Xbp1-Independent Ire1 Signaling Is Required for Photoreceptor Differentiation and Rhabdomere Morphogenesis in Drosophila

Diana S. Coelho, Maria Fatima Cairrao, Xiaomei Zeng, Elisabete Pires, Ana Maria Coelho, David Ron, Pedro Manuel Domingos, Hyung Don Ryoo

Research output: Contribution to journalArticle

44 Citations (Scopus)

Abstract

The unfolded protein response (UPR) is composed by homeostatic signaling pathways that are activated by excessive protein misfolding in the endoplasmic reticulum. Ire1 signaling is an important mediator of the UPR, leading to the activation of the transcription factor Xbp1. Here, we show that Drosophila Ire1 mutant photoreceptors have defects in the delivery of rhodopsin-1 to the rhabdomere and in the secretion of Spacemaker/Eyes Shut into the interrhabdomeral space. However, these defects are not observed in Xbp1 mutant photoreceptors. Ire1 mutant retinas have higher mRNA levels for targets of regulated Ire1-dependent decay (RIDD), including for the fatty acid transport protein (fatp). Importantly, the downregulation of fatp by RNAi rescues the rhodopsin-1 delivery defects observed in Ire1 mutant photoreceptors. Our results show that the role of Ire1 during photoreceptor differentiation is independent of Xbp1 function and demonstrate the physiological relevance of the RIDD mechanism in this specific paradigm.
Original languageUnknown
Pages (from-to)791-801
JournalCELL REPORTS
Volume5
Issue number3
DOIs
Publication statusPublished - 1 Jan 2013

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