Project description:Metabolic dysfunction of skeletal muscle is often prevalent at an early stage in the development of several non-communicable diseases. Here, we investigated the effect of a myokine, secreted protein acidic and rich in cysteine (SPARC), on glucose tolerance in human and mouse skeletal muscles. SPARC knockout mice showed marked decreases in parameters for whole-body glucose metabolism, along with reduced phosphorylation of AMPK and Akt in skeletal muscle tissues compared with wild-type mice. Furthermore, mice injected with SPARC showed improved glucose tolerance concomitant with AMPK activation. Exogenous SPARC treatment accelerated glucose uptake in muscle tissues isolated from wild-type mice but not from AMPKγ3 knockout mice. In muscle cells, SPARC increased glucose uptake concomitant with AMPK activation, mediated by a calcium-dependent signal. Chronic treatment of SPARC restored metabolic functions in diet-induced obese mice. These findings suggest that SPARC improves glucose metabolism via AMPK activation in skeletal muscle, providing mechanistic insights on exercise-induced metabolic benefits and physical inactivity-induced glucose intolerance.
Project description:Secreted MOdular Calcium-binding protein-2 (SMOC2) belongs to the SPARC (Secreted Protein Acidic and Rich in Cysteines) family of matricellular proteins whose members are known for their secretion into the extracellular space to modulate cell-cell and cel
Project description:Hepatocellular carcinoma (HCC), the most common type of primary liver cancer, is characterized as a highly aggressive tumor entity and has become a health challenge worldwide. Intracellular secreted protein acidic and rich in cysteine (SPARC) has been described as secreted protein that serves as paracrine mediator between cells extracellular matrix (ECM), however, its intracellular role remains unclear. Genetically modified HCC cell lines, cancer patient-derived organoids, and mouse models were used to analyze SPARC on metabolic processes, as well as the invasive behavior and sorafenib resistance of HCC cells. Transcriptome, interactome, and biochemical analyses were performed to study how SPARC regulate cholesterol homeostasis. High expression of intracellular SPARC was significantly associated with elevated cholesterol levels and an enhanced invasive phenotype in HCC. Our findings unveil a previously unrecognized interplay between SPARC and cholesterol homeostasis. Targeting SPARC-triggered cholesterol-dependent oncogenic signaling serves as a promising strategy for treating advanced HCC.
Project description:The gut microbiome is a key factor regulating energy-metabolism, glucose tolerance and the immune system. Akkermansia muciniphila has been identified as being beneficial gut bacterium for metabolic diseases, including obesity and type 2 diabetes (T2D); however, the molecular mechanisms involved in host interactions have yet to be known. Here, we described the effects of A. muciniphila on thermogenesis and GLP-1 secretion through the specific secretory protein produced by A. muciniphila and its mode of action. A. muciniphila significantly elevated thermogenesis with induction of uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) and systemic glucagon-like peptide-1 (GLP-1) secretion. Using fast protein liquid chromatography (FPLC) and liquid chromatography (LC)-mass spectrophotometry (MS)/MS analysis, we discovered that a novel 84-kDa protein, P9 is secreted by A. muciniphila and this protein improves obesity and glucose tolerance by inducing GLP-1 secretion and BAT thermogenesis. P9 induces GLP-1 secretion with direct interaction with the specific host protein, intercellular adhesion molecule-2 (ICAM-2), via IL-6 dependent pathway. This novel host-microbe interaction between P9 and ICAM-2 may become a therapeutic target for metabolic diseases.
Project description:Cell polarity is crucial for the maintenance of epithelial cell function and its loss may have an im-portant role in the development and progression of cancer. We here show that overexpression and cytoplasmic enrichment of the baso-lateral polarity complex protein Scribble (Scrib) correlates with poor prognosis of hepatocellular cancer (HCC) patients. Expression of the cytoplasmic ScribP305L in hepatocellular cells induces epithelial to mesenchymal transition (EMT) and supports HCC cell invasion in comparison to cells expressing membrane-localized ScribWT. ScribP305L induces AKT signalling through destabilization of the phosphatases phosphatase and tensin homolog (PTEN) and PH domain and leucine rich repeat protein phosphatase 1 (PHLPP1). Moreover, cytoplasmic ScribP305L stimulates the expression of secreted protein acidic and cysteine rich (SPARC) de-pending on the AP1 constituents ATF2 and JunB, which drives HCC cell invasiveness. In vivo, combined hydrodynamic delivery of ScribP305L but not ScribWT and c-MYC initiates tumour for-mation in hepatocytes and cytoplasmic Scrib correlates with AKT phosphorylation, and AP1 ex-pression in human HCC tissues. Together, overexpression and mislocalization of Scrib represents an early event involved in the initiation and progression of liver cancer.
Project description:The lateral ventricle subventricular zone (SVZ) is a frequent site of high-grade glioma (HGG) spread and tumor invasion of the SVZ is a predictor of a worse clinical prognosis. A range of HGG types invade the stem cell niche of the SVZ, including both adult glioblastoma and pediatric high-grade gliomas such as diffuse intrinsic pontine glioma (DIPG). The cellular and molecular mechanisms mediating this frequent invasion of the SVZ are poorly understood. Here we demonstrate that neural precursor cell (NPC):glioma cell communication underpins the propensity of glioma to colonize the SVZ. SVZ NPCs secrete chemoattractant signals toward which glioma cells home. Biochemical and proteomic analyses of factors secreted by SVZ NPCs revealed a discrete list of candidate proteins. Necessity and sufficiency testing implicated the neurite outgrowth-promoting factor pleiotrophin, along with three required binding partners (secreted protein acidic and rich in cysteine (SPARC), SPARC-like protein 1, and heat shock protein 90B), as key mediators of this chemoattractant effect. Pleiotrophin protein expression is strongly enriched in the SVZ, and knockdown of pleiotrophin expression starkly reduced glioma invasion of the SVZ in the adult murine brain. Pleiotrophin, in complex with the three binding partners, activated the Rho/ROCK pathway in DIPG cells, and inhibition of ROCK resulted in decreased DIPG invasion toward SVZ neural precursor cell-secreted factors. These findings demonstrate a pathogenic role for neural precursor cell – glioma interactions and potential therapeutic targets to limit glioma invasion.
Project description:MicroRNAs (miRNAs) are small noncoding RNAs that critically regulate gene expression. Their abundance and function have been linked to processes such as senescence and aging. In aged monkey muscle, miR-451a and miR-144-3p were highly upregulated compared to young animals. This led us to hypothesize that the miRNAs 451a/144-3p may be involved in muscle differentiation. We found that these miRNAs are downregulated during the differentiation of C2C12 myoblasts. Overexpression of miR-451a, but not miR-144-3p, robustly impeded the differentiation, suggesting an inhibitory role for miR-451a. We further investigated the potential regulatory targets of miR-451a and identified Sparc mRNA, encoding a secreted protein acidic and rich in cysteine (SPARC), which is involved in wound healing and cellular differentiation. Interestingly, we found that miR-451a suppresses Sparc mRNA translation according to the analysis of polysome profile. Our findings show that miR-451a is downregulated in differentiated myoblasts and decreases C2C12 differentiation at least in part by the suppression of SPARC biosynthesis.
Project description:APEX2 proximity mapping of GLUT4 glucose transporter in in vitro differentiated human skeletal muscle cells with and without stimulation of AMP kinase.