Project description:Elevated inositol trisphosphate receptor (IP3R) levels have been previously reported in skeletal muscle myotubes derived from patients with ryanodine receptor 1 (RyR1) mutation related core myopathies. However, the functional relevance and the relationship of IP3R mediated Ca2+ signalling with the pathophysiology of the disease is unclear. It has also been suggested that mitochondrial dysfunction underlies the development of central and diffuse multi-mini-cores, devoid of mitochondrial activity, a key pathological consequence of RyR1 mutations. Here we used muscle biopsies of central core and multi-minicore disease patients with RyR1 mutations, as well as cellular and in vivo mouse models of the disease to characterise whole genome and mitochondrial gene expression to assess if remodeling of skeletal muscle following loss of functional RyR1 mediates bioenergetic adaptation.
Project description:Elevated inositol trisphosphate receptor (IP3R) levels have been previously reported in skeletal muscle myotubes derived from patients with ryanodine receptor 1 (RyR1) mutation related core myopathies. However, the functional relevance and the relationship of IP3R mediated Ca2+ signalling with the pathophysiology of the disease is unclear. It has also been suggested that mitochondrial dysfunction underlies the development of central and diffuse multi-mini-cores, devoid of mitochondrial activity, a key pathological consequence of RyR1 mutations. Here we used muscle biopsies of central core and multi-minicore disease patients with RyR1 mutations, as well as cellular and in vivo mouse models of the disease to characterise whole genome and mitochondrial gene expression to assess if remodeling of skeletal muscle following loss of functional RyR1 mediates bioenergetic adaptation.
Project description:Inositol 1,4,5-trisphosphate 3-kinase A (IP3K-A) is a molecule enriched in the brain and neurons that regulates intracellular calcium levels via signaling through the inositol trisphosphate receptor. In the present study, we found that IP3K-A expression is highly enriched in the central nucleus of the amygdala (CeA), which plays a pivotal role in the processing and expression of emotional phenotypes in mammals. We used microarray to identify differentially expressed genes in the amydala of wild type (WT) and IP3K-A KO mice.
Project description:Mutations in inositol trisphosphate receptor type 3 (ITPR3) have been linked to immunodeficiency, including an expansion of effector memory (EM) CD4+ T cells within peripheral tissues. We developed a mouse model that genocopied a single allelic (p.R2524C) ITPR3 mutation found in humans.
Project description:Nutrient cues shape adipose homeostasis; however, the mechanism by which inorganic signals engage organelle networks to drive white fat browning remains unclear. Here, we identify a nitrate-Sialin2 pathway that converts dietary nitrate into a spatially confined thermogenic program. Sialin2 localizes to mitochondria and endoplasmic reticulum (ER) to strengthen ER-mitochondria contacts and engage the inositol 1,4,5-trisphosphate receptor type 1 (IP3R1)-voltage-dependent anion channel 1 (VDAC1)-mitochondrial calcium uniporter 1 (MCU1) conduit, boosting inducible mitochondrial Ca2+ uptake. In parallel, Sialin2 associates with lysosomal acid lipase (LIPA), Acyl-CoA Synthetase Long Chain Family Member 3 (ACSL3), and carnitine palmitoyltransferase 1A (CPT1A) to direct lipid-droplet-derived fatty acids into β-oxidation, thereby fueling the tricarboxylic acid (TCA) cycle and uncoupling protein 1 (UCP1)-dependent respiration. Loss of Slc17a5 abolishes nitrate-evoked browning and metabolic benefits, whereas nitrate supplementation improves adipose thermogenesis and systemic indices in diet-induced obesity without adrenergic stimulation. These findings reveal an organelle-specific nitrate-sensing mechanism that couples ionic signaling with substrate routing to reprogram adipocytes, providing a non-hormonal strategy for restoring metabolic homeostasis.
Project description:The polyglutamine expansion in huntingtin (Htt) protein is a cause of Huntington’s disease (HD). Htt is an essential gene as deletion of the mouse Htt gene homolog (Hdh) is embryonic lethal in mice. Therefore, in addition to elucidating the mechanisms responsible for polyQ-mediated pathology, it is also important to understand the normal function of Htt protein for both basic biology and for HD. To systematically search for a mouse Htt function, we took advantage of the Hdh +/- and Hdh-floxed mice and generated four mouse embryonic fibroblast (MEF) cells lines which contain a single copy of the Hdh gene (Hdh-HET) and four MEF lines in which the Hdh gene was deleted (Hdh-KO). The function of Htt in calcium (Ca2+) signaling was analyzed in Ca2+ imaging experiments with generated cell lines. We found that the cytoplasmic Ca2+ spikes resulting from the activation of inositol 1,4,5-trisphosphate receptor (InsP3R) and the ensuing mitochondrial Ca2+ signals were suppressed in the Hdh-KO cells when compared to Hdh-HET cells. Furthermore, in experiments with permeabilized cells we found that the InsP3-sensitivity of Ca2+ mobilization from endoplasmic reticulum was reduced in Hdh-KO cells. These results indicated that Htt plays an important role in modulating InsP3R-mediated Ca2+ signaling. To further evaluate function of Htt, we performed genome-wide transcription profiling of generated Hdh-HET and Hdh-KO cells by microarray. Our results revealed that 106 unique transcripts were downregulated by more than two-fold with p < 0.05 and 173 unique transcripts were upregulated at least two-fold with p < 0.05 in Hdh-KO cells when compared to Hdh-HET cells. The microarray results were confirmed by quantitative real-time PCR for a number of affected transcripts. Several signaling pathways affected by Hdh gene deletion were identified from annotation of the microarray results. The unbiased approach used in our study provides novel and unique information about the normal function of Htt in cells, which may contribute to our understanding and treatment of HD. Keywords: cell type comparison we generate four Hdh-HET MEF cell lines and four Hdh-KO MEF cell lines, and performed genome-wide transcription profiling of generated Hdh-HET and Hdh-KO cells by microarray.
Project description:Nutrient cues shape adipose homeostasis; however, the mechanism by which inorganic signals engage organelle networks to drive white fat browning remains unclear. Here, we identify a nitrate-Sialin2 pathway that converts dietary nitrate into a spatially confined thermogenic program. Sialin2 localizes to mitochondria and endoplasmic reticulum (ER) to strengthen ER-mitochondria contacts and engage the inositol 1,4,5-trisphosphate receptor type 1 (IP3R1)-voltage-dependent anion channel 1 (VDAC1)-mitochondrial calcium uniporter 1 (MCU1) conduit, boosting inducible mitochondrial Ca2+ uptake. In parallel, Sialin2 associates with lysosomal acid lipase (LIPA), Acyl-CoA Synthetase Long Chain Family Member 3 (ACSL3), and carnitine palmitoyltransferase 1A (CPT1A) to direct lipid-droplet-derived fatty acids into β-oxidation, thereby fueling the tricarboxylic acid (TCA) cycle and uncoupling protein 1 (UCP1)-dependent respiration. Loss of Slc17a5 abolishes nitrate-evoked browning and metabolic benefits, whereas nitrate supplementation improves adipose thermogenesis and systemic indices in diet-induced obesity without adrenergic stimulation. These findings reveal an organelle-specific nitrate-sensing mechanism that couples ionic signaling with substrate routing to reprogram adipocytes, providing a non-hormonal strategy for restoring metabolic homeostasis.