Abstract:
Protein kinase C (PKC) is a family of protein kinases controlling protein phosphorylation
and playing important roles in the regulation of metabolism. We have investigated expression levels of PKC isoforms in pancreatic islets and liver of diabetic Goto-Kakizaki (GK) rats
with and without insulin treatment to evaluate their association with glucose homeostasis.
mRNA and protein expression levels of PKC isoforms were assessed in pancreatic islets
and liver of Wistar rats and GK rats with or without insulin treatment. PKCα and PKCζ
mRNA expressions were down-regulated in islets of GK compared with Wistar rats. PKCα
and phosphorylated PKCα (p-PKCα) protein expressions were decreased in islets of GK
compared with insulin-treated GK and Wistar rats. PKCζ protein expression in islets was
reduced in GK and insulin-treated GK compared with Wistar rats, but p-PKCζ was
decreased only in GK rats. Islet PKCε mRNA and protein expressions were lower in GK
compared with insulin-treated GK and Wistar rats. In liver, PKCδ and PKCζ mRNA expressions were decreased in both GK and insulin-treated GK compared with Wistar rats. Hepatic
PKCζ protein expression was diminished in both GK rats with and without insulin treatment
compared with Wistar rats. Hepatic PKCε mRNA expression was down-regulated in insulintreated GK compared with GK and Wistar rats. PKCα, PKCε, and p-PKCζ expressions were
secondary to hyperglycaemia in GK rat islets. Hepatic PKCδ and PKCζ mRNA expressions
were primarily linked to hyperglycaemia. Additionally, hepatic PKCε mRNA expression
could be under control of insulin.
