Alterations in specific protein-tyrosine phosphatases accompany insulin resistance of streptozotocin diabetes

F Ahmad, BJ Goldstein - American Journal of Physiology …, 1995 - journals.physiology.org
American Journal of Physiology-Endocrinology And Metabolism, 1995journals.physiology.org
To test whether protein tyrosine phosphatases (PTPases) may play a role in the insulin
resistance of insulinopenic diabetes, we assessed PTPase activity as well as the protein and
mRNA abundance of three major candidate PTPases in subcellular fractions of liver and
skeletal muscle of streptozotocin-diabetic rats before and after insulin treatment. PTPase
activity against the insulin receptor in liver and muscle cytosol increased to 120-125% of
control in the diabetic animals and by an additional 5-10% after insulin treatment. In the …
To test whether protein tyrosine phosphatases (PTPases) may play a role in the insulin resistance of insulinopenic diabetes, we assessed PTPase activity as well as the protein and mRNA abundance of three major candidate PTPases in subcellular fractions of liver and skeletal muscle of streptozotocin-diabetic rats before and after insulin treatment. PTPase activity against the insulin receptor in liver and muscle cytosol increased to 120-125% of control in the diabetic animals and by an additional 5-10% after insulin treatment. In the particulate fraction, PTPase activity decreased to 65-70% of control in diabetic liver and muscle and increased to 115-120% of control after insulin treatment. Protein for the leukocyte common antigen-related PTPase paralleled the changes in the PTPase activity in the particulate fraction. SH-PTP2/syp and PTPase 1B were both significantly increased in diabetes. SH-PTP2/syp also exhibited an increased ratio of particulate to cytosol distribution in diabetic tissues (1.8-1.9) that was reversed after insulin treatment (0.79-0.95). Northern analysis suggested that the PTPases were regulated at a pretranslational level. These changes in the abundance and distribution of specific PTPases may be involved in the pathogenesis of insulin resistance in insulinopenic diabetes.
American Physiological Society