Cleavage of beta 4 integrin by matrilysin

Overexpression of the matrix metalloproteinase matrilysin and the absence of beta 4 integrin are two features characteristic of human prostate carcinoma. In the following study we demonstrate that the beta 4 integrin, but not the alpha 6 or beta 1 integrin subunits, is cleaved by matrilysin in vitro. A specific fragment of 90 kDa is generated using matrilysin, which is not observed with other proteases. Two putative cleavage sites for matrilysin within the extracellular domain of the beta 4 integrin at residues 107 (isoleucine, prior to the ligand-binding region) and 417 (leucine, prior to cysteine-rich region) are identified by sequence comparisons with known matrilysin substrates. The selective cleavage of the beta 4 integrin by matrilysin may partly explain the loss of beta 4 integrin expression in invasive prostate carcinoma.