Effects of Sex, Strain, and Energy Intake on Hallmarks of Aging in Mice

Calorie restriction (CR) is the most robust non-genetic intervention to universally delay the onset of age-related diseases and extend mean and maximum lifespan. However, species, strain, sex, diet, age of onset, and level of CR are emerging as important variables to consider for a successful CR response. Here, we investigated the role of strain, sex and level of CR on outcomes of health and survival in mice. Response to CR varied from lifespan extension to no effect on survival, while consistently delaying the onset and impact of diseases independently of strain, sex and level of dietary restriction. CR led to transcriptional and metabolomics changes in the liver indicating anaplerotic filling of the Krebs cycle together with fatty acid fueling of mitochondria. Additionally, CR prevented the age-associated decline in the proteostasis network. Further, CR increased mitochondrial number and preserved their ultrastructure and function with age. Abrogation of mitochondrial function by deletion of fumarate hydratase or malate dehydrogenase 2 negated the life-prolonging effects of CR in yeast and worms. In F1 hybrid strains of mice, the lifespan response to CR tracked with the dam, indicating that the mitochondrial haplotype is an important regulator of CR. Our data illustrate the complexity of the CR responses within a single animal species in the context of aging, with a clear separation of outcomes related to health and survival, highlighting the complexities of translation of CR into human interventions. The study examines the effects of sex (male/female), mouse strain (DBA2/J versus C57BL/J), and diet (Ad libitum, 20% caloric restriction (20%CR), or 40%CR) using six biological replicate samples per group.热量限制（Calorie restriction, CR）是目前已被证实最为有效的非遗传干预手段，可普遍延缓衰老相关疾病的发病进程，并延长实验动物的平均寿命与最大寿命。然而，物种、品系、性别、饮食方案、干预起始年龄以及热量限制强度，均为影响热量限制响应效果的关键考量变量。本研究以小鼠为模型，探究了品系、性别以及热量限制强度对小鼠健康与存活相关结局的影响。小鼠对热量限制的响应差异显著，从寿命延长到对存活无影响皆有出现；但无论品系、性别与饮食限制强度如何，热量限制均能稳定延缓疾病的发病进程与病情严重程度。热量限制可引发肝脏的转录组与代谢组学改变，表现为三羧酸循环的回补反应被激活，同时线粒体的脂肪酸供能途径得到增强。此外，热量限制可阻止衰老过程中蛋白质稳态网络的功能衰退。进一步研究发现，热量限制还能随衰老进程增加线粒体数量，并维持其超微结构与功能完整性。通过敲除延胡索酸水合酶（fumarate hydratase）或苹果酸脱氢酶2（malate dehydrogenase 2）以阻断线粒体功能后，热量限制在酵母与线虫中延长寿命的效应被完全抵消。在小鼠F1杂交品系中，热量限制的寿命响应效果与母系遗传一致，表明线粒体单倍型是调控热量限制效应的关键因素。本研究数据揭示了单一动物物种在衰老背景下热量限制响应的复杂性，其健康相关结局与存活相关结局呈现明显分化，凸显了将热量限制转化为人类干预手段的挑战。本研究设置了以下实验变量：性别（雄性/雌性）、小鼠品系（DBA2/J与C57BL/J）以及饮食方案（自由进食、20%热量限制（20%CR）或40%热量限制（40%CR）），每组均设置6个生物学重复样本。