INTRODUCTION 46 9 down-regulated by DAF-16 and TCER-1 too, the shared group (JOINT DOWN) 179 showed a much higher overlap with the NHR-49 DOWN class (~36%, 26/73, R 5.5, 180 P <2.094e-13) as compared to genes specifically down-regulated by either factor 181 alone (Fig. S1B) . Thus, NHR-49 targets share the largest overlap with genes whose 182 In this study, we demonstrate that NHR-49 is a pro-longevity factor that modulates 368 lifespan and immunity through distinct mechanisms. NHR-49 is influenced differently 369 by, and orchestrates distinct responses to, the acute stress of pathogen attack vs. a We found that NHR-49 expression in neurons alone could rescue the immunity 391 deficits of germline-less, nhr-49;glp-1 mutants, whereas, their lifespan was 392 substantially restored by expression in any somatic tissue. In fertile, nhr-49 single 393 mutants, immunity was restored by presence in neurons or intestine, but lifespan 394 could be rescued from other tissues as well. This suggests that pathogen response 395 may be more sensitive to NHR-49's location as compared to longevity. Interestingly, 396 NHR-49 expression in muscles provided little or no immunity benefit in any of the 397 genetic backgrounds we tested, irrespective of the presence or absence of the 398 germline in the animal. In fact, expression in muscles mostly diminished immunity. 399
This is in noticeable contrast to the broad immunity advantages conferred by tissues including the liver, brain, heart, muscles and immune cells (e.g., 488 macrophages, monocytes, and lymphocytes). Importantly, PPARα performs distinct 489 functions in these tissues and its activity is governed by tissue-specific mechanisms. 490
For instance, it mediates fatty acid oxidation in liver and heart, but its endogenous 491 ligands and their sources are different in the two organs. In liver, a lipid species, 492 16:0/18:1-GPC, derived by Fatty Acid Synthase (FAS)-mediated de novo 493 lipogenesis, serves as its endogenous ligand (Chakravarthy et al., 2009) generated. Transgene-carrying strains were maintained and selected for lifespan 599 and pathogen stress assays using a Leica M165C microscope with a fluorescence 600 attachment. A complete listing of all strains created for this study is provided in Table  601 S7. 602 603 Fenofibrate supplementation assay: 100 µL of 10 µM Fenofibrate (Sigma F6020) 604 in 0.1% DMSO were placed onto both NGM and slow-killing plates before seeding 605 with OP50 or PA14, respectively, as described above (Brandstädt et al., 2013; 606 Leiteritz et al., 2020). Upon the drying and growth of the bacterial lawn, eggs were 607 grown to L4 on either the Fenofibrate or 0.1% DMSO control plates, then transferred 608 to PA14 plates (similarly supplemented with Fibrate or DMSO) at L4 larval stage and 609 survival monitored. Worms were transferred to fresh plates as described above. Fig. 3 Trial 3
Trial 2 