Abnormal protein tyrosine phosphorylation in fibroblasts from hyperapobetalipoproteinemia subjects

Mahnaz Motevalli, Pascal Goldschmidt-Clermont, Donna Virgil, Peter O. Kwiterovich

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The stimulatory effects of three normal human serum basic proteins (BP), BP I (M(r) 14,000, pI 9.10), BP II (M(r) 27, 500, pI 8.48), and BP III (M(r) 55,000, pI 8.73) on cellular triglyceride and cholesterol formation require intact protein-tyrosine kinase phosphorylation (TKP). Here we examined whether there is an abnormality in TKP in cultured fibroblasts from 11 patients with hyperapobetalipoproteinemia (hyperapoB) that manifest two acylation-stimulatory defects, decreased stimulation of triglyceride synthesis by BP I but enhanced formation of cholesterol by BP II. Soluble and insoluble proteins in Triton X-100 extracts were isolated by immunoprecipitation with a monoclonal anti-phosphotyrosine antibody (MAPA) bound to agarose beads and by ultracentrifugation, respectively, from confluent fibroblasts after incubation for 24 h in supplemented serum-free and lipid-free medium (DMEM/F12). Western blots of insoluble proteins showed that group (Gp) II (M(r) 36,000-55,000) and Gp III (M(r) 14,000-35,000) from hyperapoB cells, grown in DMEM/F12 medium without BP, had significantly decreased reactivity to MAPA. No significant differences in reactivity to MAPA were detected between normal and hyperapoB cells for Gp I (M(r) 97- 120,000). BP II, but not BP I or BP III, reversed the decreased reactivity of Gp II and Gp III to MAPA in hyperapoB cells. Sodium vanadate, an inhibitor of phosphotyrosine phosphatases, did not reverse the deficiency in TKP or the 50% deficiency in the stimulation of mass triglyceride by BP I in hyperapoB cells. Tyrosine-phosphorylated Erk-2, a mitogen-activated protein kinase, identified as one of the proteins in Gp II, was significantly decreased in hyperapoB cells. These results provide further evidence for abnormal protein TKP in hyperapoB cells and suggest a possible link between atherosclerotic changes in hyperapoB patients and growth factors upstream from mitogen- activated protein kinase.

Original languageEnglish
Pages (from-to)24703-24709
Number of pages7
JournalJournal of Biological Chemistry
Volume272
Issue number39
DOIs
StatePublished - Sep 26 1997
Externally publishedYes

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Phosphorylation
Fibroblasts
Tyrosine
Phosphotyrosine
Protein-Tyrosine Kinases
Proteins
Anti-Idiotypic Antibodies
Monoclonal Antibodies
Triglycerides
Antibodies
Mitogen-Activated Protein Kinases
Cholesterol
Protein Tyrosine Phosphatases
Vanadates
Acylation
Mitogen-Activated Protein Kinase 1
Ultracentrifugation
Octoxynol
Immunoprecipitation
Sepharose

ASJC Scopus subject areas

  • Biochemistry

Cite this

Abnormal protein tyrosine phosphorylation in fibroblasts from hyperapobetalipoproteinemia subjects. / Motevalli, Mahnaz; Goldschmidt-Clermont, Pascal; Virgil, Donna; Kwiterovich, Peter O.

In: Journal of Biological Chemistry, Vol. 272, No. 39, 26.09.1997, p. 24703-24709.

Research output: Contribution to journalArticle

Motevalli, M, Goldschmidt-Clermont, P, Virgil, D & Kwiterovich, PO 1997, 'Abnormal protein tyrosine phosphorylation in fibroblasts from hyperapobetalipoproteinemia subjects', Journal of Biological Chemistry, vol. 272, no. 39, pp. 24703-24709. https://doi.org/10.1074/jbc.272.39.24703
Motevalli, Mahnaz ; Goldschmidt-Clermont, Pascal ; Virgil, Donna ; Kwiterovich, Peter O. / Abnormal protein tyrosine phosphorylation in fibroblasts from hyperapobetalipoproteinemia subjects. In: Journal of Biological Chemistry. 1997 ; Vol. 272, No. 39. pp. 24703-24709.
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