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Phorbol 12‐myristate 13‐acetic acid inhibits PTP1B activity in human mesangial cells A possible mechanism of enhanced tyrosine phosphorylation
Author(s) -
Kiyomoto Hideyasu,
Fouqueray Bruno,
Abboud Hanna E.,
Choudhury Goutam Ghosh
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)01039-0
Subject(s) - phosphorylation , tyrosine phosphorylation , mesangial cell , phorbol , tyrosine , chemistry , acetic acid , mechanism (biology) , microbiology and biotechnology , endocrinology , biochemistry , protein kinase c , medicine , biology , in vitro , philosophy , epistemology
Activation of protein kinase C (PKC) by phorbol 12‐myristate 13‐acetic acid (PMA) stimulates DNA synthesis in human glomerular mesangial cells. Incubation of these cells with PMA stimulates the tyrosine phosphorylation of a set of proteins ranging from 110 to 39 kDa with different time kinetics. PMA inhibits total protein tyrosine phosphatase (PTPase) activity in these cells. Immunoprecipitation of PTP1B, an intracytoplasmic tyrosine phosphatase, with subsequent assay of the immunobeads for PTPase shows a significant inhibition of its activity in PMA‐treated cells. Immunoblot analysis of mesangial cell lysates using the same antibody revealed that PMA does not affect the level of this 50 kDa PTP1B protein. These data indicate that inhibition of total PTPase, and specifically PTP1B, activity may provide a mechanism for stimulation of tyrosine phosphorylation by PMA in these cells and thereby contribute to its mitogenic effect.