Sirtuins are associated with -

Ans. is 'b' i.e., Metabolism o Sirtuins are a family of highly conserved NAD+ dependent deacetylase 5 that act as cellular sensors to detect energy availability and modulate metabolic process.o Two mammalian sirtuins are involved in controling metabolic process : SIRT-1 (in nucleus) and SIRT-2 (in mitochondria).o They are activated by high NAD+ levels (low cellular energy status). They, then, deacetylate a variety' of proteins causing induction of catabolic processes and inhibition of anabolic processes.o SIRT-1 and SIRT-3 coordinated increase cellular energy' stores and ultimately maintain cellular energy homeostasis,o Genetic variant in SIRT-1 gene is associated lower risk of cardiovascular mortality and with better cognitive functioning.o SIRT-l variants are associated with decreased basal energy expenditure and a lower lipid peroxidation rate. Therefore, it has been proposed that genetic variation in SIRT-l may determine the response rates of individuales undergoing caloric restriction and increased physical activity,o Genetic variants of SIRT-3 may be associated with increased longevity (increased lifespan), but there is no evidence of such an association.o Mammals have seven sirtuins :1) SIRT-1- Intranuclear2) SIRT-2- Cytoplasmic3) SIRT-3, SIRT-4, SIRT-5- Mitochondrial4) SIRT-6- Heterochromatin-associated nuclear5) SJRT-7- Nucleolaro SIRT-1 and SIRT-3 have been studied the most in relation to phenotypes in human.