Membrane type-1 matrix metalloproteinase (MT1-MMP) processing of pro-alphav integrin regulates cross-talk between alphavbeta3 and alpha2beta1 integrins in breast carcinoma cells.
ABSTRACT We have recently demonstrated that in breast carcinoma MCF7 cells MT1-MMP processes the alphav, alpha3, and alpha5 integrin precursors generating the respective mature S-S-linked heavy and light alpha-chains. The precursor of alpha2 integrin subunit was found resistant to MT1-MMP proteolysis. The processing of the alphav subunit by MT1-MMP facilitated alphavbeta3-dependent adhesion, activation of FAK signaling pathway, and migration of MCF7 cells on vitronectin. To elucidate further the effects of MT1-MMP on cellular integrins, we examined the functional activity of alpha5beta1 and alpha2beta1 integrins in MCF7 cells expressing MT1-MMP. Either expression of MT1-MMP alone or its coexpression with alphavbeta3 failed to affect the functionality of alpha5beta1 integrin, and adhesion of cells to fibronectin. MT1-MMP, however, profoundly affected the cross-talk involving alphavbeta3 and alpha2beta1 integrins. In MT1-MMP-deficient cells, integrin alphavbeta3 suppressed the functional activity of the collagen-binding alpha2beta1 integrin receptor and diminished cell adhesion to type I collagen. Coexpression of MT1-MMP with integrin alphavbeta3 restored the functionality of alpha2beta1 integrin and, consequently, the ability of MCF7 cells to adhere efficiently to collagen. We conclude that the MT1-MMP-controlled cross-talk between alphavbeta3 and alpha2beta1 integrins supports binding of aggressive, MT1-MMP-, and alphavbeta3 integrin-expressing malignant cells on type I collagen, the most common substratum of the extracellular matrix.
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ABSTRACT: Parasitic protozoa are among the most important pathogens worldwide. Diseases such as malaria, leishmaniasis, amoebiasis, giardiasis, trichomoniasis, and trypanosomiasis affect millions of people. Humans are constantly threatened by infections caused by these pathogens. Parasites engage a plethora of surface and secreted molecules to attach to and enter mammalian cells. The secretion of lytic enzymes by parasites into host organs mediates critical interactions because of the invasion and destruction of interstitial tissues, enabling parasite migration to other sites within the hosts. Extracellular matrix is a complex, cross-linked structure that holds cells together in an organized assembly and that forms the basement membrane lining (basal lamina). The extracellular matrix represents a major barrier to parasites. Therefore, the evolution of mechanisms for connective-tissue degradation may be of great importance for parasite survival. Recent advances have been achieved in our understanding of the biochemistry and molecular biology of proteases from parasitic protozoa. The focus of this paper is to discuss the role of protozoan parasitic proteases in the degradation of host ECM proteins and the participation of these molecules as virulence factors. We divide the paper into two sections, extracellular and intracellular protozoa.Journal of Parasitology Research 01/2012; 2012:748206.
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ABSTRACT: BACKGROUND: There is a growing appreciation of the role of proteolytic processes in human health and disease, but tools for analysis of such processes on a proteome-wide scale are limited. Furin is a ubiquitous proprotein convertase that cleaves after basic residues and transforms secretory proproteins into biologically active proteins. Despite this important role, many furin substrates remain unknown in the human proteome. METHODOLOGY/PRINCIPAL FINDINGS: We devised an approach for proteinase target identification that combines an in silico discovery pipeline with highly multiplexed proteinase activity assays. We performed in silico analysis of the human proteome and identified over 1,050 secretory proteins as potential furin substrates. We then used a multiplexed protease assay to validate these tentative targets. The assay was carried out on over 3,260 overlapping peptides designed to represent P7-P1' and P4-P4' positions of furin cleavage sites in the candidate proteins. The obtained results greatly increased our knowledge of the unique cleavage preferences of furin, revealed the importance of both short-range (P4-P1) and long-range (P7-P6) interactions in defining furin cleavage specificity, demonstrated that the R-X-R/K/X-R↓ motif alone is insufficient for predicting furin proteolysis of the substrate, and identified ∼490 potential protein substrates of furin in the human proteome. CONCLUSIONS/SIGNIFICANCE: The assignment of these substrates to cellular pathways suggests an important role of furin in development, including axonal guidance, cardiogenesis, and maintenance of stem cell pluripotency. The novel approach proposed in this study can be readily applied to other proteinases.PLoS ONE 01/2013; 8(1):e54290. · 3.73 Impact Factor
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ABSTRACT: Monocyte infiltration and subsequent differentiation into macrophages has been shown to be crucial during inflammation. Metalloproteinases are key enzymes in these processes, but the role of MMP-14 remains largely unknown. To address this question, we generated animals with conditional ablation of MMP-14 in the monocyte/macrophage lineage. The knockout (KO) animals (LysM-Cre(+)MMP-14(fl/fl)) were healthy and fertile, and neither skin architecture nor differentiation was altered from the wild type (WT). Full-thickness wounds were induced, and careful analysis of wound closure, granulation tissue formation, and angiogenesis revealed no differences between genotypes. The inflammatory response, monocyte influx, differentiation, and lymphocyte infiltration was also similar in KO and WT animals. Ear swelling after croton oil application was similar in the KO and WT animals. Interestingly, the number of monocytes and macrophages, as well as of T cells, was significantly reduced in KO animals, compared with WT animals. Similarly, both P-selectin and proinflammatory cytokine levels were markedly reduced in KO animals. In vitro, the migratory capacity of isolated KO macrophages was significantly impaired on fibronectin, a substrate of MMP-14. These data point to a role of MMP-14 during transendothelial migration of monocytes and T-cell attraction.American Journal Of Pathology 03/2013; 182(3):755-64. · 4.52 Impact Factor