Characterization and distribution of protein kinase C in ovarian tissue

Abstract

Although protein kinase C, an enzyme dependent on calcium, phospholipid and diacylglycerol, has been found in high levels in ovarian tissues, its biologic function is yet unknown. In initial studies on the role of this enzyme in regulating ovarian functions, we compared protein kinase C activity in subcellular fractions of porcine corpora lutea and medium follicles. Highest protein kinase C-specific activities were found in the cytosol, followed by microsomes and mitochondria for both follicles and luteal tissues. Solubilization of all membrane-containing fractions by 0.2% Triton X-100 was required for full expression (a 4-fold average increase) of protein kinase activity. Extraction of membrane fractions with 0.5 M NaCl or sonication in a hypotonic medium revealed that 90% of the total mitochondrial protein kinase C activity and 50% of the microsomal activity was tightly membrane-bound. Characterization of both cytosolic and Triton X-100 extracted membrane preparations of luteal tissue by diethylaminoethyl (DEAE)-cellulose chromatography revealed a single peak of protein kinase C activity eluting at 80 mM NaCl. Cytosolic fractions of corpora lutea contained 3 times more protein kinase C-specific activity than did cytosolic fractions of follicles. In contrast, mitochondria from medium follicles contained 30% more specific protein kinase C activity than did luteal mitochondria. These higher cytosolic levels of protein kinase C-specific activity in corpora lutea suggest that the enzyme may play an important role in the process of luteinization or in the regulation of luteal function.

Cell Signaling through Protein Kinase C Oxidation and Activation

“…The presence of PKCs in the mitochondria has long been known, but their functions are not well defined [47,49]. The activation of PKCδ with phorbol myristate acetate (PMA) or H 2 O 2 stimulates its accumulation in the mitochondria, and this fact can be related to apoptosis in different cell types [50–52].…”

Feedback Regulation of ATP-induced Ca2+ Signaling in HL-60 Cells Is Mediated by Protein Kinase A- and C-mediated Changes in Capacitative Ca2+ Entry

“…Assay of PKC Activity-PKC activity was measured by determining the incorporation of 32 P from [␥-32 P]ATP into histone IIIS as described previously (17,19), with some modifications. HL-60 cells were harvested and treated with inhibitor mixture containing 10 M H89 and 1 M KN62 and then stimulated with 30 or 300 M ATP and 100 nM PMA.…”

Differential actions of second messenger systems in the corpus luteum

“…Protein kinase C activity has been detected in luteal cells from cattle, sheep and pigs (Davis & Clark, 1983;Noland & Dimino, 1986;Wheeler & Veldhuis, 1987;Hoyer & Kong, 1989;Wiltbank et al, 1989b). Protein kinase C activity has been reported to be 2.7-fold greater in pig corpora lutea than in medium-sized follicles (Noland & Dimino, 1986), whereas protein kinase A activity was greater in follicles than in corpora lutea (Dimino et al, 1981). Three chromatographically distinct forms of protein kinase C have been detected in the cytosol from pig luteal cells (Wheeler & Veldhuis, 1989) and these different forms of protein kinase C may have distinct actions (Kosaka et al, 1988).…”