Open AccessRegulation of Membrane‐Type Matrix Metalloproteinase‐1 Expression by Growth Factors and Phorbol 12‐Myristate 13‐Acetate
Author(s) -
Lohi Jouko,
Lehti Kaisa,
Westermarck Jukka,
Kähäri VeliMatti,
KeskiOja Jorma
Publication year - 1996
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1996.0239u.x
Subject(s) - cycloheximide , gelatinase , concanavalin a , fibroblast activation protein, alpha , microbiology and biotechnology , fibroblast , phorbol , gelatinase a , cell culture , matrix metalloproteinase , messenger rna , biology , tetradecanoylphorbol acetate , chemistry , biochemistry , protein biosynthesis , enzyme , gene , protein kinase c , in vitro , genetics , cancer
Overexpression of membrane‐type matrix metalloproteinase (MT‐MMP‐1) results in the activation of both endogenous and exogenous 72‐kDa gelatinase. To understand the effects of MT‐MMP‐1 on 72‐kDa gelatinase activation, we analyzed its expression in human fibroblasts and HT‐1080 fibrosarcoma cells. Both cell types expressed the MT‐MMP‐1 mRNA constitutively at a considerable level and treatment of cells with PMA enhanced the expression about 2–3‐fold. Concanavalin A treatment increased MT‐MMP‐1 mRNA levels in fibroblasts about 4‐fold. Induction of MT‐MMP‐1 by phorbol 12‐myristate 13‐acetate (PMA) required protein synthesis as shown by cycloheximide inhibition. The induction was also inhibited by dexamethasone. Analysis of MT‐MMP‐1 mRNA stability using actinomycin D indicated that the half‐life was rather long and not affected by PMA, suggesting transcriptional regulation. Only HT‐1080 cells had significant 72‐kDa gelatinase processing activity after treatment with PMA or concanavalin A, while fibroblasts were virtually negative. Immunoblotting analysis of fibroblast lysates indicated that MT‐MMP‐1 was present mainly in a 60‐kDa form. PMA and concanavalin A caused 2–4‐fold increases in its protein levels, while in HT‐1080 cells PMA, concanavalin A, or overexpression of MT‐MMP‐1 did not significantly enhance the level of the 60‐kDa protein. Instead, an immunoreactive, proteolytically processed 43‐kDa form was observed, and its appearance correlated to 72‐kDa gelatinase processing activity. Thus 72‐kDa gelatinase activation, while enhanced by MT‐MMP‐1 expression, needs additional co‐operating factors.