bims-toxgon Biomed News
on Toxoplasma gondii metabolism
Issue of 2022–09–18
sixteen papers selected by
Lakesh Kumar, BITS Pilani
  1. Conoid extrusion regulates glideosome assembly to control motility and invasion in Apicomplexa.
  2. Association between Toxoplasma gondii and systemic lupus erythematosus: A systematic review and meta-analysis.
  3. Modulation of autophagy as a therapeutic strategy for Toxoplasma gondii infection.
  4. Apicoplast biogenesis mediated by ATG8 requires the ATG12-ATG5-ATG16L and SNAP29 complexes in Toxoplasma gondii.
  5. Detection of antibodies against toxoplasma from human serum sample using Elisa.
  6. An Overview of DNA Vaccines Development Studies Against Toxoplasma gondii
  7. Shared pathobiology identifies AMPK as a therapeutic target for obesity and autosomal dominant polycystic kidney disease.
  8. Beyond splicing: serine-arginine proteins as emerging multifaceted regulators of RNA metabolism in malaria parasites.
  9. cAMP-Protein Kinase A and Stress-Activated MAP Kinase signaling mediate transcriptional control of autophagy in fission yeast during glucose limitation or starvation.
  10. Global proteomic profiling of multiple organs of cats (Felis catus) and proteome-transcriptome correlation during acute Toxoplasma gondii infection.
  11. A Coccidia-Specific Phosphate Transporter Is Essential for the Growth of Toxoplasma gondii Parasites.
  12. Metabolomics reveals mouse plasma metabolite responses to acute exercise and effects of disrupting AMPK-glycogen interactions.
  13. AMPK and Diseases: State of the Art Regulation by AMPK-Targeting Molecules.
  14. Engineered kinases as a tool for phosphorylation of selected targets in vivo.
  15. An AMPK phosphoregulated RhoGEF feedback loop tunes cortical flow-driven amoeboid migration in vivo.
  16. ULK1 inhibition attenuates telomerase activity in hepatic cells.
  1. Nat Microbiol. 2022 Sep 15.
    Conoid extrusion regulates glideosome assembly to control motility and invasion in Apicomplexa.
    Nicolas Dos Santos Pacheco, Lorenzo Brusini, Romuald Haase, Nicolò Tosetti, Bohumil Maco, Mathieu Brochet, Oscar Vadas, Dominique Soldati-Favre.
      Members of Apicomplexa are defined by apical cytoskeletal structures and secretory organelles, tailored for motility, invasion and egress. Gliding is powered by actomyosin-dependent rearward translocation of apically secreted transmembrane adhesins. In the human parasite Toxoplasma gondii, the conoid, composed of tubulin fibres and preconoidal rings (PCRs), is a dynamic organelle of undefined function. Here, using ultrastructure expansion microscopy, we established that PCRs serve as a hub for glideosome components including Formin1. We also identified components of the PCRs conserved in Apicomplexa, Pcr4 and Pcr5, that contain B-box zinc-finger domains, assemble in heterodimer and are essential for the formation of the structure. The fitness conferring Pcr6 tethers the PCRs to the cone of tubulin fibres. F-actin produced by Formin1 is used by Myosin H to generate the force for conoid extrusion which directs the flux of F-actin to the pellicular space, serving as gatekeeper to control parasite motility.
    DOI:  https://doi.org/10.1038/s41564-022-01212-x
  2. J Transl Autoimmun. 2022 ;5 100163
    Association between Toxoplasma gondii and systemic lupus erythematosus: A systematic review and meta-analysis.
    Pierce Bassett, Brinley N Zabriskie, Ashley Catchpole, Dawson Hedges.
      Infecting approximately one-third of the world's population, the intraneuronal parasite Toxoplasma gondii has been associated with several autoimmune diseases. While Toxoplasma gondii may be protective against multiple sclerosis, other findings have negatively associated Toxoplasma gondii with different autoimmune diseases, including systemic lupus erythematosus. To further characterize the association between Toxoplasma gondii and systemic lupus erythematosus, we completed a systematic review and meta-analysis of published studies looking at the association between Toxoplasma gondii and systemic lupus erythematosus. The primary results of a random-effects model showed an odds ratio of 2.34 (95% confidence interval 1.17-4.69, P = 0.017), indicating the odds of Toxoplasma gondii seropositivity were 2.34 times higher in the group with systemic lupus erythematosus than in the healthy control group. Few available source studies, an overall lack of information about immunosuppressive status, and little information about sex composition and assays limit this finding and indicate the need for additional research to further characterize the association between systemic lupus erythematosus and Toxoplasma gondii.
    Keywords:  SLE; Toxoplasma gondii; systemic lupus erythematosus; toxoplasmosis
    DOI:  https://doi.org/10.1016/j.jtauto.2022.100163
  3. Front Cell Infect Microbiol. 2022 ;12 902428
    Modulation of autophagy as a therapeutic strategy for Toxoplasma gondii infection.
    Ao Cheng, Huanan Zhang, Baike Chen, Shengyao Zheng, Hongyi Wang, Yijia Shi, Siyao You, Ming Li, Liping Jiang.
      Toxoplasma gondii infection is a severe health threat that endangers billions of people worldwide. T. gondii utilizes the host cell membrane to form a parasitophorous vacuole (PV), thereby fully isolating itself from the host cell cytoplasm and making intracellular clearance difficult. PV can be targeted and destroyed by autophagy. Autophagic targeting results in T. gondii killing via the fusion of autophagosomes and lysosomes. However, T. gondii has developed many strategies to suppress autophagic targeting. Accordingly, the interplay between host cell autophagy and T. gondii is an emerging area with important practical implications. By promoting the canonical autophagy pathway or attenuating the suppression of autophagic targeting, autophagy can be effectively utilized in the development of novel therapeutic strategies against T gondii. Here, we have illustrated the complex interplay between host cell mediated autophagy and T. gondii. Different strategies to promote autophagy in order to target the parasite have been elucidated. Besides, we have analyzed some potential new drug molecules from the DrugBank database using bioinformatics tools, which can modulate autophagy. Various challenges and opportunities focusing autophagy mediated T. gondii clearance have been discussed, which will provide new insights for the development of novel drugs against the parasite.
    Keywords:  AMPK; CD40; IFN-γ; Toxoplasma gondii; autophagy; mTOR
    DOI:  https://doi.org/10.3389/fcimb.2022.902428
  4. Autophagy. 2022 Sep 12.
    Apicoplast biogenesis mediated by ATG8 requires the ATG12-ATG5-ATG16L and SNAP29 complexes in Toxoplasma gondii.
    Jiawen Fu, Lin Zhao, Yu Pang, Heming Chen, Hayashi Yamamoto, Yuntong Chen, Zhaoran Li, Noboru Mizushima, Honglin Jia.
      In apicomplexan parasites, the macroautophagy/autophagy machinery is repurposed to maintain the plastid-like organelle apicoplast. Previously, we showed that in Toxoplasma and Plasmodium, ATG12 interacts with ATG5 in a non-covalent manner, in contrast to the covalent interaction in most organisms. However, it remained unknown whether apicomplexan parasites have functional orthologs of ATG16L1, a protein that is essential for the function of the covalent ATG12-ATG5 complex in vivo in other organisms. Furthermore, the mechanism used by the autophagy machinery to maintain the apicoplast is unclear. We report that the ATG12-ATG5-ATG16L complex exists in Toxoplasma gondii (Tg). This complex is localized on isolated structures at the periphery of the apicoplast dependent on TgATG16L. Inducible depletion of TgATG12, TgATG5, or TgATG16L caused loss of the apicoplast and affected parasite growth. We found that a putative soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) protein, synaptosomal-associated protein 29 (TgSNAP29, Qbc SNARE), is required to maintain the apicoplast in T. gondii. TgSNAP29 depletion disrupted TgATG8 localization at the apicoplast. Additionally, we identified a putative ubiquitin-interacting motif-docking site (UDS) of TgATG8. Mutation of the UDS site abolished TgATG8 localization on the apicoplast but not lipidation. These findings suggest that the TgATG12-TgATG5-TgATG16L complex is required for biogenesis of the apicoplast, in which TgATG8 is translocated to the apicoplast via vesicles in a SNARE -dependent manner in T. gondii.
    Keywords:  Apicoplast; T. gondii; TgATG12–TgATG5-TgATG16L; TgATG8; TgSNAP29; ubiquitin-interacting motif
    DOI:  https://doi.org/10.1080/15548627.2022.2123639
  5. Infect Disord Drug Targets. 2022 Sep 13.
    Detection of antibodies against toxoplasma from human serum sample using Elisa.
    Kirtika Sharma, Saumya Srivastava, Aditya Kundu, Vibhor Tak.
       BACKGROUND: Toxoplasmosis is a common worldwide zoonotic infection affecting warm blooded animals and humans is caused by Toxoplasma gondii. Clinical features range from mildfebrile illness and lymphadenopathy in the immunocompetent host to encephalitisin the immunosuppressed host (E.g. HIV infected patients). Congenital infection can also occur. For effective control andtreatment of toxoplasmosis, accurate detection of T. gondii infection is important.
    OBJECTIVE: In this study, ELISA detecting anti-toxoplasma antibodies IgM and IgG has been used for diagnosing Toxoplasmosis in patients.
    METHODS: Enzyme-linked immunosorbentassay (ELISA) was carried out in serum samples collected from 40 patients to detect anti-toxoplasma IgG and IgM antibodies as a part of work up in suspected cases. Relevant clinical history was also taken.
    RESULT: Of the total 40 samples taken, only one sample came positive for IgM and 9 came positive for IgG antibody. All patients who were seropositivefor T. gondii antibodies had HIV infection. 5 patients were in the age group between 30 to 40 years.
    CONCLUSION: From the limited data available in this study, it may be recommended to screen for T. gondii antibodies in HIV patients.
    Keywords:  ELISA; HIV; IgG; IgM; Toxoplasma gondii; Toxoplasmosis
    DOI:  https://doi.org/10.2174/1871526522666220913152447
  6. Turkiye Parazitol Derg. 2022 09 12. 46(3): 253-270
    An Overview of DNA Vaccines Development Studies Against Toxoplasma gondii
    Ceren Gül, Tuğba Karakavuk, Muhammet Karakavuk, Hüseyin Can, Aysu Değirmenci Döşkaya, Aytül Gül, Sedef Erkunt Alak, Adnan Yüksel Gürüz, Cemal Ün, Mert Döşkaya.
      Toxoplasma gondii (T. gondii) is an obligate intracellular parasite that can infect almost all warm-blooded animals, including humans, and one-third of the global population is thought to be infected with this parasite. Infection can occur through consumption of contaminated food, contact with an infected host, or congenital transmission. While toxoplasmosis is asemptomatic in people with a healthy immune system, it can cause severe infections in people with a suppressed immune system or with immunodeficiency. In addition to causing diseases in humans, it also causes infections in livestock and may result in stillbirth and abortion in sheep and goats. There is no 100% effective medicine or vaccination against the parasite that causes major clinical symptoms and financial losses. There is a need for an effective, safe, and durable vaccine that can provide protective immunity for use in humans and animals. Vaccination studies against toxoplasmosis have gathered speed since the 1990s. Today, studies can be carried out to develop effective and safe vaccines depending on the developments in molecular biology, biotechnology, and immunology. DNA vaccines are a promising vaccine platform against toxoplasmosis because they are easy to produce, they are safe, they do not need a cold chain, and they can stimulate both humoral and cellular immune responses. This review provides an overview of the complex life cycle, pathogenesis, and epidemiology of the parasite; the immune response that develops in the host against the infection it causes; and the DNA vaccines developed against toxoplasmosis and these vaccines.
    Keywords:  DNA vaccines; toxoplasma; immunization
    DOI:  https://doi.org/10.4274/tpd.galenos.2022.02486
  7. Front Mol Biosci. 2022 ;9 962933
    Shared pathobiology identifies AMPK as a therapeutic target for obesity and autosomal dominant polycystic kidney disease.
    Ioan-Andrei Iliuta, Xuewen Song, Lauren Pickel, Amirreza Haghighi, Ravi Retnakaran, James Scholey, Hoon-Ki Sung, Gregory R Steinberg, York Pei.
      Autosomal dominant polycystic kidney disease (ADPKD) is the most common Mendelian kidney disease, affecting approximately one in 1,000 births and accounting for 5% of end-stage kidney disease in developed countries. The pathophysiology of ADPKD is strongly linked to metabolic dysregulation, which may be secondary to defective polycystin function. Overweight and obesity are highly prevalent in patients with ADPKD and constitute an independent risk factor for progression. Recent studies have highlighted reduced AMP-activated protein kinase (AMPK) activity, increased mammalian target of rapamycin (mTOR) signaling, and mitochondrial dysfunction as shared pathobiology between ADPKD and overweight/obesity. Notably, mTOR and AMPK are two diametrically opposed sensors of energy metabolism that regulate cell growth and proliferation. However, treatment with the current generation of mTOR inhibitors is poorly tolerated due to their toxicity, making clinical translation difficult. By contrast, multiple preclinical and clinical studies have shown that pharmacological activation of AMPK provides a promising approach to treat ADPKD. In this narrative review, we summarize the pleiotropic functions of AMPK as a regulator of cellular proliferation, macromolecule metabolism, and mitochondrial biogenesis, and discuss the potential for pharmacological activation of AMPK to treat ADPKD and obesity-related kidney disease.
    Keywords:  AMPK; autosomal dominant polycystic kidney disease; energy metabolism; metabolic dysregulation; obesity
    DOI:  https://doi.org/10.3389/fmolb.2022.962933
  8. Curr Opin Microbiol. 2022 Sep 07. pii: S1369-5274(22)00085-6. [Epub ahead of print]70 102201
    Beyond splicing: serine-arginine proteins as emerging multifaceted regulators of RNA metabolism in malaria parasites.
    Manish Goyal, Karina Simantov, Ron Dzikowski.
      The serine-arginine-rich (SR) proteins play an exceptionally important role in eukaryotic gene expression, primarily by regulating constitutive and alternative splicing events. In addition to their primary role as splicing factors, SR proteins have emerged as multifunctional RNA-binding proteins that act as key regulators of almost every step of RNA metabolism. As in higher eukaryotes, Plasmodium parasites encode several SR proteins, which were implicated in pre-mRNA splicing. However, only a few have been characterized and their biological roles remain understudied. Intriguingly, in addition to splicing regulation, unexpected functions of particular SR proteins have been reported in Plasmodium in recent years. Here, we highlight the key characteristics and different noncanonical splicing functions of SR proteins and discuss potential mechanisms, which might be involved in their multifaceted functionality in Plasmodium.
    DOI:  https://doi.org/10.1016/j.mib.2022.102201
  9. Autophagy. 2022 Sep 15.
    cAMP-Protein Kinase A and Stress-Activated MAP Kinase signaling mediate transcriptional control of autophagy in fission yeast during glucose limitation or starvation.
    Armando Jesús Pérez-Díaz, Beatriz Vázquez-Marín, Jero Vicente-Soler, Francisco Prieto-Ruiz, Teresa Soto, Alejandro Franco, José Cansado, Marisa Madrid.
      Macroautophagy/autophagy is an essential adaptive physiological response in eukaryotes induced during nutrient starvation, including glucose, the primary immediate carbon and energy source for most cells. Although the molecular mechanisms that induce autophagy during glucose starvation have been extensively explored in the budding yeast Saccharomyces cerevisiae, little is known about how this coping response is regulated in the evolutionary distant fission yeast Schizosaccharomyces pombe. Here, we show that S. pombe autophagy in response to glucose limitation relies on mitochondrial respiration and the electron transport chain (ETC), but, in contrast to S. cerevisiae, the AMP-activated protein kinase (AMPK) and DNA damage response pathway components do not modulate fission yeast autophagic flux under these conditions. In the presence of glucose, the cAMP-protein kinase A (PKA) signaling pathway constitutively represses S. pombe autophagy by downregulating the transcription factor Rst2, which promotes the expression of respiratory genes required for autophagy induction under limited glucose availability. Furthermore, the stress-activated protein kinase (SAPK) signaling pathway, and its central mitogen-activated protein kinase (MAPK) Sty1, positively modulate autophagy upon glucose limitation at the transcriptional level through its downstream effector Atf1 and by direct in vivo phosphorylation of Rst2 at S292. Thus, our data indicate that the signaling pathways that govern autophagy during glucose shortage or starvation have evolved differently in S. pombe and uncover the existence of sophisticated and multifaceted mechanisms that control this self-preservation and survival response.
    Keywords:  Autophagy; MAP kinase; Schizosaccharomyces pombe; cAMP-protein kinase A; fermentation; glucose; respiration; transcription
    DOI:  https://doi.org/10.1080/15548627.2022.2125204
  10. Infect Dis Poverty. 2022 Sep 14. 11(1): 96
    Global proteomic profiling of multiple organs of cats (Felis catus) and proteome-transcriptome correlation during acute Toxoplasma gondii infection.
    Lan-Bi Nie, Wei Cong, Jun-Jun He, Wen-Bin Zheng, Xing-Quan Zhu.
       BACKGROUND: Toxoplasma gondii is a protozoan parasite which can infect almost all warm-blooded animals and humans. Understanding the differential expression of proteins and transcripts associated with T. gondii infection in its definitive host (cat) may improve our knowledge of how the parasite manipulates the molecular microenvironment of its definitive host. The aim of this study was to explore the global proteomic alterations in the major organs of cats during acute T. gondii infection.
    METHODS: iTRAQ-based quantitative proteomic profiling was performed on six organs (brain, liver, lung, spleen, heart and small intestine) of cats on day 7 post-infection by cysts of T. gondii PRU strain (Genotype II). Mascot software was used to conduct the student's t-test. Proteins with P values < 0.05 and fold change > 1.2 or < 0.83 were considered as differentially expressed proteins (DEPs).
    RESULTS: A total of 32,657 proteins were identified in the six organs, including 2556 DEPs; of which 1325 were up-regulated and 1231 were down-regulated. The brain, liver, lung, spleen, heart and small intestine exhibited 125 DEPs, 463 DEPs, 255 DEPs, 283 DEPs, 855 DEPs and 575 DEPs, respectively. Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of all proteins and DEPs in all organs showed that many proteins were enriched in binding, cell part, cell growth and death, signal transduction, translation, sorting and degradation, extracellular matrix remodeling, tryptophan catabolism, and immune system. Correlations between differentially expressed proteins and transcripts were detected in the liver (n = 19), small intestine (n = 17), heart (n = 9), lung (n = 9) and spleen (n = 3).
    CONCLUSIONS: The present study identified 2556 DEPs in six cat tissues on day 7 after infection by T. gondii PRU strain, and functional enrichment analyses showed that these DEPs were associated with various cellular and metabolic processes. These findings provide a solid base for further in-depth investigation of the complex proteotranscriptomic reprogramming that mediates the dynamic interplays between T. gondii and the different feline tissues.
    Keywords:  Cat; Proteomics; Toxoplasma gondii; Transcriptomics; mRNA-protein correlation
    DOI:  https://doi.org/10.1186/s40249-022-01022-7
  11. Microbiol Spectr. 2022 Sep 12. e0218622
    A Coccidia-Specific Phosphate Transporter Is Essential for the Growth of Toxoplasma gondii Parasites.
    Jianmin Cui, Xuke Yang, Jichao Yang, Ruilian Jia, Yaoyu Feng, Bang Shen.
      Toxoplasma gondii is an obligate intracellular parasite that acquires all necessary nutrients from the hosts, but the exact nutrient acquisition mechanisms are poorly understood. Here, we identified three putative phosphate transporters in T. gondii. TgPiT and TgPT2 are mainly on the plasma membrane, whereas TgmPT is localized to the mitochondrion. TgPiT and TgmPT are widely present and conserved in apicomplexan parasites that include Plasmodium and Eimeria species. Nonetheless, they are dispensable for the growth and virulence of Toxoplasma. TgPT2, on the other hand, is restricted to coccidia parasites and is essential for Toxoplasma survival. TgPT2 depletion led to reduced motility and invasion, as well as growth arrest of the parasites both in vitro and in vivo. Both TgPiT and TgPT2 have phosphate transport activities and contribute to parasites' inorganic phosphate (Pi) absorption. Interestingly, the Pi importing activity of Toxoplasma parasites could be competitively inhibited by ATP and AMP. Furthermore, direct uptake of 32P-ATP was also observed, indicating the parasites' ability to scavenge host ATP. Nonetheless, ATP/AMP import is not mediated by TgPiT or TgPT2, suggesting additional mechanisms. Together, these results show the complex pathways of phosphate transport in Toxoplasma, and TgPT2 is a potential target for antitoxoplasmic intervention design due to its essential role in parasite growth. IMPORTANCE To grow and survive within host cells, Toxoplasma must scavenge necessary nutrients from hosts to support its parasitism. Transporters located in the plasma membrane of the parasites play critical roles in nutrient acquisition. Toxoplasma encodes a large number of transporters, but so far, only a few have been characterized. In this study, we identified two phosphate transporters, TgPiT and TgPT2, to localize to the plasma membrane of Toxoplasma. Although both TgPiT and TgPT2 possess phosphate transport activities, only the novel transporter TgPT2 was essential for parasite growth, both in vitro and in vivo. In addition, TgPT2 and its orthologs are only present in coccidia parasites. As such, TgPT2 represents a potential target for drug design against toxoplasmosis. In addition, our data indicated that Toxoplasma can take up ATP and AMP from the environment, providing new insights into the energy metabolism of Toxoplasma.
    Keywords:  ATP scavenge; Toxoplasma; coccidia; phosphate transporter
    DOI:  https://doi.org/10.1128/spectrum.02186-22
  12. Front Mol Biosci. 2022 ;9 957549
    Metabolomics reveals mouse plasma metabolite responses to acute exercise and effects of disrupting AMPK-glycogen interactions.
    Mehdi R Belhaj, Nathan G Lawler, John A Hawley, David I Broadhurst, Nolan J Hoffman, Stacey N Reinke.
      Introduction: The AMP-activated protein kinase (AMPK) is a master regulator of energy homeostasis that becomes activated by exercise and binds glycogen, an important energy store required to meet exercise-induced energy demands. Disruption of AMPK-glycogen interactions in mice reduces exercise capacity and impairs whole-body metabolism. However, the mechanisms underlying these phenotypic effects at rest and following exercise are unknown. Furthermore, the plasma metabolite responses to an acute exercise challenge in mice remain largely uncharacterized. Methods: Plasma samples were collected from wild type (WT) and AMPK double knock-in (DKI) mice with disrupted AMPK-glycogen binding at rest and following 30-min submaximal treadmill running. An untargeted metabolomics approach was utilized to determine the breadth of plasma metabolite changes occurring in response to acute exercise and the effects of disrupting AMPK-glycogen binding. Results: Relative to WT mice, DKI mice had reduced maximal running speed (p < 0.0001) concomitant with increased body mass (p < 0.01) and adiposity (p < 0.001). A total of 83 plasma metabolites were identified/annotated, with 17 metabolites significantly different (p < 0.05; FDR<0.1) in exercised (↑6; ↓11) versus rested mice, including amino acids, acylcarnitines and steroid hormones. Pantothenic acid was reduced in DKI mice versus WT. Distinct plasma metabolite profiles were observed between the rest and exercise conditions and between WT and DKI mice at rest, while metabolite profiles of both genotypes converged following exercise. These differences in metabolite profiles were primarily explained by exercise-associated increases in acylcarnitines and steroid hormones as well as decreases in amino acids and derivatives following exercise. DKI plasma showed greater decreases in amino acids following exercise versus WT. Conclusion: This is the first study to map mouse plasma metabolomic changes following a bout of acute exercise in WT mice and the effects of disrupting AMPK-glycogen interactions in DKI mice. Untargeted metabolomics revealed alterations in metabolite profiles between rested and exercised mice in both genotypes, and between genotypes at rest. This study has uncovered known and previously unreported plasma metabolite responses to acute exercise in WT mice, as well as greater decreases in amino acids following exercise in DKI plasma. Reduced pantothenic acid levels may contribute to differences in fuel utilization in DKI mice.
    Keywords:  AMP-activated protein kinase; acylcarnitines; amino acids; exercise metabolism; glycogen; metabolomics; pantothenic acid; plasma metabolite
    DOI:  https://doi.org/10.3389/fmolb.2022.957549
  13. Biology (Basel). 2022 Jul 11. pii: 1041. [Epub ahead of print]11(7):
    AMPK and Diseases: State of the Art Regulation by AMPK-Targeting Molecules.
    Olga Tarasiuk, Matteo Miceli, Alessandro Di Domizio, Gabriella Nicolini.
      5'-adenosine monophosphate (AMP)-activated protein kinase (AMPK) is an enzyme that regulates cellular energy homeostasis, glucose, fatty acid uptake, and oxidation at low cellular ATP levels. AMPK plays an important role in several molecular mechanisms and physiological conditions. It has been shown that AMPK can be dysregulated in different chronic diseases, such as inflammation, diabetes, obesity, and cancer. Due to its fundamental role in physiological and pathological cellular processes, AMPK is considered one of the most important targets for treating different diseases. Over decades, different AMPK targeting compounds have been discovered, starting from those that activate AMPK indirectly by altering intracellular AMP:ATP ratio to compounds that activate AMPK directly by binding to its activation sites. However, indirect altering of intracellular AMP:ATP ratio influences different cellular processes and induces side effects. Direct AMPK activators showed more promising results in eliminating side effects as well as the possibility to engineer drugs for specific AMPK isoforms activation. In this review, we discuss AMPK targeting drugs, especially concentrating on those compounds that activate AMPK by mimicking AMP. These compounds are poorly described in the literature and still, a lot of questions remain unanswered about the exact mechanism of AMP regulation. Future investigation of the mechanism of AMP binding will make it possible to develop new compounds that, in combination with others, can activate AMPK in a synergistic manner.
    Keywords:  ADaM site; AMP; AMP mimicking; AMPK regulation; direct and indirect AMPK activators
    DOI:  https://doi.org/10.3390/biology11071041
  14. J Cell Biol. 2022 Oct 03. pii: e202106179. [Epub ahead of print]221(10):
    Engineered kinases as a tool for phosphorylation of selected targets in vivo.
    Katarzyna Lepeta, Chantal Roubinet, Milena Bauer, M Alessandra Vigano, Gustavo Aguilar, Oguz Kanca, Amanda Ochoa-Espinosa, Dimitri Bieli, Clemens Cabernard, Emmanuel Caussinus, Markus Affolter.
      Reversible protein phosphorylation by kinases controls a plethora of processes essential for the proper development and homeostasis of multicellular organisms. One main obstacle in studying the role of a defined kinase-substrate interaction is that kinases form complex signaling networks and most often phosphorylate multiple substrates involved in various cellular processes. In recent years, several new approaches have been developed to control the activity of a given kinase. However, most of them fail to regulate a single protein target, likely hiding the effect of a unique kinase-substrate interaction by pleiotropic effects. To overcome this limitation, we have created protein binder-based engineered kinases that permit a direct, robust, and tissue-specific phosphorylation of fluorescent fusion proteins in vivo. We show the detailed characterization of two engineered kinases based on Rho-associated protein kinase (ROCK) and Src. Expression of synthetic kinases in the developing fly embryo resulted in phosphorylation of their respective GFP-fusion targets, providing for the first time a means to direct the phosphorylation to a chosen and tagged target in vivo. We presume that after careful optimization, the novel approach we describe here can be adapted to other kinases and targets in various eukaryotic genetic systems to regulate specific downstream effectors.
    DOI:  https://doi.org/10.1083/jcb.202106179
  15. Sci Adv. 2022 Sep 16. 8(37): eabo0323
    An AMPK phosphoregulated RhoGEF feedback loop tunes cortical flow-driven amoeboid migration in vivo.
    Benjamin Lin, Jonathan Luo, Ruth Lehmann.
      Development, morphogenesis, immune system function, and cancer metastasis rely on the ability of cells to move through diverse tissues. To dissect migratory cell behavior in vivo, we developed cell type-specific imaging and perturbation techniques for Drosophila primordial germ cells (PGCs). We find that PGCs use global, retrograde cortical actin flows for orientation and propulsion during guided developmental homing. PGCs use RhoGEF2, a RhoA-specific RGS-RhoGEF, as a dose-dependent regulator of cortical flow through a feedback loop requiring its conserved PDZ and PH domains for membrane anchoring and local RhoA activation. This feedback loop is regulated for directional migration by RhoGEF2 availability and requires AMPK rather than canonical Gα12/13 signaling. AMPK multisite phosphorylation of RhoGEF2 near a conserved EB1 microtubule-binding SxIP motif releases RhoGEF2 from microtubule-dependent inhibition. Thus, we establish the mechanism by which global cortical flow and polarized RhoA activation can be dynamically adapted during natural cell navigation in a changing environment.
    DOI:  https://doi.org/10.1126/sciadv.abo0323
  16. Biochim Biophys Acta Mol Cell Res. 2022 Sep 13. pii: S0167-4889(22)00147-1. [Epub ahead of print] 119355
    ULK1 inhibition attenuates telomerase activity in hepatic cells.
    Sana Raza, Sangam Rajak, Jyotika Srivastava, Archana Tewari, Pratima Gupta, Bandana Chakravarti, Sujoy Ghosh, Chandra P Chaturvedi, Rohit A Sinha.
      Autophagy and telomere maintenance are two cellular survival processes that show a strong correlation during human ageing and cancer growth, however, their causal relationship remains unclear. In this study, using an unbiased transcriptomics approach, we uncover a novel role of autophagy genes in regulating telomere extension and maintenance pathways. Concomitantly, the pharmacological inhibition of ULK1 (Unc-51 like autophagy activating kinase 1) attenuated human telomerase reverse transcriptase (hTERT) gene expression and telomerase activity in HepG2 cells. Furthermore, the suppression of telomerase activity upon ULK1 inhibition was associated with telomere shortening and onset of cellular senescence in HepG2 cells. These results, thus, demonstrate a direct role of autophagy in maintaining cellular longevity via regulation of telomerase activity, which may have implications in the pathophysiology of ageing and cancers.
    DOI:  https://doi.org/10.1016/j.bbamcr.2022.119355
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