Role of the SIK2–p35–PJA2 complex in pancreatic β-cell functional compensation

JI Sakamaki, A Fu, C Reeks, S Baird, C Depatie… - Nature cell …, 2014 - nature.com
JI Sakamaki, A Fu, C Reeks, S Baird, C Depatie, M Al Azzabi, N Bardeesy, AC Gingras
Nature cell biology, 2014nature.com
Energy sensing by the AMP-activated protein kinase (AMPK) is of fundamental importance
in cell biology. In the pancreatic β-cell, AMPK is a central regulator of insulin secretion. The
capacity of the β-cell to increase insulin output is a critical compensatory mechanism in
prediabetes, yet its molecular underpinnings are unclear. Here we delineate a complex
consisting of the AMPK-related kinase SIK2, the CDK5 activator CDK5R1 (also known as
p35) and the E3 ligase PJA2 essential for β-cell functional compensation. Following glucose …
Abstract
Energy sensing by the AMP-activated protein kinase (AMPK) is of fundamental importance in cell biology. In the pancreatic β-cell, AMPK is a central regulator of insulin secretion. The capacity of the β-cell to increase insulin output is a critical compensatory mechanism in prediabetes, yet its molecular underpinnings are unclear. Here we delineate a complex consisting of the AMPK-related kinase SIK2, the CDK5 activator CDK5R1 (also known as p35) and the E3 ligase PJA2 essential for β-cell functional compensation. Following glucose stimulation, SIK2 phosphorylates p35 at Ser 91, to trigger its ubiquitylation by PJA2 and promote insulin secretion. Furthermore, SIK2 accumulates in β-cells in models of metabolic syndrome to permit compensatory secretion; in contrast, β-cell knockout of SIK2 leads to accumulation of p35 and impaired secretion. This work demonstrates that the SIK2–p35–PJA2 complex is essential for glucose homeostasis and provides a link between p35–CDK5 and the AMPK family in excitable cells.
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