Extended Data Fig. 4: Gut-derived Upd2 and Upd3 are sufficient and required for infection-induced STAT activation in the glia.

a, Gut-derived Upd proteins and their possible effect on the AL. b, Glial expression of nuclear mCherry driven by Mex1::Gal4 in the gut and brain of adult flies. c, d, Activity of 2xSTAT::GFP reporter in the central brain of flies overexpressing upd2, upd3 in enterocytes, driven by Mex1::Gal4;tubG80^ts, during homeostasis (c) and of infected flies loss of upd2, upd3 in enterocytes (d). Representative images were generated from 30-μm z-sections, and the AL region was magnified. Numbers of GFP⁺, repo⁺ glia per AL were quantified in Fig. 1g. e, f, Preference index of flies expressing mCherry^RNAi, UAS::LacZ, LacZ^RNAi, UAS::upd2, UAS::upd3 and RNAi lines targeting upd2 or upd3 in enterocytes with or without Ecc15 infection. g, qPCR analysis confirming the knockdown efficiency of multiple RNAi lines targeting upd2 or upd3 correspondingly. h, j, Activity of 2xSTAT::GFP reporter in the central brain of flies overexpressing upd2 or upd3 in haemocytes (driven by hm1::Gal4) during homeostasis and of infected flies loss of upd3 in haemocytes. Numbers of GFP⁺ repo⁺ cells per AL were quantified from 30-μm z-sections in j, and the AL region was magnified. i, k, Activity of 2xSTAT::GFP reporter in the central brain of flies overexpressing upd2 in fatbody (driven by cg::Gal4) during homeostasis and of infected flies loss of upd3 in fatbody. Numbers of GFP⁺ repo⁺ cells per AL were quantified from 30-μm z-sections in k, and the AL region was zoomed in. Data are mean and s.e.m. The sample size is as follows: n = 6, 5, 5, 7, 6 and 9 independently performed experiments per condition (from left to right) in e, n = 4 or 5 independently performed experiments per condition in f, n = 3, 4 and 4 biological replicates per condition (from left to right) in g (left), n = 3, 4 and 2 biological replicates per condition (from left to right) in g (right), n = 12, 14, 11, 9 and 11 brains per condition (from left to right) in j, n = 7, 6, 10 and 13 brains per condition (from left to right) in k. Data in c and d are representative of three independently performed experiments; data shown in b, g–k are representative of two independently performed experiments. P values from two-tailed Mann–Whitney test in f, j and k when comparing two groups; other P values from Kruskal–Wallis test.

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