Alternative mode

An alternative mode of epithelial polarity in the Drosophila midgut.  bioRxiv, doi: 10.1101/307579
Apical-basal polarity is essential for the formation and function of epithelial tissues, whereas loss of polarity is a hallmark of tumours.  Studies in Drosophila have identified conserved polarity factors that define the apical (Crumbs, Stardust, Par-6, aPKC), junctional (Baz/Par-3) and basolateral (Scribbled, Discs large, Lgl) domains of epithelial cells.  Because these conserved factors mark equivalent domains in diverse vertebrate and invertebrate epithelial types, it is generally assumed that this system organises polarity in all epithelia.  Here we show that this is not the case, as none of these canonical factors are required for the polarisation of the endodermal epithelium of the Drosophila adult midgut.  Furthermore, unlike other Drosophila epithelia, the midgut forms occluding junctions above adherens junctions, as in vertebrates, and requires the integrin adhesion complex for polarity.  Thus, Drosophila contains two types of epithelia that polarise by different mechanisms.  Since knock-outs of canonical polarity factors often have little effect on the polarity of vertebrate epithelia, this diversity of polarity mechanisms is likely to be conserved in other animals.

先週プレプリントサーバに出てきたDr. DSJラボからの論文。Drosophila adult midgutのepithelial cellは、apical-basal polarityの構造と形成メカニズムが、今まで他の上皮で報告されているものとは異なっているという。このmidgut cellでは、septate junctionがadherens junctionのapical側に位置しており、vertebrateのものと似ている（Drosophilaの他の上皮では逆）。しかも、crumbs、stardust、bazooka、Par-6、aPKC、scrib、dlg、lglのどのmutant cloneもmidgut epitheliaではpolarity defectのphenotypeを示さない。Integrin adhesion complexが壊れてbasement membraneとの接着が外れたり、septate junction componentが壊れて隣接細胞とのseptate junctionが形成されないと、さすがにpolarizeできないようだが。。。
まぁまだ査読前ということもあってデータは不十分なんだけど、もしこれが本当なら色々とオモシロイね。