Shanmugam, M. M. | bioRxiv Science

bioRxiv2025

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

BackgroundPhosphatidylinositol 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. MethodsC. 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. Resultspitp-1 negatively regulates lifespan and healthspan 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. ConclusionThese 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.

genetics↗

bioRxiv2025

Methylglyoxal-induced glycation stress promotes aortic stiffening: Putative mechanistic roles of oxidative stress and cellular senescence

BackgroundHere, we assessed the role of the advanced glycation end-product (AGE) precursor methylglyoxal (MGO) and its non-crosslinking AGE MGO-derived hydroimidazolone (MGH)-1 in aortic stiffening and explored the potential of a glycation stress-lowering compound (Gly-Low) to mitigate these effects. MethodsYoung (3-6 month) C57BL/6 mice were supplemented with MGO (in water) and Gly-Low (in chow). Aortic stiffness was assessed in vivo via pulse wave velocity (PWV) and ex vivo through elastic modulus. Putative mechanisms underlying MGO- and MGH-1-induced aortic stiffening were explored using complementary experimental approaches in aortic tissue and cultured human aortic endothelial cells (HAECs). Moreover, aortic stiffness was assessed in old (24 month) mice after consumption of Gly-Low-enriched chow. ResultsMGO-induced glycation stress increased PWV in young mice by 21% (P<0.05 vs. control), which was prevented with Gly-Low (P=0.93 vs. control). Ex vivo, MGO increased aortic elastic modulus 2-fold (P<0.05), superoxide production by [~]40% (P<0.05), and MGH-1 expression by 50% (P<0.05), which were all mitigated by Gly-Low. Chronic MGO exposure elevated biomarkers of cellular senescence in HAECs, comparable to a known senescence inducer Doxorubicin, an effect partially blocked by Gly-Low. Moreover, elevated aortic elastic modulus induced by Doxorubicin (P<0.05 vs. control) was prevented with Gly-Low (P=0.71 vs. control). Aortic RNA sequencing implicated preservation of endogenous cellular detoxification pathways with Gly-Low following exposure to MGH-1. Old mice supplemented with Gly-Low had lower PWV (P<0.05) relative to old control mice. ConclusionsMGO-induced glycation stress contributes to aortic stiffening and glycation stress lowering compounds hold promise for mitigating these effects. What Is New?This study provides the first comprehensive line of evidence that methylglyoxal (MGO)-induced glycation stress directly contributes to aortic stiffening and does so through mechanisms involving oxidative stress and cellular senescence. Using complementary in vivo, ex vivo, and in vitro experimental models, we establish that MGO-mediated glycation stress independently induces aortic stiffening. Furthermore, we demonstrate that the glycation-lowering compound, Gly-Low, mitigates MGO-induced aortic stiffening by mitigating excessive oxidative stress and cellular senescence, and can lower aortic stiffness in old mice. Mechanistically, activation of the detoxification enzyme, glyoxalase-1 (Glo-1), is a novel pathway by which Gly-Low mediates its therapeutic effects on aortic stiffening. Lastly, we show that Gly-Low holds promise for lowering aortic stiffness in old age. What Is Relevant?Aortic stiffening is a major risk factor for cardiovascular diseases (CVD) and a significant predictor of CV-related morbidity and mortality. Yet, the underlying mechanisms driving this process remain incompletely understood. This study identifies MGO-derived glycation stress as a critical and modifiable factor contributing to aortic stiffening through pathways involving excessive oxidative stress and cellular senescence. By establishing the efficacy of Gly-Low in mitigating these effects, our findings underscore the importance of targeting glycation stress in the context of aging, and likely in other settings of glycation stress, to improve arterial health and reduce CVD risk. Clinical/Pathophysiological ImplicationsThese findings have significant clinical implications, as they demonstrate that glycation stress is a viable and modifiable therapeutic target for the prevention and treatment of aortic stiffening. Gly-Low offers a promising therapeutic approach to ameliorate glycation stress- and age-related aortic stiffening, by directly targeting excess glycation stress, oxidative stress, and cellular senescence. Additionally, the involvement of the Glo-1 detoxification pathway suggests a specific molecular target for future interventions aimed at improving arterial health and mitigating the progression of CVD.

molecular biology↗