Expansion of adult beta-cell mass in response to increased metabolic demand is dependent on HNF-4alpha
Department of Pediatrics
Medical Subject Headings
Animals; Base Sequence; Cell Proliferation; DNA-Binding Proteins; Extracellular Signal-Regulated MAP Kinases; Female; Hepatocyte Nuclear Factor 4; Insulin-Secreting Cells; Islets of Langerhans; Mice; Mice, Transgenic; Models, Genetic; Molecular Sequence Data; Pregnancy; Signal Transduction; Transcription, Genetic; Tumor Suppressor Proteins; ras Proteins
Endocrinology, Diabetes, and Metabolism | Pediatrics
The failure to expand functional pancreatic beta-cell mass in response to increased metabolic demand is a hallmark of type 2 diabetes. Lineage tracing studies indicate that replication of existing beta-cells is the principle mechanism for beta-cell expansion in adult mice. Here we demonstrate that the proliferative response of beta-cells is dependent on the orphan nuclear receptor hepatocyte nuclear factor-4alpha (HNF-4alpha), the gene that is mutated in Maturity-Onset Diabetes of the Young 1 (MODY1). Computational analysis of microarray expression profiles from isolated islets of mice lacking HNF-4alpha in pancreatic beta-cells reveals that HNF-4alpha regulates selected genes in the beta-cell, many of which are involved in proliferation. Using a physiological model of beta-cell expansion, we show that HNF-4alpha is required for beta-cell replication and the activation of the Ras/ERK signaling cascade in islets. This phenotype correlates with the down-regulation of suppression of tumorigenicity 5 (ST5) in HNF-4alpha mutants, which we identify as a novel regulator of ERK phosphorylation in beta-cells and a direct transcriptional target of HNF-4alpha in vivo. Together, these results indicate that HNF-4alpha is essential for the physiological expansion of adult beta-cell mass in response to increased metabolic demand.
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Citation: Genes Dev. 2007 Apr 1;21(7):756-69. Link to article on publisher's site