| Abstract: |
Activity of the Ca2+/phospholipid-dependent protein kinase C has been shown to increase during differentiation of the human promyelocytic leukemia cell line HL-60 by dimethyl sulfoxide and retinoic acid (Zylber-Katz, E., and Glazer, R.I. (1985) Cancer Res. 45, 5159-5164). Antipeptide antibodies were prepared that specifically recognize the α, β, and γ isozymes of protein kinase C in rat brain cytosol and HL-60 cell extracts. The three isozymes do not share a common tissue distribution pattern. The γ enzyme is abundant in brain but a relatively minor component in HL-60 cells; the opposite is true for the α enzyme. All three isozymes increase at least 2-fold in abundance in HL-60 cells exposed to 1.2% dimethyl sulfoxide for 48 h. The increase in abundance of the α and β isoforms reaches 7- and 5-fold, respectively, by 96 h without further increase in the abundance of the γ isozyme. Similarly, all three isozymes increase at least 1.5-fold in abundance after 48 h and 3-fold after 96 h with 1 μM retinoic acid. No further increase in the abundance of any of the isozymes is seen between 96 and 144 h of incubation with retinoic acid. The increase in protein kinase C activity is not limited to the cytosolic forms of the enyzme; a parallel increase in membrane-associated protein kinase C is also observed during differentiation. Approximately 10% of total protein kinase C activity is membrane-associated in both control and differentiating cells. These studies provide the first immunochemical evidence that all three protein kinase C isozymes increase during HL-60 cell differentiation, and they suggest that the increase in the isozyme levels may be coordinately regulated. |
| Keywords: |
human cell; comparative study; animal; cell differentiation; tumor cells, cultured; dimethyl sulfoxide; amino acid sequence; molecular sequence data; cell culture; tissue distribution; brain; leukemia, myeloid; protein kinase c; cattle; rats; sequence homology, nucleic acid; retinoic acid; cytosol; isoenzymes; electrophoresis, polyacrylamide gel; tetradecanoylphorbol acetate; rabbits; tretinoin; human; support, non-u.s. gov't; support, u.s. gov't, p.h.s.
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