Figure 6. endu-2 mRNA Expression Is Induced by Perturbation of NT Levels and Genotoxicity.

(A–C) qPCR results for endu-2 mRNA level in young adults. An increase was seen with ctps-1(RNAi) (A), in cddko worms (B), or when WT worms were treated with 100 mM U, T, or C (C).

(D–F) qPCR results showing that endu-2 mRNA was up-regulated by HU treatment (D). glp-1(−) (E) or chk-1(RNAi) (F) blocked the induction of endu-2 by HU treatment in adults, but not in L1 larvae. L1 larvae were treated with 20 mM HU for 12 h. Adults were treated with 50 mM HU for 30 h. glp-1(e2141) worms were grown at 25°C to induce the germline loss and were then subjected to the same treatment as in (D). Error bars, SDs. Asterisks indicate significant differences in all of the panels.

(G) qPCR results for EndoU mRNA level. Expression was increased in HeLa cells treated with indicated concentrations of HU for 3 days. Tukey’s range test, FWER = 0.01, was used to calculate statistical significance.

(H) WST-8 cell proliferation assay results. EndoU RNAi-treated HeLa cells had reduced viability after 3 days of 5-FU treatment. *p < 0.0001 using 2-way ANOVA test.

(I) A model depicting the proposed role of ENDU-2 as a sensor and regulator of NT levels and genotoxic stresses. Arrows and T-bars indicate positive and negative regulation, respectively. The dashed arrow and the T-bar indicate that the mechanism by which germline proliferation is regulated by CTPS-1 is not known. It could be done through inhibitory regulation by non-phosphorylated CTPS-1, but a promotional regulation by phosphorylated CTPS-1 cannot be excluded (see Discussion).

(A–F) Student’s t test, unpaired, 2-tailed, and Bonferroni correction was carried out in (C)–(F). α = 0.01 (A and B), 0.0018 (C), and 0.008 (D)–(F).