journal of Biological Chemistry|
|Early online date||2016 Jan 20|
|Publication status||Published - 2016|