Project description:Proteomic analysis of murine stress granule and G3BP1 granulome in infected cells. BV2 GFP-G3BP1 cells were either treated with 0.1 mM arsenite for 1h to induce SG assembly or infected with MNV for 9h. G3BP1 granules were enriched by sequential centrifugation and purified by immunoprecipitation using antibodies to GFP (to trap GFP-G3BP1) or IgG (as a control) followed by pull down with Protein A-conjugated epoxy Dynabeads as previously described. To characterize the identity of G3BP1 partners within these, Mass Spectrometric analysis was performed.
Project description:We examine the role of G3bp1, a RNA binding protein and site specific endoribonuclease in gene expression in isolated neonatal cardiomyocytes. RNAseq data from cardiomyocytes were infected with adenoviruses expressing shRNA against G3bp1 (ad-siG3bp1) or Luciferase (ad-siLUC, control) showed significant decrease in transcript abudnnace of cardiac-enriched genes involved in Calcium handling, contraction, action potential and sacromere function. On the other hand increase was observed in genes that regulate Hippo, TNF and TGFb signaling. Knockdown of G3bp1 inhibited endothelin-1 induced cardiomyocyte hypertrophy.
Project description:Mitochondrial calcium signaling plays a critical role in mitochondrial homeostasis during non-alcoholic steatohepatitis (NASH) progression. Here, we report Ras‐GTPase activating protein SH3 domain‐binding protein 1 (G3BP1), a core protein of stress granule (SG), significantly upregulated in NAFLD/NASH patients, mouse models and palmitic acid-stimulated hepatocytes. Hepatocyte-specific G3BP1 deficiency attenuates NASH in two dietary mouse models. SG and the mitochondrial import protein TOM70 collaboratively mediate the translocation of G3BP1 to the mitochondria. G3BP1 interacts and stabilizes mitochondrial calcium uptake 1 (MICU1) via inhibiting YME1L1-mediated degradation of MICU1, and also impedes MCU complex activity and assembly, leading to mitochondrial calcium overload. Moreover, metabolic stress suppresses TRIM25-mediated K63-ubiquitination of G3BP1 and subsequent SG disassembly. Pharmacological inhibition of G3BP1 impairs the G3BP1-MICU1 interaction and prevents mitochondrial homeostasis imbalance and NASH progression. Collectively, we uncover the significant role of mitochondrial G3BP1 in mitochondrial homeostasis and NASH progression, which provides a potential target for therapeutic interventions.
Project description:We previously identified the stimuli-responsive lncRNA CALA to impact endothelial cell function and identified G3BP1 as a main interaction partner of CALA in the cytoplasm of human umblical vein endothelial cells (HUVECs). To uncover the role of the lncRNA CALA in G3BP1-RNPs in the cytoplasm, we purified the G3BP1 interactome in control and CALA-silenced HUVECs via anti-G3BP1 immunoprecipitation followed by mass spectrometry. We thereby uncover the basal G3BP1 protein interactome in HUVECs and additionally identify lncRNA-dependent protein interactions of G3BP1 in the cytoplasm of HUVEC.
Project description:we identify G3BP1 as a novel rG4-binding protein, and reveal that G3BP1 can modulate mRNA stability through its binding with rG4 structures
Project description:Speckle-type POZ protein (SPOP), an E3 ubiquitin ligase, acts as a tumor suppressor. We identified G3BP1 as non-substrate interactor of SPOP. G3BP1 is a well-known oncogene in many cancer types, but its role in prostate cancer (PCa) remains largely elusive. We showed that G3BP1 functions as an upstream regulator and potent endogenous inhibitor of Cul3SPOP, suggesting a distinctive Cul3SPOP inactivation independent of SPOP mutations. Transcriptomic analysis together with functional studies revealed that the G3BP1-SPOP ubiquitin signaling axis is involved in PCa progression through activating AR signaling. Further, AR upregulates G3BP1 to potentiate feed-forward amplification of signaling through G3BP1-SPOP axis. Overall, we show G3BP1high PCa tumors constitute a new subset where G3BP1 inhibits Cul3SPOP function to upregulate AR signaling, and promotes tumorigenesis.