Protein kinase C (PKC) is an important regulatory enzyme whose physiological activation requires it to become membrane-bound. This occurs via the simultaneous presence of calcium, an acidic phospholipid such as phosphatidyl serine (PS), and a diglyceride. The presence of the latter is of great regulatory significance because it is the product of polyphosphatidylinositol turnover. The diglyceride requirement can be satisfied by structurally diverse tumor promoters such as the phorbol esters, teleocidin, and the debromoaplysiatoxins. It is likely that PKC is an important target for the tumor promoters. In addition, PKC plays an important role in platelet aggregation, cardiac function, and neural function. The major focus of this grant is to understand the mechanism of the novel activation process of PKC. Of particular interest is the unravelling the structural basis for PKC activator function. On the one hand, PKC is exceedingly selective with respect to the chemical structure of diglyceride activators. At the same time, structurally diverse tumor promoters belonging to the diterpene, peptide, and macrolide series , can all potently activate the enzyme. These observations are reconciled here with the presentation of a new unifying structural hypothesis on PKC activators which are based on experiments described in the progress report. This new hypothesis makes predictions concerning novel diglyceride and peptide analogs which should potently interact with the kinase. These molecules will be synthesized and studied as putative PKC activators and inhibitors. Finally, novel cyclic PS analogs will be prepared to study the specificity of the phospholipid binding-site of PKC. Complimentary studies on the nature of activator binding-site are also anticipated. The PKC regulatory domain binding-site will be covalently labeled with activator-based photoaffinity probes and the labeled region will be sequenced. Taken together, these studies should bring us closer to an understanding of the regulation of PKC at a molecular level and the general issue of how proteins can interact with and bind to membranes. Finally, the structural information obtained here will serve to map the PKC diglyceride binding-site and can be used as a starting point to prepare potent inhibitors of the enzyme.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL034346-09
Application #
2217539
Study Section
Bio-Organic and Natural Products Chemistry Study Section (BNP)
Project Start
1985-09-01
Project End
1996-06-30
Budget Start
1994-07-01
Budget End
1996-06-30
Support Year
9
Fiscal Year
1994
Total Cost
Indirect Cost
Name
Harvard University
Department
Pharmacology
Type
Schools of Medicine
DUNS #
082359691
City
Boston
State
MA
Country
United States
Zip Code
02115
Ma, Y T; Gilbert, B A; Rando, R R (1995) Farnesylcysteine analogs to probe role of prenylated protein methyltransferase. Methods Enzymol 250:226-34
Gilbert, B A; Lim, Y H; Ding, J et al. (1995) Farnesyl thiotriazole, a potent neutrophil agonist and structurally novel activator of protein kinase C. Biochemistry 34:3916-20
Ma, Y T; Shi, Y Q; Lim, Y H et al. (1994) Mechanistic studies on human platelet isoprenylated protein methyltransferase: farnesylcysteine analogs block platelet aggregation without inhibiting the methyltransferase. Biochemistry 33:5414-20
Ding, J; Lu, D J; Perez-Sala, D et al. (1994) Farnesyl-L-cysteine analogs can inhibit or initiate superoxide release by human neutrophils. J Biol Chem 269:16837-44
Shi, Y Q; Rando, R R (1992) Kinetic mechanism of isoprenylated protein methyltransferase. J Biol Chem 267:9547-51
Rando, R R; Kishi, Y (1992) Structural basis of protein kinase C activation by diacylglycerols and tumor promoters. Biochemistry 31:2211-8
Kong, F H; Kishi, Y; Perez-Sala, D et al. (1991) The pharmacophore of debromoaplysiatoxin responsible for protein kinase C activation. Proc Natl Acad Sci U S A 88:1973-6
Kong, F; Kishi, Y; Perez-Sala, D et al. (1990) The stereochemical requirement for protein kinase C activation by 3-methyldiglycerides matches that found in naturally occurring tumor promoters aplysiatoxins. FEBS Lett 274:203-6
Nakamura, H; Kishi, Y; Pajares, M A et al. (1989) Structural basis of protein kinase C activation by tumor promoters. Proc Natl Acad Sci U S A 86:9672-6
Rando, R R (1988) Regulation of protein kinase C activity by lipids. FASEB J 2:2348-55

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