Figure 1

MiR-307a regulates Wg secretion and initiates ER stress in wg-expressing cells.

All the wing discs hereafter are oriented anterior left, dorsal up. The dotted lines were used to indicate the Anterior/Posterior (A/P) compartment boundary. (a) Immunostaining of Wg in wild-type wing disc. (b-e’, i-i”’) Expression of UAS-miR-307a (marked by GFP) was induced in the P compartment using hhGal4 driver. (b-b’) The arrow and arrowhead indicate Wg is accumulated in its expressing cells. (c) Immunostaining of extracellular Wg. The arrowheads indicate reduction of extracellular Wg staining. (d-d’) Immunostaining of Sens (red). The arrowheads indicate the loss of Sens expression in the miR-307a-expressing P compartment. (e-e’) Transcription of wg (wg-lacZ) is not regulated by miR-307a overexpression. (f-f’) Immunostaining of Bip and Wg in wild-type wing disc. (g, h) Expression of UAS-bip or UAS-bipRNAi transgene was induced using hhGal4. (g) The yellow asterisk indicates the increasing of Bip levels. (h) The wing discs were treated with 5 mM DTT (in M3 medium) for 16 h before immunostaining for inducing ER stress. Upregulation of Bip occurs in the wild-type tissue (white asterisk) but not in bip depletion tissue (yellow asterisk). (i-i”’) Overexpression of miR-307a causes an ectopic expression of Bip specifically in the wg-expressing cells (arrow and arrowhead in i). Scale bar = 50 μm.