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: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: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. Male IP3K-A KO mice and their wild-type (WT) littermate controls from a C57BL/6N background were used at 10 to 15 weeks old. Mice were housed in temperature (22°C-23°C)- and humidity (50%)-controlled quarters under a 12-hr light/dark photoperiod (lights on at 08:00a.m.) with free access to food and water. Mice were sacrificed by cervical dislocation between 02:00p.m. and 04:00p.m. Amygdala tissue was rapidly dissected from 1-mm thick slices and frozen in liquid nitrogen.
Project description:Congenital heart defects (CHDs) occur in 0.5–1% of live births, yet the underlying genetic etiology remains mostly unknown. Recently, a new source of myocardial cells, namely the second heart field (SHF), was discovered in the splanchnic mesoderm. Abnormal development of the SHF leads to a spectrum of outflow tract defects, such as persistent truncus arteriosus and tetralogy of Fallot. Intracellular Ca2+ signaling is known to be essential formany aspects of heart biology including heart development, but its role in the SHF is uncertain. Here, we analyzed mice deficient for genes encoding inositol 1,4,5-trisphosphate receptors (IP3Rs), which are intracellular Ca2+ release channels on the endo/sarcoplasmic reticulum that mediate Ca2+ mobilization. Mouse embryos that are double mutant for IP3R type 1 and type 3 (IP3R1−/−IP3R3−/−) show hypoplasia of the outflow tract and the right ventricle, reduced expression of specific molecular markers and enhanced apoptosis ofmesodermal cells in the SHF. Gene expression analyses suggest that IP3R-mediated Ca2+ signalingmay involve, at least in part, theMef2C–Smyd1 pathway, a transcriptional cascade essential for the SHF. These data reveal that IP3R type 1 and type 3 may play a redundant role in the development of the SHF. In total 4 samples were analyzed, they represent two different genotypes (wt, double ko) that were tested in duplicate each.
Project description:Activated Foxp3+ regulatory T (Treg) cells differentiate into effector Treg (eTreg) cells to maintain peripheral immune homeostasis and tolerance. T cell receptor (TCR)-mediated induction and regulation of store-operated Ca2+ entry (SOCE) is essential for eTreg cell differentiation and function. However, SOCE regulation in Treg cells remains unclear. Here we show that inositol polyphosphate multikinase (IPMK), which generates inositol tetrakisphosphate and inositol pentakisphosphate, is a pivotal regulator of Treg cell differentiation downstream of TCR signaling. IPMK is highly expressed in TCR-stimulated Treg cells and promotes a TCR-induced Treg cell program. IPMK-deficient Treg cells display aberrant T cell activation and impaired differentiation into RORγt+ Treg cells, and tissue-resident Treg cells. Mechanistically, IPMK controls the generation of higher-order inositol phosphates, thereby promoting Ca2+ mobilization and Treg cell effector functions. Our findings identify IPMK as a critical regulator of TCR-mediated Ca2+ influx and highlight the importance of IPMK in Treg cell-mediated immune homeostasis.