Mechanisms of Dietary Restriction in Drosophila

University Of Michigan At Ann Arbor, Ann Arbor MI

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Abstract

Abstract Dietary restriction has effectively increased lifespan of nearly every species to which it has been applied. In mammals, DR also ameliorates or eliminates a range of aging-related pathologies, including cancer, inflammation, neurodegeneration, and diabetes. Despite a wealth of information regarding the physiological and regulatory changes induced by DR in mice and in primates, the causal mechanisms underlying improved health and longevity remain largely unknown. Invertebrate model systems have contributed to remarkable progress over the last few years on the genetic mechanisms of DR, and as a result, a clear model of DR in metazoans is emerging. The longevity response to altered nutrient availability is a regulated response that starts in the brain, where specific populations of neurons detect changes in the availability of specific nutrients, alterations in cellular energy levels, and/or modification in the activity of critical stress montoring pathways. These cells subsequently communicate with neuroendocrine systems via unknown neural circuits to induce the secretion of one or more hormones. The hormone(s) target receptors and pathways in peripheral tissues to modulate respiration, cellular redox status, and/or lipid homeostasis to promote somatic endurance and organism longevity. In this renewal, we build upon the results from the parent award to test key predictions of our model and to continue our dissection of the molecular mechanisms of DR. First, neuronal control of the DR response will be examined by elucidating the mechanisms through which the gene ponchik modulates obesity, feeding behavior, and longevity. We will also take advantage of a completed genetic screen to identify new modulators of dietary restriction that act exclusively in the fly brain. Second, our preliminary data implicate the transsulferation pathway as essential for enacting the dietary restriction response, and we will test whether this requirement depends on the putative energy sensing molecule cystathionine [unreadable]-synthase (CBS). Third, we will explore the interactions between DR and lipid homeostasis by determining the molecular mechanism underlying longevity extension by mutation of Lsd2, a major modulator of energy balance in Drosophila. Studies of DR in invertebrate models have been exceptionally successful in reshaping ideas about how diet impacts organism health and longevity. Our studies will continue this trend and identify specific molecules and genetic pathways that link diet composition with adult longevity and physiology in Drosophila, which may illuminate how similar neuronal, endocrine, and metabolic networks coordinate homologous processes in mammals.