scholarly journals Role of Protein Kinase C in Diabetic Complications

Author(s):  
Simran ◽  
Amarjot Kaur Grewal ◽  
Sandeep Arora ◽  
Thakur Gurjeet Singh

Diabetes is the most common and systemic disorder associated with hyperglycemia which is the significant factor in the development of micro- and macrovascular changes. Many mechanistic approaches i.e. activation of Protein kinase C, glycation end products production, hexosamine pathway and polyol pathway induce cellular damage and lead to the development of diabetic complications like nephropathy, neuropathy, retinopathy, and myopathy. One of the adverse effects of long-lasting hyperglycemia is activation of PKC (intracellular signaling enzyme) and has become a field of great research interest. Hence, in this review special emphasis is placed on microvascular complications which are due to activation of PKC. Clinical trials have also been conducted using selective PKC inhibitors and have shown positive results against hyperglycemia.

2005 ◽  
Vol 39 (10) ◽  
pp. 1693-1699 ◽  
Author(s):  
Scott V Joy ◽  
Ann C Scates ◽  
Srilaxmi Bearelly ◽  
Moahad Dar ◽  
Christina A Taulien ◽  
...  

OBJECTIVE: To review current clinical data regarding the pharmacologic actions of ruboxistaurin (LY333531) mesylate, an inhibitor of protein kinase C (PKC) β, and its role to potentially reduce the development and/or the progression of diabetic microvascular complications. DATA SOURCES: Primary literature was obtained via a MEDLINE search (1966–August 2004) and through review of pertinent abstracts and presentations at major medical meetings. STUDY SELECTION AND DATA EXTRACTION: Literature relevant to PKC physiology, the pharmacokinetics of ruboxistaurin, and data evaluating the use of ruboxistaurin in treating diabetic microvascular complications in human and relevant animal models was reviewed. DATA SYNTHESIS: PKC is part of a group of intracellular signaling molecules activated in response to various specific hormonal, neuronal, and growth factor stimuli. Hyperglycemia leads to PKC β 1 and 2 isoform activation, which experimentally has been shown to contribute to the development and progression of diabetic microvascular complications (retinopathy, nephropathy, neuropathy) through various biochemical mechanisms. Animal and/or human studies using ruboxistaurin mesylate, a novel, highly selective inhibitor of PKC β, have shown delay in the progression and, in some cases, reversal of diabetic retinopathy, nephropathy, and neuropathy. CONCLUSIONS: Ruboxistaurin mesylate, by inhibiting excessive activation of certain PKC isoforms, has the potential to reduce the burden of microvascular complications for patients with diabetes.


2005 ◽  
Vol 26 (3) ◽  
pp. 380-392 ◽  
Author(s):  
Satish K. Srivastava ◽  
Kota V. Ramana ◽  
Aruni Bhatnagar

Aldose reductase (AR) is widely expressed aldehyde-metabolizing enzyme. The reduction of glucose by the AR-catalyzed polyol pathway has been linked to the development of secondary diabetic complications. Although treatment with AR inhibitors has been shown to prevent tissue injury in animal models of diabetes, the clinical efficacy of these drugs remains to be established. Recent studies suggest that glucose may be an incidental substrate of AR, which appears to be more adept in catalyzing the reduction of a wide range of aldehydes generated from lipid peroxidation. Moreover, inhibition of the enzyme has been shown to increase inflammation-induced vascular oxidative stress and prevent myocardial protection associated with the late phase of ischemic preconditioning. On the basis of these studies, several investigators have ascribed an important antioxidant role to the enzyme. Additionally, ongoing work indicates that AR is a critical component of intracellular signaling, and inhibition of the enzyme prevents high glucose-, cytokine-, or growth factor-induced activation of protein kinase C and nuclear factor-κ-binding protein. Thus, treatment with AR inhibitors prevents vascular smooth muscle cell growth and endothelial cell apoptosis in culture and inflammation and restenosis in vivo. Additional studies indicate that the antioxidant and signaling roles of AR are interlinked and that AR regulates protein kinase C and nuclear factor-κB via redox-sensitive mechanisms. These data underscore the need for reevaluating anti-AR interventions for the treatment of diabetic complications. Potentially, the development of newer drugs that selectively inhibit ARmediated glucose metabolism and signaling, without affecting aldehyde detoxification, may be useful in preventing inflammation associated with the development of diabetic complications, particularly micro- and macrovascular diseases.


Development ◽  
2000 ◽  
Vol 127 (1) ◽  
pp. 33-44 ◽  
Author(s):  
J. Wang ◽  
L. Mayernik ◽  
J.F. Schultz ◽  
D.R. Armant

Heparin-binding EGF-like growth factor (HB-EGF) is expressed in the mouse endometrial epithelium during implantation exclusively at sites apposed to embryos and accelerates the development of cultured blastocysts, suggesting that it may regulate peri-implantation development in utero. We have examined the influence of HB-EGF on mouse trophoblast differentiation in vitro and the associated intracellular signaling pathways. HB-EGF both induced intracellular Ca2+ signaling and accelerated trophoblast development to an adhesion-competent stage, but only late on gestation day 4 after ErbB4, a receptor for HB-EGF, translocated from the cytoplasm to the apical surface of trophoblast cells. The acceleration of blastocyst differentiation by HB-EGF was attenuated after inhibition of protein tyrosine kinase activity or removal of surface heparan sulfate, as expected. Chelation of intracellular Ca2+ blocked the ability of HB-EGF to accelerate development, as did inhibitors of protein kinase C or calmodulin. The absence of any effect by a phospholipase C inhibitor and the requirement for extracellular Ca2+ suggested that the accrued free cytoplasmic Ca2+ did not originate from inositol phosphate-sensitive intracellular stores, but through Ca2+ influx. Indeed, N-type Ca2+ channel blockers specifically inhibited the ability of HB-EGF to both induce Ca2+ signaling and accelerate trophoblast development. We conclude that HB-EGF accelerates the differentiation of trophoblast cells to an adhesion-competent stage by inducing Ca2+ influx, which activates calmodulin and protein kinase C. An upstream role for ErbB4 in this pathway is implicated by the timing of its translocation to the trophoblast surface.


1998 ◽  
Vol 79 (2) ◽  
pp. 1127-1131 ◽  
Author(s):  
Rainer W. Friedrich ◽  
G. F. Molnar ◽  
Michael Schiebe ◽  
A. Joffre Mercier

Friedrich, Rainer W., G. F. Molnar, Michael Schiebe, and A. Joffre Mercier. Protein kinase C is required for long-lasting synaptic enhancement by the neuropeptide DRNFLRFamide in crayfish. J. Neurophysiol. 79: 1127–1131, 1998. The FMRFamide-related neuropeptide AspArgAsnPheLeuArgPhe-NH2 (DRNFLRFamide, DF2) induces a long-lasting enhancement of synaptic transmission at neuromuscular junctions on the crayfish deep abdominal extensor muscles. Here we investigated the function of protein kinase C (PKC) in this effect because PKC has been implied in the control of long-term synaptic modulation in other systems. The general kinase antagonist staurosporine reduced both the initial increase in excitatory postsynaptic potential (EPSP) amplitude and the duration of synaptic enhancement. Unlike staurosporine, the selective PKC inhibitors, chelerythrine and bisindolylmaleimide, augmented the initial EPSP increase. However, like staurosporine, they also reduced the duration of synaptic enhancement. The PKC activator, phorbol-12-myristate 13-acetate, induced a long-lasting synaptic enhancement that was blocked by chelerythrine. These results show that synaptic enhancement by DF2 is mediated by different intracellular signaling systems that act in temporal sequence. The initial increase in EPSP amplitudes is negatively regulated by PKC and involves another, staurosporine-sensitive, kinase; whereas, the maintenance of synaptic enhancement requires PKC.


2003 ◽  
Vol 19 (2) ◽  
pp. 131-139 ◽  
Author(s):  
Hideki Kamiya ◽  
Jiro Nakamura ◽  
Yoji Hamada ◽  
Eitaro Nakashima ◽  
Keiko Naruse ◽  
...  

1993 ◽  
Vol 264 (5) ◽  
pp. F845-F853
Author(s):  
M. M. Friedlaender ◽  
D. Jain ◽  
Z. Ahmed ◽  
D. Hart ◽  
R. L. Barnett ◽  
...  

Previous work from this laboratory has identified an endothelin (ET) type A (ETA) receptor on cultured rat renal medullary interstitial cells (RMIC), coupled to phosphatidylinositol-specific phospholipase C (PI-PLC), dihydropyridine-insensitive receptor-operated Ca2+ channels, and phospholipase A2. The current studies explored a role for ET stimulation of phosphatidylcholine-specific phospholipase D (PC-PLD) in intracellular signaling of this cell type. ET stimulated PLD activation, as measured by phosphatidic acid (PA) or phosphatidylethanol (PEt) accumulation, in a time- and concentration-dependent manner. Inhibition of diacylglycerol (DAG) kinase by ethylene glycol dioctanoate or 6-(2)4-[(4-fluorophenyl)-phenylmethylene]-1-piperadinyl]ethy l-7-methyl-5H - thiaxolo-[3,2-alpyrimidin]-5-one (R 59022) failed to blunt PA accumulation, indicating that PLD, and not DAG, was the source of PA. Inhibition of PA phosphohydrolase (PAP) by propranolol increased late accumulation of PA, suggesting that the prevailing metabolic flow was in the direction of PA to DAG. Phorbol 12-myristate 13-acetate (PMA) augmented ET-evoked PEt accumulation, whereas downregulation of protein kinase C (PKC) obviated agonist-induced PEt production. PMA augmentation of PLD activity proceeded independent of cytosolic free Ca2+ concentration. Ca2+ derived from either intracellular or extracellular sources enhanced ET-related PEt accumulation but was without effect in PKC-downregulated cells. Collectively, these observations indicate that ET stimulates PLD production in RMIC. PKC is the major regulator of this process, with Ca2+ playing a secondary, modulatory role. In addition, these data suggest that PC-PLD is coupled to the ETA receptor.


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