Shared Mechanisms for Longevity via Calorie Restriction and AC5 Knockout

One of the handful of genetic alterations shown to extend life in mice is removal of adenylyl cyclase 5 (AC5). Researchers have noted in the past that this seems to share mechanisms with the longevity induced by calorie restriction - indeed, it is suspected that many of the varied known ways of altering laboratory animals to extend healthy life are in fact different methods to activate the same few base changes in metabolism. Here is another paper on this topic:

Adenylyl cyclase type 5 knockout mice (AC5 KO) live longer and are stress resistant, similar to calorie restriction (CR). AC5 KO mice eat more, but actually weigh less and accumulate less fat compared to [wild type] mice. CR applied to AC5 KO result in rapid decrease in body weight, metabolic deterioration and death. These data suggest that despite restricted food intake in CR, but augmented food intake in AC5 KO, the two models affect longevity and metabolism similarly.

To determine shared molecular mechanisms, mRNA expression was examined genome-wide for brain, heart, skeletal muscle and liver. Significantly more genes were regulated commonly rather than oppositely in all the tissues in both models, indicating commonality between AC5 KO and CR.

Gene Ontology analysis identified many significantly regulated, tissue-specific pathways shared by the two models, including sensory perception in heart and brain, muscle function in skeletal muscle, and lipid metabolism in liver. Moreover, when comparing gene expression changes in the heart under stress, the glutathione regulatory pathway was consistently upregulated in the longevity models but downregulated with stress. In addition, AC5 and CR shared changes in genes and proteins involved in the regulation of longevity and stress resistance, including Sirt1, ApoD and olfactory receptors in both young and intermediate age mice. Thus, the similarly regulated genes and pathways in AC5 KO and CR [suggest] a unified theory for longevity and stress resistance.



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