SRT1460

Developing of small mol. modulators of SIRT1 activity opens up opportunities for delaying age-related diseases.Therefore, the design of novel modulators is a promising therapeutic approach.Here, we synthesized a series of imidazole derivatives and studied their modulatory activity of against SIRT1 using high-throughput fluorescent assay screening and mol. docking calculationsWe found that despite some structural similarity with the known imidazothiazole-based activators, such as SRT1460 and SRT1720, our synthesized derivatives demonstrated an essentially different modulating behavior.In particular, all synthesized derivatives revealed significant inhibiting activity, so that compounds 7a and 8b were characterized by the almost complete inhibition (up to 98-100%) of SIRT1 enzymic activity.Mol. docking calculations suggest that all studied imidazole derivatives favor a strong binding to the catalytic domain of SITR1, similar to the known inhibitors, such as (S)-selisistat.On the opposite, SRT1460 and SRT1720 activators occupied allosteric sites terminal to the catalytic domain of SIRT1.These findings demonstrate the essentially different mol. mechanisms of modulating SIRT1 enzyme activity by these two groups of imidazothiazole derivatives and help further understand SIRT1 action.

Osteoarthritis (OA) is a common joint disease characterized by inflammation and cartilage degeneration. Accumulating evidences support that endoplasmic reticulum (ER) stress induced OA chondrocytes apoptosis. The hypoglycemic and anti-inflammatory properties render Dapagliflozin (DAPA) effective in reducing ER stress on cells. However, its impact and potential mechanisms on the OA pathology are still obscure. The present study aimed to investigate whether DAPA attenuates ER stress in chondrocytes by activating sirt1 and delays the progression of OA.

In vitro, we first investigated the effect of DAPA on chondrocytes viability with IL-1β or not for 24 or 48 h. Then, chondrocytes were treated with 10 ng/ml IL-1β and 10 μM dapagliflozin with10 μM thapsigargin, 5 μM SRT1460 or not. Chondrocytes apoptosis in each group were detected by Tunel staining and flow cytometric. Immunofluorescence staining was applied to quantify the expression levels of cleaved caspase-3, Sirt1 and CHOP in chondrocytes. Inhibition of ER stress in chondrocytes associated with sirt1 activation were verified by PCR and western blotting. In addition, the effects of DAPA on cartilage were validated by a series of experiments in OA rat model, such as micro-CT, histological and immunohistochemical assay.

The data demonstrated that DAPA alleviates IL-1β induced ER stress related chondrocytes apoptosis, and PCR and western blotting data confirmed that DAPA inhibits the PERK-eIF2α-CHOP pathway by activating Sirt1. Besides, immunohistochemical results showed that DAPA enhanced the expression of Sirt1 and Collagen II in OA rats, and inhibited the expression of CHOP and cleaved caspase-3. Meanwhile, histological staining and micro-CT photography also confirmed that DAPA alleviated inflammation and cartilage degeneration in OA rat.

The study demonstrated the relationship of ER stress and inflammation in the progression of OA, and verified that DAPA could inhibit PERK-eIF2α-CHOP axis of the ER stress response by activating Sirt1 in IL-1β treated rat chondrocytes and potentially prevent the OA development.