Downregulation of Rpn1 and Rpn2 19S cap proteasome subunits severely affects eye morphogenesis.

<p>(A) Confocal Laser Scanning Microscopy (CLSM) images, illustrating the organ-specific and targeted overexpression of EGFP (enhanced green fluorescent protein) reporter protein exclusively in the (a) eye disc of double transgenic flies carrying the GAL4-ninaE.GMR/UAS-2xEGFP strain genotype and (b) dorsal wing disc of double transgenic flies characterized by the P{GawB}Bx^MS1096/UAS-2xEGFP strain genotype, and therefore reflecting the functional reliability and efficiency of the cell type-dependent genetic scheme employed in the present study. (B) Stereo-microscopical (a, e and i), Optical (d, h and l {semi-thin sections}) and Scanning Electron Microscopy (SEM) (b, c, f, g, g′, j and k) images, demonstrating Drosophila compound eye morphology and structural organization in Rpn1 and Rpn2 functionally deficient cellular environments. (a–d) GAL4-ninaE.GMR single transgenic adult fly compound eyes (dashed circle: ommatidium; 1–7: photoreceptor cells) (utilized as control condition; identical phenotypes are also observed for single transgenic flies grown at 29°C, and for triple transgenic flies overexpressing the β2^ts and β6^ts -conditional- mutant proteasome components raised at 25°C {data not shown}). (e–h) GAL4-ninaE.GMR/UAS-Rpn1_RNAi double transgenic fly eyes, carrying reduced Rpn1 protein contents. (i–l) GAL4-ninaE.GMR/UAS-Rpn2_RNAi double transgenic fly eyes, characterized by downregulated Rpn2 proteasome subunit expression levels. Arrows: lesion area(s). Scale Bars: 50 µm.