Competitive inhibitors and allosteric activators of protein kinase C isoenzymes: a personal account and progress report on transferring academic discoveries to the clinic

2007 ◽  
Vol 35 (5) ◽  
pp. 1021-1026 ◽  
Author(s):  
G.R. Budas ◽  
T. Koyanagi ◽  
E.N. Churchill ◽  
D. Mochly-Rosen
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Basic Research ◽  
Competitive Inhibitor ◽  
Personal Account ◽  
Protein Protein Interaction ◽  
Kinase C ◽  
Competitive Inhibitors ◽  
Pkc Protein Kinase C ◽  
Drug Leads

PKC (protein kinase C) isoenzymes are related protein kinases, involved in many signalling events in normal state and in disease. Basic research into identifying the molecular basis of PKC selectivity led to simple strategies to identify selective competitive inhibitor peptides and allosteric agonist peptides of individual PKC isoenzymes. The strategies and rationale used to identify these peptide regulators of protein–protein interaction may be applicable to other signalling events. Importantly, the PKC-regulating peptides proved to be useful pharmacological tools and may serve as drugs or drug leads for a variety of human diseases.

Occupational hazards: allosteric regulation of protein kinases through the nucleotide-binding pocket

2011 ◽  
Vol 39 (2) ◽  
pp. 472-476 ◽  
Author(s):  
Angus J.M. Cameron
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Protein Kinases ◽  
Binding Pocket ◽  
Occupational Hazards ◽  
Kinase C ◽  
Competitive Inhibitors ◽  
Central Activity ◽  
Pkc Protein Kinase C ◽  
Significant Opportunity

Targeting the protein kinase ATP-binding pocket provides a significant opportunity for the treatment of disease. Recent studies have revealed a central activity-independent role for nucleotide pocket occupation in the allosteric behaviour of diverse kinases. Regulation of nucleotide pocket conformation with either nucleotides or ATP competitive inhibitors has revealed an added dimension to the targeting of kinases. In the present paper, using PKC (protein kinase C) as a paradigm, the liabilities and opportunities associated with the occupation of the nucleotide pocket are explored.

scholarly journals Mechanism of membrane redistribution of protein kinase C by its ATP-competitive inhibitors

2007 ◽  
Vol 405 (2) ◽  
pp. 331-340 ◽  
Author(s):  
Hideyuki Takahashi ◽  
Hideo Namiki
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Fluorescent Protein ◽  
Immunoblot Analysis ◽  
Competitive Inhibitor ◽  
Atp Binding Site ◽  
Kinase C ◽  
C1 Domain ◽  
Competitive Inhibitors ◽  
Gf 109203X

ATP-competitive inhibitors of PKC (protein kinase C) such as the bisindolylmaleimide GF 109203X, which interact with the ATP-binding site in the PKC molecule, have also been shown to affect several redistribution events of PKC. However, the reason why these inhibitors affect the redistribution is still controversial. In the present study, using immunoblot analysis and GFP (green fluorescent protein)-tagged PKC, we showed that, at commonly used concentrations, these ATP-competitive inhibitors alone induced redistribution of DAG (diacylglycerol)-sensitive PKCα, PKCβII, PKCδ and PKCϵ, but not atypical PKCζ, to the endomembrane or the plasma membrane. Studies with deletion and point mutants showed that the DAG-sensitive C1 domain of PKC was required for membrane redistribution by these inhibitors. Furthermore, membrane redistribution was prevented by the aminosteroid PLC (phospholipase C) inhibitor U-73122, although an ATP-competitive inhibitor had no significant effect on acute DAG generation. Immunoblot analysis showed that an ATP-competitive inhibitor enhanced cell-permeable DAG analogue- or phorbol-ester-induced translocation of endogenous PKC. Furthermore, these inhibitors also enhanced [3H]phorbol 12,13-dibutyrate binding to the cytosolic fractions from PKCα–GFP-overexpressing cells. These results clearly demonstrate that ATP-competitive inhibitors cause redistribution of DAG-sensitive PKCs to membranes containing endogenous DAG by altering the DAG sensitivity of PKC and support the idea that the inhibitors destabilize the closed conformation of PKC and make the C1 domain accessible to DAG. Most importantly, our findings provide novel insights for the interpretation of studies using ATP-competitive inhibitors, and, especially, suggest caution about the interpretation of the relationship between the redistribution and kinase activity of PKC.

Lifespan regulation of conventional protein kinase C isotypes

2007 ◽  
Vol 35 (5) ◽  
pp. 1043-1045 ◽  
Author(s):  
D. Carmena ◽  
A. Sardini
Keyword(s):  
Signal Transduction ◽  
Plasma Membrane ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Second Messengers ◽  
Therapeutic Strategies ◽  
Kinase C ◽  
Signalling Network ◽  
Pkc Protein Kinase C ◽  
Lifespan Regulation

Plasma membrane translocation, following allosteric binding of second messengers, initiates the signal transduction process mediated by cPKC [conventional PKC (protein kinase C)] isotypes. Mechanisms regulating the lifespan of the active enzyme such as its phosphorylation, internalization, dephosphorylation and degradation are key elements of the signalling network. The understanding of such mechanisms is essential for the design of therapeutic strategies targeting PKC isoenzymes.

Regulation of exocytosis by protein kinase C

2005 ◽  
Vol 33 (6) ◽  
pp. 1341-1344 ◽  
Author(s):  
A. Morgan ◽  
R.D. Burgoyne ◽  
J.W. Barclay ◽  
T.J. Craig ◽  
G.R. Prescott ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cell Types ◽  
Neuroendocrine Cells ◽  
Protein Targets ◽  
Site Specific ◽  
Regulated Exocytosis ◽  
Kinase C ◽  
Pkc Protein Kinase C

PKC (protein kinase C) has been known for many years to modulate regulated exocytosis in a wide variety of cell types. In neurons and neuroendocrine cells, PKC regulates several different stages of the exocytotic process, suggesting that these multiple actions of PKC are mediated by phosphorylation of distinct protein targets. In recent years, a variety of exocytotic proteins have been identified as PKC substrates, the best characterized of which are SNAP-25 (25 kDa synaptosome-associated protein) and Munc18. In the present study, we review recent evidence suggesting that site-specific phosphorylation of SNAP-25 and Munc18 by PKC regulates distinct stages of exocytosis.

Protein kinases, from B to C

2007 ◽  
Vol 35 (5) ◽  
pp. 1013-1017 ◽  
Author(s):  
A.J. Cameron ◽  
M. De Rycker ◽  
V. Calleja ◽  
D. Alcor ◽  
S. Kjaer ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Experimental Evidence ◽  
Protein Kinases ◽  
Protein Kinase B ◽  
Regulatory Domains ◽  
Catalytic Domains ◽  
Kinase C ◽  
Pkc Protein Kinase C ◽  
Underlying Mechanisms

The PKB (protein kinase B) and PKC (protein kinase C) families display highly related catalytic domains that require a largely conserved series of phosphorylations for the expression of their optimum activities. However, in cells, the dynamics of these modifications are quite distinct. Based on experimental evidence, it is argued that the underlying mechanisms determining these divergent behaviours relate to the very different manner in which their variant regulatory domains interact with their respective catalytic domains. It is concluded that the distinct behaviours of PKB and PKC proteins are defined by the typical ground states of these proteins.

scholarly journals PKC (Protein Kinase C)-δ Modulates AT (Antithrombin) Signaling in Vascular Endothelial Cells

2020 ◽  
Vol 40 (7) ◽  
pp. 1748-1762
Author(s):  
Sumith R. Panicker ◽  
Indranil Biswas ◽  
Hemant Giri ◽  
Xiaofeng Cai ◽  
Alireza R. Rezaie
Keyword(s):  
Endothelial Cells ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Intracellular Signaling ◽  
Vascular Endothelial Cells ◽  
Dominant Negative ◽  
Vascular Endothelial ◽  
Kinase C ◽  
Pkc Protein Kinase C ◽  
Anti Inflammatory

Objective: Native and latent conformers of AT (antithrombin) induce anti-inflammatory and proapoptotic signaling activities, respectively, in vascular endothelial cells by unknown mechanisms. Synd-4 (syndecan-4) has been identified as a receptor that is involved in transmitting signaling activities of AT in endothelial cells. Approach and Results: In this study, we used flow cytometry, signaling assays, immunoblotting and confocal immunofluorescence microscopy to investigate the mechanism of the paradoxical signaling activities of high-affinity heparin (native) and low-affinity heparin (latent) conformers of AT in endothelial cells. We discovered that native AT binds to glycosaminoglycans on vascular endothelial cells via its heparin-binding D-helix to induce anti-inflammatory signaling responses by recruiting PKC (protein kinase C)-δ to the plasma membrane and promoting phosphorylation of the Synd-4 cytoplasmic domain at Ser179. By contrast, the binding of latent AT to endothelial cells to a site(s), which is not competed by the native AT, induces a proapoptotic effect by localizing PKC-δ to the perinuclear/nuclear compartment in endothelial cells. Overexpression of a dominant-negative form of PKC-δ resulted in inhibition of anti-inflammatory and proapoptotic signaling activities of both native and latent AT. Conclusions: These results indicate that the native and latent conformers of AT may exert their distinct intracellular signaling effects through differentially modulating the subcellular localization of PKC-δ in endothelial cells.

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