<i>Phosphatidylinositol Transfer Protein-1</i> Integrates Insulin/IGF-1 and TOR Signaling to Negatively Regulate Lifespan and Healthspan in <i>Caenorhabditis elegans</i>

<h4>Background</h4> Phosphatidylinositol transfer protein-1 ( pitp-1 ) is involved in phosphoinositide turnover. The role of pitp-1 in promoting healthy longevity remains unknown. Our previous work showed that the phosphoinositide turnover genes dagl-1 and dgk-5 regulates lifespan, as overexpression of dagl-1 or knockdown of dgk-5 prolongs lifespan and enhances oxidative stress resistance through TOR signaling. As pitp-1 is a key component of this pathway, we investigated its role in lifespan regulation and the underlying mechanisms, aiming to clarify whether it represents a critical regulator of healthy longevity and how it coordinates conserved signaling pathways to regulate aging. <h4>Methods</h4> C. elegans mutants, RNAi-mediated knockdown, and transgenic overexpression were applied to assess lifespan, motility, stress resistance. Temporal and tissue-specific RNAi were applied to identify the critical time window and tissue for pitp-1 -mediated lifespan regulation. TOR signaling was measured by phosphorylated S6 kinase and puromycin incorporation, and transcriptomic analysis identified affected pathways. <h4>Results</h4> pitp-1 negatively regulates lifespan and healthspan(definition) in Caenorhabditis elegans . Genetic deletion or RNAi-mediated knockdown of pitp-1 extends lifespan, attenuates age-related motility decline, and increases oxidative stress resistance. Temporal and spatial analyses reveal that suppression of pitp-1 in neurons during early adulthood is sufficient to promote healthy longevity. Mechanistically, these beneficial effects upon pitp-1 reduction are mediated by suppressing TOR signaling. Conversely, pitp-1 overexpression shortens lifespan and impairs healthspan via TOR activation. Moreover, pitp-1 is transcriptionally repressed by DAF-16 downstream of insulin/IGF-1 signaling (IIS), and contributes to IIS-mediated lifespan extension. <h4>Conclusion</h4> These findings identify pitp-1 as a novel regulator of healthy aging that integrates IIS and TOR pathways, providing new insights into conserved mechanisms for promoting healthy longevity.