Gelatinase A Activation Is Regulated by the Organization of the Polymerized Actin Cytoskeleton

doi:10.1074/jbc.272.11.7482

Gelatinase A Activation Is Regulated by the Organization of the Polymerized Actin Cytoskeleton*

From the Departments of ^‡ Anatomical Sciences and
^¶ Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104

^§ To whom correspondence and reprint request should be addressed:
Dept. of Anatomical Sciences, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Blvd., BMSB 536, Oklahoma City, OK 73104.
Tel.: 405-271-2377; Fax: 405-271-3548.

Abstract

Gelatinase A (GL-A) is a matrix metalloproteinase (MMP) involved in both connective tissue remodeling and tumor invasion. GL-A activation is mediated by a membrane-type MMP (MT-MMP) that cleaves the GL-A propeptide. In this study, we examined the role of the actin cytoskeleton in regulating GL-A activation and MT-MMP-1 expression. Human palmar fascia fibroblasts and human fetal lung fibroblasts were cultured on a planar substratum or within different types of collagen lattices. Fibroblasts that formed stress fibers, either on a planar substratum or within an attached collagen lattice, showed reduced GL-A activation compared with fibroblasts lacking stress fibers, within either floating or stress-released collagen lattices. To determine whether changes in the organization of the actin cytoskeleton could promote GL-A activation, fibroblasts with stress fibers were treated with cytochalasin D. Within 24 h after treatment, GL-A activation was dramatically increased. Associated with this GL-A activation was an increase in MT-MMP-1 mRNA as determined by Northern blot analysis. Treatment with nocodazole, which induced microtubule depolymerization and cell shape changes without affecting stress fibers, did not promote GL-A activation. These results suggest that the extracellular matrix and the actin cytoskeleton transduce signals that modulate GL-A activation and regulate tissue remodeling.

Footnotes

↵* This work was supported by Oklahoma Center for the Advancement of Science and Technology Grants HR4-098 and HN5-030, Presbyterian Health Foundation Grant PHF 922, and grants from the American Diabetes Association and the Arthritis Foundation. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

MMP

matrix metalloproteinase

MT-MMP

membrane-type matrix metalloproteinase

cyto D

cytochalasin D

ECM

extracellular matrix

F-actin

filamentous actin

GAPDH

glyceraldehyde-3-phosphate dehydrogenase

GL-A

gelatinase A.
- Received October 10, 1996.
- Revision received December 19, 1996.