Regulation and function of extracellular matrix in intestinal epithelial restitution in vitro. G[diaeresis]oke, Michael, Anna Zuk, and Daniel K. Podolsky. Gastrointestinal Unit and Center for the Study of Inflammatory Bowel Disease, and Renal Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
APStracts 3:0081G, 1996.
Repair of epithelial injury in the gastrointestinal tract is initially accomplished by migration of epithelial cells from the wound edge ("restitution"). To assess expression and function of the extracellular matrix (ECM) in the restitution phase after epithelial injury, in vitro studies using wounded monolayers of a rat intestinal epithelial derived cell line (IEC-6) were undertaken. IEC-6 cells expressed fibronectin (FN) mRNA and protein in large amounts and lesser quantities of laminin [beta]1 and [gamma]1 (LN[beta]1 and LN[gamma]1). Collagen IV (Col IV) was weakly expressed and laminin [alpha]1 (LN[alpha]1) was not detected. After wounding, a significant decrease in FN, LN[beta]1, LN[gamma]1, and Col IV[alpha]1 mRNA steady-state levels was observed; mean content 24 hours after wounding was reduced by 75-90%. FN, LN, and Col IV proteins were also reduced. The down-regulation of these ECM transcripts and proteins could be substantially prevented by TGF-[beta]1, a restitution promoting growth factor. In addition to changes of expression, the distribution of FN and LN was also altered in migrating cells after wounding as assessed by immunofluorescence. RGD peptides that recognize the major cell attachment site on FN and antibodies recognizing the main noncollagenous domain of Col IV inhibited cell migration but immunoneutralizing anti-LN antisera did not affect restitution. In conclusion, although paradoxically down-regulated after wounding, ECM, in particular FN and Col IV molecules, are able to enhance intestinal epithelial restitution. 

Received 18 October 1995; accepted in final form 30 March 1996.
APS Manuscript Number G456-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 23 April 96