H. Eldar-finkelman et al., Increased glycogen synthase kinase-3 activity in diabetes- and obesity-prone C57BL/6J mice, DIABETES, 48(8), 1999, pp. 1662-1666
Although the precise mechanisms contributing to insulin resistance and type
2 diabetes are unknown, it is believed that defects in downstream componen
ts of the insulin signaling pathway may be involved. In this work, we hypot
hesize that a serine/threonine kinase, glycogen synthase kinase-3 (GSK-3),
may be pertinent in this regard. To test this hypothesis, we examined GSK-3
activity in two inbred mouse strains known to be susceptible (C57BL/6J) or
resistant (A/J) to diet-induced obesity and diabetes. Examination of GSK-3
in fat, liver, and muscle tissues of C57BL/6J mice revealed that GSK-3 act
ivity increased twofold in the epididymal fat tissue and remained unchanged
in muscle and liver of mice fed a high-fat diet, compared with their low-f
at diet-fed counterparts. In contrast, GSK-3 activity did not change in the
epididymal fat tissue of A/J mice, regardless of the type of diet they wer
e fed. In addition, both basal and diet-induced GSK-3 activity tvas higher
(2.3- and 3.2-fold, respectively) in the adipose tissue of C57BL/6J mice co
mpared with that in A/J mice, Taken together, our studies suggest an unsusp
ected Link between increased GSK-3 activity and development of insulin resi
stance and type 2 diabetes in fat tissue of C57BL/6J mice, and implicate GS
K-3 as a potential factor contributing to susceptibility of C57BL/6J mice t
o diet-induced diabetes.