TITLE

Depletion of the catalytic subunit of protein phosphatase-2A (PP2Ac) markedly attenuates glucose-stimulated insulin secretion in pancreatic β-cells

AUTHOR(S)
Giridhar Jangati; Rajakrishnan Veluthakal; Laura Susick; Scott Gruber; Anjaneyulu Kowluru
PUB. DATE
June 2007
SOURCE
Endocrine (1355008X);Jun2007, Vol. 31 Issue 3, p248
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Among various phosphatases, the protein phosphatase 2A (PP2A) is relatively well studied in the islet. Previously, we have demonstrated that the catalytic subunit of PP2A (PP2Ac) undergoes okadaic acid (OKA)-sensitive, reversible carboxylmethylation (CML), which appears to be requisite for glucose-stimulated insulin secretion (GSIS). Using the siRNA approach, we examined, herein, the contributory roles of PP2Ac in GSIS from insulin-secreting pancreatic β-(INS-1 832/13) cells. Immunologically, PP2Ac was detectable in all the subcellular fractions studied in rank order of: cytosol > microsomes > secretory granules = nucleus > mitochondria. Transfection of PP2Ac-specific, but not scrambled-siRNA, markedly attenuated PP2A activity and GSIS in these cells. Together, our findings provide a direct evidence for a positive modulatory role for PP2Ac in signaling steps leading to GSIS.
ACCESSION #
27039252

 

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