Phorbol ester synergizes with Ca2+ ionophore in activation of protein kinase C (PKC)alpha and PKC beta isoenzymes in human T cells and in induction of related cellular functions.

摘要: Studies described herein were designed to examine the effects of 12-O-tetradecanoyl phorbol-13-acetate (TPA), and a Ca2+ ionophore (ionomycin), singly or in combination, on activation expression Ca(2+)-dependent protein kinase C (PKC) isoenzymes (alpha, beta gamma) at messenger RNA (mRNA) levels T cells. These two agents induce proliferation lymphocytes by mimicking action inositol phospholipid-derived second messengers normally generated triggering antigen-specific T-cell receptor (TcR)/CD3 complex. TPA-induced proliferation, interleukin-2 receptor-alpha subunit (IL-2R alpha) transferrin receptor, CD3 down-regulation and, lastly, cytosol-to-membrane PKC translocation (determined an enzymatic assay immunoblotting with cross-reactive anti-PKC peptide antibody) all facilitated ionomycin. Immunoblots isoenzyme-specific monoclonal antibodies demonstrated immunoreactive alpha, gamma proteins that translocated membrane upon TPA plus ionomycin stimulation. Resting cells expressed abundant mRNA for alpha beta, but very low (relative brain) gamma. increased two- threefold not gamma, within 12 hr Ionomycin synergized increasing mRNA. The also inducing additional activation/growth-associated genes, namely c-myc protooncogene, ornithine decarboxylase (ODC) IL-2R alpha. alone was inactive (or marginally active) these assays. distinct up-regulation suggest least are involved discrete steps pathway leading proliferation. Moreover, combined function cell-surface antigen appear be due, part, their synergistic isoenzyme(s).