Laminin-2, a heterotrimer composed of α2, β1, and γ1 subunits, is the primary laminin isoform found in muscle and peripheral nerve and is essential for the development and stability of basement membranes in these tissues. Expression of a domain VI-truncated laminin α2-chain results in muscle degeneration and peripheral nerve dysmyelination in the dy(2J) dystrophic mouse. We have expressed amino-terminal domains VI through IVb of the laminin α2-chain, as well as its laminin-1 α1-chain counterpart, to identify candidate cell-interactive functions of this critical region. Using integrin- specific antibodies, recognition sites for the α1β1 and α2β1 integrins wore identified in the short arms of both laminin α1- and α2-chain isoforms. Comparisons with a β-α chimeric short arm protein possessing β1- chain domain VI further localized these activities to α-chain domain VI. In addition, we found that the laminin α2-chain short arm supported neurite outgrowth independent of other laminin-2 subunits. A heparin/heparan sulfate binding activity was also localized to this region of the laminin α2 subunit. These data provide the first evidence that domain VI of the laminin α2-chain mediates interactions with cell surface receptors and suggest that these integrin and heparin binding sites, alone or in concert, may play an important role in muscle and peripheral nerve function.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology