# Mutual regulation of spermatogenesis-specific Argonaute proteins and Insulin/IGF-1 signaling in aging control

## TL;DR

This study shows that Argonaute proteins ALG-3 and ALG-4 interact with insulin/IGF-1 signaling to regulate aging in worms, possibly by controlling sperm proteins that affect Eph receptor and PTEN levels.

## Contribution

The study reveals a novel mutual regulatory relationship between spermatogenesis-specific Argonautes and IIS in aging control.

## Key findings

- Loss of ALG-3 and ALG-4 in a weak IIS mutant background extends lifespan by 53%.
- ALG-3/4 regulate Major Sperm Protein genes, which may have life-extending functions.
- ALG-3/4 loss disrupts EphR localization and increases PTEN levels in oocytes.

## Abstract

The potential role of small interfering RNAs (siRNAs) produced from double-stranded RNA in aging has not been fully addressed. The networks of genes regulated by siRNAs and their partner Argonaute proteins are best understood in C. elegans, a pioneering model of aging and small RNA studies. Here, we describe synergistic lifespan extension of insulin/IGF-1 signaling (IIS) mutant age-1(hx546) by rde-4 or alg-3; alg-4 deficiencies. By analyzing gene expression and siRNA populations in these IIS and RNAi mutants, we show here that redundant spermatogenesis-specific Argonautes ALG-3 and ALG-4 are capable of regulating IIS, potentially through direct control of the Major Sperm Protein (MSP) genes in the germline. MSPs and MSP domains of some mammalian proteins are secreted and directly inhibit the Eph receptor (EphR). In turn, EphR interacts with and destabilizes PTEN, a major negative regulator of IIS. We show that enhanced MSP expression correlates with EphR mislocalization and elevated PTEN levels in oocytes of alg-3/4(-) worms. At the same time, ALG-3/4 expression is regulated by IIS. Thus, we propose mutual regulation of IIS and ALG-3/4 through secreted ligands.

Argonaute genes alg-3 and alg-4 genetically interact with the Insulin/IGF-1 signaling pathway to promote aging. They impact EphR localization and PTEN levels in oocytes, potentially through direct inhibition of secreted Major Sperm Protein genes.

Loss of ALG-3 and ALG-4 in a weak IIS mutant background causes 53% lifespan extension.ALG-3 expression in the spermatogenic germline is promoted by IIS.ALG-3 and ALG-4 repress Major Sperm Protein genes with potential life-extending function.ALG-3/4 loss leads to disrupted localization of EphR and increased accumulation of PTEN in oocytes.

Loss of ALG-3 and ALG-4 in a weak IIS mutant background causes 53% lifespan extension.

ALG-3 expression in the spermatogenic germline is promoted by IIS.

ALG-3 and ALG-4 repress Major Sperm Protein genes with potential life-extending function.

ALG-3/4 loss leads to disrupted localization of EphR and increased accumulation of PTEN in oocytes.

Argonaute genes alg-3 and alg-4 genetically interact with the Insulin/IGF-1 signaling pathway to promote aging. They impact EphR localization and PTEN levels in oocytes, potentially through direct inhibition of secreted Major Sperm Protein genes.