Cellular activation of mesangial gelatinase A by cytochalasin D is accompanied by enhanced mRNA expression of both gelatinase A and its membrane-associated gelatinase A activator (MT-MMP).
Activation of gelatinase A represents a crucial regulatory step in the control of its enzymic activity. Rat kidney mesangial cells secrete predominantly latent gelatinase A that can be activated following treatment with cytochalasin D. In the present paper we provide new evidence, using reverse transcription-PCR, that treatment of rat mesangial cells with cytochalasin D enhances the steady-state level of mRNA of the membrane-type matrix metalloproteinase (MT-MMP), as well as of gelatinase A, with no change in the level of tissue inhibitor of metalloproteinases-2 (TIMP-2) mRNA. Since the TIMP-2 protein level is reduced in conditioned medium from cytochalasin D-treated cells, the results of the present study are consistent with a model in which the action of cytochalasin D is to cause extracellular gelatinase A and TIMP-2 to be sequestered at the plasma membrane, forming a heterotrimeric complex with MT-MMP. In this manner, TIMP-2 may assume a bifunctional role causing: (i) inhibition of gelatinase A in the extracellular compartment; and (ii) guiding gelatinase A to activation through a membrane association with MT-MMP.
Ailenberg
M
M
Department of Medicine, University of Toronto, Ontario, Canada.
Silverman
M
M
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D015638:Cytochalasin D / Q000494:pharmacology*; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects; D018093:Gelatinases / Q000235:genetics* / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D005920:Glomerular Mesangium / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D020778:Matrix Metalloproteinase 2; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000235:genetics* / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D051381:Rats
D017931:DNA Primers; D018076:DNA, Complementary; D012333:RNA, Messenger; D015638:Cytochalasin D; D018093:Gelatinases; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2