Project description:The Aster-C protein (encoded by the Gramd1c gene) is an endoplasmic reticulum (ER) resident protein that has been reported to transport cholesterol from the plasma membrane to the ER . Although there is a clear role for the closely-related Aster-B protein in cholesterol transport and downstream esterification in the adrenal gland, the specific role for Aster-C in tissue cholesterol homeostasis is not well understood. Here, we have examined whole body cholesterol balance in mice globally lacking Aster-C under low or high dietary cholesterol conditions.transport and metabolism under divergent dietary cholesterol conditions. These results strongly suggest that Aster-C alone is not sufficient to control whole body cholesterol balance, but can modestly impact circulating cortisol and bile acid levels when dietary cholesterol is limited.
Project description:Intestinal cholesterol absorption is an important determinant of systemic cholesterol homeostasis. Niemann-Pick C1 Like 1 (NPC1L1), the target of the drug ezetimibe, is a critical player in dietary cholesterol uptake. But how cholesterol moves within the cell downstream of NPC1L1 is unknown. Here we show that the nonvesicular sterol transporters Aster-B and -C cooperate with NPC1L1 to deliver dietary cholesterol from the gut lumen to the enterocyte ER for chylomicron packaging. Aster proteins are recruited to the enterocyte plasma membrane (PM) in response to NPC1L1-dependent cholesterol accumulation. Mice lacking Asters in intestine have impaired cholesterol absorption, and reduced plasma cholesterol. NanoSIMS imaging and tracer studies reveal delayed lipid trafficking into chylomicrons in Aster-deficient enterocytes. Interestingly, in addition to potently blocking NPC1L1, ezetimibe is also a low-affinity inhibitor of Aster-B and -C but not -A, and the structure of the Aster-C-ezetimibe complex reveals the basis for this selectivity. Our findings support a model in which NPC1L1 enriches dietary cholesterol at the apical PM, and ASTERs subsequently traffic this cholesterol to the ER. The findings identify the enterocyte Aster pathway as potential target for treatment of hypercholesterolemia. Alessandra Ferrari, PhD
Project description:We performed shallow whole genome sequencing (WGS) on circulating free (cf)DNA extracted from plasma or cerebrospinal fluid (CSF), and shallow WGS on the tissue DNA extracted from the biopsy in order to evaluate the correlation between the two biomaterials. After library construction and sequencing (Hiseq3000 or Ion Proton), copy number variations were called with WisecondorX.
Project description:The intrinsic pathways that control membrane organization in immune cells and the impact of such pathways on cellular functions are not well defined. Here we show that the nonvesicular cholesterol transporter Aster-A links plasma membrane (PM) cholesterol availability in T cells to immune signaling and systemic metabolism. Aster-A is recruited to the PM during T-cell receptor (TCR) activation, where it facilitates the removal of newly generated “accessible” cholesterol. Loss of Aster-A leads to excess PM cholesterol accumulation, resulting in enhanced TCR nano-clustering and signaling, and in Th17 cytokine production. Furthermore, Aster-A associates with STIM1 and negatively regulates STIM1-dependent calcium flux during activation of mouse and human T cells. Finally, mucosal Th17 response towards commensals is restrained by PM cholesterol remodeling. Ablation of Aster-A in T cells stimulates IL-22 production, which reduces intestinal fatty acid absorption, and confers resistance to diet-induced obesity. These findings delineate a multi-tiered regulatory scheme linking immune cell lipid flux to nutrient absorption and systemic physiology.
Project description:The intrinsic pathways that control membrane organization in immune cells and the impact of such pathways on cellular functions are not well defined. Here we show that the nonvesicular cholesterol transporter Aster-A links plasma membrane (PM) cholesterol availability in T cells to immune signaling and systemic metabolism. Aster-A is recruited to the PM during T-cell receptor (TCR) activation, where it facilitates the removal of newly generated “accessible” cholesterol. Loss of Aster-A leads to excess PM cholesterol accumulation, resulting in enhanced TCR nano-clustering and signaling, and in Th17 cytokine production. Furthermore, Aster-A associates with STIM1 and negatively regulates STIM1-dependent calcium flux during activation of mouse and human T cells. Finally, mucosal Th17 response towards commensals is restrained by PM cholesterol remodeling. Ablation of Aster-A in T cells stimulates IL-22 production, which reduces intestinal fatty acid absorption, and confers resistance to diet-induced obesity. These findings delineate a multi-tiered regulatory scheme linking immune cell lipid flux to nutrient absorption and systemic physiology.
Project description:Whole genome sequencing (WGS) of tongue cancer samples and cell line was performed to identify the fusion gene translocation breakpoint. WGS raw data was aligned to human reference genome (GRCh38.p12) using BWA-MEM (v0.7.17). The BAM files generated were further analysed using SvABA (v1.1.3) tool to identify translocation breakpoints. The translocation breakpoints were annotated using custom scripts, using the reference GENCODE GTF (v30). The fusion breakpoints identified in the SvABA analysis were additionally confirmed using MANTA tool (v1.6.0).