bims-toxgon 2022-11-27 papers

bims-toxgon

Biomed News

on Toxoplasma gondii metabolism

Issue of 2022–11–27
ten papers selected by
Lakesh Kumar, BITS Pilani

Acetyl-CoA regulates lipid metabolism and histone acetylation modification in cancer.
Nutrient-sensing mTORC1 and AMPK pathways in chronic kidney diseases.
Toxoplasma gondii induces MLTC-1 apoptosis via ERS pathway.
Zika virus infection triggers lipophagy by stimulating the AMPK-ULK1 signaling in human hepatoma cells.
The phosphorylation of AMPKβ1 is critical for increasing autophagy and maintaining mitochondrial homeostasis in response to fatty acids.
Immunological evaluation of a novel multi-antigenic DNA vaccine encoding SAG1, SAG3, MIC4, GRA5, GRA7, AMA1and BAG1 against Toxoplasma gondii in BALB/c mice.
The roles and mechanisms of circular RNAs related to mTOR in cancers.
Directional regulation of cytosolic PEPCK catalysis is mediated by competitive binding of anions.
Mechanistic insights on impact of Adenosine monophosphate-activated protein kinase (AMPK) mediated signalling pathways on cerebral ischemic injury.
Characterization of the Expression and Role of Histone Acetylation and Deacetylation in Dental Pulp Cells.

Biochim Biophys Acta Rev Cancer. 2022 Nov 17. pii: S0304-419X(22)00162-7. [Epub ahead of print]1878(1): 188837

Acetyl-CoA regulates lipid metabolism and histone acetylation modification in cancer.

Weijing He, Qingguo Li, Xinxiang Li.

  Acetyl-CoA, as an important molecule, not only participates in multiple intracellular metabolic reactions, but also affects the post-translational modification of proteins, playing a key role in the metabolic activity and epigenetic inheritance of cells. Cancer cells require extensive lipid metabolism to fuel for their growth, while also require histone acetylation modifications to increase the expression of cancer-promoting genes. As a raw material for de novo lipid synthesis and histone acetylation, acetyl-CoA has a major impact on lipid metabolism and histone acetylation in cancer. More importantly, in cancer, acetyl-CoA connects lipid metabolism with histone acetylation, forming a more complex regulatory mechanism that influences cancer growth, proliferation, metastasis.

Keywords:  Acetyl-coenzyme A (acetyl-CoA); Cancer; Histone acetylation; Lipid metabolism

DOI:  https://doi.org/10.1016/j.bbcan.2022.188837
Nat Rev Nephrol. 2022 Nov 24.

Nutrient-sensing mTORC1 and AMPK pathways in chronic kidney diseases.

Christopher Huynh, Jaewhee Ryu, Jooho Lee, Ayaka Inoki, Ken Inoki.

Nutrients such as glucose, amino acids and lipids are fundamental sources for the maintenance of essential cellular processes and homeostasis in all organisms. The nutrient-sensing kinases mechanistic target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK) are expressed in many cell types and have key roles in the control of cell growth, proliferation, differentiation, metabolism and survival, ultimately contributing to the physiological development and functions of various organs, including the kidney. Dysregulation of these kinases leads to many human health problems, including cancer, neurodegenerative diseases, metabolic disorders and kidney diseases. In the kidney, physiological levels of mTOR and AMPK activity are required to support kidney cell growth and differentiation and to maintain kidney cell integrity and normal nephron function, including transport of electrolytes, water and glucose. mTOR forms two functional multi-protein kinase complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). Hyperactivation of mTORC1 leads to podocyte and tubular cell dysfunction and vulnerability to injury, thereby contributing to the development of chronic kidney diseases, including diabetic kidney disease, obesity-related kidney disease and polycystic kidney disease. Emerging evidence suggests that targeting mTOR and/or AMPK could be an effective therapeutic approach to controlling or preventing these diseases.

DOI: https://doi.org/10.1038/s41581-022-00648-y
Exp Parasitol. 2022 Nov 17. pii: S0014-4894(22)00223-5. [Epub ahead of print]244 108429

Toxoplasma gondii induces MLTC-1 apoptosis via ERS pathway.

Lei Wang, Hailun Wang, Shihao Wei, Xiaoyu Huang, Chunchen Yu, Qingrui Meng, Dengfeng Wang, Guangwen Yin, Zhijian Huang.

  Toxoplasma gondii (T. gondii) is a serious intracellular parasite and mammalian infection can damage the reproductive system and lead to apoptosis of Murine Leydig tumor cells (MLTC-1); however, the mechanism is unclear. The testis Leydig cell is the main testosterone synthesis cell in male mammals. We studied the mechanism of T. gondii infection on Leydig cell apoptosis in vitro. MLTC-1 were divided into control and experimental groups. Experiment group cells and tachyzoites were co-cultured, in a 1:20 ratio, for 3, 6, 9, and 12 h. T. gondii entered the cells and caused lesions at 12 h. Flow cytometry showed that the apoptosis rate of the experiment group increased with time and was significantly higher (P < 0.05) than the control group. RT-qPCR and western blot demonstrated that the expression of P53, Caspase-3, and Bax were significantly increased at 12 h (P < 0.05). Bcl-2 expression was significantly increased at 12 h (P < 0.05). The ER stress (ERS) pathway was important in cell apoptosis. RT-qPCR and western blot showed that the expression of CHOP was significantly increased at 12 h (P < 0.05). These data indicate that T. gondii induced MLTC-1 cell apoptosis may occur via the ERS pathway.

Keywords:  Apoptosis; CHOP; ERS; Leydig cell; Toxoplasma gondii

DOI:  https://doi.org/10.1016/j.exppara.2022.108429
Front Cell Infect Microbiol. 2022 ;12 959029

Zika virus infection triggers lipophagy by stimulating the AMPK-ULK1 signaling in human hepatoma cells.

Zhao-Ling Qin, Qiu-Feng Yao, Ping Zhao, Hao Ren, Zhong-Tian Qi.

  Zika virus (ZIKV) is a globally transmitted mosquito-borne pathogen, and no effective treatment or vaccine is available yet. Lipophagy, a selective autophagy targeting lipid droplets (LDs), is an emerging subject in cellular lipid metabolism and energy homeostasis. However, the regulatory mechanism of lipid metabolism and the role of lipophagy in Zika virus infection remain largely unknown. Here, we demonstrated that ZIKV induced lipophagy by activating unc-51-like kinase 1 (ULK1) through activation of 5' adenosine monophosphate (AMP)-activated protein kinase (AMPK) in Huh7 cells. Upon ZIKV infection, the average size and triglyceride content of LDs significantly decreased. Moreover, ZIKV infection significantly increased lysosomal biosynthesis and LD-lysosome fusion. The activities of AMPK at Thr-172 and ULK1 at Ser-556 were increased in ZIKV-infected cells and closely correlated with lipophagy induction. Silencing of AMPK expression inhibited ZIKV infection, autophagy induction, and LD-lysosome fusion and decreased the triglyceride content of the cells. The activities of mammalian target of rapamycin (mTOR) at Ser-2448 and ULK1 at Ser-757 were suppressed independently of AMPK during ZIKV infection. Therefore, ZIKV infection triggers AMPK-mediated lipophagy, and the LD-related lipid metabolism during ZIKV infection is mainly regulated via the AMPK-ULK1 signaling pathway.

Keywords:  AMPK; ULK1; Zika virus; lipid metabolism; lipophagy; mTOR

DOI:  https://doi.org/10.3389/fcimb.2022.959029
Proc Natl Acad Sci U S A. 2022 Nov 29. 119(48): e2119824119

The phosphorylation of AMPKβ1 is critical for increasing autophagy and maintaining mitochondrial homeostasis in response to fatty acids.

Eric M Desjardins, Brennan K Smith, Emily A Day, Serge Ducommun, Matthew J Sanders, Joshua P Nederveen, Rebecca J Ford, Stephen L Pinkosky, Logan K Townsend, Robert M Gutgesell, Rachel Lu, Kei Sakamoto, Gregory R Steinberg.

  Fatty acids are vital for the survival of eukaryotes, but when present in excess can have deleterious consequences. The AMP-activated protein kinase (AMPK) is an important regulator of multiple branches of metabolism. Studies in purified enzyme preparations and cultured cells have shown that AMPK is allosterically activated by small molecules as well as fatty acyl-CoAs through a mechanism involving Ser108 within the regulatory AMPK β1 isoform. However, the in vivo physiological significance of this residue has not been evaluated. In the current study, we generated mice with a targeted germline knock-in (KI) mutation of AMPKβ1 Ser108 to Ala (S108A-KI), which renders the site phospho-deficient. S108A-KI mice had reduced AMPK activity (50 to 75%) in the liver but not in the skeletal muscle. On a chow diet, S108A-KI mice had impairments in exogenous lipid-induced fatty acid oxidation. Studies in mice fed a high-fat diet found that S108A-KI mice had a tendency for greater glucose intolerance and elevated liver triglycerides. Consistent with increased liver triglycerides, livers of S108A-KI mice had reductions in mitochondrial content and respiration that were accompanied by enlarged mitochondria, suggestive of impairments in mitophagy. Subsequent studies in primary hepatocytes found that S108A-KI mice had reductions in palmitate- stimulated Cpt1a and Ppargc1a mRNA, ULK1 phosphorylation and autophagic/mitophagic flux. These data demonstrate an important physiological role of AMPKβ1 Ser108 phosphorylation in promoting fatty acid oxidation, mitochondrial biogenesis and autophagy under conditions of high lipid availability. As both ketogenic diets and intermittent fasting increase circulating free fatty acid levels, AMPK activity, mitochondrial biogenesis, and mitophagy, these data suggest a potential unifying mechanism which may be important in mediating these effects.

Keywords:  AMPK; NAFLD; autophagy; fat oxidation; mitochondria

DOI:  https://doi.org/10.1073/pnas.2119824119
Exp Parasitol. 2022 Nov 17. pii: S0014-4894(22)00203-X. [Epub ahead of print] 108409

Immunological evaluation of a novel multi-antigenic DNA vaccine encoding SAG1, SAG3, MIC4, GRA5, GRA7, AMA1and BAG1 against Toxoplasma gondii in BALB/c mice.

Mohammadreza Alijani, Behnaz Saffar, Hossein Yosefi Darani, Mohammadreza Mahzounieh, Mahdi Fasihi-Ramandi, Mostafa Niaee, Sodabe Soltani, Amir Ghaemi, Sadegh Shirian.

  Many recent studies have been conducted to find new DNA vaccines based on Toxoplasma gondii antigens. DNA vaccines encoding complex of different antigens showed better immune responses compared to single antigen vaccine. In this study, we constructed a DNA vaccine encoding SAG1, SAG3, MIC4, GRA5, GRA7, AMA1 and BAG1 against T. gondii, and evaluated the immune response it induced in BALB/c mice. For this purposes, thirty BALB/c mice were randomly divided into three groups containing tenmice each. There were two negative control groups (PBSand pVAX1 vector) and one vaccination group (pVAX1-MAF, Multantigenic Fragment). On days 0, 14 and 28, the mice were immunized intramuscularly, and 5 weeks later they were challenged with T. gondii RH strain. The immune responses were evaluated using lymphocyte proliferation assay, T-cell subsets detection, and measurement of antibody and cytokine levels. The results showed that mice immunized with pVAX1-MAF developed high levels of IL-2, IL-12, IgG and IFN- γ as well as CD3+CD4+ T cells. In addition, the survival time of mice immunized by pVAX1-MAF was longer than that control mice. In conclusion, our results show that the multiple DNA vaccine encodingSAG1, SAG3, mic4, GRA5, GRA7, AMA and BAG1effectively enhanced humoral and cellular immune responses, and prolonged the survival time. Together this would suggest that further investigation may result in a promising candidate vaccine to treat toxoplasmosis.

Keywords:  DNA vaccine; Immune evaluation; Toxoplasma gondii

DOI:  https://doi.org/10.1016/j.exppara.2022.108409
J Clin Lab Anal. 2022 Nov 25. e24783

The roles and mechanisms of circular RNAs related to mTOR in cancers.

Chunli Cao, Yao Wang, Xinxin Wu, Zhe Li, Junming Guo, Weiliang Sun.

   BACKGROUND: Circular RNAs (circRNAs) are stable molecules with covalently closed structures that have an irreplaceable role in the occurrence, progression, and even treatment of plenty of cancers. Mammalian/mechanistic target of rapamycin (mTOR) is a key regulator in cancers and plays several biological functions, such as proliferation, migration, invasion, autophagy, and apoptosis.
METHODS: All data were collected through PubMed and CNKI, using terms including "circRNA," "mTOR," "caner," "signaling pathway," "biomarker," "diagnosis," "treatment." Articles published in Chinese and English were included.
RESULTS: In this review, the expression, function, and mechanism of circRNA-associated mTOR in cancers were described. CircRNA-associated-mTOR can regulate the progression and therapy of a variety of cancers in multiple signaling pathways, such as phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mTOR, mitogen-activated protein kinase (MAPK)/mTOR, and AMP-activated protein kinase (AMPK)/mTOR axis. These cancers including esophageal carcinoma (circLPAR3, ciRS-7), gastric cancer (circNRIP1, hsa_circ_0010882, hsa_circ_0000117, hsa_circ_0072309, and circST3GAL6), colorectal cancer (hsa_circ_0000392, hsa_circ_0084927, hsa_circ_0104631, and circFBXW7), liver cancer (circC16orf62, hsa_circ_100338, hsa_circ_0004001, hsa_circ_0004123, hsa_circ_0075792, hsa_circ_0079299, and hsa_circ_0002130), pancreatic cancer (circ-IARS and circRHOBTB3), renal carcinoma (ciRS-7), bladder cancer (circUBE2K), prostate cancer (circMBOAT2 and circ-ITCH), ovarian cancer (circEEF2, circRAB11FIP1, circMYLK, and circTPCN), endometrial cancer (hsa_circ_0002577 and circWHSC1), lung cancer (circHIPK3, hsa_circ_0001666), thyroid cancer (hsa_circ_0007694 and hsa_circ_0008274), glioma (circGFRA1, circ-MAPK4, circPCMTD1, and hsa_circ_0037251), osteosarcoma (circTCF25), leukemia (circ-PRKDC), and breast cancer (hsa_circ_0000199, circUBAP2, and circWHSC1).

Keywords:  cancer; circRNA; function; mTOR; mechanism

DOI:  https://doi.org/10.1002/jcla.24783
Biochem Biophys Res Commun. 2022 Nov 11. pii: S0006-291X(22)01566-2. [Epub ahead of print]637 218-223

Directional regulation of cytosolic PEPCK catalysis is mediated by competitive binding of anions.

Sarah A E Barwell, Ramona Duman, Armin Wagner, Todd Holyoak.

Phosphoenolpyruvate carboxykinase (PEPCK) is a well-characterized enzyme involved in primary glucose metabolism, responsible for catalyzing one of the key steps of gluconeogenesis. It is well demonstrated that PEPCK can efficiently catalyze the reversible interconversion of oxaloacetic acid (OAA) to phosphoenolpyruvate (PEP) in vitro, but the enzyme is typically ascribed a metabolic role that requires preferential catalysis in the direction of PEP synthesis in vivo. Here we present structural and functional data that demonstrate the preferential synthesis of PEP from OAA catalyzed by PEPCK in vivo is facilitated by anion-mediated enzyme inhibition that reduces enzyme activity more significantly in the direction of OAA synthesis than in the direction of PEP synthesis. From our studies we conclude that the specific binding of small, ubiquitous anions like chloride, present in millimolar concentrations under normal cellular conditions allows for metabolic control by restricting PEPCK to function in the direction of PEP synthesis.

DOI: https://doi.org/10.1016/j.bbrc.2022.11.025
Neurosci Res. 2022 Nov 17. pii: S0168-0102(22)00286-3. [Epub ahead of print]

Mechanistic insights on impact of Adenosine monophosphate-activated protein kinase (AMPK) mediated signalling pathways on cerebral ischemic injury.

Palak Kalra, Heena Khan, Thakur Gurjeet Singh, Amarjot Kaur Grewal.

  Cerebral ischemia is the primary cause of morbidity and mortality worldwide due to the perturbations in the blood supply to the brain. The brain triggers a cascade of complex metabolic and cellular defects in response to ischemic stress. However, due to the disease heterogeneity and complexity, ischemic injury's metabolic and cellular pathologies remain elusive, and the link between various pathological mechanisms is difficult to determine. Efforts to develop effective treatments for these disorders have yielded limited efficacy, with no proper cure available to date. Recent clinical and experimental research indicates that several neuronal diseases commonly coexist with metabolic dysfunction, which may aggravate neurological symptoms. As a result, it stands to a reason that metabolic hormones could be a potential therapeutic target for major NDDs. Moreover, fasting signals also influence the circadian clock, as AMPK phosphorylates and promotes the degradation of the photo-sensing receptor (cryptochrome). Here, the interplay of AMPK signaling between metabolic regulation and neuronal death and its role for pathogenesis and therapeutics has been studied. We have also highlighted a significant signaling pathway, i.e., the adenosine monophosphate-activated protein kinase (AMPK) involved in the relationship between the metabolism and ischemia, which could be used as a target for future studies therapeutics, and review some of the clinical progress in this area.

Keywords:  Adenosine monophosphate-activated protein kinase; Adiponectin; Ghrelin; Insulin; Ischemia; Leptin; Neuroprotection; metabolic

DOI:  https://doi.org/10.1016/j.neures.2022.11.006
Methods Mol Biol. 2023 ;2588 279-293

Characterization of the Expression and Role of Histone Acetylation and Deacetylation in Dental Pulp Cells.

Yukako Yamauchi, Henry F Duncan.

  Histone acetylation and deacetylation of DNA-associated proteins have been shown to alter the architecture of chromatin, affecting gene expression and controlling a wide range of biological events. These events are balanced by two sets of cellular enzymes, histone-deacetylases (HDACs) and histone acetyl-transferases (HATs). Pharmacological inhibition of histone-deacetylases (HDACs) using HDAC-inhibitors (HDACis) has been shown to promote dental pulp cell reparative processes with therapeutic implications in various fields including regenerative dentistry. To date, pan-HDACi have generally been used rather than isoform-specific HDACi targeting, despite the fact that HDAC-specific inhibitors have been developed to target HDACs in several tissues. To identify potential therapeutic targets in the tooth, the expression and distribution of HDAC-isoforms need to be analyzed. This chapter focuses on techniques to analyze expression, location, and distribution of individual HDAC-isoforms under mineralizing conditions using both histology and cell biology, along with a description of basic techniques for culturing and mineralization of rodent dental pulp cells.

Keywords:  Dental pulp cells; Dental pulp regeneration; Epigenetics; Histone acetylation/deacetylation; Immunohistochemistry; Mineralization; Protein expression

DOI:  https://doi.org/10.1007/978-1-0716-2780-8_17