Activation of protein kinase C by intracellular free calcium in the motoneuron cell line NSC-19

Abstract

The relationship between intracellular free calcium ([Ca2+]i) and the activation of protein kinase C (PKC) and Ca2+/calmodulin-dependent protein kinase II (CaMKII) was investigated in the NSC-19 motoneuron cell line. Increased extracellular calcium ([Ca2+]o) up to 10 mM resulted in sustained elevations of [Ca2+]i. Control cell cultures (1.3 mM [Ca2+]o, [Ca2+]i = 83 +/- 17 nM) contained Ca2+- and PS/DO lipid-dependent PKC activity predominantly in the cytosol. However, elevation of [Ca2+]o up to 5 mM ([Ca2+]i = 232 +/- 24 nM) resulted in almost complete loss of cytosolic PKC activity. Cells incubated in 10 mM [Ca2+]o ([Ca2+]i = 365 +/- 13 nM) showed increased levels of both cytosolic and membrane PKC activity compared to control. These alterations in PKC activity appeared to be translocation-independent, since PKC protein levels were unchanged as demonstrated by Western blotting analysis. When cells were exposed to 25 or 50 mM [Ca2+]o, [Ca2+]i rose transiently to over 600 and 900 nM, respectively, and then returned to near basal values. Under these conditions, total PKC activity decreased, and increased amounts of the catalytic fragment of PKC, protein kinase M, were generated. Extracts from cells exposed to [Ca2+]o between 1.3 and 25 mM did not differ significantly in the levels of measurable CaMKII activity 10 min following the change in [Ca2+]o.

Proteomic Analyses of Lung Lysates from Short-Term Exposure of Fischer 344 Rats to Cigarette Smoke

“…High structural and sequence homology among the classic PKC isoforms in the phosphorylation regions makes it possible that both of the phosphorylation signals originate from a single PKC, which is further supported by the identical molecular masses of the PKC bands with each antibody and a common 42 cross-reactive protein as well as the common trends in smoke-induced changes. However, even if cross-reactivity explains the similar trend among the classic PKCs, the novel and atypical isoforms are structurally distinct and their likelihood of cross-reactivity is low. , Finally, the PKCs may be undergoing catalytic processing to a different form that was not quantified because of its shift in molecular weight, as has been demonstrated in tissues exhibiting increased cell death through apoptosis. , The rise in level of the 42 kDa protein detected with the PKCα Ser-657 antibody with 200 mg TPM/m 3 in the female rats shown in Figure D supports this contention, because this corresponds to the size of the catalytic fragment of PKC known as PKM . Also supporting this idea are the bands of 43, 40, and 43 kDa detected by the Thr-514 PKCγ, the pan-PKCδ, and the pan-PKCζ antibodies, respectively.…”

“…16,17 The rise in level of the 42 kDa protein detected with the PKCR Ser-657 antibody with 200 mg TPM/m 3 in the female rats shown in Figure 4D supports this contention, because this corresponds to the size of the catalytic fragment of PKC known as PKM. 18 Also supporting this idea are the bands of 43, 40, and 43 kDa detected by the Thr-514 PKCγ, the pan-PKCδ, and the pan-PKCζ antibodies, respectively. Thus, a smoke-induced shift in molecular weight subsequent to cleavage to the catalytic fragment seems the most likely scenario that explains the commonality of response among the PKC families.…”

Promotion of Sophora subprosrate polysaccharide on nitric oxide and interleukin-2 production in murine T lymphocytes: implicated Ca2+ and protein kinase C

“…Intracellular free Ca 2 + and PKC, involved the T cells activation and subsequent proliferation, altered level of calcium ions, protein kinase activities will influence cell growth, differentiation and malignant transformation [36]. PKC activation occurs by translocation when the concentration of intracellular free Ca 2 + is slightly elevated [37], and Ca 2 + combines with CaM that is able to activate iNOS in immunocytes to release NO [38]. Interestingly, our observation showed that treatment of the T lymphocytes in vitro with SSP1 involved the increase of activity PKC in membrane and concentration of Ca 2 + .…”