scholarly journals Anabolic SIRT4 exerts retrograde control over TORC1 signalling by glutamine sparing in the mitochondria

2019 ◽  
Author(s):  
Eisha Shaw ◽  
Manasi Talwadekar ◽  
Nitya Mohan ◽  
Aishwarya Acharya ◽  
Ullas Kolthur-Seetharam
Keyword(s):  
Cell Proliferation ◽  
Differential Expression ◽  
Tca Cycle ◽  
Glutamine Metabolism ◽  
Signalling Pathways ◽  
Nutrient Inputs ◽  
Catabolic Pathways ◽  
Fed State ◽  
Mitochondrial Functions ◽  
Mtor Signalling

AbstractAnabolic and catabolic signalling mediated via mTOR and AMPK have to be intrinsically coupled to mitochondrial functions for maintaining homeostasis and mitigate cellular/organismal stress. Although, glutamine is known to activate mTOR, if/how differential mitochondrial utilization of glutamine impinges on mTOR signalling is less explored. Mitochondrial SIRT4, which unlike other sirtuins is induced in a fed state, is known to inhibit catabolic signalling/pathways through AMPK-PGC1a/SIRT1-PPARa axis and negatively regulate glutamine metabolism via TCA cycle. However, physiological significance of SIRT4 functions during a fed state is still unknown. Here, we establish SIRT4 as key anabolic factor that activates TORC1 signalling and regulates lipogenesis, autophagy and cell proliferation. Mechanistically, we demonstrate that the ability of SIRT4 to inhibit anaplerotic conversion of glutamine to α-ketoglutarate potentiates TORC1. Interestingly, we also show that mitochondrial glutamine sparing or utilization is critical for differentially regulating TORC1 under fed and fasted conditions. Moreover, we conclusively show that differential expression of SIRT4 during fed and fasted states is vital for coupling mitochondrial energetics and glutamine utilization with anabolic pathways. These significant findings also illustrate that SIRT4 integrates nutrient inputs with mitochondrial retrograde signals to maintain a balance between anabolic and catabolic pathways.

scholarly journals Anabolic SIRT4 Exerts Retrograde Control over TORC1 Signaling by Glutamine Sparing in the Mitochondria

2019 ◽  
Vol 40 (2) ◽  
Author(s):  
Eisha Shaw ◽  
Manasi Talwadekar ◽  
Zeenat Rashida ◽  
Nitya Mohan ◽  
Aishwarya Acharya ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Glutamine Metabolism ◽  
Peroxisome Proliferator ◽  
Nutrient Inputs ◽  
Peroxisome Proliferator Activated Receptor ◽  
Fed State ◽  
Acid Cycle ◽  
Mitochondrial Functions

ABSTRACT Anabolic and catabolic signaling mediated via mTOR and AMPK (AMP-activated kinase) have to be intrinsically coupled to mitochondrial functions for maintaining homeostasis and mitigate cellular/organismal stress. Although glutamine is known to activate mTOR, whether and how differential mitochondrial utilization of glutamine impinges on mTOR signaling has been less explored. Mitochondrial SIRT4, which unlike other sirtuins is induced in a fed state, is known to inhibit catabolic signaling/pathways through the AMPK-PGC1α/SIRT1–peroxisome proliferator-activated receptor α (PPARα) axis and negatively regulate glutamine metabolism via the tricarboxylic acid cycle. However, physiological significance of SIRT4 functions during a fed state is still unknown. Here, we establish SIRT4 as key anabolic factor that activates TORC1 signaling and regulates lipogenesis, autophagy, and cell proliferation. Mechanistically, we demonstrate that the ability of SIRT4 to inhibit anaplerotic conversion of glutamine to α-ketoglutarate potentiates TORC1. Interestingly, we also show that mitochondrial glutamine sparing or utilization is critical for differentially regulating TORC1 under fed and fasted conditions. Moreover, we conclusively show that differential expression of SIRT4 during fed and fasted states is vital for coupling mitochondrial energetics and glutamine utilization with anabolic pathways. These significant findings also illustrate that SIRT4 integrates nutrient inputs with mitochondrial retrograde signals to maintain a balance between anabolic and catabolic pathways.

scholarly journals A Critical Role of Glutamine and Asparagine γ-Nitrogen in Nucleotide Biosynthesis in Cancer Cells Hijacked by an Oncogenic Virus

mBio ◽  
2017 ◽  
Vol 8 (4) ◽  
Author(s):  
Ying Zhu ◽  
Tingting Li ◽  
Suzane Ramos da Silva ◽  
Jae-Jin Lee ◽  
Chun Lu ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cancer Cells ◽  
Metabolic Pathway ◽  
Tca Cycle ◽  
Glutamine Metabolism ◽  
Transformed Cells ◽  
Oncogenic Virus ◽  
Phosphoribosyl Pyrophosphate ◽  
Rate Limiting

ABSTRACT While glutamine is a nonessential amino acid that can be synthesized from glucose, some cancer cells primarily depend on glutamine for their growth, proliferation, and survival. Numerous types of cancer also depend on asparagine for cell proliferation. The underlying mechanisms of the glutamine and asparagine requirement in cancer cells in different contexts remain unclear. In this study, we show that the oncogenic virus Kaposi’s sarcoma-associated herpesvirus (KSHV) accelerates the glutamine metabolism of glucose-independent proliferation of cancer cells by upregulating the expression of numerous critical enzymes, including glutaminase 2 (GLS2), glutamate dehydrogenase 1 (GLUD1), and glutamic-oxaloacetic transaminase 2 (GOT2), to support cell proliferation. Surprisingly, cell crisis is rescued only completely by supplementation with asparagine but minimally by supplementation with α-ketoglutarate, aspartate, or glutamate upon glutamine deprivation, implying an essential role of γ-nitrogen in glutamine and asparagine for cell proliferation. Specifically, glutamine and asparagine provide the critical γ-nitrogen for purine and pyrimidine biosynthesis, as knockdown of four rate-limiting enzymes in the pathways, including carbamoylphosphate synthetase 2 (CAD), phosphoribosyl pyrophosphate amidotransferase (PPAT), and phosphoribosyl pyrophosphate synthetases 1 and 2 (PRPS1 and PRPS2, respectively), suppresses cell proliferation. These findings indicate that glutamine and asparagine are shunted to the biosynthesis of nucleotides and nonessential amino acids from the tricarboxylic acid (TCA) cycle to support the anabolic proliferation of KSHV-transformed cells. Our results illustrate a novel mechanism by which an oncogenic virus hijacks a metabolic pathway for cell proliferation and imply potential therapeutic applications in specific types of cancer that depend on this pathway. IMPORTANCE We have previously found that Kaposi’s sarcoma-associated herpesvirus (KSHV) can efficiently infect and transform primary mesenchymal stem cells; however, the metabolic pathways supporting the anabolic proliferation of KSHV-transformed cells remain unknown. Glutamine and asparagine are essential for supporting the growth, proliferation, and survival of some cancer cells. In this study, we have found that KSHV accelerates glutamine metabolism by upregulating numerous critical metabolic enzymes. Unlike most cancer cells that primarily utilize glutamine and asparagine to replenish the TCA cycle, KSHV-transformed cells depend on glutamine and asparagine for providing γ-nitrogen for purine and pyrimidine biosynthesis. We identified four rate-limiting enzymes in this pathway that are essential for the proliferation of KSHV-transformed cells. Our results demonstrate a novel mechanism by which an oncogenic virus hijacks a metabolic pathway for cell proliferation and imply potential therapeutic applications in specific types of cancer that depend on this pathway.

scholarly journals VOPP1 promotes hepatocellular carcinoma proliferation through MAPK14 and RPS6KB1

2019 ◽  
Author(s):  
Haojiang Dai ◽  
Peng Hu ◽  
Binfeng Wang ◽  
Qiuyue Han ◽  
Yongfu Xu ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Cell Proliferation ◽  
Annexin V ◽  
Tumor Xenograft ◽  
Signalling Pathways ◽  
Proliferation And Apoptosis ◽  
Apoptosis Detection ◽  
Mtor Signalling

Abstract Background: The present study aimed to investigate the role of VOPP1 in hepatocellular carcinoma (HCC). Methods: Immunohistochemistry(IHC), Western blot and Reverse-transcription polymerase chain reaction (RT-PCR) were used to analyze the expression of VOPP1 protein, the expression of VOPP1, MAPK14, RPS6KB1, CYLD and TWIST1 and the mRNA expression of VOPP1, MAPK14, RPS6KB1, CYLD and TWIST1. The cell proliferation and apoptosis were tested using Celigo cell imaging analyzer and annexin V-APC apoptosis detection kit respectively. Colony formation and tumor xenograft assays was performed to understand their roles in tumorigenicity. Results: The expression of VOPP1 in HCC samples was higher than that in adjacent noncancerous tissues by immunohistochemistry. In addition, the deletion of VOPP1 using shRNA inhibited cell proliferation and tumour growth, and induced cell apoptosis in vitro and in vivo. Furthermore, VOPP1 silencing decreased the expression of MAPK14 and RPS6KB1, indicating that the MAPK and mTOR signalling pathways might be involved in VOPP1-mediated cancer cell proliferation. Conclusion: The present data indicates that VOPP1 may play an important role in the progression of HCC by targeting the MAPK and mTOR signalling pathways, and that VOPP1 may potentially be a candidate as a novel molecular target for HCC therapy.

scholarly journals Anemoside B4 ameliorates TNBS-induced colitis through S100A9/MAPK/NF-κB signaling pathway

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Yong Zhang ◽  
Zhengxia Zha ◽  
Wenhua Shen ◽  
Dan Li ◽  
Naixin Kang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Signaling Pathway ◽  
Tca Cycle ◽  
Mapk Signaling ◽  
Enzyme Linked Immunosorbent Assay ◽  
Trinitrobenzene Sulfonic Acid ◽  
Therapeutic Effects ◽  
Triterpenoid Saponin ◽  
Label Free

Abstract Background Despite the increased morbidity of ulcerative colitis (UC) in the developing countries, available treatments remain unsatisfactory. Therefore, it is urgent to discover more effective therapeutic strategies. Pulsatilla chinensis was widely used for the treatment of inflamed intestinal diseases including UC for thousands of years in China. Anemoside B4, the most abundant triterpenoid saponin isolated from P. chinensis, exerts anti-inflammatory and antioxidant effects and may be the most active compounds, which is responsible for the therapeutic effects. However, the mechanism how anemoside B4 executes its biological functions is still elusive. Methods Here, we used the 2, 4, 6-trinitrobenzene sulfonic acid (TNBS)-induced colitis rat model to evaluate the therapeutic effect of anemoside B4. Blood samples of colitis rats were collected for hematology analysis. The inflammation-associated factors were investigated by enzyme-linked immunosorbent assay (ELISA). Cell proliferation and apoptosis was determined with EdU cell proliferation assay and TUNEL assay. The proteins regulated by anemoside B4 were identified by label-free quantitative proteomics. The significantly down-regulated proteins were verified by Western blotting analysis. mRNA expression was analyzed by quantitative real-time RT-PCR. Results The results showed that anemoside B4 ameliorated TNBS-induced colitis symptoms, including tissue damage, inflammatory cell infiltration, and pro-inflammatory cytokine production, apoptosis and slowed proliferation in colon. Quantitative proteomic analyses discovered that 56 proteins were significantly altered by anemoside B4 in the TNBS-induced rats. These proteins mainly clustered in tricarboxylic acid (TCA) cycle and respiratory electron transport chain. Among the altered proteins, S100A9 is one of the most significantly down-regulated proteins and associated with NF-κB and MAPK signaling pathways in the pathogenesis of UC. Further experiments revealed that anemoside B4 suppressed the expression of S100A9 and its downstream genes including TLR4 and NF-κB in colon. In vitro, anemoside B4 could inhibit the NF-κB signaling pathway induced by recombinant S100A9 protein in human intestinal epithelial Caco-2 cells. Moreover, anemoside B4 inhibits neutrophils recruitment and activation in colon induced by TNBS. Conclusions Our results demonstrate that anemoside B4 prevents TNBS-induced colitis by inhibiting the NF-κB signaling pathway through deactivating S100A9, suggesting that anemoside B4 is a promising therapeutic candidate for colitis.

scholarly journals LONP1 and ClpP cooperatively regulate mitochondrial proteostasis for cancer cell survival

Oncogenesis ◽  
2021 ◽  
Vol 10 (2) ◽  
Author(s):  
Yu Geon Lee ◽  
Hui Won Kim ◽  
Yeji Nam ◽  
Kyeong Jin Shin ◽  
Yu Jin Lee ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Growth ◽  
Cell Survival ◽  
Cancer Cell ◽  
Stress Responses ◽  
Molecular Mechanisms ◽  
Tca Cycle ◽  
Mitochondrial Matrix ◽  
Mitochondrial Functions ◽  
Cancer Cell Survival

AbstractMitochondrial proteases are key components in mitochondrial stress responses that maintain proteostasis and mitochondrial integrity in harsh environmental conditions, which leads to the acquisition of aggressive phenotypes, including chemoresistance and metastasis. However, the molecular mechanisms and exact role of mitochondrial proteases in cancer remain largely unexplored. Here, we identified functional crosstalk between LONP1 and ClpP, which are two mitochondrial matrix proteases that cooperate to attenuate proteotoxic stress and protect mitochondrial functions for cancer cell survival. LONP1 and ClpP genes closely localized on chromosome 19 and were co-expressed at high levels in most human cancers. Depletion of both genes synergistically attenuated cancer cell growth and induced cell death due to impaired mitochondrial functions and increased oxidative stress. Using mitochondrial matrix proteomic analysis with an engineered peroxidase (APEX)-mediated proximity biotinylation method, we identified the specific target substrates of these proteases, which were crucial components of mitochondrial functions, including oxidative phosphorylation, the TCA cycle, and amino acid and lipid metabolism. Furthermore, we found that LONP1 and ClpP shared many substrates, including serine hydroxymethyltransferase 2 (SHMT2). Inhibition of both LONP1 and ClpP additively increased the amount of unfolded SHMT2 protein and enhanced sensitivity to SHMT2 inhibitor, resulting in significantly reduced cell growth and increased cell death under metabolic stress. Additionally, prostate cancer patients with higher LONP1 and ClpP expression exhibited poorer survival. These results suggest that interventions targeting the mitochondrial proteostasis network via LONP1 and ClpP could be potential therapeutic strategies for cancer.

Importance of Glutamine Metabolism in Leukemia Cells by Energy Production Through TCA Cycle and by Redox Homeostasis

2014 ◽  
Vol 32 (6) ◽  
pp. 241-247 ◽  
Author(s):  
Mineaki Goto ◽  
Hiroshi Miwa ◽  
Masato Shikami ◽  
Norikazu Tsunekawa-Imai ◽  
Kazuto Suganuma ◽  
...  
Keyword(s):  
Energy Production ◽  
Redox Homeostasis ◽  
Tca Cycle ◽  
Glutamine Metabolism ◽  
Leukemia Cells

scholarly journals Differential expression and regulation of Tdo2 during mouse decidualization

2013 ◽  
Vol 220 (1) ◽  
pp. 73-83 ◽  
Author(s):  
Dang-Dang Li ◽  
Ying-Jie Gao ◽  
Xue-Chao Tian ◽  
Zhan-Qing Yang ◽  
Hang Cao ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Differential Expression ◽  
Stromal Cells ◽  
Real Time Pcr ◽  
Mouse Uterus ◽  
Decidual Cells ◽  
High Level ◽  
Rate Limiting

Tryptophan 2,3-dioxygenase (Tdo2) is a rate-limiting enzyme which directs the conversion of tryptophan to kynurenine. The aim of this study was to examine the expression and regulation of Tdo2 in mouse uterus during decidualization. Tdo2 mRNA was mainly expressed in the decidua on days 6–8 of pregnancy. By real-time PCR, a high level of Tdo2 expression was observed in the uteri from days 6 to 8 of pregnancy, although Tdo2 expression was observed on days 1–8. Simultaneously, Tdo2 mRNA was also detected under in vivo and in vitro artificial decidualization. Estrogen, progesterone, and 8-bromoadenosine-cAMP could induce the expression of Tdo2 in the ovariectomized mouse uterus and uterine stromal cells. Tdo2 could regulate cell proliferation and stimulate the expression of decidual marker Dtprp in the uterine stromal cells and decidual cells. Overexpression of Tdo2 could upregulate the expression of Ahr, Cox2, and Vegf genes in uterine stromal cells, while Tdo2 inhibitor 680C91 could downregulate the expression of Cox2 and Vegf genes in uterine decidual cells. These data indicate that Tdo2 may play an important role during mouse decidualization and be regulated by estrogen, progesterone, and cAMP.

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