[Induction of apoptosis by fibronectin via its interaction with VLA5].

Little is known how Extra cellular matrix (ECM) molecules regulate proliferation of human hematopoietic progenitor cells. Fibronectin (FN) strikingly inhibited a human growth factor dependent cell line, M07E, cell proliferation. DNA content analysis revealed that FN treatment resulted in the appearance of subdiploid peak. Furthermore, FN induced oligonucleosomal DNA fragmentation and chromatin condensation, suggesting the involvement of apoptosis in the FN induced growth suppression. The apoptosis was rescued by anti-VLA5 mAb and the FN-induced apoptosis was detectable only VLA5-positive human cell lines but not in any of the VLA5-negative cell lines. These results suggest that FN induces apoptosis via its interaction with VLA5, and also raise the possibility that the FN-VLA5 interaction may contribute to negative regulation of hematopoiesis.