Expression and distribution of functional integrins in rat CNS glia

In previous studies, we have reported on the expression of beta 1 integrins in type 1 astrocytes and their function in cell-substratum attachment (Tawil et al., J Cell Biol 120:261-271, 1993). Here we extend those findings by providing evidence that type 1 astrocytes express integrins of the beta 3 and possibly beta 4 subclasses and that the former (alpha v beta 3) functions in attachment by recognizing the peptide, Arg-Gly-Asp, in vitronectin. In addition, we have examined immunocytochemically the expression of beta 1 integrins on type 2 astrocytes and oligodendrocytes. The pattern of expression of integrins on these two cell types is distinct from type 1 astrocytes; most notably type 1 astrocytes but not oligodendrocytes or type 2 astrocytes express alpha 1 beta 1 heterodimers. Since type 2 astrocytes and oligodendrocytes originate from a common precursor (O-2A), the alpha 1 beta 1 heterodimer may be a functional marker which distinguishes O-2A-derived cells from those of the type 1 astrocyte lineage.