Laminin α1 chain mediated reduction of laminin α2 chain deficient muscular dystrophy involves integrin α7β1 and dystroglycan

Transgenically introduced laminin (LN) α1 chain prevents muscular dystrophy in LNα2 chain deficient mice. We now report increased integrin α7Bβ1D synthesis in dystrophic LNα2 chain deficient muscle. Yet, immunofluorescence demonstrated a reduced expression of integrin α7B subunit at the sarcolemma. Transgenic expression of LNα1 chain reconstituted integrin α7B at the sarcolemma. Expression of α- and β-dystroglycan is enhanced in LNα2 chain deficient muscle and normalized by transgenic expression of LNα1 chain. We suggest that LNα1 chain in part ameliorates the development of LNα2 chain deficient muscular dystrophy by retaining the binding sites for integrin α7Bβ1D and α-dystroglycan, respectively.