Exp Mol Med.  1999 Dec;31(4):179-184.

Increased expression of Galphaq protein in the heart of streptozotocin-induced diabetic rats

• Yang JM
• Cho CH
• Kong KA
• Jang IS
• Kim HW
• Juhnn YS

Abstract

Heart disease is one of the major cause of death in diabetic patients, but the thogenesis of diabetic cardio-myopathy remains unclear. In this experiment, to sess the significance of G protein signaling pathways in the pathogenesis of abetic cardiomyopathy, we analyzed the expression of G proteins and the tivities of second messenger dependent protein kinases: cAMP-dependent protein nase (PKA), DAG-mediated protein kinase C (PKC), and calmodulin dependent otein kinase II (CaM kinase II) in the streptozotocin induced diabetic rat art. The expression of Galphaq was increased by slightly over 10% (P<0.05) in abetic rat heart, while Galphas, Galphai, and Gbeta remained unchanged. The A activity in the heart did not change significantly but increased by 27%<0.01) in the liver. Insulin treatment did not restore the increased activity the liver. Total PKC activity in the heart was increased by 56% (P<0.01), and sulin treatment did not restore such increase. The CaM kinase II activity in e heart remained at the same level but was slightly increased in the liver 4% increase, P<0.05). These findings of increased expression of Galphaq in the reptozotocin-diabetic rat heart that are reflected by the increased level of C activity and insensitivity to insulin demonstrate that alteration of Galphaq y underlie, at least partly, the cardiac dysfunction that is associated with abetes. Copyright 2000 Academic Press.

Keyword

G proteins; protein kinase; cAMP dependent protein kinase; protein kinase C

MeSH Terms

Animal
Ca(2+)-Calmodulin Dependent Protein Kinase/metabolism
Cyclic AMP-Dependent Protein Kinases/metabolism
Diabetes Mellitus, Experimental/metabolism*
Diabetes Mellitus, Experimental/drug therapy
Diabetes Mellitus, Experimental/chemically induced
GTP-Binding Proteins/metabolism*
Insulin/pharmacology
Liver/metabolism
Liver/drug effects
Male
Myocardium/metabolism*
Protein Kinase C/metabolism
Rats
Rats, Sprague-Dawley
Signal Transduction
Streptozocin