The overall direction of the Molecular Mechanisms of Tumor Promotion Section is to elucidate the mechanisms of action of the phorbol esters and their endogenous analog, the lipophilic second messenger sn-1,2-diacylglycerol. Protein kinase C (PKC) is the major receptor for these compounds, and our emphasis is correspondingly directed at this family of isozymes. In a collaborative effort, we seek to combine mutational analysis with computer modeling and chemical synthesis to probe ligand - PKC interactions. An important concept to emerge is that different ligands interact through a combination of common and unique contacts. A related issue is the significance of twin phorbol ester binding domains in typical PKCs. By mutating the individual binding domains, we find that the two binding domains of PKC delta are not equivalent; rather, the second domain plays the predominant role in translocation of PKC to the membrane in the presence of phorbol ester. For PKC alpha, in contrast, occupancy of both domains appears essential for translocation, and the rate of translocation depends on the binding affinities of the two domains. Our long term objective is to exploit such isotype differences to dissect subpathways of PKC mediated signal transduction. The bryostatins, although activators of PKC in vitro, function as partial antagonists in intact cells. Consistent with their possessing additional sites of action other than PKC, we find that growth inhibition of B16 melanoma cells by bryostatin 1 does not depend on PKC; rather, derivatives modified to bind PKC only weakly still maintain their growth inhibitory activity. The phorbol-related diterpene resiniferatoxin acts as an ultrapotent analog of capsaicin and has permitted characterization of specific capsaicin receptors. We are now able to define distinct receptor subclasses with distinct functions. In particular, the resiniferatoxin selective subclass is involved in desensitization whereas the capsaicin selective subclass is involved in acute responses. These two subclasses, furthermore, use different signaling pathways. These findings have important implications for the therapeutic development of vanilloids in the treatment of pain.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Intramural Research (Z01)
Project #
1Z01BC005270-15
Application #
2463615
Study Section
Special Emphasis Panel (CCTP)
Project Start
Project End
Budget Start
Budget End
Support Year
15
Fiscal Year
1996
Total Cost
Indirect Cost
Name
National Cancer Institute Division of Basic Sciences
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Cooke, Mariana; Zhou, Xiaoling; Casado-Medrano, Victoria et al. (2018) Characterization of AJH-836, a diacylglycerol-lactone with selectivity for novel PKC isozymes. J Biol Chem 293:8330-8341
Das, Joydip; Kedei, Noemi; Kelsey, Jessica S et al. (2018) Critical Role of Trp-588 of Presynaptic Munc13-1 for Ligand Binding and Membrane Translocation. Biochemistry 57:732-741
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Elhalem, Eleonora; Donadío, Lucía Gandolfi; Zhou, Xiaoling et al. (2017) Exploring the influence of indololactone structure on selectivity for binding to the C1 domains of PKC?, PKC?, and RasGRP. Bioorg Med Chem 25:2971-2980
Czikora, Agnes; Kedei, Noemi; Kalish, Heather et al. (2017) Importance of the REM (Ras exchange) domain for membrane interactions by RasGRP3. Biochim Biophys Acta Biomembr 1859:2350-2360
Ketcham, John M; Volchkov, Ivan; Chen, Te-Yu et al. (2016) Evaluation of Chromane-Based Bryostatin Analogues Prepared via Hydrogen-Mediated C-C Bond Formation: Potency Does Not Confer Bryostatin-like Biology. J Am Chem Soc 138:13415-13423
Czikora, Agnes; Lundberg, Daniel J; Abramovitz, Adelle et al. (2016) Structural Basis for the Failure of the C1 Domain of Ras Guanine Nucleotide Releasing Protein 2 (RasGRP2) to Bind Phorbol Ester with High Affinity. J Biol Chem 291:11133-47
Feng, Zhiwei; Pearce, Larry V; Zhang, Yu et al. (2016) Multi-Functional Diarylurea Small Molecule Inhibitors of TRPV1 with Therapeutic Potential for Neuroinflammation. AAPS J 18:898-913
Zhang, Feng; Hanson, Sonya M; Jara-Oseguera, Andres et al. (2016) Engineering vanilloid-sensitivity into the rat TRPV2 channel. Elife 5:
Petersen, Mark E; Kedei, Noemi; Lewin, Nancy E et al. (2016) Replacement of the Bryostatin A- and B-Pyran Rings With Phenyl Rings Leads to Loss of High Affinity Binding With PKC. Tetrahedron Lett 57:4749-4753

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