Insulin increases membrane and cytosolic protein kinase C activity in BC3H-1 myocytes

• Published in: The Journal of biological chemistry 1987-03, Vol.262 (8), p.3633-3639
• Main Authors: Cooper, D.R., Konda, T.S., Standaert, M.L., Davis, J.S., Pollet, R.J., Farese, R.V.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Cell Line; Cell Membrane - enzymology; Cell physiology; Cytosol - enzymology; Fundamental and applied biological sciences. Psychology; Hormonal regulation; insulin; Insulin - pharmacology; Kinetics; Mice; Molecular and cellular biology; Muscles - enzymology; myocytes; Phenylephrine - pharmacology; protein kinase C; Protein Kinase C - metabolism; Tetradecanoylphorbol Acetate - pharmacology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)61400-0

Insulin treatment stimulated the activity of the Ca2+- and phospholipid-dependent protein kinase (protein kinase C) in both cytosolic and membrane fractions of BC3H-1 myocytes. Within 60 s of insulin treatment, membrane protein kinase C activity increased 2-fold, diminished toward control levels transiently, and then increased 2-fold again after 15 min. Cytosolic protein kinase C activity increased more gradually and steadily up to 80% over a 20-min period. Increases in protein kinase C activity were dose-dependent and were not simply a result of translocation of cytosolic enzyme (although this may have occurred), as total activity was also increased. The increase in protein kinase C activity was not inhibited by cycloheximide (which also increased protein kinase C activity and 2-deoxyglucose transport) and was still evident following anion exchange chromatography. The insulin effect was decidedly different from those of 12-O-tetradecanoylphorbol-13-acetate and phenylephrine using histone III-S as substrate. Phenylephrine decreased cytosolic protein kinase C activity while increasing membrane activity; 12-O-tetradecanoylphorbol-13-acetate only decreased cytosolic protein kinase C activity. The early insulin-induced increases in membrane protein kinase C activity may be related to increased diacylglycerol generation from de novo phosphatidic acid synthesis, as there were rapid increases in [3H]glycerol incorporation into diacylglycerol, and transient increases in phospholipid hydrolysis, as there were transient rapid increases in [3H]diacylglycerol in cells prelabeled with [3H]arachidonate. Later, sustained increases in membrane and cytosolic protein kinase C activity may reflect the continuous activation of de novo phospholipid synthesis, as there were associated increases in [3H]glycerol incorporation into diacylglycerol at later, as well as very early time points.