# Elucidating mechanisms of SIRT1 activation

> **NIH NIH R01** · HARVARD MEDICAL SCHOOL · 2020 · $487,967

## Abstract

Project Summary
Knowledge gained over the past 75 years on enzyme inhibition by small molecules has formed the basis of
modern medicine. However, our understanding of how enzymes can be activated by small molecules is far less
advanced. This lack of knowledge limits the scope of medicines we can develop. Sirtuins are a family of NAD+-
dependent deacetylases that are thought to have evolved to increase an organism's chances of surviving
adverse conditions. There are seven mammalian sirtuins, SIRT1-7. SIRT1 is the best studied and coordinates
central processes including DNA repair, fatty acid and glucose metabolism, mitochondrial function, hypoxic
responses, autophagy, and anti-apoptotic mechanisms.
Over 100 SIRT1 activating molecules (STACs), including resveratrol and SRT1720, have been described.
These molecules produce similar effects on gene expression and impart a diverse array of health benefits
including protection from type II diabetes, obesity, hepatic steatosis, inflammation, cardiovascular disease, and
neurodegeneration. But whether these effects are due to direct SIRT1 activation or an alternative mechanism
is hotly debated.
Even though STACs were discovered using a variety of assays and different substrates, our preliminary results
indicate that there is in fact a common mechanism of activation. We have identified a structured activation
domain (AD) in the N-terminus of SIRT1 where these small molecules bind, and in particular one amino acid in
this domain (E230) that is required for SIRT1 activation by over 100 STACs both in vitro and in cells.
Substituting SIRT1-E230 in primary cells blocks the effects of resveratrol and synthetic STACs indicating that
direct activation is a mechanism. We also show that fluorophores linked to SIRT1 substrates enhance
activation in vitro because they mimic hydrophobic amino acids in endogenous substrates, such as PGC-1α,
FOXO3a, and eIF2a. The identification of a consensus target sequence for activation (X6-K(Ac)[Y,W,F]-X5, X6-
K(Ac)X5-[Y,W,F]) has allowed us to predict which substrates will be modulated by SIRT1 activation in vivo.
In this study, we will take advantage of these new discoveries to determine mechanistically and structurally
how SIRT1 is activated. We will generate primary cells and utilize knock-in mouse with the SIRT1-E230K
mutation (E222K in mice) to determine which of the biological effects are due to SIRT1 activation in vivo.
Together, these studies are aimed at providing fundamental mechanistic insights into how protein-modifying
enzymes recognize specific targets in cells and how their enzymatic activity may be modulated in vivo. This will
provide fundamental insights into how complex enzymes work and how they might be targeted by small
molecules.

## Key facts

- **NIH application ID:** 9970472
- **Project number:** 5R01DK100263-05
- **Recipient organization:** HARVARD MEDICAL SCHOOL
- **Principal Investigator:** DAVID A. SINCLAIR
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $487,967
- **Award type:** 5
- **Project period:** 2016-07-15 → 2022-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9970472

## Citation

> US National Institutes of Health, RePORTER application 9970472, Elucidating mechanisms of SIRT1 activation (5R01DK100263-05). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9970472. Licensed CC0.

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