Open AccessA modified UPR stress sensing system reveals a novel tissue distribution of IRE1/XBP1 activity during normal Drosophila development
Author(s) -
Michio Sone,
Xiaomei Zeng,
Joseph Larese,
Hyung Don Ryoo
Publication year - 2013
Publication title -
cell stress and chaperones
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.994
H-Index - 87
eISSN - 1466-1268
pISSN - 1355-8145
DOI - 10.1007/s12192-012-0383-x
Subject(s) - xbp1 , unfolded protein response , atf6 , endoplasmic reticulum , microbiology and biotechnology , biology , drosophila melanogaster , malpighian tubule system , homeostasis , rna splicing , genetics , gene , rna , midgut , larva , botany
Eukaryotic cells respond to stress caused by the accumulation of unfolded/misfolded proteins in the endoplasmic reticulum by activating the intracellular signaling pathways referred to as the unfolded protein response (UPR). In metazoans, UPR consists of three parallel branches, each characterized by its stress sensor protein, IRE1, ATF6, and PERK, respectively. In Drosophila, IRE1/XBP1 pathway is considered to function as a major branch of UPR; however, its physiological roles during the normal development and homeostasis remain poorly understood. To visualize IRE1/XBP1 activity in fly tissues under normal physiological conditions, we modified previously reported XBP1 stress sensing systems (Souid et al., Dev Genes Evol 217: 159-167, 2007; Ryoo et al., EMBO J 26: 242-252, 2007), based on the recent reports regarding the unconventional splicing of XBP1/HAC1 mRNA (Aragon et al., Nature 457: 736-740, 2009; Yanagitani et al., Mol Cell 34: 191-200, 2009; Science 331: 586-589, 2011). The improved XBP1 stress sensing system allowed us to detect new IRE1/XBP1 activities in the brain, gut, Malpighian tubules, and trachea of third instar larvae and in the adult male reproductive organ. Specifically, in the larval brain, IRE1/XBP1 activity was detected exclusively in glia, although previous reports have largely focused on IRE1/XBP1 activity in neurons. Unexpected glial IRE1/XBP1 activity may provide us with novel insights into the brain homeostasis regulated by the UPR.