BAG3 promotes autophagy and glutaminolysis via stabilizing glutaminase.
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ABSTRACT:
SUBMITTER: Zhao S
PROVIDER: S-EPMC6433946 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Deamidation of glutamine to glutamate by glutaminase 1 (GLS1, also called GLS) and GLS2 is an essential step in both glutaminolysis and glutathione (GSH) biosynthesis. However, mechanisms whereby cancer cells regulate glutamine catabolism remains largely unknown. We report here that N-Myc, an essential Myc family member, promotes conversion of glutamine to glutamate in MYCN-amplified neuroblastoma cells by directly activating GLS2, but not GLS1, transcription. Abrogation of GLS2 function profoundly inhibited glutaminolysis, which resulted in feedback inhibition of aerobic glycolysis likely due to thioredoxin-interacting protein (TXNIP) activation, dramatically decreasing cell proliferation and survival in vitro and in vivo. Moreover, elevated GLS2 expression is significantly elevated in MYCN-amplified neuroblastomas in comparison with non-amplified ones, correlating with unfavorable patient survival. In aggregate, these results reveal a novel mechanism deciphering context-dependent regulation of metabolic heterogeneities, uncovering a previously unsuspected link between Myc, GLS2 and tumor metabolism.
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Project description:BackgroundNeuroinflammation mediated by microglia plays a key role in the pathogenesis of Parkinson's disease (PD), and our previous studies showed this was significantly inhibited by enhanced autophagy. In the autophagy pathway, Bcl2-associated athanogene (BAG)3 is a prominent co-chaperone, and we have shown BAG3 can regulate autophagy to clear the PD pathogenic protein α-synuclein. However, the connection between BAG3 and microglia mediated neuroinflammation is not clear.MethodsIn this study, we explored whether BAG3 regulated related neuroinflammation and its original mechanism in PD. An inflammatory model of PD was established by injecting adeno-associated virus (AAV)-BAG3 into the bilateral striatum of C57BL/6 male mice to induce overexpression of BAG3, followed by injection of lipopolysaccharide (LPS). The striatum was extracted at 3 days after injection of LPS for Western blotting and reverse transcription quantitative polymerase chain reaction (RT-qPCR), and immunohistochemical staining was performed at 21 days after injection. At the same time, LPS was used to induce activation of BV2 cells to verify the effect of BAG3 in vitro.ResultsOverexpression of BAG3 reduced LPS-induced pyroptosis by reducing activation of caspase-1, the NOD-like receptor family, and the pyrin domain-containing 3 (NLRP3) inflammasome, and by release of interleukin (IL)-1β and tumor necrosis factor (TNF)-α. The LPS-induced inflammatory environment inhibits autophagy, and overexpression of BAG3 can restore autophagy, which may be the mechanism by which BAG3 reduces neuronal inflammation in PD.ConclusionsOur results demonstrate BAG3 promotes autophagy and suppresses NLRP3 inflammasome formation in PD.
| S-EPMC9761134 | biostudies-literature
Project description:Atherosclerosis is a chronic systemic inflammatory disease that causes severe cardiovascular events. B cell lymphoma 2-associated athanogene (BAG3) was proven to participate in the regulation of tumor angiogenesis, neurodegenerative diseases, and cardiac diseases, but its role in atherosclerosis remains unclear. Here, we aim to investigate the role of BAG3 in atherosclerosis and elucidate the potential molecular mechanism. In this study, ApoE-/- mice were given a tail-vein injection of BAG3-overexpressing lentivirus and fed a 12-week high-fat diet (HFD) to investigate the role of BAG3 in atherosclerosis. The overexpression of BAG3 reduced plaque areas and improved atherosclerosis in ApoE-/- mice. Our research proves that BAG3 promotes autophagy in vitro, contributing to the suppression of EndMT in human umbilical vein endothelial cells (HUVECs). Mechanically, autophagy activation is mediated by BAG3 via the interaction between BAG3 and its chaperones HSP70 and HSPB8. In conclusion, BAG3 facilitates autophagy activation via the formation of the chaperone-assisted selective autophagy (CASA) complex interacting with HSP70 and HSPB8, leading to the inhibition of EndMT during the progression of atherosclerosis and indicating that BAG3 is a potential therapeutic target for atherosclerosis.
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Project description:Gastric cancer (GC) is one of the most common malignant tumors all over the world. And recurrence and metastasis are still the main causes of low survival rate for advanced GC. USP1 has been shown overexpressed in multiple cancers, which indicate its important biomarker in tumorigenesis and development. Our study is aimed at defining the exact role of USP1 on GC metastasis and the underlying mechanism. USP1 was firstly found overexpressed in GC tissues and relatively high-expression levels conferred poor survival rates. Then, real-time cellular analysis (RTCA) showed that USP1 knockdown inhibited GC metastasis both in vitro and in vivo. Mechanically, we demonstrated that USP1 promoted GC metastasis via upregulating ID2 expression and further confirmed that USP1 stabilized ID2 expression through deubiquitinating ID2 in GC. In conclusion, our study showed that USP1 promoted GC metastasis via stabilizing ID2 expression, which provides a potential biomarker and therapy target for GC.
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Project description:Altered glutamine metabolism is an important aspect of cancer metabolic reprogramming. The GLS isoform GAC (glutaminase C), the rate-limiting enzyme in glutaminolysis, plays a vital role in cancer initiation and progression. Our previous studies demonstrated that phosphorylation of GAC was essential for its high enzymatic activity. However, the molecular mechanisms for GAC in maintaining its high enzymatic activity and protein stability still need to be further clarified. FAIM/FAIM1 (Fas apoptotic inhibitory molecule) is known as an important anti-apoptotic protein, but little is known about its function in tumorigenesis. Here, we found that knocking down FAIM induced macroautophagy/autophagy through suppressing the activation of the MTOR pathway in lung adenocarcinoma. Further studies demonstrated that FAIM could promote the tetramer formation of GAC through increasing PRKCE/PKCε-mediated phosphorylation. What's more, FAIM also stabilized GAC through sequestering GAC from degradation by protease ClpXP. These effects increased the production of α-ketoglutarate, leading to the activation of MTOR. Besides, FAIM also promoted the association of ULK1 and MTOR and this further suppressed autophagy induction. These findings discovered new functions of FAIM and elucidated an important molecular mechanism for GAC in maintaining its high enzymatic activity and protein stability.
| S-EPMC9225548 | biostudies-literature
Project description:Tuberculosis has the highest mortality rate worldwide for a chronic infectious disease caused by a single pathogen. RNA-binding proteins (RBPs) are involved in autophagy - a key defense mechanism against Mycobacterium tuberculosis (M. tuberculosis) infection - by modulating RNA stability and forming intricate regulatory networks. However, the functions of host RBPs during M. tuberculosis infection remain relatively unexplored. Zinc finger NFX1-type containing 1 (ZNFX1), a conserved RBP critically involved in immune deficiency diseases and mycobacterial infections, is significantly upregulated in M. tuberculosis-infected macrophages. Here, we aimed to explore the immunoregulatory functions of ZNFX1 during M. tuberculosis infection. We observed that Znfx1 knockout markedly compromised the multifaceted immune responses mediated by macrophages. This compromise resulted in reduced phagocytosis, suppressed macrophage activation, increased M. tuberculosis burden, progressive lung tissue injury, and chronic inflammation in M. tuberculosis-infected mice. Mechanistic investigations revealed that the absence of ZNFX1 inhibited autophagy, consequently mediating immune suppression. ZNFX1 critically maintained AMPK-regulated autophagic flux by stabilizing protein kinase AMP-activated catalytic subunit alpha 2 mRNA, which encodes a key catalytic α subunit of AMPK, through its zinc finger region. This process contributed to M. tuberculosis growth suppression. These findings reveal a function of ZNFX1 in establishing anti-M. tuberculosis immune responses, enhancing our understanding of the roles of RBPs in tuberculosis immunity and providing a promising approach to bolster antituberculosis immunotherapy.
| S-EPMC10906457 | biostudies-literature
Project description:Gastric cancer is one of the most common malignancies worldwide and has been identified as the third leading cause of cancer-related mortality. Flotillin-1 is a lipid raft-associated scaffolding protein and plays an important role in the progression and development of several malignant carcinomas. Flotillin-1 is involved in epithelial-mesenchymal transition (EMT) process of several solid tumors to promote metastasis. However, the detailed characteristics and mechanisms of Flotillin-1 in gastric cancer have rarely been investigated. In this study, we found Flotillin-1 upregulated in gastric cancer, and the high expression of Flotillin-1 correlated with a worse prognosis. The migration and invasion ability of gastric cancer cells was upregulated by overexpressing Flotillin-1. Knockdown of Flotillin-1 inhibits gastric cancer cells metastasis. Flotillin-1 is a key regulator of EMT process and promotes gastric cancer cells metastasis through inducing EMT. Flotillin-1 may interact with a deubiquitinase to inhibit the ubiquitination of Snail in gastric cancer cells to promote EMT process. Our study provides a rationale and potential target for the treatment of gastric cancer.
| S-EPMC9387518 | biostudies-literature
Project description:BACKGROUND:Autophagy plays a crucial role in sustaining the homeostasis in various malignant diseases. It has also been reported to promote tumor development in multiple cancers. Glutaminolysis instead of Warburg Effect produce adequate ATP and provide nitrogen and carbon to replenish the TCA cycle which has been discovered to be a new energy source for tumor cells recently. By means of degrading intracellular particles including amino acids, nucleotides, fatty acids, sugars and aged organisms, autophagy can recycle the aforementioned particles into bioenergetics and biosynthesis pathways, finally favoring tumor cells. MicroRNA is a kind of noncoding RNA that regulates the targeting gene expression mostly at post-transcription level. Among these miRNAs, microRNA-133a-3p is reported to be a tumor suppressor in numerous cancers. METHODS:We characterized the down-regulated expression level of microRNA-133a-3p in gastric cancer via TCGA database. Subsequently, we verified the tumor suppressor role of microRNA-133a-3p in gastric cancer cells through a series biological function assay. We used immunofluorescence and transmission electron microscope to observe the negative effect of microRNA-133a-3p on autophagy and used dual-luciferase report assay to identify the candidate gene GABARAPL1 of microRNA-133A-3p.Then we used high performance liquid phase mass spectrometry and seahorse analysis to detect whether miR-133a-3p could block the glutaminolysis metabolism through autophagy. At last, we confirmed the tumor suppressor role of microRNA-133a-3p in vivo on PDX mice model. RESULTS:We demonstrated that microRNA-133a-3p overexpression could block the activation of autophagy to ruin the abnormal glutaminolysis and further inhibit the growth and metastasis of gastric cancer cells. We successfully proved gastric cancer cells can replenish glutaminolysis via autophagy and microRNA-133a-3p could block aforementioned pathway by targeting core autophagy participants GABARAPL1 and ATG13.We then verified the negative function of microRNA-133a-3p on autophagy-mediated glutaminolysis both in PDX model and human gastric cancer organoid model. CONCLUSIONS:MicroRNA-133a-3p targets GABARAPL1 to block autophagy-mediated glutaminolysis, further repressing gastric cancer growth and metastasis.
| S-EPMC6302516 | biostudies-literature
Project description:As glutamine plays a central role in cancer metabolism, inhibition of glutaminolysis has become an ideal anticancer therapeutic target. However, glutaminolysis inhibition leads to activation of autophagy, which compromises its antitumor effect. Hence, we investigated the mechanism underlying glutaminolysis inhibition-induced pro-survival autophagy. Methods: High-throughput sequencing was performed on colorectal cancer (CRC) cells before and after glutaminolysis inhibition to identify differentially expressed genes. Activating transcription factor 4 (ATF4) pathway enrichment in glutaminolysis inhibited cells was identified through gene set enrichment analysis. ATF4 expression was assessed by quantitative real-time PCR (qRT-PCR) and western blotting. The function of ATF4 on mechanistic target of rapamycin (mTOR) regulation was assessed by western blotting. Luciferase reporter assays and chromatin immunoprecipitation were used to confirm the regulation of DNA damage inducible transcript 4 (DDIT4) by ATF4. mRNA half-life assays, RNA immunoprecipitation, qRT-PCR and western blotting were performed to determine the relationship between FTO alpha-ketoglutarate dependent dioxygenase (FTO), YTH N6-methyladenosine RNA binding protein 2 (YTHDF2), and ATF4. ATF4 regulation of pro-survival autophagy was measured by tandem monomeric red fluorescent protein-green fluorescent protein fluorescence microscopy. Finally, the synergistic effect of autophagy and glutaminolysis inhibition was analyzed in an azoxymethane/dextran sodium sulfate mouse model. Results: The ATF4 pathway was activated in CRC cells upon glutaminolysis inhibition. Functionally, ATF4 transcriptionally upregulated DDIT4 to suppress mTOR, which induced pro-survival autophagy during glutaminolysis inhibition. Interestingly, glutaminolysis inhibition promoted ATF4 mRNA expression by abrogating N6-methyladenosine (m6A) modification and YTHDF2-mediated RNA decay. Finally, inhibition of ATF4-induced autophagy enhanced the antitumor efficacy of glutaminolysis inhibition. Conclusion: Glutaminolysis inhibition upregulated ATF4 expression in an m6A-dependent manner to activate pro-survival autophagy through transcriptional activation of the mTOR inhibitor DDIT4. Targeting ATF4-induced autophagy is a new strategy to synergize glutaminolysis-targeting therapies for cancer treatment.
| S-EPMC8343999 | biostudies-literature
Project description:Nonsmall cell lung cancer (NSCLC) is one of the most commonly diagnosed and lethal cancers characterized by relatively low overall cure and poor survival rates with great challenge for consistent effective clinical treatment. Here we demonstrated that the antifungal sertaconazole displays potent anti-NSCLC effect by promoting apoptosis in vitro and in vivo. Further studies found that sertaconazole induces complete autophagic flux, which contributes to sertaconazole-induced apoptosis and subsequent growth suppression in NSCLC cells. Further studies demonstrated that sertaconazole provokes TNF receptor type 1 associated death domain protein (TRADD) expression via stabilizing it from ubiquitination-mediated degradation, which results in Akt dephosphorylation and thereby triggers proapoptotic autophagy in NSCLC cells. Moreover, we found that TRADD suppression reverses sertaconazole-induced proapoptotic autophagy and relieves growth suppression, indicating the vital role of TRADD-regulated proapoptotic autophagy in the anti-NSCLC activity of sertaconazole. In summary, our findings suggest that sertaconazole could be a highly promising anti-NSCLC drug by triggering proapoptotic autophagy via stabilizing TRADD, which may provide a new potential therapeutic option for patients with NSCLC.
| S-EPMC8706745 | biostudies-literature