The UPR^ER as a rheostat for stem cell proliferation.

<p>(A) Quantification of pH3⁺ cells in wild-type flies and in flies over-expressing Xbp1 (<i>xbp1^d08698</i>, <i>xbp1^EP2112</i>), Hrd1, or Hsc3 under the control of esg::Gal4 exposed to mock treatment (5% sucrose) or tunicamycin (TM). Averages and SEM are shown. P values from Student's T test, N = 10. (B) Quantification of pH3⁺ cells in wild-type flies and in flies over-expressing Xbp1 (<i>Xbp1^d08698</i>, <i>Xbp1^EP2112</i>), Hrd1, or Hsc3 under the control of esg::Gal4, UAS::GFP; tub::Gal80^ts exposed to mock treatment (5% sucrose) or tunicamycin (TM). Averages and SEM are shown. P values from Student's T test, N = 10. (C) Quantification of pH3⁺ cells in wild-type flies and in flies over-expressing Xbp1 (<i>Xbp1^d08698</i>, <i>Xbp1^EP2112</i>), or Hsc3 under the control of esg::Gal4, UAS-GFP; tubG80^ts exposed to mock (5% sucrose) and oxidative-stress inducer paraquat (5 mM PQ). Averages and SEM are shown. P values from Student's Test, N = 10. (D) Spliced Xbp1 prevents ISC over-proliferation induced by excessive ER stress. Quantification of mitotic figures of wild-type flies and flies over-expressing spliced Xbp1 (Xbp1^spliced) in ISCs/EBs (esg::Gal4, UAS-GFP; tubG80^ts) exposed to mock treatment (5% sucrose) or paraquat (5 mM) or tunicamycin(50 µM). Averages and SEM are shown. P values from Student's Test, N = 10. (E) Over-expressing spliced Xbp1 in ISCs only (using esg::Gal4, Su(H)-Gbe::G80,tub::Gal80ts) inhibits stress-induced ISC proliferation. Averages and SEM are shown. P values from Student's T test, N>10. (F) Over-expressing spliced Xbp1 in ECs has no effect on ISC proliferation upon stress. Quantification of PH3⁺ cells in intestines of wild-type flies and in flies expressing Xbp1^spliced specifically in ECs (using NP1::Gal4; tub::Gal80^ts). Averages and SEM are shown. P values from Student's T test, N = 10. (G) Quantification of pH3⁺ cells in intestines of wild-type flies and in flies expressing spliced Xbp1 (Xbp1^DSΔ28) or Hrd1 specifically in EBs (using Su(H)Gbe::Gal4,tubG80^ts) exposed to mock treatment (5% sucrose), paraquat (5 mM), or tunicamycin (50 µM). Averages and SEM are shown. P values from Student's Test, N = 10. See also <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1004568#pgen.1004568.s001" target="_blank">Figure S1</a>, <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1004568#pgen.1004568.s002" target="_blank">S2</a>.