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S1PR2 Signaling in Chronic Glucocorticoid Exposure-Induced Metabolic Disorders

ABSTRACT: Glucocorticoids play a key role in metabolic adaptation during stress, such as fasting and starvation. Excess and/or chronic glucocorticoid exposure, however, cause metabolic disorders that include insulin resistance dyslipidemia and hepatic steatosis. We previously showed that chronic glucocorticoid treatment elevates hepatic production of ceramides and sphingosine-1-phosphate (S1P). Ceramides are converted to sphingosine that is further converted to S1P. We showed that ceramide-initiated signaling in turn inhibits insulin signaling and increases lipogenic program in hepatocytes. However, the role of S1P, a signaling molecule that modulates physiological responses through membrane S1P receptors (S1PRs), in glucocorticoid actions is unclear. Here we found that inhibiting S1PR2 activity, but not S1PR1 and S1PR3, resulted in improved glucocorticoid-induced insulin resistance. Similarly, reducing hepatic S1PR2 expression showed similar results. Interestingly, reducing S1PR2 expression did not affect the ability of glucocorticoids to modify insulin signaling. Instead, glucocorticoids enhanced gluconeogenesis was reduced. Moreover, glucocorticoid-induced dyslipidemia and fatty liver was also compromised in mice with reduced hepatic S1PR2 expression. Indeed, RNA sequencing analysis showed that lipogenic, gluconeogenic and glycolytic genes are significantly lower in glucocorticoid-treated hepatic S1PR2 knockdown mice than those of glucocorticoid-treated hepatic scramble small hairpin RNA (shRNA) expressing mice (Control). Overall, our studies highlight the importance role of S1PR2 signaling in the mediating glucocorticoid regulation on gluconeogenesis and hepatic lipid homeostasis.

ORGANISM(S): Mus musculus

PROVIDER: GSE150626 | GEO | 2023/05/13

REPOSITORIES: GEO

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Project description:Clinically significant radiation-induced lung injury (RILI) is associated with significant morbidity and mortality and a common toxicity in patients administered thoracic radiotherapy. While the molecular etiology of RILI is poorly understood, we previously characterized a murine model of RILI in which alterations in lung endothelial barrier integrity surfaced as a potentially important pathobiologic event. In these studies, inhibition of HMG-CoA reductase activity (simvastatin) reduced murine RILI-associated lung inflammation and vascular leak and attenuated radiation-induced dysregulation of sphingolipid metabolic pathway genes identified by genome-wide lung gene expression profiling. In the present study, we test the hypothesis that sphingolipid signaling components serve as important modulators of RILI pathobiology and novel therapeutic targets. Sphingolipid involvement in murine RILI was confirmed by radiation-induced increases in lung expression of sphingosine kinase (SphK) isoforms 1 and 2 and increases in the ratio of ceramide to cumulative sphingosine-1-phosphate (S1P) and dihydro-S1P (DHS1P) levels in plasma, bronchoalveolar lavage (BAL) fluid and lung tissue following 25 Gy exposure (6 weeks). Moreover, genetically-engineered mice with either targeted deletion of SphK1 (SphK1-/-), or with reduced expression of selective members of the S1P receptor family (S1PR1+/-, S1PR2-/-, S1PR3-/-,), exhibited marked susceptibility to RILI-mediated lung inflammation. Finally, we assessed the efficacy of three potent vascular barrier-protective S1P analogues FTY720 (FTY), fTysiponate (fTyS) and SEW-2871 (SEW) in attenuating indices of RILI. The phosphonate analogue, fTyS, and to a lesser degree SEW, exhibited significant attenuation of RILI and RILI-induced gene dysregulation compared to control RILI-challenged mice (6 weeks). In contrast, FTY failed to significantly alter physiologic or genomic changes compared to RILI-challenged controls. Together, these results support the targeting of sphingolipid components as a novel and effective therapeutic strategy in RILI. Four mice were treated with PBS as a control. Three mice were treated with (S)-FTY-phosphonate (0.1mg/kg) as a drug control. Three mice were treated with SEW-2871 (0.1mg/kg) as a drug control. Three mice were treated with FTY720 (0.1mg/kg) as a drug control. Three mice were treated with administered radiation (25 Gy) alone. Three mice were treated with both administered radiation (25 Gy) and (S)-FTY-phosphonate (0.1mg/kg). Three mice were treated with both administered radiation (25 Gy) and SEW-2871 (0.1mg/kg). Three mice were treated with both administered radiation (25 Gy) and FTY720 (0.1mg/kg).

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S1PR2 Signaling in Chronic Glucocorticoid Exposure-Induced Metabolic Disorders

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