Differential effects of pertussis toxin on insulin-stimulated phosphatidylcholine hydrolysis and glycerolipid synthesis de novo. Studies in BC3H-1 myocytes and rat adipocytes

Journal Article · Tue Apr 02 00:00:00 EST 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00227a021· OSTI ID:5558045

Hoffman, J M; Standaert, M L; Nair, G P; Farese, R V ^[1]

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1. Univ. of South Florida, Tampa (USA)

Insulin-induced increases in diacylglycerol (DAG) have been suggested to result from stimulation of de novo phosphatidic acid (PA) synthesis and phosphatidylcholine (PC) hydrolysis. Presently, the authors found that insulin decreased PC levels of BC3H-1 myocytes and rat adipocytes by approximately 10-25% within 30 s. These decreases were rapidly reversed in both cell types, apparently because of increased PC synthesis de novo. In BC3H-1 myocytes, pertussis toxin inhibited PC resynthesis and insulin effects on the pathway of de novo PA-DAG-PC synthesis, as evidenced by changes in ({sup 3}H)glycerol incorporation, but did not inhibit insulin-stimulated PC hydrolysis. Pertussis toxin also blocked the later, but not the initial, increase in DAG production in the myocytes. Phorbol esters activated PC hydrolysis in both myocytes and adipocytes, but insulin-induced stimulation of PC hydrolysis was not dependent upon activation of PKC, since this hydrolysis was not inhibited by 500 {mu}M sangivamycin, an effective PKC inhibitor. The results indicate that insulin increases DAG by pertussis toxin sensitive and insensitive (PC hydrolysis) mechanisms, which are mechanistically separate, but functionally interdependent and integrated. PC hydrolysis may contribute importantly to initial increases in DAG, but later sustained increases are apparently largely dependent on insulin-induced stimulation of the pathway of de novo phospholipid synthesis.

• OSTI ID: 5558045
• Journal Information: Biochemistry; (United States), Vol. 30:13; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
PHOSPHOLIPIDS
ENZYMATIC HYDROLYSIS
TOXINS
BIOLOGICAL EFFECTS
TRITIUM COMPOUNDS
UPTAKE
ADIPOSE TISSUE
CELL CULTURES
CHOLINE
FAT CELLS
GLYCEROL
INSULIN
ALCOHOLS
AMINES
AMMONIUM COMPOUNDS
ANIMAL CELLS
ANIMAL TISSUES
ANTIGENS
BODY
CHEMICAL REACTIONS
CONNECTIVE TISSUE
CONNECTIVE TISSUE CELLS
DECOMPOSITION
DRUGS
ESTERS
HORMONES
HYDROGEN COMPOUNDS
HYDROLYSIS
HYDROXY COMPOUNDS
LIPIDS
LIPOTROPIC FACTORS
LYSIS
MATERIALS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PEPTIDE HORMONES
PROTEINS
QUATERNARY COMPOUNDS
SOLVOLYSIS
SOMATIC CELLS
TISSUES
TOXIC MATERIALS
550201* - Biochemistry- Tracer Techniques