Overexpression of protein kinase C. beta. 1 enhances phospholipase D activity and diacylglycerol formation in phorbol ester-stimulated rat fibroblasts

Journal Article · Tue Jan 15 00:00:00 EST 1991 · Proceedings of the National Academy of Sciences of the United States of America; (United States)

DOI:https://doi.org/10.1073/pnas.88.2.598· OSTI ID:5030689

Pai, Jinkeon; Pachter, J A; Bishop, W R ^[1]; Weinstein, I B ^[2]

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1. Schering-Plough Research, Bloomfield, NJ (United States)
2. Columbia Univ., New York, NY (United States)

The authors are using a Rat-6 fibroblast cell line that stably overexpresses the {beta}1 isozyme of protein kinase C (PKC) to study regulation of phospholipid hydrolysis by PKC. Stimulation of control (R6-C1) or overexpressing (R6-PKC3) cells with phorbol ester results in an increase in diacylglycerol (DAG) mass with no increase in inositol phosphates, indicating that DAG is not formed by inositol phospholipid breakdown. A more dramatic DAG increase occurs in R6-PKC3 cells compared to R6-C1 cells. To further define the source of DAG, phosphatidylcholine (PC) pools were labeled with ({sup 3}H)myristic acid or with ({sup 3}H)- or ({sup 32}P)alkyllyso-PC and formation of labeled phosphatidylethanol, an unambiguous marker of phospholipase D activation, was monitored. Phorbol ester-stimulated phosphatidylethanel formation is 5-fold greater in the R6-PKC3 cell line. Formation of radiolabeled phosphatidic acid (PA) is also enhanced by PKC overepression. In cells double-labeled with ({sup 3}H)- and ({sup 32}P)-alkyl-lysoPC, the {sup 3}H/{sup 32}P ratio of PA and PC are identical 15 min after stimulation, suggesting that a phospholipase D mechanism predominates. These results indicate that phospholipase D is regulated by the action of PKC. Enhanced phospholipase D activity may contribute to the growth abnormalities seen in PKC-overexpressing cells.

• OSTI ID: 5030689
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (United States), Vol. 88:2; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
PHORBOL ESTERS
BIOLOGICAL EFFECTS
PHOSPHOLIPIDS
ENZYMATIC HYDROLYSIS
PHOSPHOTRANSFERASES
GENE REGULATION
DOUBLE LABELLING
ENZYME ACTIVITY
FIBROBLASTS
ISOENZYMES
LIPASES
PHOSPHORUS 32
TRITIUM COMPOUNDS
ANIMAL CELLS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOXYLESTERASES
CARCINOGENS
CHEMICAL REACTIONS
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
DECOMPOSITION
ENZYMES
ESTERASES
ESTERS
HYDROGEN COMPOUNDS
HYDROLASES
HYDROLYSIS
ISOTOPES
LABELLING
LIGHT NUCLEI
LIPIDS
LYSIS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
RADIOISOTOPES
SOLVOLYSIS
SOMATIC CELLS
TRANSFERASES
550201* - Biochemistry- Tracer Techniques