What is SR9009?

REV-ERBα and REV-ERBβ nuclear receptors are transcriptional repressors that coordinate circadian rhythm and metabolic pathways in a heme-dependent manner. SR9009 is a REV-ERB agonist that increases the constitutive repression of genes regulated by REV-ERBα and REV-ERBβ with IC50 values of 670 and 800 nM, respectively. Through activation of REV-ERB, SR9009 has been shown to decrease circadian locomotor activity during the dark phase and to alter the expression pattern of core clock genes in the hypothalami of mice. The circadian pattern of expression of an array of metabolic genes in the liver, skeletal muscle and adipose tissue was also shown to be altered in mice exposed to SR9009, resulting in increased energy expenditure. Diet-induced obese mice treated with 100 mg/kg SR9009 (i.p. two times a day for 30 days) have been reported to display decreased fat mass and markedly improved dyslipidemia and hyperglycemia.

In Vitro

SR9009 dose-dependently increases the REV-ERB-dependent repressor activity assessed in HEK293 cells expressing a chimeric Gal4 DNA Binding Domain (DBD)-REV-ERB ligand binding domain (LBD)α or β and a Gal4-responsive luciferase reporter (SR9009: REV-ERBα IC50=670 nM, REV-ERBβ IC50=800 nM). SR9009 potently and efficaciously suppresses transcription in a cotransfection assay using full-length REV-ERBα along with a luciferase reporter driven by the Bmal1 promoter (IC50=710 nM). SR9009 suppresses the expression of BMAL1 mRNA in HepG2 cells in a REV-ERBα/β-dependent manner. Direct binding of the SR9009 to REV-ERBα is also confirmed using circular dichrosim analysis (Kd=800 nM).

In Vivo

While the stress of handling and twice-daily injections caused weight loss in vehicle-treated controls, weight loss of SR9009-treated animals is 60% greater. SR9009 (100 mg/kg ,i.p.) treated mice exhibit a more severe reduction in adiposity. Plasma non-esterified fatty acids (NEFA) are also reduced (23%) along with plasma glucose (19%) in the SR9009 treated animals. In the white adipose tissue (WAT) , SR9009 treatment results in a decrease in expression of genes encoding enzymes involved in triglyceride (TG) synthesis as is also observed in lean mice.

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