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[摘要]：Peripheral nerve development involves multiple classes of glia that cooperate to form overlapping glial layers paired with the deposition of a surrounding extracellular matrix (ECM). The formation of this tubular structure protects the ensheathed axons from physical and pathogenic damage and from changes in the ionic environment. Integrins, a major family of ECM receptors, play a number of roles in the development of myelinating Schwann cells, one class of glia ensheathing the peripheral nerves of vertebrates. However, the identity and the role of the integrin complexes utilized by the other classes of peripheral nerve glia have not been determined in any animal. Here, we show that, in the peripheral nerves of Drosophila melanogaster, two integrin complexes (alpha PS2 beta PS and alpha PS3 beta PS) are expressed in the different glial layers and form adhesion complexes with integrin-linked kinase and Talin. Knockdown of the common beta subunit (beta PS) using inducible RNAi in all glial cells results in lethality and glial defects. Analysis of integrin complex function in specific glial layers showed that loss of beta PS in the outermost layer ( the perineurial glia) results in a failure to wrap the nerve, a phenotype similar to that of Matrix metalloproteinase 2-mediated degradation of the ECM. Knockdown of beta PS integrin in the innermost wrapping glia causes a loss of glial processes around axons. Together, our data suggest that integrins are employed in different glial layers to mediate the development and maintenance of the protective glial sheath in Drosophila peripheral nerves. |
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