Evolutionary conservation of laminin-binding proteins

RESUMO

The virulence of pathogens and metastatic capacity of cancer cells seems to correlate with the ability to adhere to cells and/or to basement components. A key feature of this mechanism in the expression of specific receptors for the basement membrane protein laminin. There different receptors have been already described in cells phylogenetically very distant, such as human white blood cells, Trichomonas vaginalis and Stapgylococcus aureus, all recognizing laminin with the same range of affinity. We have shown that laminin, which is also found in the circulation, enchances phagocytosis of S. aureus by macrophages in a species-specific fashion. Also, monoclonal antibodies (MAb) raised against the bacterial receptor inhibit the phagocytic enhancement mediated by laminin and recognize laminin-binding proteins in unicellular parasites and mammalian cells. The same Mab 1.H12 elutes a 52-kDa protein from bacterial extracts and a 67-kDa band from cancer cells extracts. Since the MAb is a monospecific reagent, results with 1.H12 strongly suggest and evolutionary conservation of the biding site of phylogenetically different laminin receptors