Effect of dietary restriction on intestinal stem cell aging

University Of Oklahoma Hlth Sciences Ctr, Oklahoma City OK

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Abstract

ABSTRACT The integrity of the intestinal epithelium is essential to the overall health of the organism. With increasing age, intestinal integrity is compromised and is one of the factors that contributes to systemic inflammation and subsequently the deterioration of healthspan. The intestinal epithelium is highly dependent on the regenerative capacity of intestinal stem cells (ISCs) and interventions that improve intestinal function (and healthspan in general) are associated with increased activity of ISCs. Although the significance of ISCs is well recognized, the etiology of the age-related changes and the potential for specific interventions to reverse these changes remain unknown. Dietary restriction (DR) has been recognized as a key intervention that increases both health span and lifespan. In response to DR, increased activity of adult stem cells has been reliably reported in multiple tissues, including the intestine. We have published seminal data that brief periods of DR can induce substantial changes in gene expression within 1 month of its implementation. These changes persisted even after DR was discontinued suggesting induction of ‘cellular memory’. This application is designed to identify the epigenetic and transcriptomic mechanisms modified with age and re-activated by DR. Our long-term goal is to move epigenetic aging research from correlational analyses to mechanisms and develop the potential for therapeutic intervention. The overall hypothesis of this application is that age represses the expression of specific genes involved in ISC proliferation and differentiation by inducing changes in DNA methylation at specific genomic sites and these changes are reversed by short-term DR. We will measure both methylation (5mC) and demethylation (5hmC-hydroxymethylation) marks which functionally can regulate chromatin status and affect the ability of transcription factors and other DNA binding proteins to access DNA. This will be the first study to evaluate with high resolution the effect of DR on both 5mC and 5hmC levels with age. The aims are: Aim 1: Determine the specific window of intervention for optimal ISC function in response to DR. Aim 2: Identify DNA methylation changes induced by age and short-term DR in ISCs. Aim 3: Assess the effects of age and short- term DR on the ISC transcriptomes. Our longer-term goal is to reveal the specific mechanisms of DR in improving intestinal integrity and ISC function. After identifying specific genomic targets related to the actions of aging and DR in ISC, we will be in a position to use epigenome editing in ISCs using nuclease-deficient dCas9- fusion proteins tethered to enzymes involved in DNA methylation (e.g., Dnmts, Tets) at specific CG sites. Dr. Matlock Jeffries (previous Phase 1 CoBRE RPL) has agreed to assist us with this approach. These long-term goals will, for the first time, have the potential to identify the specific actions of DR on ISCs and have critical implications for aging and the effects of DR.