Schaeffer JM et al. (1989) Biochem J "MK-801 is a potent nematocidal agent. Characterization of MK-801 binding sites in Caenorhabditis elegans."

Turner MJ, Bergstrom AR, Schaeffer JM

[Biochem J, 1989]

MK-801, an N-methyl-D-aspartate antagonist in mammalian brain tissue, is a potent nematocidal agent. Specific MK-801 binding sites have been identified and characterized in a membrane fraction prepared from the free-living nematode Caenorhabditis elegans. The high-affinity MK-801 binding site has an apparent dissociation constant, Kd, of 225 nM. Unlike the MK-801 binding site in mammalian tissues, the C. elegans binding site is not effected by glutamate or glycine, and polyamines are potent inhibitors of specific MK-801 binding.

Schaeffer JM et al. (1991) International C. elegans Meeting "NEMATOCIDAL ACTIVITY OF MK-801 ANALOGS AND RELATED DRUGS: STRUCTURE- ACTIVITY RELATIONSHIPS."

Frazier EG, Bergstrom AR, Underwood D, Schaeffer JM

[International C. elegans Meeting, 1991]

MK-801 is a potent and selective noncompetitive antagonist of the N- methyl-D-aspartate (NMDA) subclass of glutamate receptors in mammalian tissues. Electrophysiological and biochemical data suggest that MK-801 binds directly in the NMDA receptor channel complex and only when the channel has been opened by glutamate. Specific high affinity MK-801 binding sites have been identified and characterized in rat brain preparations. We recently reported that MK-801 has nematocidal activity and this activity is mediated via a ligand receptor interaction. A series of MK-801 analogs were evaluated for their affinity to the MK-801 binding site in Caenorhabditis elegans membranes and their nematocidal activity. A good correlation was observed, with the most potent inhibitors also being the most potent nematocidal compounds. Other noncompetitive inhibitors of the NMDA site were examined and a series of dibenzoguanidines were found to be potent nematocidal compounds. These compounds were competitive inhibitors of MK-801 binding. Molecular modeling studies support the hypothesis that the dibenzoguanidines and MK-801 are binding to the same site and suggest that more potent compounds may be developed by effective modeling of the existing compounds.

Schaeffer JM et al. (1994) Biochem Pharmacol "Nematocidal activity of MK-801 analogs and related drugs. Structure-activity relationships."

Bergstrom AR, Frazier EG, Underwood D, Schaeffer JM

[Biochem Pharmacol, 1994]

A series of dibenzo[a,d]cycloalkenimines were evaluated for their affinity to the (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801) binding site in Caenorhabditis elegans membranes and their nematocidal activity. The (+)-MK-801 enantiomer (1) had a higher affinity (Kd = 240 nM) for its specific binding site and was a more potent nematocidal agent than the (-)-MK-801 enantiomer (-1). Ring expansion to form the dibenzo[a,d]cyclooctenimine analogs generally resulted in more potent compounds. The most potent of this series (23) was approximately 7-fold more potent than (+)-MK-801. A good correlation was established between binding affinities and nematocidal activity for all of the analogs that were tested. However, there was no correlation between binding to C. elegans membranes and affinity for mammalian MK-801 binding sites. Other noncompetitive inhibitors of the mammalian N-methyl-D-aspartate site were examined, and a series of diphenylguanidines were identified as potent competitive inhibitors of MK-801 binding to C. elegans membranes, in addition to displaying potent nematocidal activity. The most potent diphenylguanidine analog (24) was approximately 80-fold more potent than (+)-MK-801 in both its affinity for the MK-801 binding site and as a nematocidal agent. Molecular modeling studies support the hypothesis that the diphenylguanidines and MK-801 are binding to the same site and suggest that more potent compounds may be developed by effective modeling of the existing compounds.

Wojtovich AP et al. (2012) FEBS Lett "Mitochondrial ATP-sensitive potassium channel activity and hypoxic preconditioning are independent of an inwardly rectifying potassium channel subunit in Caenorhabditis elegans."

Wojtovich AP, Nehrke K, DiStefano P, Sherman T, Brookes PS

[FEBS Lett, 2012]

Hypoxic preconditioning (HP) is an evolutionarily-conserved mechanism that protects an organism against stress. The mitochondrial ATP-sensitive K(+) channel (mK(ATP)) plays an essential role in the protective signaling, but remains molecularly undefined. Several lines of evidence suggest that mK(ATP) may arise from an inward rectifying K(+) channel (Kir). The genetic model organism Caenorhabditis elegans exhibits HP and displays mK(ATP) activity. Here, we investigate the tissue expression profile of the three C. elegans Kir genes and demonstrate that mutant strains where the irk genes have been deleted either individually or in combination can be protected by HP and exhibit robust mK(ATP) channel activity in purified mitochondria. These data suggest that the mK(ATP) in C. elegans does not arise from a Kir derived channel.

Tsai RT et al. (2020) Int J Mol Sci "Maackiain Ameliorates 6-Hydroxydopamine and SNCA Pathologies by Modulating the PINK1/Parkin Pathway in Models of Parkinson's Disease in Caenorhabditis elegans and the SH-SY5Y Cell Line."

Shyu WC, Lin SZ, Tsai RT, Fu RH, Tsai CW, Kuo YH, Hung HS, Chao PM, Gao JX, Liu SP

[Int J Mol Sci, 2020]

The movement disorder Parkinson's disease (PD) is the second most frequently diagnosed neurodegenerative disease, and is associated with aging, the environment, and genetic factors. The intracellular aggregation of -synuclein and the loss of dopaminergic neurons in the substantia nigra pars compacta are the pathological hallmark of PD. At present, there is no successful treatment for PD. Maackiain (MK) is a flavonoid extracted from dried roots of <i>Sophora flavescens</i> Aiton. MK has emerged as a novel agent for PD treatment that acts by inhibiting monoamine oxidase B. In this study, we assessed the neuroprotective potential of MK in <i>Caenorhabditis elegans</i> and investigated possible mechanism of this neuroprotection in the human SH-SY5Y cell line. We found that MK significantly reduced dopaminergic neuron damage in 6-hydroxydopamine (6-OHDA)-exposed worms of the BZ555 strain, with corresponding improvements in food-sensing behavior and life-span. In transgenic worms of strain NL5901 treated with 0.25 mM MK, the accumulation of -synuclein was diminished by 27% (<i>p</i> &lt; 0.01) compared with that in untreated worms. Moreover, in worms and the SH-SY5Y cell line, we confirmed that the mechanism of MK-mediated protection against PD pathology may include blocking apoptosis, enhancing the ubiquitin-proteasome system, and augmenting autophagy by increasing <i>PINK1/parkin</i> expression. The use of small interfering RNA to downregulate parkin expression in vivo and in vitro could reverse the benefits of MK in PD models. MK may have considerable therapeutic applications in PD.

Wojtovich AP et al. (2008) Biochem Biophys Res Commun "The C. elegans mitochondrial K+(ATP) channel: a potential target for preconditioning."

Burwell LS, Sherman TA, Brookes PS, Nehrke KW, Wojtovich AP

[Biochem Biophys Res Commun, 2008]

Ischemic preconditioning (IPC) is an evolutionarily conserved endogenous mechanism whereby short periods of non-lethal exposure to hypoxia alleviate damage caused by subsequent ischemia reperfusion (IR). Pharmacologic targeting has suggested that the mitochondrial ATP-sensitive potassium channel (mK(ATP)) is central to IPC signaling, despite its lack of molecular identity. Here, we report that isolated Caenorhabditis elegans mitochondria have an mK(ATP) channel with the same physiologic and pharmacologic characteristics as the vertebrate channel. Since C. elegans also exhibit IPC, our observations provide a framework to study the role of mK(ATP) in IR injury in a genetic model organism.

Bhar S et al. (2024) Cell Chem Biol "An acyl-CoA thioesterase is essential for the biosynthesis of a key dauer pheromone in C. elegans."

Bailey LS, Mai K, Prajapati DV, Basso KB, Butcher RA, Yoon CS, Steffen CL, Han J, Bhar S, Wang Y

[Cell Chem Biol, 2024]

Methyl ketone (MK)-ascarosides represent essential components of several pheromones in Caenorhabditis elegans, including the dauer pheromone, which triggers the stress-resistant dauer larval stage, and the male-attracting sex pheromone. Here, we identify an acyl-CoA thioesterase, ACOT-15, that is required for the biosynthesis of MK-ascarosides. We propose a model in which ACOT-15 hydrolyzes the &#x3b2;-keto acyl-CoA side chain of an ascaroside intermediate during &#x3b2;-oxidation, leading to decarboxylation and formation of the MK. Using comparative metabolomics, we identify additional ACOT-15-dependent metabolites, including an unusual piperidyl-modified ascaroside, reminiscent of the alkaloid pelletierine. The &#x3b2;-keto acid generated by ACOT-15 likely couples to 1-piperideine to produce the piperidyl ascaroside, which is much less dauer-inducing than the dauer pheromone, asc-C6-MK (ascr#2, 1). The bacterial food provided influences production of the piperidyl ascaroside by the worm. Our work shows how the biosynthesis of MK- and piperidyl ascarosides intersect and how bacterial food may impact chemical signaling in the worm.

Massey HC et al. (2006) Int J Parasitol "The fork head transcription factor FKTF-1b from Strongyloides stercoralis restores DAF-16 developmental function to mutant Caenorhabditis elegans."

Massey HC, Bhopale MK, Castelletto M, Li X, Lok JB

[Int J Parasitol, 2006]

The purpose of this study was to determine whether Strongyloides stercoralis FKTF-1, a transcription factor of the FOXO/FKH family and the likely output of insulin/IGF signal transduction in that parasite, has the same or similar developmental regulatory capabilities as DAF-16, its structural ortholog in Caenorhabditis elegans. To this end, both splice variants of the fktf-1 message were expressed under the control of the daf-16alpha promoter in C. elegans carrying loss of function mutations in both daf-2 (the insulin/IGF receptor kinase) and daf-16. Under well-fed culture conditions the majority (91%) of untransformed daf-2; daf-16 double mutants developed via the continuous reproductive cycle, whereas under the same conditions 100% of daf-2 single mutants formed dauers. Transgenic daf-2; daf-16 individuals expressing fktf-1b showed a reversal of the double mutant phenotype with 75% of the population forming dauers under well-fed conditions. This phenotype was even more pronounced than that of daf-2; daf-16 mutants transformed with a homologous rescuing construct, daf-16alpha::daf-16a (56% dauers under well fed conditions), indicating that S. stercoralis fktf-1b can almost fully rescue loss-of-function mutants in C. elegans daf-16. By contrast, daf-2; daf-16 mutants expressing S. stercoralis fktf-1a, encoding the second splice variant of FKTF-1, showed a predominantly continuous pattern of development identical to that of the parental double mutant stock. This indicates that, unlike FKTF-1b, the S. stercoralis transcription factor FKTF-1a cannot trigger the shift to dauer-specific gene expression in C. elegans.

Dong C et al. (2018) J Org Chem "Comparative Ascaroside Profiling of Caenorhabditis Exometabolomes Reveals Species-Specific () and ( - 2)-Hydroxylation Downstream of Peroxisomal -Oxidation."

Dong C, Bergame C, Srinivasan J, von Reuss SH, Dolke F, Reilly DK

[J Org Chem, 2018]

Chemical communication in nematodes, such as the model organism Caenorhabditis elegans, is modulated by a variety of glycosides based on the dideoxysugar L-ascarylose. Comparative ascaroside profiling of nematode exometabolome extracts using a GC-EIMS screen reveals that several basic components including ascr#1 (asc-C7), ascr#2 (asc-C6-MK), ascr#3 (asc-C9), ascr#5 (asc-C3), and ascr#10 (asc-C9) are highly conserved among the Caenorhabditis. Three novel, side chain hydroxylated ascaroside derivatives were exclusively detected in the distantly related C. nigoni and C. afra. Molecular structures of these species-specific, putative signaling molecules were elucidated by NMR spectroscopy and confirmed by total synthesis and chemical correlations. Biological activities were evaluated using attraction assays. The identification of ()- and ( - 2)-hydroxyacyl ascarosides demonstrates how GC-EIMS-based ascaroside profiling facilitates the detection of novel ascaroside components and exemplifies how species-specific hydroxylation of ascaroside aglycones downstream of peroxisomal -oxidation increases the structural diversity of this highly conserved class of nematode signaling molecules.

Muir RE et al. (2007) Int J Syst Evol Microbiol "Leucobacter chromiireducens subsp. solipictus subsp. nov., a pigmented bacterium isolated from the nematode Caenorhabditis elegans, and emended description of L. chromiireducens."

Muir RE, Tan MW

[Int J Syst Evol Microbiol, 2007]

A yellow-pigmented, Gram-positive, aerobic, non-motile, non-spore-forming, irregular rod-shaped bacterium (strain TAN 31504(T)) was isolated from the bacteriophagous nematode Caenorhabditis elegans. Based on 16S rRNA gene sequence similarity, DNA G+C content of 69.5 mol%, 2,4-diaminobutyric acid in the cell-wall peptidoglycan, major menaquinone MK-11, abundance of anteiso- and iso-fatty acids, polar lipids diphosphatidylglycerol and phosphatidylglycerol and a number of shared biochemical characteristics, strain TAN 31504(T) was placed in the genus Leucobacter. DNA-DNA hybridization comparisons demonstrated a 91 % DNA-DNA relatedness between strain TAN 31504(T) and Leucobacter chromiireducens LMG 22506(T) indicating that these two strains belong to the same species, when the recommended threshold value of 70 % DNA-DNA relatedness for the definition of a bacterial species by the ad hoc committee on reconciliation of approaches to bacterial systematics is considered. Based on distinct differences in morphology, physiology, chemotaxonomic markers and various biochemical characteristics, it is proposed to split the species L. chromiireducens into two novel subspecies, Leucobacter chromiireducens subsp. chromiireducens subsp. nov. (type strain L-1(T)=CIP 108389(T)=LMG 22506(T)) and Leucobacter chromiireducens subsp. solipictus subsp. nov. (type strain TAN 31504(T)=DSM 18340(T)=ATCC BAA-1336(T)).