Expression of Laminin Chains in the Neuronal Cells of Mouse Brain

ABSTRACT

Laminin-1 is biologically active and can effect cellular proliferation, differentiation, migration, and apoptosis. In the central nervous system, neuronal cells are rarely reported to give positive reaction by laminin antibody staining. However, the original cell type which can produce the laminin molecule has not been well established. Since the neuronal cells of brain are derived from neuroectoderm, we thought that the neuronal cells should be able to produce the laminin molecules as other epithelial cells. In this study we aimed to explore whether the neuronal cells express the laminin chain mRNAs, and further to identify which types of laminin isoform are expressed at the specific sites of the brain structure. We found that neuronal cell was the important cell type in mouse brain, which could produce laminin isoforms. Although immunostainings disclosed reactivity of laminins in the basement membrane of capillaries as well as neuronal cells, mRNA expressions of laminins were intense only in the neuronal cells. It was relatively weak in the endothelial cells. Among neuronal cells the cortical cells of cerebrum, pyramidal cells of hippocampus, and Purkinje cells of cerebellum showed pronounced expression of laminin chain mRNA. Glial cells, especially astrocytes, were negative for laminin subtypes both in immunohistochemistry and in situ hybridization. Taken together, our data indicate that the neuronal cells of mouse brain actively produce laminin isoforms, and the resultant polymerized laminins are accumulated mainly in the basement membrane of capillaries. In conclusion, the results indicate that neuronal cells produce and utilize the different laminin chains to maintain the neurovascular environment of brain.