MicroRNA miR-263b-5p Regulates Developmental Growth and Cell Association by Suppressing Laminin A in Drosophila .

Basement membranes (BMs) play important roles under various physiological conditions in animals, including ecdysozoans. During development, BMs undergo alterations through diverse intrinsic and extrinsic regulatory mechanisms; however, the full complement of pathways controlling these changes remain unclear. Here, we found that fat body-overexpression of Drosophila miR-263b , which is highly expressed during the larval-to-pupal transition, resulted in a decrease in the overall size of the larval fat body, and ultimately, in a severe growth defect accompanied by a reduction in cell proliferation and cell size. Interestingly, we further observed that a large proportion of the larval fat body cells were prematurely disassociated from each other. Moreover, we present evidence that miR-263b-5p suppresses the main component of BMs, Laminin A ( LanA ). Through experiments using RNA interference (RNAi) of LanA , we found that its depletion phenocopied the effects in miR-263b -overexpressing flies. Overall, our findings suggest a potential role for miR-263b in developmental growth and cell association by suppressing LanA expression in the Drosophila fat body.