Fig. 6.

ROS-p38 signaling in ECs promotes ISC proliferation upon damage. a–c ROS are required for p38 activation in ECs upon P.e. infection. p38 activation increases in ECs in P.e.-infected control midguts (EC-specific, Myo1A^ts) (b below, red) compared with uninfected control midguts (a below, red). p38 activation is blocked, however, in P.e.-infected midguts overexpressing Nrf2 (Cnc) in ECs for 5 days with Myo1A^ts (c below, red) compared with P.e.-infected control midguts. d, e Nrf2 overexpression in ECs blocks ISC-mediated regeneration upon P.e. infection and detergent exposure. The ISC response is blocked in P.e.-infected midguts overexpressing Nrf2 in ECs for 2 days with Myo1A^ts compared with P.e.-infected control midguts (Mann–Whitney; p < 0.0001). ISC mitoses are increased in midguts overexpressing Nrf2 for 2 days compared with control midguts (Mann–Whitney; p = 0.0011). The mean number of phosphorylated histone H3 Ser 10-positive cells per midgut with s.e.m. in control midguts (Myo1A^ts) (n = 13 midguts), P.e.-infected control midguts (n = 20 midguts), midguts expressing Nrf2 (cnc) in ECs for 2 days with Myo1A^ts (n = 22 midguts) and in P.e.-infected midguts expressing cnc in ECs for 2 days (n = 23 midguts). Midguts pooled from two independent experiments. d ISC-mediated regeneration is blocked in SDS-fed (20 h) midguts overexpressing Nrf2 (Cnc) in ECs for 6 days with Myo1A^ts compared with SDS-fed control midguts (unpaired t; p < 0.0001). ISC mitoses are increased in midguts overexpressing Nrf2 for 6 days compared with control midguts (unpaired t; p < 0.0001). The mean number of phosphorylated histone H3 Ser 10-positive cells per midgut with s.e.m. from one representative experiment in control midguts (Myo1A^ts > Dcr-2) (n = 9 midguts), SDS-fed control midguts (n = 9 midguts), midguts expressing Nrf2 (Cnc) in ECs for 6 days with Myo1A^ts (n = 7 midguts) and in SDS-fed midguts expressing Cnc in ECs for 6 days (n = 15 midguts) (e). f Multiple stresses induce ROS-Nrf2 target gene GstD1 expression. Mean relative GstD1 mRNA levels with s.e.m. from n = 3 independent experiments (one-way ANOVA: p = 0.0086; Dunnett’s: P.e. < 0.0001, Ecc15 < 0.0001, H₂O₂ < 0.0001, SDS < 0.0001, bleomycin < 0.0001, heat shock < 0.0001) determined by qPCR from stressed and unstressed w¹¹¹⁸ midguts. DNA is in blue. Scale bars in a–c are 50 μm. Representative images in a–c from three experiments. Source data are provided as a Source Data File