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:Cells limit energy-consuming mRNA translation during stress to maintain metabolic homeostasis. Sequestration of mRNAs by RNA binding proteins (RBPs) into stress granules (SGs) reduces translation, but it remains unclear whether SGs also function in partitioning of specific transcripts to polysomes (PSs) to guide selective translation and stress-adaptation in cancer. Transcripts enriched in PSs, defined by polysome fractionation and RNAseq, were compared with mRNAs complexed with the SG-nucleator protein, G3BP1, defined by spatially-restricted enzymatic tagging. Short-term oxidative stress profoundly altered mRNA translation by promoting selective enrichment of transcripts within SGs or PSs. G3BP1 participates in this compartmentalisation by sequestering transcripts in SGs. Under stress, G3BP1-bound transcripts are PS-depleted and encode proteins involved in mRNA translation, pro-apoptosis, and mitochondrial function. In contrast, specific PS-enriched transcripts disassociate from G3BP1 under stress to encode proteins involved in diverse cellular cytoprotective pathways. Therefore, G3BP1 partitioning guides selective translation to support stress adaptation and cell survival.
Project description:Cells limit energy-consuming mRNA translation during stress to maintain metabolic homeostasis. Sequestration of mRNAs by RNA binding proteins (RBPs) into stress granules (SGs) reduces translation, but it remains unclear whether SGs also function in partitioning of specific transcripts to polysomes (PSs) to guide selective translation and stress-adaptation in cancer. Transcripts enriched in PSs, defined by polysome fractionation and RNAseq, were compared with mRNAs complexed with the SG-nucleator protein, G3BP1, defined by spatially-restricted enzymatic tagging. Short-term oxidative stress profoundly altered mRNA translation by promoting selective enrichment of transcripts within SGs or PSs. G3BP1 participates in this compartmentalisation by sequestering transcripts in SGs. Under stress, G3BP1-bound transcripts are PS-depleted and encode proteins involved in mRNA translation, pro-apoptosis, and mitochondrial function. In contrast, specific PS-enriched transcripts disassociate from G3BP1 under stress to encode proteins involved in diverse cellular cytoprotective pathways. Therefore, G3BP1 partitioning guides selective translation to support stress adaptation and cell survival.
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.
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.