bims-toxgon Biomed News
on Toxoplasma gondii metabolism
Issue of 2024–08–25
twenty papers selected by
Lakesh Kumar, BITS Pilani
  1. Orthologs of Plasmodium ICM1 are dispensable for Ca2+ mobilization in Toxoplasma gondii.
  2. Protein disulfide isomerase PDI8 is indispensable for parasite growth and associated with secretory protein processing in Toxoplasma gondii.
  3. Decoding Toxoplasma gondii virulence: the mechanisms of IRG protein inactivation.
  4. Calcium-binding protein TgpCaBP regulates calcium storage of the zoonotic parasite Toxoplasma gondii.
  5. Antiparasitic Effects of Niosomal Formulations of Curcumin and Silymarin Against Toxoplasma gondii In Vitro.
  6. Diversity of genes encoding immune-related GTPase B2 protein, an inherited element responsible for resistance against virulent Toxoplasma gondii strains, among wild Mus musculus in local area of Japan.
  7. Proteostasis is a key driver of the pathogenesis in Apicomplexa.
  8. Nutrient Sensing of mTORC1 signaling in cancer and aging.
  9. The anticancer mechanisms of Toxoplasma gondii rhoptry protein 16 on lung adenocarcinoma cells.
  10. miRNA, New Perspective to World of Intestinal Protozoa and Toxoplasma.
  11. The influential responsibility of sirtuins in senescence and associated diseases: A review.
  12. Epigenetic Regulation of Neural Activity in the Depressed Brain: The Two Faces of the Histone Deacetylase SIRT1.
  13. Rag-Ragulator is the central organizer of the physical architecture of the mTORC1 nutrient-sensing pathway.
  14. The phosphatase inhibitor BVT-948 can be used to efficiently screen functional sexual development proteins in the malaria parasite Plasmodium berghei.
  15. Role of sirtuins in sepsis and sepsis-induced organ dysfunction: A review.
  16. THE GENETICALLY ENCODED CALCIUM INDICATOR GCAMP3 REVEALS SPONTANEOUS CALCIUM OSCILLATIONS AT ASEXUAL STAGES OF THE HUMAN MALARIA PARASITE PLASMODIUM FALCIPARUM.
  17. HDAC6 inhibition disrupts HDAC6-P300 interaction reshaping the cancer chromatin landscape.
  18. NMN partially rescues cuproptosis by upregulating sirt2 to increase intracellular NADPH.
  19. The role of SIRT3 in homeostasis and cellular health.
  20. Optimization of a DiCre recombinase system with reduced leakage for conditional genome editing of Cryptosporidium.
  1. Microbiol Spectr. 2024 Aug 20. e0122924
    Orthologs of Plasmodium ICM1 are dispensable for Ca2+ mobilization in Toxoplasma gondii.
    Gabriel Cabral, Bingjian Ren, Hugo Bisio, Dawson Otey, Dominique Soldati-Favre, Kevin M Brown.
      Apicomplexan parasites mobilize ionic calcium (Ca2+) from intracellular stores to promote microneme secretion and facilitate motile processes including gliding motility, invasion, and egress. Recently, a multipass transmembrane protein, ICM1, was found to be important for calcium mobilization in Plasmodium falciparum and P. berghei. Comparative genomics and phylogenetics have revealed putative ICM orthologs in Toxoplasma gondii and other apicomplexans. T. gondii possesses two ICM-like proteins, which we have named TgICM1-L (TGGT1_305470) and TgICM2-L (TGGT1_309910). TgICM1-L and TgICM2-L localized to undefined puncta within the parasite cytosol. TgICM1-L and TgICM2-L are individually dispensable in tachyzoites, suggesting a potential compensatory relationship between the two proteins may exist. Surprisingly, mutants lacking both TgICM1-L and TgICM2-L are fully viable, exhibiting no obvious defects in growth, microneme secretion, invasion, or egress. Furthermore, loss of TgICM1-L, TgICM2-L, or both does not impair the parasite's ability to mobilize Ca2+. These findings suggest that additional proteins may participate in Ca2+ mobilization or import in Apicomplexa, reducing the dependence on ICM-like proteins in T. gondii. Collectively, these results highlight similar yet distinct mechanisms of Ca2+ mobilization between T. gondii and Plasmodium.IMPORTANCECa2+ signaling plays a crucial role in governing apicomplexan motility; yet, the mechanisms underlying Ca2+ mobilization from intracellular stores in these parasites remain unclear. In Plasmodium, the necessity of ICM1 for Ca2+ mobilization raises the question of whether this mechanism is conserved in other apicomplexans. Investigation into the orthologs of Plasmodium ICM1 in T. gondii revealed a differing requirement for ICM proteins between the two parasites. This study suggests that T. gondii employs ICM-independent mechanisms to regulate Ca2+ homeostasis and mobilization. Proteins involved in Ca2+ signaling in apicomplexans represent promising targets for therapeutic development.
    Keywords:  Apicomplexa; Plasmodium; Toxoplasma; Toxoplasma gondii; apicomplexan; cAMP; cGMP; calcium; calcium flux; calcium signaling; cyclic GMP; motility
    DOI:  https://doi.org/10.1128/spectrum.01229-24
  2. mBio. 2024 Aug 20. e0205124
    Protein disulfide isomerase PDI8 is indispensable for parasite growth and associated with secretory protein processing in Toxoplasma gondii.
    Chaoyue Wang, Pei Sun, Yonggen Jia, Xinming Tang, Xianyong Liu, Xun Suo, Hongjuan Peng.
      Protein disulfide isomerase, containing thioredoxin (Trx) domains, serves as a vital enzyme responsible for oxidative protein folding (the formation, reduction, and isomerization of disulfide bonds in newly synthesized proteins) in the endoplasmic reticulum (ER). However, the role of ER-localized PDI proteins in parasite growth and their interaction with secretory proteins remain poorly understood. In this study, we identified two ER-localized PDI proteins, TgPDI8 and TgPDI6, in Toxoplasma gondii. Conditional knockdown of TgPDI8 resulted in a significant reduction in intracellular proliferation and invasion abilities, leading to a complete block in plaque formation on human foreskin fibroblast monolayers, whereas parasites lacking TgPDI6 did not exhibit any apparent fitness defects. The complementation of TgPDI8 with mutant variants highlighted the critical role of the CXXC active site cysteines within its Trx domains for its enzymatic activity. By utilizing TurboID-based proximity labeling, we uncovered a close association between PDI proteins and canonical secretory proteins. Furthermore, parasites lacking TgPDI8 showed a significant reduction in the expression of secretory proteins, especially those from micronemes and dense granules. In summary, our study elucidates the roles of TgPDI8 and sets the stage for future drug discovery studies.
    IMPORTANCE: Apicomplexans, a phylum of intracellular parasites, encompass various zoonotic pathogens, including Plasmodium, Cryptosporidium, Toxoplasma, and Babesia, causing a significant economic burden on human populations. These parasites exhibit hypersensitivity to disruptions in endoplasmic reticulum (ER) redox homeostasis, necessitating the presence of ER-localized thioredoxin (Trx) superfamily proteins, particularly protein disulfide isomerase (PDI), for proper oxidative folding. However, the functional characteristics of ER-localized PDI proteins in Toxoplasma gondii remain largely unexplored. In this study, we identified two ER-localized proteins, namely, TgPDI8 and TgPDI6, and demonstrated the indispensable role of TgPDI8 in parasite survival. Through a comprehensive multi-omics analysis, we elucidated the crucial role of TgPDI8 in the processing of secretory proteins in T. gondii. Additionally, we introduced a novel ER-anchored TurboID method to label and identify canonical secretory proteins in T. gondii. This research opens up new avenues for understanding oxidative folding and the secretory pathway in apicomplexan parasites, laying the groundwork for future advancements in antiparasitic drug development.
    Keywords:  Toxoplasma gondii; invasion; protein disulfide isomerase; protein processing; secretory protein
    DOI:  https://doi.org/10.1128/mbio.02051-24
  3. Trends Parasitol. 2024 Aug 20. pii: S1471-4922(24)00201-0. [Epub ahead of print]
    Decoding Toxoplasma gondii virulence: the mechanisms of IRG protein inactivation.
    Mateo Murillo-Léon, Aura María Bastidas-Quintero, Tobias Steinfeldt.
      Toxoplasmosis is a common parasitic zoonosis that can be life-threatening in immunocompromised patients. About one-third of the human population is infected with Toxoplasma gondii. Primary infection triggers an innate immune response wherein IFN-γ-induced host cell GTPases, namely IRG and GBP proteins, serve as a vital component for host cell resistance. In the past decades, interest in elucidating the function of these GTPase families in controlling various intracellular pathogens has emerged. Numerous T. gondii effectors were identified to inactivate particular IRG proteins. T. gondii is re-optimizing its effectors to combat IRG function and in this way secures transmission. We discuss the IRG-specific effectors employed by the parasite in murine infections, contributing to a better understanding of T. gondii virulence.
    Keywords:  Guanylate Binding Proteins; Immunity-Related GTPases; Toxoplasma gondii; parasite effectors
    DOI:  https://doi.org/10.1016/j.pt.2024.07.009
  4. Microbiol Spectr. 2024 Aug 20. e0066124
    Calcium-binding protein TgpCaBP regulates calcium storage of the zoonotic parasite Toxoplasma gondii.
    Weisong Sun, Ning Jiang, Qilong Li, Yize Liu, Yiwei Zhang, Ran Chen, Ying Feng, Xiaoyu Sang, Shaojun Long, Qijun Chen.
      Toxoplasma gondii, the causative parasite of toxoplasmosis, is an apicomplexan parasite that infects warm-blooded mammals. The ability of the calcium-binding proteins (CBPs) to transport large amounts of Ca2+ appears to be critical for the biological activity of T. gondii. However, the functions of some members of the CBP family have not yet been deciphered. Here, we characterized a putative CBP of T. gondii, TgpCaBP (TGME49_229480), which is composed of four EF-hand motifs with Ca2+-binding capability. TgpCaBP was localized in the cytosol and ER of T. gondii, and parasites lacking the TgpCaBP gene exhibited diminished abilities in cell invasion, intracellular growth, egress, and motility. These phenomena were due to the abnormalities in intracellular Ca2+ efflux and ER Ca2+ storage, and the reduction in motility was associated with a decrease in the discharge of secretory proteins. Therefore, we propose that TgpCaBP is a Ca2+ transporter and signaling molecule involved in Ca2+ regulation and parasitization in the hosts.IMPORTANCECa2+ signaling is essential in the development of T. gondii. In this study, we identified a calcium-binding protein in T. gondii, named TgpCaBP, which actively regulates intracellular Ca2+ levels in the parasite. Deletion of the gene coding for TgpCaBP caused serious deficits in the parasite's ability to maintain a stable intracellular calcium environment, which also impaired the secretory protein discharged from the parasite, and its capacity of gliding motility, cell invasion, intracellular growth, and egress from host cells. In summary, we have identified a novel calcium-binding protein, TgpCaBP, in the zoonotic parasite T. gondii, which is a potential therapeutic target for toxoplasmosis.
    Keywords:  Ca2+ signaling; TgpCaBP; Toxoplasma gondii; calcium binding; parasite biology
    DOI:  https://doi.org/10.1128/spectrum.00661-24
  5. Vector Borne Zoonotic Dis. 2024 Aug 20.
    Antiparasitic Effects of Niosomal Formulations of Curcumin and Silymarin Against Toxoplasma gondii In Vitro.
    Hiba Riyadh Al-Abodi.
      Background: Toxoplasmosis is caused by infection with Toxoplasma gondii. No Symptoms in healthy people. Notably, very dangerous symptoms in immunocompromised, or patients with immune diseases. Previous research has shown that the parasite's resistance to drugs continues to emerge and has indicated this resistance as a cause for concern. In this context, researchers have a great responsibility to search for alternative treatments, as well as to develop existing ones. Essentially, this improves the therapeutic efficacy of drugs and prevents the emergence of resistance to them. The present study aims to evaluate antitoxoplasma effects of niosomal loaded curcumin and silymarin and their synergistic effects with clindamycin against T. gondii RH strain in vitro. Materials and Methods: Experiments were conducted on the tachyzoites of T. gondii RH-strain, based on: the free and nieosomal compounds of curcumin and silymarin, in addition to the drug clindamycin. Data were collected to estimate parasite viability during exposure to the therapeutic compounds under study using a special MTT assay ((3-(4, 5-dimethylthiazolyl-2)-2,5-diphenyltetrazolioum bromide) assay: is a colorimetric assay for measuring cellular growth) kit provided by (Bio Idea Company, Tehran, Iran). Hence, the effect of the therapeutic compounds on the parasite load was studied using the quantitative molecular technique real-time PCR. Results: The results indicate that the combination of N-silymarin and N-curcumin with clindamycin has active synergistic effects against T. gondii leading to complete elimination of the parasite. Data revealed that curcumin and silymarin in both their free and nisomal forms had inhibitory effects on the parasite, and minimal toxic effects on normal cells. Conclusions: The results highlight the successful synergistic effect of clindamycin and the niosomal compounds curcumin and silymarin in completely eradicating the T. gondii RH-strain. This finding contributes positively to the field of safe and effective treatments.
    Keywords:  Silymarin; Toxoplasma gondii; antiparasitic drugs; curcumin; niosomal formulations
    DOI:  https://doi.org/10.1089/vbz.2024.0044
  6. J Vet Med Sci. 2024 Aug 16.
    Diversity of genes encoding immune-related GTPase B2 protein, an inherited element responsible for resistance against virulent Toxoplasma gondii strains, among wild Mus musculus in local area of Japan.
    Nikolai D Shamaev, Tatiana Batanova, Yuki Iwatake, Junji Moribe, Hisako Kyan, Tatsunori Masatani, Yuko Kitamura, Keisuke Nakagawa, Taizo Saito, Yasuhiro Takashima.
      The major genetic group of Toxoplasma gondii, known as type I, generally displays high lethality in laboratory Mus musculus (mouse) strains, with few exceptions. However, because rodents are the primary reservoir hosts for T. gondii, if this characteristic manifests in the wild, type I strains would be extinct. Therefore, we hypothesized that populations of wild rodents capable of harboring type I T. gondii asymptomatically exist globally and are not limited to a few localized areas, as previously thought. The strength of mouse resistance to T. gondii is known to depend on the affinity of the mouse-expressed immunity-related GTPases B2 (IRGB2) protein for the T. gondii-expressed rphoptry protein 5B (ROP5B) protein. Therefore, the Irgb2 gene sequences of 12 individuals mice captured at two animal farms in Gifu Prefecture, and on an island in Okinawa Prefecture, Japan were determined, and subjected to a molecular phylogenetic analysis together with those of various mouse strains worldwide. The Irgb2 gene of M. musculus individuals captured on one farm and one island showed diverse sequences. The sequences from two individual mice captured in an animal farm formed a single clade with a wild mouse derived CAST/EiJ strain, known for its exceptional resistance to type I T. gondii lethality. These results suggest that M. musuculus individuals resistant to the Type I T. gondii strain may be present in Japan, in addition to the previously known populations in South Asia, Thailand and India.
    Keywords:  Mus musculus; Toxoplasma gondii; immunity-related GTPases B2 protein
    DOI:  https://doi.org/10.1292/jvms.24-0059
  7. Biochim Biophys Acta Mol Cell Res. 2024 Aug 19. pii: S0167-4889(24)00167-8. [Epub ahead of print] 119824
    Proteostasis is a key driver of the pathogenesis in Apicomplexa.
    Pallabi Mitra, Abhijit S Deshmukh.
      Proteostasis, including protein folding mediated by molecular chaperones, protein degradation, and stress response pathways in organelles like ER (unfolded protein response: UPR), are responsible for cellular protein quality control. This is essential for cell survival as it regulates and reprograms cellular processes. Here, we underscore the role of the proteostasis pathway in Apicomplexan parasites with respect to their well-characterized roles as well as potential roles in many parasite functions, including survival, multiplication, persistence, and emerging drug resistance. In addition to the diverse physiological importance of proteostasis in Apicomplexa, we assess the potential of the pathway's components as chemotherapeutic targets.
    Keywords:  Apicomplexa; Chaperones; ER stress; Heat shock response (HSR); Plasmodium; Proteasome; Proteostasis; Toxoplasma; UPR; UPS
    DOI:  https://doi.org/10.1016/j.bbamcr.2024.119824
  8. Semin Cancer Biol. 2024 Aug 14. pii: S1044-579X(24)00059-2. [Epub ahead of print]
    Nutrient Sensing of mTORC1 signaling in cancer and aging.
    Cong Jiang, Xiao Tan, Ning Liu, Peiqiang Yan, Tao Hou, Wenyi Wei.
      The mechanistic target of rapamycin complex 1 (mTORC1) is indispensable for preserving cellular and organismal homeostasis by balancing the anabolic and catabolic processes in response to various environmental cues, such as nutrients, growth factors, energy status, oxygen levels, and stress. Dysregulation of mTORC1 signaling is associated with the progression of many types of human disorders including cancer, age-related diseases, neurodegenerative disorders, and metabolic diseases. The way mTORC1 senses various upstream signals and converts them into specific downstream responses remains a crucial question with significant impacts for our perception of the related physiological and pathological process. In this review, we discuss the recent molecular and functional insights into the nutrient sensing of the mTORC1 signaling pathway, along with the emerging role of deregulating nutrient-mTORC1 signaling in cancer and age-related disorders.
    Keywords:  amino acid; kinase; mTOR; mTORC1; mTORC2; nutrient sensing; phosphorylation; tumorigenesis
    DOI:  https://doi.org/10.1016/j.semcancer.2024.08.001
  9. Cancer Biol Ther. 2024 Dec 31. 25(1): 2392902
    The anticancer mechanisms of Toxoplasma gondii rhoptry protein 16 on lung adenocarcinoma cells.
    Guangqi Li, Qinhui Li, Yongqing Tong, Jin Zeng, Tiantian Dang, Ningai Yang, Yuning Zhou, Lei Ma, Qirui Ge, Zhijun Zhao.
      Lung adenocarcinoma is the most prevalent subtype of lung cancer, which is the leading cause of cancer-related mortality worldwide. Toxoplasma gondii (T.gondii) Rhoptry protein 16 (ROP16) has been shown to quickly enter the nucleus, and through activate host cell signaling pathways by phosphorylation STAT3 and may affect the survival of tumor cells. This study constructed recombinant lentiviral expression vector of T. gondii ROP16 I/II/III and stably transfected them into A549 cells, and the effects of ROP16 on cell proliferation, cell cycle, apoptosis, invasion, and migration of A549 cells were explored by utilizing CCK-8, flow cytometry, qPCR, Western blotting, TUNEL, Transwell assay, and cell scratch assay, and these effects were confirmed in the primary human lung adenocarcinoma cells from postoperative cancer tissues of patients. The type I and III ROP16 activate STAT3 and inhibited A549 cell proliferation, regulated the expression of p21, CDK6, CyclinD1, and induced cell cycle arrest at the G1 phase. ROP16 also regulated the Bax, Bcl-2, p53, cleaved-Caspase3, and Caspase9, inducing cell apoptosis, and reduced the invasion and migration of A549 cells, while type II ROP16 protein had no such effect. Furthermore, in the regulation of ROP16 on primary lung adenocarcinoma cells, type I and III ROP16 showed the same anticancer potential. These findings confirmed the anti-lung adenocarcinoma effect of type I and III ROP16, offering fresh perspectives on the possible application of ROP16 as a target with adjuvant therapy for lung adenocarcinoma and propelling the field of precision therapy research toward parasite treatment of tumors.
    Keywords:  A549; ROP16; STAT3; Toxoplasma gondii; cell phenotype; lung cancer
    DOI:  https://doi.org/10.1080/15384047.2024.2392902
  10. Acta Parasitol. 2024 Aug 19.
    miRNA, New Perspective to World of Intestinal Protozoa and Toxoplasma.
    Faezeh Hamidi, Niloofar Taghipour.
       BACKGROUND: miRNAs are known as non-coding RNAs that can regulate gene expression. They are reported in many microorganisms and their host cells. Parasite infection can change or shift host miRNAs expression, which can aim at both parasite eradication and infection.
    PURPOSE: This study dealt with examination of miRNA expressed in intestinal protozoan, coccidia , as well as profile changes in host cell miRNA after parasitic infection and their role in protozoan clearance/ survival.
    METHODS: The authors searched ISI Web of Sciences, Pubmed, Scholar, Scopus, another databases and articles published up to 2024 were included. The keywords of miRNA, intestinal protozoa, toxoplasma and some words associated with topics were used in this search.
    RESULTS: Transfection of miRNA mimics or inhibitors can control parasitic diseases, and be introduced as a new therapeutic option in parasitology.
    CONCLUSION: This review can be used to provide up-to date knowledge for future research on these issues.
    Keywords:   Toxoplasma ; Intestinal Protozoan; Survival; Therapeutic; miRNA
    DOI:  https://doi.org/10.1007/s11686-024-00888-x
  11. J Biochem Mol Toxicol. 2024 Sep;38(9): e23812
    The influential responsibility of sirtuins in senescence and associated diseases: A review.
    Deepak Mishra, Lucy Mohapatra, Alok S Tripathi, Shravan Kumar Paswan.
      Aging is a process of time-associated depletion in the physiological functions, essential for the survival and reproducibility of living beings. Some age-related disorders can be successfully controlled with some biomedical techniques or pharmaceutical approaches. There are some precise remedies that demonstrate conspicuous promise in the preclinical and clinical setup of extending lifespan or enhancing health by altering natural senescence. The sirtuin family of proteins is one of the most favorable targets for antiaging strategies. Sirtuins were initially identified as transcription repressors in yeast, but today they are known to exist in bacteria and eukaryotes, as well as humans. The SIRT (1-7) family of proteins in humans is made up of seven members, each of which has either mono-ADP ribosyl transferase or deacetylase activity. Researchers suggest that sirtuins are essential for cell metabolism and play a major role in how cells react to various stimuli, such as oxidative or genotoxic stress. A healthy lifestyle, which includes exercise and a balanced diet, has been demonstrated to impact health span by adjusting the levels of sirtuins, suggesting the involvement of sirtuins in extending human longevity. The hunt for sirtuin activators is among the most extensive and comprehensive research subjects in the present scenario. Some optimism has been generated to investigate antiaging therapies by natural compounds, such as curcumin and others. This review article highlights the role of sirtuins in native senescence and their primordial roles in the progression of several life-threatening diseases. Further, it also provides recent information on the sirtuin activators and inhibitors and their therapeutic benefits.
    Keywords:  SIRT‐inhibitors; SIRT‐promoters; cancer; diabetes; neurodegeneration; obesity; senescence; sirtuins
    DOI:  https://doi.org/10.1002/jbt.23812
  12. Biol Psychiatry. 2024 Sep 15. pii: S0006-3223(24)01454-9. [Epub ahead of print]96(6): e7-e9
    Epigenetic Regulation of Neural Activity in the Depressed Brain: The Two Faces of the Histone Deacetylase SIRT1.
    Angélica Torres-Berrío.
      
    DOI:  https://doi.org/10.1016/j.biopsych.2024.07.006
  13. Proc Natl Acad Sci U S A. 2024 Aug 27. 121(35): e2322755121
    Rag-Ragulator is the central organizer of the physical architecture of the mTORC1 nutrient-sensing pathway.
    Max L Valenstein, Pranav V Lalgudi, Xin Gu, Jibril F Kedir, Martin S Taylor, Raghu R Chivukula, David M Sabatini.
      The mechanistic target of rapamycin complex 1 (mTORC1) pathway regulates cell growth and metabolism in response to many environmental cues, including nutrients. Amino acids signal to mTORC1 by modulating the guanine nucleotide loading states of the heterodimeric Rag GTPases, which bind and recruit mTORC1 to the lysosomal surface, its site of activation. The Rag GTPases are tethered to the lysosome by the Ragulator complex and regulated by the GATOR1, GATOR2, and KICSTOR multiprotein complexes that localize to the lysosomal surface through an unknown mechanism(s). Here, we show that mTORC1 is completely insensitive to amino acids in cells lacking the Rag GTPases or the Ragulator component p18. Moreover, not only are the Rag GTPases and Ragulator required for amino acids to regulate mTORC1, they are also essential for the lysosomal recruitment of the GATOR1, GATOR2, and KICSTOR complexes, which stably associate and traffic to the lysosome as the "GATOR" supercomplex. The nucleotide state of RagA/B controls the lysosomal association of GATOR, in a fashion competitively antagonized by the N terminus of the amino acid transporter SLC38A9. Targeting of Ragulator to the surface of mitochondria is sufficient to relocalize the Rags and GATOR to this organelle, but not to enable the nutrient-regulated recruitment of mTORC1 to mitochondria. Thus, our results reveal that the Rag-Ragulator complex is the central organizer of the physical architecture of the mTORC1 nutrient-sensing pathway and underscore that mTORC1 activation requires signal transduction on the lysosomal surface.
    Keywords:  biochemistry; mTOR signaling; nutrient sensing
    DOI:  https://doi.org/10.1073/pnas.2322755121
  14. Int J Parasitol Drugs Drug Resist. 2024 Aug 14. pii: S2211-3207(24)00044-7. [Epub ahead of print]26 100563
    The phosphatase inhibitor BVT-948 can be used to efficiently screen functional sexual development proteins in the malaria parasite Plasmodium berghei.
    Xitong Jia, Yong Wang, Meilian Wang, Hui Min, Zehou Fang, Haifeng Lu, Jiao Li, Yaming Cao, Lunhao Bai, Jinghan Lu.
       BACKGROUND: Studying and discovering the molecular mechanism of Plasmodium sexual development is crucial for the development of transmission blocking drugs and malaria eradication. The aim of this study was to investigate the feasibility of using phosphatase inhibitors as a tool for screening proteins essential for Plasmodium sexual development and to discover proteins affecting the sexual development of malaria parasites.
    METHODS: Differences in protein phosphorylation among Plasmodium gametocytes incubated with BVT-948 under in vitro ookinete culture conditions were evaluated using phosphoproteomic methods. Gene Ontology (GO) analysis was performed to predict the mechanism by which BVT-948 affected gametocyte-ookinete conversion. The functions of 8 putative proteins involved in Plasmodium berghei sexual development were evaluated. Bioinformatic analysis was used to evaluate the possible mechanism of PBANKA_0100800 in gametogenesis and subsequent sexual development.
    RESULTS: The phosphorylation levels of 265 proteins decreased while those of 67 increased after treatment with BVT-948. Seven of the 8 genes selected for phenotype screening play roles in P. berghei sexual development, and 4 of these were associated with gametocytogenesis. PBANKA_0100800 plays essential roles in gametocyte-ookinete conversion and transmission to mosquitoes.
    CONCLUSIONS: Seven proteins identified by screening affect P. berghei sexual development, suggesting that phosphatase inhibitors can be used for functional protein screening.
    Keywords:  Malaria; Phosphatase inhibitor; Plasmodium berghei; Transmission
    DOI:  https://doi.org/10.1016/j.ijpddr.2024.100563
  15. Int J Biol Macromol. 2024 Aug 18. pii: S0141-8130(24)05658-7. [Epub ahead of print] 134853
    Role of sirtuins in sepsis and sepsis-induced organ dysfunction: A review.
    Xin-Ru Yang, Ri Wen, Ni Yang, Tie-Ning Zhang.
      Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Sepsis causes a high mortality rate and current treatment focuses on supportive therapies but lacks specific therapeutic targets. Notably, sirtuins (SIRTs) shows potential clinical application in the treatment of sepsis. It has been demonstrated that SIRTs, the nicotinamide adenine dinucleotide+(NAD+)-dependent deacetylases that regulate key signaling pathways in eukaryotes and prokaryotes, are involved in a variety of biological processes. To date, seven mammalian yeast Sir2 homologs have been identified. SIRTs can regulate inflammation, oxidative stress, apoptosis, autophagy, and other pathways that play important roles in sepsis-induced organ dysfunction. However, the existing studies on SIRTs in sepsis are too scattered, and there is no relevant literature to integrate them. This review innovatively summarizes the different mechanisms of SIRTs in sepsis organ dysfunction according to the different systems, and focuses on SIRT agonists, inhibitors, and targeted drugs that have been proved to be effective in the treatment of sepsis, so as to integrate the clinical research and basic research closely. We searched PubMed for all literature related to SIRTs and sepsis since its inception using the following medical subject headings: sirtuins, SIRTs, and sepsis. Data on the mechanisms of SIRTs in sepsis-induced organ damage and their potential as targets for disease treatment were extracted.
    Keywords:  Agonists; Inhibitors; Organ dysfunction; Post-translational modifications; Sepsis; Sirtuins
    DOI:  https://doi.org/10.1016/j.ijbiomac.2024.134853
  16. Mol Biochem Parasitol. 2024 Aug 14. pii: S0166-6851(24)00043-4. [Epub ahead of print] 111650
    THE GENETICALLY ENCODED CALCIUM INDICATOR GCAMP3 REVEALS SPONTANEOUS CALCIUM OSCILLATIONS AT ASEXUAL STAGES OF THE HUMAN MALARIA PARASITE PLASMODIUM FALCIPARUM.
    Benedito M Dos Santos, Mateus F Pecenin, Lucas Borges-Pereira, Eric Springer, Jude M Przyborski, David C Martins-Jr, Ronaldo F Hashimoto, Célia R S Garcia.
      Most protocols used to study the dynamics of calcium (Ca2+) in the malaria parasite are based on dyes, which are invasive and do not allow discrimination between the signal from the host cell and the parasite. To avoid this pitfall, we have generated a parasite line expressing the genetically encoded calcium sensor GCaMP3. The PfGCaMP3 parasite line is an innovative tool for studying spontaneous intracellular Ca2+ oscillations without external markers. Using this parasite line, we demonstrate the occurrence of spontaneous Ca2+ oscillations in the ring, trophozoite, and schizont stages in Plasmodium falciparum. Using the Fourier transform to fluorescence intensity data extracted from different experiments, we observe cytosolic Ca2+ fluctuations. These spontaneous cytosolic Ca2+ oscillations occur in the three intraerythrocytic stages of the parasite, with most oscillations occurring in the ring and trophozoite stages. A control parasite line expressing only a GFP control did not reveal such fluctuations, demonstrating the specificity of the observations. Our results clearly show dynamic, spontaneous Ca2+ oscillations during the asexual stage in P. falciparum, independent from external stimuli.
    Keywords:  Calcium (Ca (2+)); Calcium indicator; Malaria; PfGCaMP3; Plasmodium falciparum; Spontaneous oscillations
    DOI:  https://doi.org/10.1016/j.molbiopara.2024.111650
  17. Clin Epigenetics. 2024 Aug 18. 16(1): 109
    HDAC6 inhibition disrupts HDAC6-P300 interaction reshaping the cancer chromatin landscape.
    Michela Gottardi Zamperla, Barbara Illi, Veronica Barbi, Chiara Cencioni, Daniele Santoni, Stella Gagliardi, Maria Garofalo, Gabriele Antonio Zingale, Irene Pandino, Diego Sbardella, Lina Cipolla, Simone Sabbioneda, Antonella Farsetti, Chiara Ripamonti, Gianluca Fossati, Christian Steinkühler, Carlo Gaetano, Sandra Atlante.
       BACKGROUND: Histone deacetylases (HDACs) are crucial regulators of gene expression, DNA synthesis, and cellular processes, making them essential targets in cancer research. HDAC6, specifically, influences protein stability and chromatin dynamics. Despite HDAC6's potential therapeutic value, its exact role in gene regulation and chromatin remodeling needs further clarification. This study examines how HDAC6 inactivation influences lysine acetyltransferase P300 stabilization and subsequent effects on chromatin structure and function in cancer cells.
    METHODS AND RESULTS: We employed the HDAC6 inhibitor ITF3756, siRNA, or CRISPR/Cas9 gene editing to inactivate HDAC6 in different epigenomic backgrounds. Constantly, this inactivation led to significant changes in chromatin accessibility, particularly increased acetylation of histone H3 lysines 9, 14, and 27 (ATAC-seq and H3K27Ac ChIP-seq analysis). Transcriptomics, proteomics, and gene ontology analysis revealed gene changes in cell proliferation, adhesion, migration, and apoptosis. Significantly, HDAC6 inactivation altered P300 ubiquitination, stabilizing P300 and leading to downregulating genes critical for cancer cell survival.
    CONCLUSIONS: Our study highlights the substantial impact of HDAC6 inactivation on the chromatin landscape of cancer cells and suggests a role for P300 in contributing to the anticancer effects. The stabilization of P300 with HDAC6 inhibition proposes a potential shift in therapeutic focus from HDAC6 itself to its interaction with P300. This finding opens new avenues for developing targeted cancer therapies, improving our understanding of epigenetic mechanisms in cancer cells.
    Keywords:  Apoptosis; Cancer; Cell cycle; Deacetylase inhibitors; HAT; HDAC; Histone acetylation; Proliferation; Tumorigenesis
    DOI:  https://doi.org/10.1186/s13148-024-01725-8
  18. Sci Rep. 2024 08 20. 14(1): 19392
    NMN partially rescues cuproptosis by upregulating sirt2 to increase intracellular NADPH.
    Yingying Zhang, Shuting Qiu, Shihan Shao, Yuejia Cao, Yu Hong, Xianrong Xu, Xuexian Fang, Chunhong Di, Jun Yang, Xiaohua Tan.
      Cuproptosis is characterized by lipoylated protein aggregation and loss of iron-sulfur (Fe-S) proteins, which are crucial for a wide range of important cellular functions, including DNA replication and damage repair. Sirt2 and sirt4 are lipoamidases that remove the lipoyl moiety from lipoylated proteins using nicotinamide adenine dinucleotide (NAD+) as a cofactor. However, to date, it is not clear whether nicotinamide mononucleotide (NMN), a precursor of NAD+, affects cellular sensitivity to cuproptosis. Therefore, in the current study, cuproptosis was induced by the copper (Cu) ionophore elesclomol (Es) in HeLa cells. It was also found that Es/Cu treatment increased cellular DNA damage level. On the other hand, NMN treatment partially rescued cuproptosis in a dose-dependent manner, as well as reduced cellular DNA damage level. In addition, NMN upregulated the expression of Fe-S protein POLD1, without affecting the aggregation of lipoylated proteins. Mechanistic study revealed that NMN increased the expression of sirt2 and cellular reduced nicotinamide adenine dinucleotide phosphate (NADPH) level. Overexpression of sirt2 and sirt4 did not change the aggregation of lipoylated proteins, however, sirt2, but not sirt4, increased cellular NADPH levels and partially rescued cuproptosis. Inhibition of NAD+ kinase (NADK), which is responsible for generating NADPH, abolished the rescuing function of NMN and sirt2 for Es/Cu induced cell death. Taken together, our results suggested that DNA damage is a characteristic feature of cuproptosis. NMN can partially rescue cuproptosis by upregulating sirt2, increase intracellular NADPH content and maintain the level of Fe-S proteins, independent of the lipoamidase activity of sirt2.
    Keywords:  Cuproptosis; DNA damage response; NADPH; Nicotinamide mononucleotide; sirt2
    DOI:  https://doi.org/10.1038/s41598-024-70245-5
  19. Front Cell Neurosci. 2024 ;18 1434459
    The role of SIRT3 in homeostasis and cellular health.
    Dennison Trinh, Lina Al Halabi, Harsimar Brar, Marie Kametani, Joanne E Nash.
      Mitochondria are responsible for maintaining cellular energy levels, and play a major role in regulating homeostasis, which ensures physiological function from the molecular to whole animal. Sirtuin 3 (SIRT3) is the major protein deacetylase of mitochondria. SIRT3 serves as a nutrient sensor; under conditions of mild metabolic stress, SIRT3 activity is increased. Within the mitochondria, SIRT3 regulates every complex of the electron transport chain, the tricarboxylic acid (TCA) and urea cycles, as well as the mitochondria membrane potential, and other free radical scavengers. This article reviews the role of SIRT3 in regulating homeostasis, and thus physiological function. We discuss the role of SIRT3 in regulating reactive oxygen species (ROS), ATP, immunological function and mitochondria dynamics.
    Keywords:  SIRT3; allostasis; homeostasis; immune response; metabolism; mitochondria; oxidative stress; proteostasis
    DOI:  https://doi.org/10.3389/fncel.2024.1434459
  20. Parasit Vectors. 2024 Aug 21. 17(1): 352
    Optimization of a DiCre recombinase system with reduced leakage for conditional genome editing of Cryptosporidium.
    Yue Huang, Jinli Li, Shifeng Pei, Heng You, Huimin Liu, Yaqiong Guo, Rui Xu, Na Li, Yaoyu Feng, Lihua Xiao.
       BACKGROUND: The dimerizable Cre recombinase system (DiCre) exhibits increased leaky activity in Cryptosporidium, leading to unintended gene editing in the absence of induction. Therefore, optimization of the current DiCre technique is necessary for functional studies of essential Cryptosporidium genes.
    METHODS: Based on the results of transcriptomic analysis of Cryptosporidium parvum stages, seven promoters with different transcriptional capabilities were screened to drive the expression of Cre fragments (FKBP-Cre59 and FRB-Cre60). Transient transfection was performed to assess the effect of promoter strength on leakage activity. In vitro and in vivo experiments were performed to evaluate the leaky activity and cleavage efficiency of the optimized DiCre system by polymerase chain reaction (PCR), nanoluciferase, and fluorescence analyses.
    RESULTS: The use of promoters with lower transcriptional activity, such as pcgd6_4110 and pcgd3_260, as opposed to strong promoters such as pActin, pα-Tubulin, and pEnolase, reduced the leakage rate of the system from 35-75% to nearly undetectable levels, as verified by transient transfection. Subsequent in vitro and in vivo experiments using stable lines further demonstrated that the optimized DiCre system had no detectable leaky activity. The system achieved 71% cleavage efficiency in vitro. In mice, a single dose of the inducer resulted in a 10% conditional gene knockout and fluorescent protein expression in oocysts. These fluorescently tagged transgenic oocysts could be enriched by flow sorting for further infection studies.
    CONCLUSIONS: A DiCre conditional gene knockout system for Cryptosporidium with good cleavage efficiency and reduced leaky activity has been successfully established.
    Keywords:   Cryptosporidium ; Conditional gene knockout; DiCre; Leaky activity; Promoter
    DOI:  https://doi.org/10.1186/s13071-024-06431-1
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