Members of the protein kinase C (PKC) family of serine/threonine kinases play
critical roles in the regulation of cellular differentiation and proliferation of diverse
cell types. Protein kinase C (PKC) is the major phorbol ester receptor.
Nine mammalian members of the PKC family have been identified and designated alpha, beta, gamma, delta, epsilon,
zeta, eta, theta, and lambda.
General function
Comment
Cellular localization
Cytoplasmic
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Ovarian function
Steroid metabolism
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Expression regulated by
Growth Factors/ cytokines
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Peluso JJ, et al reported that basic fibroblast growth factor maintains calcium homeostasis
and granulosa cell viability by stimulating calcium efflux via
a PKC delta-dependent pathway.
Previous studies have demonstrated that basic fibroblast growth factor
prevents granulosa cell apoptosis. Granulosa cells, as well as spontaneously immortalized
granulosa cells, were shown to express PKC delta, -lambda, and -zeta. Finally,
the PKC delta -specific inhibitor, rottlerin, blocked basic fibroblast growth
factor's antiapoptotic action in granulosa cells and spontaneously
immortalized granulosa cells. These studies suggest that basic fibroblast
growth factor regulates intracellular free calcium through a PKC delta
-dependent mechanism and that a sustained increase in intracellular free
calcium is sufficient to induce and is required for granulosa cell apoptosis.
Ovarian localization
Granulosa, Luteal cells
Comment
Tai CJ, et al 2001 reported the antigonadotropic action of adenosine triphosphate in human
granulosa-luteal cells and the involvement of protein kinase c alpha.
The presence of P2U purinoceptor in human granulosa-luteal cells (hGLCs)
indicates a potential role of ATP in regulating ovarian function and an inhibitory effect of ATP on hCG-induced cAMP production was observed.
Extracellular ATP has been shown to activate protein kinase C (PKC) after
binding to a purinoceptor. To further investigate the involvement of PKC isoforms
in mediating the inhibitory effect of ATP, the presence of PKC isoforms in
cultured human granulosa luteal cells (hGLCs) was examined by Western blot using monoclonal antibodies
against specific isoforms. Translocation of PKC isoforms from cytosolic
fraction to membrane fraction was studied to identify the active PKC isozymes
subsequent to ATP treatment. The change in PKC isoform in PKC-depleted cells
was also examined. The results
demonstrated the presence of PKC alpha, -delta, -iota, and -lambda isoforms in
hGLCs and the translocation of PKCa subsequent to ATP treatment. In
PKC-depleted cells the PKCa level was reduced, and no significant effect of
ATP on hCG-stimulated cAMP production was observed.