Involvement of Per–Arnt–Sim (PAS) kinase in the stimulation of preproinsulin and pancreatic duodenum homeobox 1 gene expression by glucose

doi:10.1073/pnas.0307737101

Involvement of Per–Arnt–Sim (PAS) kinase in the stimulation of preproinsulin and pancreatic duodenum homeobox 1 gene expression by glucose

^*Henry Wellcome Signalling Laboratories and Department of Biochemistry, University of Bristol, Bristol BS8 ITD, United Kingdom; and ^†Department of Biochemistry, University of Utah, Salt Lake City, UT 83132

Edited by Donald F. Steiner, University of Chicago, Chicago, IL (received for review November 21, 2003)

Abstract

Per–Arnt–Sim (PAS) domain-containing kinases are common in prokaryotes, but a mammalian counterpart has only recently been described. Although the PAS domain of the mammalian PAS kinase (PASK) is closely related to the bacterial oxygen sensor FixL, it is unclear whether PASK activity is changed in mammalian cells in response to nutrients and might therefore contribute to signal transduction by these or other stimuli. Here, we show that elevated glucose concentrations rapidly increase PASK activity in pancreatic islet β cells, an event followed by the accumulation of both PASK mRNA and protein. Demonstrating a physiological role for PASK activation, comicroinjection into clonal β cells of cDNA encoding wild-type PASK, or PASK protein itself, mimics the induction of preproinsulin promoter activity by high glucose concentrations. Conversely, anti-PASK antibodies block promoter activation by the sugar, and the silencing of PASK expression by RNA interference suppresses the up-regulation by glucose of preproinsulin and pancreatic duodenum homeobox 1 gene expression, without affecting glucose-induced changes in the levels of mRNAs encoding glucokinase or uncoupling protein 2. We conclude that PASK is an important metabolic sensor in nutrient-sensitive mammalian cells and plays an unexpected role in the regulation of key genes involved in maintaining the differentiated phenotype of pancreatic β cells.

Footnotes

↵ ‡ To whom correspondence should be addressed. E-mail: g.a.rutter{at}bristol.ac.uk.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations: AMPK, 5′-AMP-activated protein kinase; hGH, human growth hormone; PASK, mammalian Per–Arnt–Sim domain protein kinase; PDX-1, pancreatic duodenum homeobox 1; siRNA, small interfering RNA.