Sirt1 counteracts decrease in membrane phospholipid unsaturation and diastolic dysfunction during saturated fatty acid overload.
Authors of this article are:
Yamamoto T, Endo J, Kataoka M, Matsuhashi T, Katsumata Y, Shirakawa K, Yoshida N, Isobe S, Moriyama H, Goto S, Yamashita K, Ohto-Nakanishi T, Nakanishi H, Shimanaka Y, Kono N, Shinmura K, Arai H, Fukuda K, Sano M.
A summary of the article is shown below:
BACKGROUND: The fatty acid (FA) composition of membrane phospholipid reflects at least in part dietary fat composition. Saturated FA (SFA) suppress Sirt1 activity, while monounsaturated FA (MUFA) counteract this effect.OBJECTIVE: We explored a role of Sirt1 in homeostatic control of the fatty acid composition of membrane phospholipid in the presence of SFA overload.METHODS AND RESULTS: Sirt1 deficiency in cardiomyocytes decreased the expression levels of liver X receptor (LXR)-target genes, particularly stearoyl-CoA desaturase-1 (Scd1), a rate-limiting enzyme in the cellular synthesis of MUFA from SFA, increased membrane SFA/MUFA ratio, and worsened left ventricular (LV) diastolic function in mice fed an SFA-rich high fat diet. In cultured cardiomyocytes, Sirt1 knockdown (KD) exacerbated the palmitate overload-induced increase in membrane SFA/MUFA ratio, which was associated with decrease in the expression of LXR-target genes, including Scd1. Forced overexpression of Scd1 in palmitate-overloaded Sirt1KD cardiomyocytes lowered the SFA/MUFA ratio. Nicotinamide mononucleotide (NMN) increased Sirt1 activity and Scd1 expression, thereby lowering membrane SFA/MUFA ratio in palmitate-overloaded cardiomyocytes. These effects of NMN were not observed for Scd1KD cardiomyocytes. LXRα/βKD exacerbated palmitate overload-induced increase in membrane SFA/MUFA ratio, while LXR agonist T0901317 alleviated it. NMN failed to rescue Scd1 protein expression and membrane SFA/MUFA ratio in palmitate-overloaded LXRα/βKD cardiomyocytes. The administration of NMN or T0901317 showed a dramatic reversal in membrane SFA/MUFA ratio and LV diastolic function in SFA-rich HFD-fed mice.CONCLUSION: Cardiac Sirt1 counteracted SFA overload-induced decrease in membrane phospholipid unsaturation and diastolic dysfunction via regulating LXR-mediated transcription of the Scd1 gene.Copyright © 2019. Published by Elsevier Ltd.
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This article is a good source of information and a good way to become familiar with topics such as: Diastolic dysfunction; Membrane fatty acid composition; Saturated fatty acid; Sirt1; Stearoyl-CoA desaturase-1.