Matriptase is required for the active form of hepatocyte growth factor induced Met, focal adhesion kinase and protein kinase B activation on neural stem/progenitor cell motility

Abstract

Hepatocyte growth factor (HGF) is a chemoattractant and inducer for neural stem/progenitor (NS/P) cell migration. Although the type II transmembrane serine protease, matriptase (MTP) is an activator of the latent HGF, MTP is indispensable on NS/P cell motility induced by the active form of HGF. This suggests that MTP's action on NS/P cell motility involves mechanisms other than proteolytic activation of HGF. In the present study, we investigate the role of MTP in HGF-stimulated signaling events. Using specific inhibitors of phosphatidylinositol-3-kinase (PI3K), protein kinase B (Akt) or focal adhesion kinase (FAK), we demonstrated that in NS/P cells HGF-activated c-Met induces PI3k-Akt signaling which then leads to FAK activation. This signaling pathway ultimately induces MMP2 expression and NS/P cell motility. Knocking down of MTP in NS/P cells with specific siRNA impaired HGF-stimulation of c-Met, Akt and FAK activation, blocked HGF-induced production of MMP2 and inhibited HGF-stimulated NS/P cell motility. MTP-knockdown NS/P cells cultured in the presence of recombinant protein of MTP protease domain or transfected with the full-length wild-type but not the protease-defected MTP restored HGF-responsive events in NS/P cells. In addition to functioning as HGF activator, our data revealed novel function of MTP on HGF-stimulated c-Met signaling activation.

Physical Binding of Endothelial MCAM and Neural Transmembrane Protease Matriptase—Novel Cell Adhesion in Neural Stem cell Vascular Niche

“…2A, variants 1,2,3,5 and 6). We also made the protease inactive MTP by changing the serine residue 805 in the catalytic triad of the protease domain to alanine 9 (Fig. 2A, variant 4).…”

“…NS/P cells were differentiated from Sox1-GFP knock-in ESC (46 C ESC) in neuronal culture medium (DMEM: neural basal medium = 1:1 supplemented with N2 and B27) as described previously 8, 9 . GFP positive neurospheres were used in all experiments.…”

“…The pcDNA3.1/myc-His (−) expression vector containing the full-length mouse MTP coding region carrying a point mutation within the MTP-siRNA recognition site 9 was used as a template to prepare all the MTP variants which contain both myc and 6His tags at the C-terminus. The protease inactive form of MTP was prepared by changing Ser residue in the catalytic triad of the protease domain to Ala as described previously 9 .…”

“…We recently reported that type II transmembrane serine protease matriptase (MTP) in brain is expressed in NS/P cells 8 . It promotes NS/P cell differentiation and motility 8, 9 . Importantly, MTP plays a critical role in cell-contact signaling between NS/P and brain endothelial (bEnd) cells 6 .…”

Recent Progress and Advances in HGF/MET-Targeted Therapeutic Agents for Cancer Treatment

“…Two recently identified HGF activation inhibitors (HAIs), HAI-1 and HAI-2, have been shown to block HGF activation. Thus, the degree of bioactive HGF formation is regulated by the activity between these activators and inhibitors [25,26,27,28]. The elevation of HGFA and reduction of HAIs have been reported in a variety of tumors, indicating that the disruption of the balance between HGF activation and inhibition may favor tumor formation [29,30,31].…”