Hur JH et al. (2010) Aging (Albany NY) "Aging: Dial M for Mitochondria."

Walker DW, Hur JH, Cho J

[Aging (Albany NY), 2010]

A major goal of aging research is to identify interventions that prolong lifespan in distantly related organisms. In recent years, genetic studies in both nematodes and rodents have reported that moderate inactivation of genes important for mitochondrial electron transport chain (ETC) function can promote longevity. We performed an RNAi screen to probe the role of ETC components in modulating lifespan in the fruit fly Drosophila melanogaster. In this Research Perspective, we discuss our findings and how they may relate to similar studies in worms and mice.

Hur JH et al. (2014) J Bioenerg Biomembr "Complex-I-ty in aging."

Stork DA, Walker DW, Hur JH

[J Bioenerg Biomembr, 2014]

The role of mitochondrial complex I in aging has been studied in both C. elegans and Drosophila, where RNAi knock down of specific complex I subunits has been shown to extend lifespan. More recently, studies in Drosophila have shown that an increase in mitochondrial activity, including complex I-like activity, can also slow aging. In this review, we discuss this apparent paradox. Improved maintenance of mitochondrial activity, mitochondrial homeostasis, may be responsible for lifespan extension in both cases. Decreased electron transport chain activity caused by reducing complex I subunit expression prompts an increase in stress response signaling that leads to enhanced mitochondrial homeostasis during aging. Increased complex I activity, as well as mitochondrial biogenesis, is expected to both directly counteract the decline in mitochondrial health that occurs during aging and may also increase cellular NAD(+) levels, which have been linked to mitochondrial homeostatic mechanisms through activation of sirtuins. We suggest that manipulations that increase or decrease complex I activity both converge on improved mitochondrial homeostasis during aging, resulting in prolonged lifespan.

Yang, Zhe et al. (2015) International Worm Meeting "A C. elegans model for Human Antigen R (HuR)."

Yang, Zhe, Buechner, Matthew

[International Worm Meeting, 2015]

Human antigen (Hu) proteins HuB, HuC, HuD, and HuR are a family of RNA-binding protein that stabilize mRNA by binding to AU-rich elements (ARE) in the 3'UTR. HuR is universally expressed in human cells, and stabilizes many tumor-related genes such as bcl-2 and XIAP. HuR is upregulated in many cancer cell types involved in breast and colon cancer. EXC-7 is the sole homologue of the Hu proteins in C. elegans. EXC-7 maintains the single-cell tubular canals of the excretory cell by stabilizing sma-1 mRNA, encoding betaH-spectrin. Mutants in exc-7 exhibit small fluid-filled cysts throughout shortened excretory canals, as well as a misshapen tailspike. Both EXC-7 and HuR contain 3 RNA-recognition motifs (RRMs), with a region between the 2nd and 3rd RRM that appears to be needed for intracellular transport. We are investigating the functional equivalence of these proteins, by determining whether human HuR can functionally replace EXC-7 in C. elegans. If so, then C. elegans could be developed as a model for studying HuR in vivo, especially for screens for chemicals that interfere with HuR function, using excretory canal phenotype as a measure of HuR activity.We have injected the hur coding region driven by various promoters to express HuR within the excretory canals. HuR appears to affect both the length and diameter of the excretory canal lumen. We plan to attach GFP to HuR to visualize the position and movement of this protein within the long excretory canals, and to make worm/human chimeric proteins to investigate domain activity of these proteins.

Yang, Zhe et al. (2017) International Worm Meeting "Creating a C.elegans model for Human Antigen R (HuR)."

Xu, Liang, Yang, Zhe, Buechner, Matthew

[International Worm Meeting, 2017]

Human antigen R (HuR) is an RNA-binding protein that binds to A-U-rich elements (ARE) at the 3' UTR of mRNAs in order to stabilize them. HuR binds to many tumor-related genes, and is up-regulated in many cancer cell types such a breast cancer and colon cancer. We are studying the C. elegans homologue of HuR in order to help understand the function of this class of protein. The nematode homologue is EXC-7, which maintains the normal lumen diameter and length of the single-cell tube of the C. elegans excretory canal cell; mutants exhibit a wide lumen with many small cysts, and the electron-dense terminal web is detached from apical membrane at the tips of the canals. EXC-7 binds to the mRNA of sma-1 (encoding beta Hspectrin) and presumably stabilizes this and other essential cytoskeletal mRNAs. Both EXC-7 and HuR contain 3 RNA-recognition motifs surrounding a central hinge domain. We are using the mutant phenotype of the excretory canal cell as a readout to see the effect of HuR in C.elegans. HuR and EXC-7 have similar structure and function, so we hypothesize that HuR binding domains can replace those of EXC-7 in C. elegans, so that the worm can be developed as a model for study of HuR function for use in potential drug screens. We are also examining the role of another RNA-binding protein, MSI-1, which has a structure similar to that of EXC-7, and whose homologue has been implicated in interactions with HuR. Preliminary evidence suggests that EXC-7 and MSI-1 proteins may cause similar phenotypes in C. elegans as well.

Hansen EL et al. (1971) Experientia "Effect of insect hormones on nematodes in axenic culture."

Hansen EL, Buecher EJ

[Experientia, 1971]

Insect juvenile hormones (JH) or JH mimetics have been shown to affect development of nematodes: Trichinella spiralis larvae and fourth stage Phocanema decipiens were inhibited, and abnormal morphology was seen in Heterodera schactii. The effects of insect hormones and analogues on development of several free-living and parasitic nematodes cultured axenically are described in the present paper.

Sim C et al. (2013) Front Physiol "Insulin signaling and the regulation of insect diapause."

Denlinger DL, Sim C

[Front Physiol, 2013]

A rich chapter in the history of insect endocrinology has focused on hormonal control of diapause, especially the major roles played by juvenile hormones (JHs), ecdysteroids, and the neuropeptides that govern JH and ecdysteroid synthesis. More recently, experiments with adult diapause in Drosophila melanogaster and the mosquito Culex pipiens, and pupal diapause in the flesh fly Sarcophaga crassipalpis provide strong evidence that insulin signaling is also an important component of the regulatory pathway leading to the diapause phenotype. Insects produce many different insulin-like peptides (ILPs), and not all are involved in the diapause response; ILP-1 appears to be the one most closely linked to diapause in C. pipiens. Many steps in the pathway leading from perception of daylength (the primary environmental cue used to program diapause) to generation of the diapause phenotype remain unknown, but the role for insulin signaling in mosquito diapause appears to be upstream of JH, as evidenced by the fact that application of exogenous JH can rescue the effects of knocking down expression of ILP-1 or the Insulin Receptor. Fat accumulation, enhancement of stress tolerance, and other features of the diapause phenotype are likely linked to the insulin pathway through the action of a key transcription factor, FOXO. This review highlights many parallels for the role of insulin signaling as a regulator in insect diapause and dauer formation in the nematode Caenorhabditis elegans.

Fodor A et al. (1989) General & Comparative Endocrinology "Effects of precocene analogs on the nematode Caenorhabditis remanei (var. Bangaloreiensis). 2. Competitions with a juvenile hormone analog (methoprene)."

Timar T, Fodor A

[General & Comparative Endocrinology, 1989]

Fourteen 7-alkoxy-2,2-dimethylchromenes were synthetized and studied in JH competition experiments: prococenes (Ps) PI and PII, and synthetic analogs (PAs) including (i) three with both antiallatal and P-like activities: 7-ethoxy-PII (7-EPII); 7-(prop-2-ynyloxy)-2,2-dimethylchromene (PPI); and 6-methoxy-7-(prop-2-yynyloxy)-2,2-dimethylchromene (PPIII); (ii) six without antiallatal activity, exerting P-like activity in nematodes; and (iii) three without either antiallatal or P-like activity, but with a strong nematocidal effect. Within the dose range 8-1000 ug/ml, different concentrations of each PA were applied to nematode growth medium which did or did not contain 1000 ug methoprene (a juvenile hormone analog JHA)/ml. Plates inoculated with Caenorhabditis embryos were incubated and scored for developmentally affected survivors. The JHA did not compete with any PA mentioned as (iii). It competed moderately with some nonantiallatal PAs (8-Me-PPI, 8-MeO-PPI, and 3,4-diCl-PPI) with strong P-like and nematocidal activities. The JHA competed most efficiently with all Ps, antiallatal PAs, and two nonantiallatal PAs (PPII and thio-PI) which exerted severe P-like activities in nematodes. Parameters assumed to be indicators of the P-like (rather than nematocidal) activity of the PAs proved more sensitive to the JHA than those of nematocidal activity. Whether the JH-compensable P-like activity of some PAs can be regarded as a real anti-JH action needs further clarification.

Landis GN et al. (2020) J Gerontol A Biol Sci Med Sci "Metabolic Signatures of Life Span Regulated by Mating, Sex Peptide and Mifepristone/RU486 in Female Drosophila melanogaster."

Abdelmesieh M, Patel P, Wang T, Tower J, Wang L, Fan Y, Promislow DEL, Doherty DV, Lee S, Vroegop J, Wu J, Shen J, Landis GN, Yen CA, Wang I, Curran SP

[J Gerontol A Biol Sci Med Sci, 2020]

Mating and transfer of male Sex Peptide (SP), or transgenic expression of SP, causes inflammation and decreased life span in female Drosophila. Mifepristone rescues these effects, yielding dramatic increases in life span. Here targeted metabolomics data were integrated with further analysis of extant transcriptomic data. Each of seven genes positively correlated with life span were expressed in the brain or eye, and involved regulation of gene expression and signaling. Genes negatively correlated with life span were preferentially expressed in midgut and involved protein degradation, amino acid metabolism, and immune response. Across all conditions, life span was positively correlated with muscle breakdown product 1/3-methylhistadine and purine breakdown product urate, and negatively correlated with tryptophan breakdown product kynurenic acid, suggesting a SP-induced shift from somatic maintenance/turnover pathways to the costly production of energy and lipids from dietary amino acids. Some limited overlap was observed between genes regulated by mifepristone and genes known to be regulated by ecdysone, however, mifepristone was unable to compete with ecdysone for activation of an ecdysone-responsive transgenic reporter. In contrast, genes regulated by mifepristone were highly enriched for genes regulated by Juvenile Hormone (JH), and mifepristone rescued the negative effect of JH analog methoprene on life span in adult virgin females. The data indicate that mifepristone increases life span and decreases inflammation in mated females by antagonizing JH signaling downstream of male SP. Finally, mifepristone increased life span of mated, but not unmated, C. elegans, in two of three trials, suggesting possible evolutionary conservation of mifepristone mechanisms.

Fodor A et al. (1987) Worm Breeder's Gazette "competition of exogenous methoprene and precocenes in nematodes: the end of the story."

Timar T, Hosztafi S, Dinya Z, Fodor A, Kiss I

[Worm Breeder's Gazette, 1987]

We have accomplished a ten year long project aimed to learn whether competition between the juvenile hormone (JH) analogue methoprene (JHA) and precocenes (P's) (chromene derivatives capable to destruct the JH producing organ (CA) in sensitive insect species tissue specifically) in C. elegans (Fodor, et. al., Gen. Comp. Endcr. 46: p. 99 (1982)) can or cannot be explained by a comparable 'anti-JH' action of P's in nematodes. Neither JH or CA like organ has been discovered in nematodes so far. There are only a few indirect data showing that insect juvenile hormones may influence certain nematodes pathogenizing insects. We adopted a 'structure/activity' approach including design, synthesis and test P analogues on nematodes in the presence and absence of JHA. If (at least part of) those analogues which capable to destruct the CA of a sensitive insect (Locusta migratoria) were also effective in nematodes and their effect could be compensated by JHA exogenously, then this hormone (analogue) should play a physiological role in the P-poisoned nematodes. If those P's could be competed by JHA, which proved effective (as 'anti-JH' compounds) in insects, but those which exerted only aspecific toxicity could not be, then it would be logical to suggest, that P's are the same kind of 'suicide compounds' for nematodes as for insects. More than 200 P derivatives were synthesized (Tim r, Hosztafi) and tested on C. elegans (Fodor) and L. migratoria (Kiss). After a detailed quantitative structure/activity relation (QSAR) analysis ( Dinya, et. al., QSAR Strat. Des. Bioact. Compd. Proc. Eur. Symp. Struct.-Act. Relat. 5th (1984) Publ. 1985) several new P analogue were designed, synthesized and tested on L. migratoria and on C. remanei var. Bangaloriensis. (We choose this nematode strain because half of its population consists of males, therefore it is easy to distinguish male adultoids from other type of retarded worms.) Altogether, 121 molecules were retested C. remanei and 17 of them was found to exert some significant biological effect. These compounds were retested again several times both in the absence and in the presence of 1 mg/ml NGM dose of JHA: altogether, more that 144,000 C. remanei embryos were counted, treated and scored afterwards. The tests on nematodes were carried out as described in our attached paper. The most characteristic data concerning precocene activity in nematodes were the following: (1) LC50: the half lethal dose (in g/ml) at which half of the embryos develops to worms (calculated by probit analysis); (2) AD50: the dose ( g/ml) at which half of the embryos develops to normal adults; (3) EC50: the dose ( g/ml) at which half of the nematodes on the plates found as 'normal' fertile adults; (4) The maximum frequency of 'adultoid mini worms' during the experiments. [See Figures 1- 2] The main conclusions are the following: About structure/activity relations: (1) All the three (P1-P3) precocene is effective in nematodes and their effects can be compensated by exogenous JHA. (2) The longer the chain of the R7 substituent the less the effect of the compounds in nematodes. (3) The 7-proparglyoxy analogues are much more effective in nematodes than any other C7 substituted compound. (compare P1 to TT51; P2 to K460; P3 to TT80; TT56 to TT58 or 3,4-diCl-P1 (inactive) to FI121.) (4) The asymmetrically disubstituted analogues are much more effective than the symmetrically disubstituted ones (compare TT80 to K460). It is true, if R7 is longer than R6. (5) Me substitution at C5 position inactivates the originally potent P's (compare TT58 to TT51) but restore the activity of originally inactive (for instance, 7-sBuO-P1) analogues (compare it to TT56). 8-MeO substitution eliminate specific P activity (compare TT51 to K464). (6) Both 8-Me and 8-MeO substitution increase toxic rather than JH compatible biological activity of P's. 8-MeO analogues are more toxic than 8-Me ones, but the consequences of the action of 8-MeO compounds in nematodes can be cured more efficiently by JHA than those concerning 8-Me compounds (compare TT100 to K475). About JHA competition experiments: JHA competed the effects of all precocenes which effected both insects and nematodes. However, the data concerning K354 and FI121 show, that there are analogues which effective only in nematodes and their effects can also be cured by exogenous JHA. Although there are aspecifically toxic analogues (like K454 or 2,3,5-triMe-7 propargO-P1) which cannot be compensated by methoprene, we cannot conclude, that our data unambiguously support the idea of existence JH-like hormones in nematodes. It seems very probable, however, that JH-like compounds can interfere with the lethal metabolism of P's.

Olsen, Anders et al. (2009) International Worm Meeting "A whole genome screen for checkpoint functions that determine lifespan in C. elegans."

Zhang, Mike, J. Lithgow, Gordon, A. Caldwell, Guy, Hamamichi, Shusei, Olsen, Anders, Zeng, Xianmin, Mark, Karla, Benedetti, Michael, A. Caldwell, Kim, L. Knight, Adam, Bhaumik, Dipa, Vantipalli, Maithili

[International Worm Meeting, 2009]

Based on our previous observation that gene encoding cell cycle checkpoint functions determined lifespan in C. elegans, we aimed to define the genetic pathways at play. Three observations prompt this study. First we isolated a mutation in the gene checkpoint gene cid-1 which causes thermotolerance, increased lifespan and resistance to hydroxyurea (HU). Second we also found that mutations in other checkpoint genes and the tumor suppressor p53 confer resistance to HU. Third, since the nematode is post-mitotic, it is possible to study the effect of knocking down these genes in a whole organism without occurrence of lethal cancers. When wild-type eggs are placed on NGM plates spotted with HU the worms arrest development in a dose dependent manner. We screened for RNAi clones that suppressed this arrested development. All hits were re-tested at multiple doses of HU and resistance quantified as body size at three days of age. ~ 50 clones reproducibly result in HU resistance (hur genes) We are currently examining the hur genes for abnormal germline development, sterility and embryonic lethality. Many known cell cycle and checkpoint mutants show sensitivity to DNA damage. Therefore, to further test for cell cycle / checkpoint phenotypes we are exposing young worms to ionizing radiation and studying three different markers of DNA damage/checkpoint inefficiency, embryonic lethality, cell cycle arrest and apoptosis in the germline. We observed thermotolerance for 21 of the hits but not for all of them. Thus, HU resistance does not stem from a generalized increase in stress resistance but from a more specific mechanism. One of the clones increases thermotolerance of daf-2, daf-16 and eat-2 mutants and seems to function independently from insulin signaling and caloric restriction. Aging is one of the biggest risk factors for cancer. Our ongoing analysis suggests that the hur gene list is highly enriched for increased lifespan although some result in shortened lifespan. We are investigating these and similar genes in a number of neuronal cell death models including human cells.