Kosztelnik M et al. (2018) FASEB J "Suppression of AMPK/aak-2 by NRF2/SKN-1 down-regulates autophagy during prolonged oxidative stress."

Szarka A, Kurucz A, Barna J, Sigmond T, Lorincz T, Traka MH, Korcsmaros T, Banhegyi G, Jones E, Kapuy O, Papp D, Vellai T, Kosztelnik M

[FASEB J, 2018]

NF-E2-related factor 2 (NRF2) transcription factor has a fundamental role in cell homeostasis maintenance as one of the master regulators of oxidative and electrophilic stress responses. Previous studies have shown that a regulatory connection exists between NRF2 and autophagy during reactive oxygen species-generated oxidative stress. The aim of the present study was to investigate how autophagy is turned off during prolonged oxidative stress, to avoid overeating and destruction of essential cellular components. AMPK is a key cellular energy sensor highly conserved in eukaryotic organisms, and it has an essential role in autophagy activation at various stress events. Here the role of human AMPK and its Caenorhabditis elegans counterpart AAK-2 was explored upon oxidative stress. We investigated the regulatory connection between NRF2 and AMPK during oxidative stress induced by tert-butyl hydroperoxide (TBHP) in HEK293T cells and C. elegans. Putative conserved NRF2/protein skinhead-1 binding sites were found in AMPK/aak-2 genes by in silico analysis and were later confirmed experimentally by using EMSA. After addition of TBHP, NRF2 and AMPK showed a quick activation; AMPK was later down-regulated, however, while NRF2 level remained high. Autophagosome formation and Unc-51-like autophagy activating kinase 1 phosphorylation were initially stimulated, but they returned to basal values after 4 h of TBHP treatment. The silencing of NRF2 resulted in a constant activation of AMPK leading to hyperactivation of autophagy during oxidative stress. We observed the same effects in C. elegans demonstrating the conservation of this self-defense mechanism to save cells from hyperactivated autophagy upon prolonged oxidative stress. We conclude that NRF2 negatively regulates autophagy through delayed down-regulation of the expression of AMPK upon prolonged oxidative stress. This regulatory connection between NRF2 and AMPK may have an important role in understanding how autophagy is regulated in chronic human morbidities characterized by oxidative stress, such as neurodegenerative diseases, certain cancer types, and in metabolic diseases.-Kosztelnik, M., Kurucz, A., Papp, D., Jones, E., Sigmond, T., Barna, J., Traka, M. H., Lorincz, T., Szarka, A., Banhegyi, G., Vellai, T., Korcsmaros, T., Kapuy, O. Suppression of AMPK/aak-2 by NRF2/SKN-1 down-regulates autophagy during prolonged oxidative stress.

Shaulov Y et al. (2018) PLoS Pathog "Escherichia coli mediated resistance of Entamoeba histolytica to oxidative stress is triggered by oxaloacetate."

Methling K, Weiss-Cerem L, Trebicz-Geffen M, Lamm AT, Lalk M, Hisaeda H, Shimokawa C, Ankri S, Shaulov Y, Nagaraja S

[PLoS Pathog, 2018]

Amebiasis, a global intestinal parasitic disease, is due to Entamoeba histolytica. This parasite, which feeds on bacteria in the large intestine of its human host, can trigger a strong inflammatory response upon invasion of the colonic mucosa. Whereas information about the mechanisms which are used by the parasite to cope with oxidative and nitrosative stresses during infection is available, knowledge about the contribution of bacteria to these mechanisms is lacking. In a recent study, we demonstrated that enteropathogenic Escherichia coli O55 protects E. histolytica against oxidative stress. Resin-assisted capture (RAC) of oxidized (OX) proteins coupled to mass spectrometry (OX-RAC) was used to investigate the oxidation status of cysteine residues in proteins present in E. histolytica trophozoites incubated with live or heat-killed E. coli O55 and then exposed to H2O2-mediated oxidative stress. We found that the redox proteome of E. histolytica exposed to heat-killed E. coli O55 is enriched with proteins involved in redox homeostasis, lipid metabolism, small molecule metabolism, carbohydrate derivative metabolism, and organonitrogen compound biosynthesis. In contrast, we found that proteins associated with redox homeostasis were the only OX-proteins that were enriched in E. histolytica trophozoites which were incubated with live E. coli O55. These data indicate that E. coli has a profound impact on the redox proteome of E. histolytica. Unexpectedly, some E. coli proteins were also co-identified with E. histolytica proteins by OX-RAC. We demonstrated that one of these proteins, E. coli malate dehydrogenase (EcMDH) and its product, oxaloacetate, are key elements of E. coli-mediated resistance of E. histolytica to oxidative stress and that oxaloacetate helps the parasite survive in the large intestine. We also provide evidence that the protective effect of oxaloacetate against oxidative stress extends to Caenorhabditis elegans.

Ye H et al. (2008) Neurobiol Learn Mem "Trace administration of vitamin E can retrieve and prevent UV-irradiation- and metal exposure-induced memory deficits in nematode Caenorhabditis elegans."

Ye B, Ye H, Wang D

[Neurobiol Learn Mem, 2008]

Vitamin E (alpha-tocopherol), a lipid-soluble anti-oxidant, prevents the uncontrolled propagation of lipid peroxidation by free radicals. Nevertheless, there is weak or no evidence of a protective effect of previous vitamin E intake on cognitive function in humans. In the present study, we explored the thermosensation model to investigate the possible effects of vitamin E administration on memory behaviors in Caenorhabditis elegans. Administration of 100 and 200mug/mL of vitamin E had no significant effects on the memory for different time intervals, whereas relatively high concentration (400mug/mL) of vitamin E exposure shortened the extinction period of the association paradigm (food at 20 degrees C). Following the UV-irradiation, post-treatment with 200mug/mL of vitamin E not only retrieved the UV-irradiation-induced memory deficits, but also enhanced the memory functions in UV-irradiating animals. Post-treatment with trace vitamin E could also ameliorate the memory deficits in metal (Al or Pb) exposed worms. In addition, pre-treatment with 200mug/mL of vitamin E could effectively prevent the occurrence of memory deficits induced by metal exposure and UV-irradiation. Therefore, the close association may exist between trace dietary vitamin E intake and memory behaviors, and a specific response mechanism may be activated after the administration of vitamin E in stress-exposed animals. Moreover, treatment with 200mug/mL of vitamin E could restore the memory deficits formed in the ncs-1 mutant worms, suggesting that exogenous treatment with trace vitamin E can largely mimic the function of NCS-1 in regulating the memory for thermosensation.

Almeida AC et al. (2024) J Cell Sci "An evolutionary perspective on the relationship between kinetochore size and CENP-E dependence for chromosome alignment."

Raas MWD, Rocha H, Kops GJPL, Sommer RJ, Witte H, Snel B, Maiato H, Almeida AC, Gassmann R

[J Cell Sci, 2024]

Chromosome alignment during mitosis can occur as a consequence of bi-orientation or is assisted by the CENP-E (kinesin-7) motor at kinetochores. We previously found that Indian muntjac chromosomes with larger kinetochores bi-orient more efficiently and are biased to align in a CENP-E-independent manner, suggesting that CENP-E dependence for chromosome alignment negatively correlates with kinetochore size. Here, we used targeted phylogenetic profiling of CENP-E in monocentric (localized centromeres) and holocentric (centromeres spanning the entire chromosome length) clades to test this hypothesis at an evolutionary scale. We found that, despite being present in common ancestors, CENP-E was lost more frequently in taxa with holocentric chromosomes, such as Hemiptera and Nematoda. Functional experiments in two nematodes with holocentric chromosomes in which a CENP-E ortholog is absent (Caenorhabditis elegans) or present (Pristionchus pacificus) revealed that targeted expression of human CENP-E to C. elegans kinetochores partially rescued chromosome alignment defects associated with attenuated polar-ejection forces, whereas CENP-E inactivation in P. pacificus had no detrimental effects on mitosis and viability. These data showcase the dispensability of CENP-E for mitotic chromosome alignment in species with larger kinetochores.

Saiki R et al. (2008) Aging Cell "Altered bacterial metabolism, not coenzyme Q content, is responsible for the lifespan extension in Caenorhabditis elegans fed an Escherichia coli diet lacking coenzyme Q."

Dang P, Lee W, Saiki R, Lunceford AL, Clarke CF, Furukawa S, Bixler T, Larsen PL

[Aging Cell, 2008]

Coenzyme Qn is a fully substituted benzoquinone containing a polyisoprene tail of distinct numbers (n) of isoprene groups. C. elegans fed E. coli devoid of Q(8) have a significant life span extension when compared to C. elegans fed a standard "Q-replete"E. coli diet. Here we examine possible mechanisms for the life span extension caused by the Q-less E. coli diet. A bioassay for Q uptake shows that a water-soluble formulation of Q(10) is effectively taken up by both clk-1 mutant and wild-type nematodes, but does not reverse life span extension mediated by the Q-less E. coli diet, indicating that life span extension is not due to the absence of dietary Q per se. The enhanced longevity mediated by the Q-less E. coli diet cannot be attributed to dietary restriction, different Qn isoforms, reduced pathogenesis or slowed growth of the Q-less E. coli, and in fact requires E. coli viability. Q-less E. coli have defects in respiratory metabolism. C. elegans fed Q-replete E. coli mutants with similarly impaired respiratory metabolism due to defects in complex V also show a pronounced life span extension, although not as dramatic as those fed the respiratory deficient Q-less E. coli diet. The data suggest that feeding respiratory incompetent E. coli, whether Q-less or Q-replete, produces a robust life extension in wild-type C. elegans. We believe the fermentation-based metabolism of the E. coli diet is an important parameter of C. elegans longevity.

Lee JH et al. (2014) Phytomedicine "Coumarins reduce biofilm formation and the virulence of Escherichia coli O157:H7."

Cho MH, Lee JH, Kim YG, Ryu SY, Cho HS, Lee J

[Phytomedicine, 2014]

E. coli O157:H7 is the most common cause of hemorrhagic colitis, and no effective therapy exists for E. coli O157:H7 infection. Biofilm formation is closely related to E. coli O157:H7 infection and constitutes a mechanism of antimicrobial resistance. Hence, the antibiofilm or antivirulence approach provides an alternative to antibiotic strategies. Coumarin and its derivatives have a broad range of biological effects, and in this study, the antibiofilm activities of nine coumarins were investigated against E. coli O157:H7. Coumarin or umbelliferone at 50g/ml was found to inhibit biofilm E. coli O157:H7 formation by more than 80% without affecting bacterial growth. Transcriptional analysis showed that coumarins repressed curli genes and motility genes in E. coli O157:H7, and these findings were in-line with observed reductions in fimbriae production, swarming motility, and biofilm formation. In addition, esculetin repressed Shiga-like toxin gene stx2 in E. coli O157:H7 and attenuated its virulence in vivo in the nematode Caenorhabditis elegans. These findings show that coumarins have potential use in antivirulence strategies against persistent E. coli O157:H7 infection.

Zuckerman BM et al. (1983) Age "Effects of vitamin E on the nematode C. elegans."

Zuckerman BM, Geist MA

[Age, 1983]

Vitamin E at 200 ug/ml significantly extended the mean lifespan and extended maximum lifespan of the nematode Caenorhabditis elegans when supplied early in the prereproductive stage. At this concentration, vitamin E increased growth, but did not affect fecundity or the length of the reproductive period. The vitamin E effect was not passed from the parents to the progeny. Evaluations of the effects of vitamin E on lipofuscin accumulation were inconclusive. The results are compared to previous studies on C. briggsae and Turbatrix aceti.

Bartolini F et al. (2005) J Cell Sci "Identification of a novel tubulin-destabilizing protein related to the chaperone cofactor E."

Tian G, Cassimeris L, Piehl M, Cowan NJ, Bartolini F, Lewis SA

[J Cell Sci, 2005]

Factors that regulate the microtubule cytoskeleton are critical in determining cell behavior. Here we describe the function of a novel protein that we term E-like based on its sequence similarity to the tubulin-specific chaperone cofactor E. We find that upon overexpression, E-like depolymerizes microtubules by committing tubulin to proteosomal degradation. Our data suggest that this function is direct and is based on the ability of E-like to disrupt the tubulin heterodimer in vitro. Suppression of E-like expression results in an increase in the number of stable microtubules and a tight clustering of endocellular membranes around the microtubule-organizing center, while the properties of dynamic microtubules are unaffected. These observations define E-like as a novel regulator of tubulin stability, and provide a link between tubulin turnover and vesicle transport.

Kaushal NA et al. (1982) J Immunol "Identification and characterization of excretory-secretory products of Brugia malayi, adult filarial parasites."

Nash TE, Kaushal NA, Ottesen EA, Hussain R

[J Immunol, 1982]

Although E-S antigens may be particularly important for both the pathogenesis and immunodiagnosis of helminth infections, little is known about the immunochemistry or functional roles in human filarial infections. In the present paper, we have done some initial identification and characterization of E-S products of adult Brugia malayi by employing a combination of sensitive biochemical and immunochemical techniques. E-S products, collected by incubating B. malayi adults in vitro in a defined protein-free medium, were radiolabeled with 125I. SDS-polyacrylamide gel electrophoresis (PAGE) and autoradiography of labeled E-S products revealed 11 protein bands in the m.w. range of 10,000 to 70,000. Comparison of radiolabeled E-S products and adult somatic antigen (B.m.A) in SDS-PAGE indicated many common bands, and crossed immunoelectrophoresis and competitive Staph-A RIA confirmed the presence of most E-S antigens in B.m.A. Of the 11 E-S bands, two appeared to be derived from the surface of the adult worms and microfilariae as shown by SDS-PAGE and autoradiography of lodogen surface-labeled parasites; the presence of two host proteins in E-S was detected by crossed-line immunoelectrophoresis. The E-S antigens were highly immunogenic when tested both with rabbit antiserum raised against B.m.A and with a serum pool of patients with natural filarial infection.

Garsin DA et al. (2001) Proc Natl Acad Sci U S A "A simple model host for identifying Gram-positive virulence factors."

Murray BE, Calderwood SB, Mylonakis E, Ausubel FM, Garsin DA, Sifri CD, Qin X, Singh KV

[Proc Natl Acad Sci U S A, 2001]

We demonstrate the use of the nematode Caenorhabditis elegans as a facile and inexpensive model host for several Gram-positive human bacterial pathogens. Enterococcus faecalis, Streptococcus pneumoniae, and Staphylococcus aureus, but not Bacillus subtilis, Enterococcus faecium, or Streptococcus pyogenes, kill adult C elegans. Focusing our studies on the enterococcal species, we found that both E. faecalis and E. faecium kill C elegans eggs and hatchlings, although only E. faecalis kills the adults. In the case of adults, a low inoculum of E, faecalis grows to a high titer in the C elegans intestine, resulting in a persistent infection that cannot be eradicated by prolonged feeding on E. faecium. Interestingly, a high titer of E. faecium also accumulates in the nematode gut, but does not affect the longevity of the worms. Two E. faecalis virulence-related factors that play an important role in mammalian models of infection, tsr, a putative quorum-sensing system, and cytolysin, are also important for nematode killing. We exploit the apparent parallels between Gram-positive infection in simple and more complex organisms by using the nematode to identify an E. faecalis virulence factor, ScrB, which is relevant to mammalian pathogenesis.