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Updated: Aug 15, 2026
Assessment of Mitochondrial Functions and Cell Viability in Renal Cells Overexpressing Protein Kinase C Isozymes
Published on: January 7, 2013
Differential expression of protein kinase C isoforms in streptozotocin-induced diabetic rats
N Kang1, G Alexander, J K Park
1Franz Volhard Clinic, Max Delbrück Center, Medizinische Fakultät der Charité, Humboldt University of Berlin, Germany.
Background:
The cellular effects of hyperglycemia are mediated by protein kinase C (PKC). However, PKC consists of several distinct isoforms, and their contribution to the pathogenesis of diabetic complications in different organs is not clear. We investigated the expression and translocation of PKC isoforms alpha, betaI, betaII, delta, epsilon, and zeta in kidney, heart, and aorta from diabetic rats.
Methods:
Hyperglycemia was induced with streptozotocin (70 mg/kg) in the rat. After four weeks, PKC isoform expression was assessed by Western blot after tissue fractionation and by immunohistochemistry.
Results:
Streptozotocin increased blood glucose from 117.0 +/- 3.6 to 510.0 +/- 19.4 mg/dl (N = 8, P < 0.01) and induced albuminuria. PKC isoforms alpha, beta, delta, epsilon, and zeta were all detected in control animals. Western blot showed increased PKC alpha expression in kidney and heart (160% and 170%, respectively). PKC betaI, betaII, and delta expression was not influenced by hyperglycemia. PKC zeta was decreased in diabetic animals in both tissues by 60%. The membrane association of PKC alpha and PKC epsilon was increased; however, the relative amount of PKC in the particulate fraction was not influenced by hyperglycemia. Immunohistochemistry revealed a marked increase in PKC alpha immunoreactivity in renal glomeruli and interstitial capillaries, cardiac capillaries, and skeletal muscle, as well as in the endothelial cells of larger arteries. PKC beta showed a small decrease in the glomeruli. PKC epsilon was increased in renal tubules in diabetic rats but was decreased in the myocardium. PKC zeta was expressed in both myocardial and glomerular cells but was decreased during hyperglycemia. Our results demonstrate that PKC isoforms are differentially regulated in kidney and heart in diabetes. High glucose increases PKC alpha expression, whereas PKC zeta is down-regulated. The finding that PKC alpha is mostly increased in endothelial cells supports a role for PKC alpha in functional endothelial disturbances observed in diabetes.
Insights
High glucose levels in diabetes increase Protein Kinase C (PKC) alpha expression, particularly in blood vessels, while decreasing PKC zeta. This suggests PKC alpha
Area of Science:
- Biochemistry
- Molecular Biology
- Physiology
Background:
- Cellular effects of hyperglycemia are mediated by Protein Kinase C (PKC).
- The specific roles of different PKC isoforms in diabetic complications are not fully understood.
- This study investigates PKC isoform expression and translocation in diabetic rat organs.
Purpose of the Study:
- To determine the expression and translocation patterns of specific PKC isoforms (alpha, betaI, betaII, delta, epsilon, zeta) in the kidney, heart, and aorta of diabetic rats.
- To elucidate the differential regulation of PKC isoforms under hyperglycemic conditions.
- To explore the potential role of PKC alpha in diabetic endothelial dysfunction.
Main Methods:
- Hyperglycemia was induced in rats using streptozotocin.
- PKC isoform expression was analyzed using Western blot and immunohistochemistry after four weeks.
- Tissue fractionation was employed to assess protein localization.
Main Results:
- Streptozotocin successfully induced hyperglycemia and albuminuria.
- PKC alpha expression significantly increased in the kidney and heart, with elevated membrane association.
- PKC zeta expression decreased in both tissues, while PKC beta and delta levels remained largely unchanged.
- Immunohistochemistry confirmed increased PKC alpha in endothelial cells of various tissues and organs.
- PKC epsilon showed differential regulation, increasing in renal tubules but decreasing in the myocardium.
- PKC zeta was reduced in myocardial and glomerular cells.
Conclusions:
- PKC isoforms are differentially regulated in the kidney and heart during diabetes.
- Hyperglycemia upregulates PKC alpha expression and downregulates PKC zeta.
- Increased PKC alpha in endothelial cells supports its role in diabetic functional endothelial disturbances.
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