Endogenous RNAi and aging control

The lifespan of humans is affected by a variety of genetic and environmental factors. The extreme longevity of individuals is notably associated with the genetic makeup, as shown by the significant presence of specific DNA polymorphisms among centenarians. Pioneering C. elegans work established the key role of the transcription factor DAF-16/FOXO in activating longevity-promoting metabolic pathways and the importance of conserved Insulin/Insulin Growth Factor-1 Signaling (IIS) in negatively regulating DAF-16. Here, we propose to investigate the contribution of genes repressed by endogenous double-stranded RNA (dsRNA)-derived small RNAs to lifespan extension. Specifically, we focus on Major Sperm Protein genes repressed by small RNAs (sRNA) and Argonaute proteins expressed in the spermatogenic germline. High expression of several MSP genes correlated with extended lifespans in genetic models of reduced IIS and dietary restriction; these same MSPs were strongly upregulated in a mutant strain lacking sRNAs. We base our research plan on i) the lifespan data demonstrating significant extension of the lifespan of a weak IIS mutant by sRNA or spermatogenic Argonaute deficiency, ii) gene expression analyses of IIS (age-1/PI3K) mutant showing significant upregulation of genes repressed by spermatogenic sRNAs, iii) discovery of spermatogenic germline Argonaute genes, alg-3 and alg-4, regulation by IIS and DAF-16. Moreover, C. elegans MSPs and MSP domains of some mammalian proteins were shown to be secreted and to directly inhibit the Eph receptor (VAB-1 in C. elegans). In turn, VAB-1 interacts with and inhibits the stability of DAF-18/PTEN, a major negative regulator of IIS. Consistently, vab-1 mutants show extended lifespan. In agreement with the possibility that high expression of MSPs in alg-3/4(-) spermatogenic germline leads to their increased secretion and affects VAB-1 and DAF-18 in other tissues, we observed a reduction in VAB-1::GFP membrane localization and elevated membrane GFP::DAF-18 levels in oocytes of alg- 3/4(-) worms. Thus, secreted MSPs might modulate lifespan through other tissues with high VAB-1 and DAF-18 expression, such as sensory neurons. We propose to investigate the potential life-extending capacity of MSPs, including their secretion, in Aim 1, identify the site of action of DAF-18 and VAB-1 in longevity control in Aim 2, and identify insulin-like peptides regulating insulin receptor DAF-2 activity in the spermatogenic germline, and, consequently, alg-3/4 and MSP gene expression levels, in Aim 3. Thus, this proposal has the potential to uncover bi-directional communication through secreted MSPs and insulin-like peptides between germline cells and somatic tissues critical for aging regulation. Project Number: 1R01AG086451-01A1 | Fiscal Year: 2026 | NIH Institute/Center: National Institute on Aging (NIA) | Principal Investigator: Alla Grishok | Institution: BOSTON UNIVERSITY MEDICAL CAMPUS, BOSTON, MA | Award Amount: $343,350 | Activity Code: R01 | Study Section: Cellular Mechanisms in Aging and Development Study Section[CMAD] View on NIH RePORTER: https://reporter.nih.gov/project-details/11366019