Transfection of MCF-7 carcinoma cells with human integrin alpha 7 cDNA promotes adhesion to laminin

The laminin-binding alpha7 beta1 integrin receptor is highly expressed by s keletal and cardiac muscles, and has been suggested to be a crucial molecul e during myogenic cell migration and differentiation. Absence of integrin a lpha7 subunit contributes to a form of muscular dystrophy in integrin alpha 7 null mice, whereas specific mutations in the alpha7 gene are associated i n humans with congenital myopathy, To examine in more detail the potential role of integrin alpha7 in human-related muscular disorders, we cloned alph a7 cDNA by RT-PCR from human skeletal muscle mRNA and then expressed the fu ll-length human integrin alpha7 cDNA by transfection in several cell lines including MCF-7, COS-7, and NIH3T3 cells. The isolated cDNA corresponds to the human alpha 7X2B alternative splice form. Expression of human alpha7 wa s further confirmed by transfection of chimeric human/mouse alpha7 cDNA con structs. To demonstrate the functionality of expressed human alpha7, adhesi on experiments with transfected MCF-7 cells have confirmed the specific bin ding of human alpha7 to laminin, In addition, mouse polyclonal and monoclon al antibodies were generated against the extracellular domain of human alph a7 and used to analyze by flow cytometry MCF-7 and NIH3T3 cells transfected with the full-length of human alpha7 cDNA. These results show for the firs t time the exogenous expression of functional full-length human alpha7 cDNA , as well. as the development of monoclonal antibodies against the human al pha7 extracellular domain. Antibodies developed will be useful for further analysis of human disorders involving alpha7 dysfunction and facilitate iso lation of muscle stem cells (satellite cells) and thereby expand the opport unities for genetically modified transplantation treatment of human disease . (C) 2001 Academic Press.