TRANSMEMBRANE CYTOPLASMIC DOMAIN-MEDIATED MEMBRANE TYPE 1-MATRIX METALLOPROTEASE DOCKING TO INVADOPODIA IS REQUIRED FOR CELL INVASION/

The invasion of human malignant melanoma cells into the extracellular matrix (ECM) involves the accumulation of proteases at sites of ECM de gradation where activation of matrix metalloproteases (MMP) occurs, He re, we show that when membrane type 1 MMP (MT-MMP) was overexpressed i n RPMI7951 human melanoma cells, the cells made contact with the ECM, activated soluble and ECM-bound MMP-2, and degraded and invaded the EC M, Further experiments demonstrated the importance of localization of the MT-MMP to invadopodia, Overexpression of MT-MMP without invadopodi al localization caused activation of soluble MMP-2, but did not facili tate ECM degradation or cell invasiveness. Up-regulation of endogenous MT-MMP with concanavalin A caused activation of MMP-2. However, conca navalin A treatment prevented invadopodial localization of MT-MMP and ECM degradation, Neither a truncated MT-MMP mutant lacking transmembra ne (TM) and cytoplasmic domains (Delta TMMT-MMP), nor a chimeric MT-MM P containing the interleukin 2 receptor alpha chain (IL-2R) TM and cyt oplasmic domains (Delta TMMT-MMP/TMIL-2R) were localized to invadopodi a or exhibited ECM degradation, Furthermore, a chimera of the TM/cytop lasmic domain of MT-MMP (TMMT-MMP) with tissue inhibitor of MMP 1 (TIM P-1/TMMT-MMP) directed the TIMP-1 molecule to invadopodia. Thus, the M T-MMP TM/cytoplasmic domain mediates the spatial organization of MT-MM P into invadopodia and subsequent degradation of the ECM.