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Hexosamine biosynthesis pathway flux contributes to insulin resistance via altering membrane phosphatidylinositol 4,5-bisphosphate and cortical filamentous actin.

Abstract：

:We recently found that plasma membrane phosphatidylinositol 4,5-bisphosphate (PIP(2))-regulated filamentous actin (F-actin) polymerization was diminished in hyperinsulinemic cell culture models of insulin resistance. Here we delineated whether increased glucose flux through the hexosamine biosynthesis pathway (HBP) causes the PIP(2)/F-actin dysregulation and insulin resistance induced by hyperinsulinemia. Increased HBP activity was detected in 3T3-L1 adipocytes cultured under conditions closely resembling physiological hyperinsulinemia (5 nm insulin for 12 h) and in cells where HBP activity was amplified by 2 mm glucosamine (GlcN). Both the physiological hyperinsulinemia and experimental GlcN challenge induced comparable losses of PIP(2) and F-actin. In addition to protecting against the insulin-induced membrane/cytoskeletal abnormality and insulin-resistant state, exogenous PIP(2) corrected the GlcN-induced insult on these parameters. Moreover, in accordance with HBP flux directly weakening PIP(2)/F-actin structure, inhibition of the rate-limiting HBP enzyme (glutamine:fructose-6-phosphate amidotransferase) restored PIP(2)-regulated F-actin structure and insulin responsiveness. Conversely, overexpression of glutamine:fructose-6-phosphate amidotransferase was associated with a loss of detectable plasma membrane PIP(2) and insulin sensitivity. A slight decrease in intracellular ATP resulted from amplifying HBP by hyperinsulinemia and GlcN. However, experimental maintenance of the intracellular ATP pool under both conditions with inosine did not reverse the PIP(2)/F-actin-based insulin-resistant state. Furthermore, less invasive challenges with glucose, in the absence of insulin, also led to PIP(2)/F-actin dysregulation. Accordingly, we suggest that the functionality of cell systems dependent on PIP(2) and/or F-actin status, such as the glucose transport system, can be critically compromised by inappropriate HBP activity.

journal_name

Endocrinology

journal_title

Endocrinology

authors

Bhonagiri P,Pattar GR,Horvath EM,Habegger KM,McCarthy AM,Elmendorf JS

doi

10.1210/en.2008-1102

subject

Has Abstract

pub_date

2009-04-01 00:00:00

pages

1636-45

issue

eissn

0013-7227

issn

1945-7170

pii

en.2008-1102

journal_volume

150

pub_type

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Hexosamine biosynthesis pathway flux contributes to insulin resistance via altering membrane phosphatidylinositol 4,5-bisphosphate and cortical filamentous actin.