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PKC Activity and Protein Phosphorylation in Regulation of sig Mediated B Cell Activation
Author(s) -
LINDSBERG M.L.,
FEUERSTEIN N.,
BALAPURE A. K.,
MOND J. J.
Publication year - 1995
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1111/j.1365-3083.1995.tb03553.x
Subject(s) - phosphorylation , protein kinase c , microbiology and biotechnology , chemistry , cancer research , biology
The inhibitory and stimulatory elements of cellular signalling associated with activation of protein kinase C ( PKC ) in murine B lymphocytes were investigated by employing two PKC activators with opposing effects on cell proliferation. Being an inhibitor of anti‐Ig mediated proliferation, the phorbol ester PDBU induced a more substantial translocation of cytosolic PKC activity than the alkaloid PKC activator indolactam, which enhances anti‐Ig mediated B cell proliferation. PDBU and indolactam were equally effective kinase activators, as determined by 32 P incorporation of the substrate proteins. Concentrations of indoiactam which induced an inhibition of anti‐Ig mediated B cell proliferation also induced a precipitous decline in detergent soluble cellular PKC activity, which was comparable with 1μM PDBU . The induced phosphoprotein patterns were similar, with an exception of the nuclear envelope protein lamin B, which was prominently phosphorylated by PDBU but not by stimulatory concentrations of indolactam. The enhanced phosphorylation of lamin B was associated with cellular growth arrest: inhibitory concentrations of indolactam induced the phosphorylation of lamin B equal to PDBU . whereas an increased phosphorylation of lamin B was never observed upon stimulation with anti‐Ig. Together, inhibition of anti‐Ig mediated B cell proliferation was related to down‐regulation of cytoplasmic PKC and induction of nuclear PKC ‐dependent phosphorylation.