Assessing therapeutic intervention of short telomere syndromes

National Institute On Aging

Investigators

Linked publications, trials & patents

Abstract

Telomere shortening contributes to the development of nonalcoholic fatty liver disease (NAFLD) in telomere biology disorders (TBD). As a hallmark of aging, telomere shortening is also associated with NAFLD risk and progression in aging populations. The molecular mechanisms underlying the association between short telomeres and the initiation of NAFLD remain poorly understood. Recent publications have shown that low methionine intake is associated with a higher risk of liver fibrosis in NAFLD patients. Our recent work showed that the third-generation Tert-/- mice (G3 Tert-/- or G3) with short telomeres exhibited substantially reduced methionine levels in their livers and experienced an accelerated development of NAFLD when subjected to a diet deficient in methionine compared to the first-generation Tert-/- mice (G1 Tert-/- or G1) with normal telomere length. Thus, in the context of telomere shortening, methionine insufficiency increases the risk of NAFLD. We have begun to examine the role of methionine deficiency and the impact of a methionine diet intervention on the development of NAFLD in G3 mice. We have begun investigating whether a methionine-enriched diet can mitigate NAFLD and elucidating the underlying mechanisms by which methionine supplementation may exert protective effects. To this end, we used G1 and G3 mice, with the latter displaying impaired glucose tolerance and greater susceptibility to high-fat, high-fructose (HFHF)-induced NAFLD, to assess the impact of varying dietary methionine levels (0.6%, 0.8%, 1%) on NAFLD development. The experimental design involves feeding G1 and G3 mice a standard diet (SD) containing 0.6% (standard), 0.8%, or 1% methionine for several weeks to manipulate methionine availability. Subsequently, these mice transition to an HFHF diet (60% kcal from fat, 20% fructose) with the same methionine concentrations for up to three months, a duration sufficient to induce NAFLD in G3 mice. We hypothesize that an HFHF diet with standard methionine levels (0.6%) will induce NAFLD in G3 mice, while higher methionine supplementation (0.8% or 1%) may counteract methionine deficiency and ameliorate NAFLD features. To verify our hypothesis, we employ a comprehensive experimental approach. We have begun to assess the severity of NAFLD and the therapeutic efficacy of methionine supplementation using histological analyses, including H&E, Oil Red O, and Masson's trichrome staining, to quantify hepatic steatosis, inflammation, and fibrosis. To obtain a holistic view of metabolic, inflammatory, and hepatic damage, we plan to measure liver cytokine profiles and blood comprehensive metabolic and liver function tests, including the concentrations of triglycerides, cholesterol, alanine transaminase, and aspartate aminotransferase. To elucidate the molecular mechanisms by which methionine supplementation may ameliorate NAFLD in G3 mice, we plan to perform RNA sequencing on liver tissues to identify gene expression changes, with particular emphasis on pathways related to lipid metabolism, inflammation, and fibrogenesis. Additionally, we will analyze the expression of key proteins involved in lipid metabolism, fatty acid β-oxidation, inflammation, and fibrosis. Our research may provide guidance for potential clinical interventions for NAFLD in TBD patients and elderly individuals affected by telomere shortening.