Expression of αvβ3 and αvβ8 integrins during oligodendrocyte precursor differentiation in the presence and absence of axons

We have shown previously that switching of the αv-associated β1 and β5 integrin subunits during differentiation of myelin-forming oligodendrocytes may regulate important aspects of cell behaviour such as migration (Milner et al., 1996: J Neurosci 16:7240-7252). In this study we have examined the developmental regulation of other αv-associated β subunits in oligodendroglial cell cultures and also the control of their expression by neurons, using xenocultures to distinguish glial and neuronal integrins. We have found that oligodendroglia express αvβ8 in addition to the previously-described αvβ1, αvβ3, and αvβ5. β8 and β3 together comprise the 80kD band seen in αv immunoprecipitations that represents the most abundant αv-associated β subunit and show reciprocal patterns of expression during development. αvβ8 is expressed at high levels on oligodendrocyte precursors and differentiated oligodendrocytes but diminishes during the intermediate stages of differentiation. αvβ3, in contrast, shows an opposite pattern of expression, with the highest levels seen at the intermediate stages of differentiation and little expression on either oligodendrocyte precursors and differentiated oligodendrocytes. The expression of αvβ3 is not altered by coculture with neurons, unlike that of αvβ8, in which the decrease seen at the intermediate stages of differentiation is less marked in the presence of neurones. Our results confirm that switching of αv-associated β subunits is an important feature of oligodendrocyte differentiation and suggest that αvβ8 and αvβ3 have distinct functions during myelination.