The SWELL1-LRRC8 complex regulates endothelial AKT-eNOS signaling and vascular function

The endothelium responds to numerous chemical and mechanical factors in regulating vascular tone, blood pressure, and blood flow. The endothelial volume-regulated anion channel (VRAC) has been proposed to be mechanosensitive and thereby sense fluid flow and hydrostatic pressure to regulate vascular function. Here, we show that the leucine-rich repeat-containing protein 8a, LRRC8A (SWELL1), is required for VRAC in human umbilical vein endothelial cells (HUVECs). Endothelial LRRC8A regulates AKT-endothelial nitric oxide synthase (eNOS) signaling under basal, stretch, and shear-flow stimulation, forms a GRB2-Cav1-eNOS signaling complex, and is required for endothelial cell alignment to laminar shear flow. Endothelium-restricte

Deletion of retinoic acid-related orphan receptor gamma reduces body weight and hepatic lipids in mice by modulating the expression of lipid metabolism genes

Aim: Retinoic acid-related orphan receptor γ (RORγ) functions as a ligand-dependent transcription factor and its loss has been shown to affect the circadian expression of lipid metabolism genes. However, its effect on body weight gain and hepatic lipids is not well understood. In this study, we investigated the impact of Rorγ gene deletion on changes in body weight and hepatic lipids.Methods: Body weight and lipids were analyzed in the plasma and liver. Expression of lipid metabolism genes in the liver was evaluated in wild type and Rorγ knockout mice.Results: We show that deletion of RORγ results in reduced body weight and fewer lipids in the liver. Analysis of gene expression showed that deletion of Rorγ resulted in an overall lower expression of genes and transcription factors involved in lipid biosynthesis. We observed a decrease in the gene expression of cholesterol biosynthesis, efflux, and esterification but an increase in bile acid synthesis. There was a decrease in fatty acid and triglycerides biosynthesis genes and an increase in the fatty acid uptake genes. The decrease in the expression of lipid biosynthesis genes was accompanied by the decrease in the sterol response element binding protein (Srebp) genes. We observed an increase in the expression of peroxisome proliferator-activated receptor alpha (Ppara) and a decrease in the expression of acetyl-CoA carboxylase 2 (Acc2) genes.Conclusion: Our data suggest that RORγ regulates body weight and lipid metabolism genes and its modulation may be beneficial for the management of obesity and related lipid metabolic disorders

Failure to upregulate cell surface PD-1 is associated with dysregulated stimulation of T cells by TGN1412-like CD28 superagonist

The CD28 superagonist (CD28SA) TGN1412 was administered to humans as an agent that can selectively activate and expand regulatory T cells but resulted in uncontrolled T cell activation accompanied by cytokine storm. The molecular mechanisms that underlie this uncontrolled T cell activation are unclear. Physiological activation of T cells leads to upregulation of not only activation molecules but also inhibitory receptors such as PD-1. We hypothesized that the uncontrolled activation of CD28SA-stimulated T cells is due to both the enhanced expression of activation molecules and the lack of or reduced inhibitory signals. In this study, we show that anti-CD3 antibody-stimulated human T cells undergo time-limited controlled DNA synthesis, proliferation and interleukin-2 secretion, accompanied by PD-1 expression. In contrast, CD28SA-activated T cells demonstrate uncontrolled activation parameters including enhanced expression of LFA-1 and CCR5 but fail to express PD-1 on the cell surface. We demonstrate the functional relevance of the lack of PD-1 mediated regulatory mechanism in CD28SA-stimulated T cells. Our findings provide a molecular explanation for the dysregulated activation of CD28SA-stimulated T cells and also highlight the potential for the use of differential expression of PD-1 as a biomarker of safety for T cell immunostimulatory biologics