Differential laminin gene expression in dorsal root ganglion neurons and nonneuronal cells

Laminin is a substrate for cell migration and process outgrowth during development and may play an important role in peripheral nerve regeneration. While most studies have emphasized the expression and production of this glycoprotein by Schwann cells, in the current study we use in situ hybridization to examine the expression of the various laminin chain genes in neuronal as well as nonneuronal cells of normal adult rat lumbar dorsal root ganglia. Hybridization using cRNA probes derived from cDNAs encoding nonhomologous regions of each laminin chain showed differential localization of the chain messages within the ganglia. B2 chain mRNA was abundant in large and small neurons, satellite cells, and Schwann cells. B1 chain message was also localized in satellite and Schwann cells, but its neuronal expression was primarily restricted to a subpopulation of smaller neurons. Message encoding merosin M chain, an A chain variant, was localized within satellite cells and Schwann cells but was absent or of very low abundance in neurons. A chain mRNA was not detectable in any of the three nervous tissue cell types. The differential expression of the four laminin chains in the DRG is discussed in relation to the functional epitopes of the molecule.