PDX1 deficiency causes mitochondrial dysfunction and defective insulin secretion through TFAM suppression.

Gauthier BR, Wiederkehr A, Baquié M, Dai C, Powers AC, Kerr-Conte J, Pattou F, MacDonald RJ, Ferrer J, Wollheim CB
Cell Metab. 2009 10 (2): 110-8

PMID: 19656489 · PMCID: PMC4012862 · DOI:10.1016/j.cmet.2009.07.002

Mutations in the transcription factor Pdx1 cause maturity-onset diabetes of the young 4 (MODY4). Islet transduction with dominant-negative Pdx1 (RIPDN79PDX1) impairs mitochondrial metabolism and glucose-stimulated insulin secretion (GSIS). Transcript profiling revealed suppression of nuclear-encoded mitochondrial factor A (TFAM). Herein, we show that Pdx1 suppression in adult mice reduces islet TFAM expression coinciding with hyperglycemia. We define TFAM as a direct target of Pdx1 both in rat INS1 cells and human islets. Adenoviral overexpression of TFAM along with RIPDN79PDX1 in isolated rat islets rescued mitochondrial DNA (mtDNA) copy number and restored respiratory chain activity as well as glucose-induced ATP synthesis and insulin secretion. CGP37157, which blocks the mitochondrial Na(+)/Ca(2+) exchanger, restored ATP generation and GSIS in RIPDN79PDX1 islets, thereby bypassing the transcriptional defect. Thus, the genetic control by the beta cell-specific factor Pdx1 of the ubiquitous gene TFAM maintains beta cell mtDNA vital for ATP production and normal GSIS.

MeSH Terms (22)

Animals Base Sequence DNA-Binding Proteins Doxycycline Glucose High Mobility Group Proteins Homeodomain Proteins Humans Insulin Insulin Secretion Islets of Langerhans Male Mice Mice, Transgenic Mitochondria Mitochondrial Proteins Promoter Regions, Genetic Rats Rats, Wistar Sodium-Calcium Exchanger Trans-Activators Transcription Factors

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