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bioRxiv · 10.1101/2021.06.25.449947

ROCK1 regulates insulin secretion from β-cells

Sung, B.-J.·Lim, S.-B.·Kim, J. H.·Yang, W.-M.·Kulkarni, R. N.·Kim, Y.-B.·Lee, M. K.
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Abstract

ObjectiveThe endocrine pancreatic {beta}-cells play a pivotal role in the maintenance of whole-body glucose homeostasis and its dysregulation is a consistent feature in all forms of diabetes. However, knowledge of intracellular regulators that modulate {beta}-cell function remains incomplete. We investigated the physiological role of ROCK1 in the regulation of insulin secretion and glucose homoeostasis. MethodsMice lacking ROCK1 in pancreatic {beta}-cells (RIP-Cre; ROCK1loxP/loxP, {beta}-ROCK1-/-) were studied. Glucose and insulin tolerance tests as well as glucose-stimulated insulin secretion (GSIS) were measured. Insulin secretion response to a direct glucose or pyruvate or pyruvate kinase (PK) activator stimulation in isolated islets from {beta}-ROCK1-/- mice or {beta}-cell lines with knockdown of ROCK1 were also evaluated. Proximity ligation assay was performed to determine the physical interactions between PK and ROCK1. ResultsMice with a deficiency of ROCK1 in pancreatic {beta}-cells exhibited significantly increased blood glucose levels and reduced serum insulin without changes in body weight. Interestingly, {beta}-ROCK1-/- mice displayed progressive impairment of glucose tolerance while maintaining insulin sensitivity mostly due to impaired GSIS. Consistently, GSIS was markedly decreased in ROCK1-deficient islets and ROCK1 knockdown INS-1 cells. Concurrently, ROCK1 blockade led to a significant decrease in intracellular calcium levels, ATP levels, and oxygen consumption rates in isolated islets and INS-1 cells. Treatment of ROCK1-deficient islets or ROCK1 knockdown {beta}-cells either with pyruvate or a PK activator rescued the impaired GSIS. Mechanistically, we observed that ROCK1 binding to PK is greatly enhanced by glucose stimulation in {beta}-cells. ConclusionsOur findings demonstrate that {beta}-cell ROCK1 is essential for glucose-stimulated insulin secretion and maintenance of glucose homeostasis and that ROCK1 acts as an upstream regulator of glycolytic pyruvate kinase signaling.

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Sung, B.-J., Lim, S.-B., Kim, J. H., Yang, W.-M., Kulkarni, R. N., Kim, Y.-B., Lee, M. K.. 2021-06-25. ROCK1 regulates insulin secretion from β-cells. https://doi.org/10.1101/2021.06.25.449947

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