Figure 7. GSCs induce cbs-1 expression in somatic tissues at cold temperature.
a, GFP expressed under cbs-1 promoter in day 5 adult-worms grown at the indicated temperatures during adulthood. At 20°C and 25°C, cbs-1 is mostly expressed in the posterior intestine. At cold temperatures, cbs-1 expression increases in the intestine and muscle. FUdR reduces cold-induced expression of cbs-1 in muscle and intestine. DIC, differential interference contrast. Scale bar, 100 μm. Images are representative of four independent experiments. b, Quantification of cbs-1p::GFP (mean ± s.e.m. relative to 10°C with no FUdR, 40 worms/condition from 4 independent experiments). Analysis by two-tailed Student’s t-test for unpaired samples: *(P<0.05), ****(P<0.0001). NS= not significant (P=0.2683). c, cbs-1p::GFP in day 7 adult-worms at 15°C. Knockdown of either iff-1 or mog-5 during adulthood decreases cbs-1 expression when compared to empty vector (EV) RNAi. Scale bar, 50 μm. Images are representative of two independent experiments. d, Quantification of cbs-1p::GFP (mean ± s.e.m. relative to EV RNAi, 20 worms/condition from 2 independent experiments). Analysis by two-tailed Student’s t-test for unpaired samples: **(P<0.01), ****(P<0.0001). e, H2S gas production in control sterile strain at day 6 of adulthood (fer-15(b26);fem-1(hc17)). Worms were raised at the restrictive temperature (25°C) and shifted to the indicated temperatures during adulthood. The images are representative of four independent experiments. f, H2S production in day 6-adult control sterile worms upon knockdown of cbs-1 during adulthood. The images are representative of four independent experiments. g, Somatic overexpression (OE) of cbs-1 increases H2S production. Two independent cbs-1(OE) lines were tested. The images are representative of two independent experiments. h, Loss of either iff-1 or mog-5 during adulthood decreases H2S production. Control sterile worms at day 6 of adulthood were examined. The images are representative of three independent experiments. i, Ubiquitous somatic overexpression of cbs-1 under sur-5 promoter extends lifespan at 20°C (P<0.0001). GFP(OE) mean ± s.e.m: 16.83 ± 0.36; cbs-1,GFP(OE) #1: 19.65 ± 0.59; cbs-1,GFP(OE) #2: 21.28 ± 0.49. j, Ubiquitous somatic cbs-1(OE) extends lifespan at 25°C (P<0.0001). GFP(OE): 10.61 ± 0.26; cbs-1,GFP(OE) #1: 12.33 ± 0.35; cbs-1,GFP(OE) #2: 12.75 ± 0.38. k, Tissue-specific overexpression of cbs-1 in the intestine (gly-19p), muscle (myo-3p) or neurons (rgef-1p) extends lifespan at 20°C (P<0.0001). Intestinal-specific OE induced longer longevity compared with muscle or neuronal overexpression (P<0.01). GFP(OE): 15.56 ± 0.34; intestinal cbs-1,GFP(OE) #1: 19.82 ± 0.59; intestinal cbs-1,GFP(OE) #2: 20.47 ± 0.66; muscle cbs-1,GFP(OE) #1: 18.31 ± 0.51; muscle cbs-1,GFP(OE) #2: 17.73 ± 0.40; neuronal cbs-1,GFP(OE) #1: 18.11 ± 0.44; neuronal cbs-1,GFP(OE) #2: 17.17 ± 0.36. Two independent tissue-specific cbs-1(OE) lines were tested for each tissue. l, Tissue-specific overexpression of cbs-1 in the intestine (P<0.0001), muscle(P=0.0002) or neurons (P=0.0034) extends lifespan at 25°C. Intestinal-specific OE induced longer lifespan compared with muscle (P=0.0142) or neuronal (P=0.0008) overexpression. GFP(OE) mean ± s.e.m: 10.24 ± 0.24; intestinal cbs-1,GFP(OE) #1: 12.82 ± 0.36; muscle cbs-1,GFP(OE) #1: 11.62 ± 0.28; neuronal cbs-1,GFP(OE) #1: 11.25 ± 0.28. In lifespan experiments, comparisons were made by two-sided log-rank test, n= 96 worms/condition. Supplementary Data 3 contains replicate data of lifespan experiments.