Loo TW et al. (2013) Biochemistry "A salt bridge in intracellular loop 2 is essential for folding of human p-glycoprotein."

Clarke DM, Loo TW

[Biochemistry, 2013]

There is no high-resolution structure of the human P-glycoprotein (P-gp, ABCB1) drug pump. Homology models based on the crystal structures of mouse and Caenorhabditis elegans P-gps show extensive contacts between intracellular loop 2 (ICL2, in the first transmembrane domain) and the second nucleotide-binding domain. Human P-gp modeled on these P-gp structures yields different ICL2 structures. Only the model based on the C. elegans P-gp structure predicts the presence of a salt bridge. We show that the Glu256-Arg276 salt bridge was critical for P-gp folding.

Loo TW et al. (2013) Biochemistry "Drug rescue distinguishes between different structural models of human P-glycoprotein."

Clarke DM, Loo TW

[Biochemistry, 2013]

There is no high-resolution crystal structure of the human P-glycoprotein (P-gp) drug pump. Homology models of human P-gp based on the crystal structures of mouse or Caenorhabditis elegans P-gps show large differences in the orientation of transmembrane segment 5 (TM5). TM5 is one of the most important transmembrane segments involved in drug-substrate interactions. Drug rescue of P-gp processing mutants containing an arginine at each position in TM5 was used to identify positions facing the lipid or internal aqueous chamber. Only the model based on the C. elegans P-gp structure was compatible with the drug rescue results.

Lee JH et al. (2022) Nutrients "Maternal Gliadin Intake Reduces Oocyte Quality with Chromosomal Aberrations and Increases Embryonic Lethality through Oxidative Stress in a Caenorhabditis elegans Model."

Min H, Shim YH, Lee M, Youn E, Lee JH

[Nutrients, 2022]

Oocyte quality is essential for reproductive capacity, but it rapidly declines with age. In addition to aging, maternal nutrition is a major concern in maintaining oocyte quality. Gliadin, a major component of gluten, causes gluten toxicity, which has been reported in a variety of gluten-related disorders. The basis of gluten toxicity in reproduction is being understood using simple animal models such as Caenorhabditis elegans. In this study, we examined the effects of gliadin peptide (GP; amino acids 151-170) intake on oocyte quality control in C. elegans. We found that GP intake impaired oocyte quality through chromosomal aberrations and mitochondrial oxidative stress, which was suppressed by antioxidant treatment. The reduced oocyte quality by GP intake consequently increased embryonic lethality. Furthermore, the expression of oxidative stress-responding genes prdx-3 and gst-4 was significantly increased by GP intake. The increased DAF-16 activity by GP intake suggests that DAF-16 is a possible transactivator of these antioxidant genes. Taken together, GP intake reduced reproductive capacity in C. elegans by decreasing oocyte quality and increasing embryonic lethality through mitochondrial oxidative stress.

Martinez-Lopez AL et al. (2021) Drug Deliv Transl Res "Zein-based nanocarriers for the oral delivery of insulin. In vivo evaluation in Caenorhabditis elegans."

Martinez-Lopez AL, Vizmanos JL, Irache JM, Gonzalez-Navarro CJ

[Drug Deliv Transl Res, 2021]

The aim was to evaluate the potential of nanocarriers, based on the coating of zein nanoparticles (ZNP) with a Gantrez AN-PEG conjugate (GP), for the oral delivery of insulin. ZNP-GP displayed less negative surface charge and a 14-fold higher diffusion coefficient in pig intestinal mucus than ZNP. Both nanoparticles showed a spherical shape and an insulin load of 77.5g/mg. Under simulated gastric conditions, ZNP-GP released significantly lower amount of insulin than ZNP, while under simulated intestinal conditions, both types of nanoparticles displayed similar behaviour. In Caenorhabditis elegans wild-type N2, grown under high glucose conditions, insulin treatments reduced glucose and fat accumulation without altering the growth rate, the worm length, or the pumping rate. The effect was significantly greater (p<0.001) when insulin was nanoencapsulated in ZNP-GP compared with that encapsulated in ZNP or formulated in solution. This would be related to the highest capability of ZNP-GP to diffuse in the dense peritrophic-like layer covering intestinal cells in worms. In daf-2 mutants, the effect on fat and glucose reduction by insulin treatment was suppressed, indicating a DAF-2 dependent mechanism. In summary, ZNP-GP is a promising platform that may offer new opportunities for the oral delivery of insulin and other therapeutic proteins.

Wang X et al. (2019) Int J Biol Macromol "The anti-aging effects of Gracilaria lemaneiformis polysaccharide in Caenorhabditis elegans."

Chen X, Zhang Z, Zhou H, Wang X, Xu N, Sun X

[Int J Biol Macromol, 2019]

The anti-aging activity of marine macroalgae Gracilaria lemaneiformis polysaccharide (GP) on Caenorhabditis elegans was evaluated by observing the lifespan, reproduction, pharyngeal pumping and stress response of worms. Moreover, quantitative fluorescence of polyglutamic acid and nuclear localization of DAF-16 were observed. The results showed that GP treatment enhanced the mean lifespan by over 16.47% and significantly increased the reproduction duration of worm in the high dose group (1000g/mL). GP exhibited little potent effects under the thermotolerance and oxidative stress. The number of polyglutamic acid aggregates in three dosage groups decreased by 24.82%, 32.08% and 30.93% (p<0.05) compared to the control. The middle dose group strongly induced DAF-16 nuclear translocation over intermediate and cytosolic localizations compared to the control (p<0.001). It was inferred that GP extended the adult lifespan of wild-type and polyQ nematodes through the insulin pathway DAF-16.

Shelton CA et al. (2000) East Coast Worm Meeting "A C. elegans gene related to S. pombe pom1 is required for microtubule-based processes in the C. elegans embryo"

Creasy CL, Livi GP, Shelton CA

[East Coast Worm Meeting, 2000]

Mutations in the Schizosaccharomyces pombe gene pom1 result in the misplacement of septa, as well as misplacement of microtubule organizing centers during cell division (1). In addition, pom1 mutants are synthetically lethal with mutations affecting either the actin or microtubule cytoskeleton; and the distribution of pom1 protein, Pom1p, within the cell depends on intact microtubules. These observations suggest that Pom1p has a role in positional regulation of the cytoskeleton during division in S. pombe. Pom1p belongs to a protein kinase family with related members in S. cerevisiae, C. elegans, Drosophila, and humans. The functional role of a C. elegans pom1-like gene was examined using RNA interference. 100% lethality was observed among embryos laid by hermaphrodites injected 24 hours prior with dsRNA corresponding to the C. elegans pom1-like gene. A reduced number of severly aneuploid cells were observed in terminal stage embryos. Observations of pronuclear-stage embryos revealed defects in pronuclear migration, spindle orientation, DNA segregation, and cytokinesis. However, actin-based processes such as pseudocleavage formation, cytoplasmic flow, and cleavage furrow formation appeared normal. Therefore, we hypothesize that the C. elegans pom1-like protein is required for microtubule dynamics in the early embryo and, given the similarities between the S. pombe and C. elegans mutant phenotypes, suggest that the yeast and worm genes are functionally conserved. 1. Bahler, J., and J.R. Pringle, Genes and Development, 12(9):1356-1370.

Frandsen J et al. (2020) ACS Chem Neurosci "Neural Glyoxalase Pathway Enhancement by Morin Derivatives in an Alzheimer's Disease Model."

Frandsen J, Narayanasamy P, Choi SR

[ACS Chem Neurosci, 2020]

The gyloxalase pathway (GP) is an antioxidant defense system that detoxifies metabolic byproduct methylglyoxal (MG). Through sequential reactions, reduced glutathione (GSH), glyoxalase I (glo-1), and glyoxalase II (glo-2) convert MG into D-lactate. Spontaneous reactions involving MG alter the structure and function of cellular macromolecules through the formation of inflammatory advanced glycation endproducts (AGEs). Accumulation of MG and AGEs in neural cells contributes to oxidative stress (OS), a state of elevated inflammation commonly found in neurodegenerative diseases including Alzheimer's Disease (AD). Morin is a common plant-produced flavonoid polyphenol that exhibits the ability to enhance the GP-mediated detoxification of MG. We hypothesize that structural modifications to morin will improve its inherent GP enhancing ability. Here we synthesized a morin derivative, dibromo-morin (DBM) and formulated a morin encapsulated nanoparticle (MNP) - and examined their efficacy in enhancing neural GP activity. Cultured mouse primary cerebellar neurons and Caenorhabditis elegans were induced to a state of OS with MG, and treated with morin, DBM, and MNP. Results indicated the morin derivatives were more effective compared to the parent compound in neural GP enhancement and preventing MG-mediated OS.

Hakala BE et al. (1993) J Biol Chem "Human cartilage gp-39, a major secretory product of articular chondrocytes and synovial cells, is a mammalian member of a chitinase protein family."

Recklies AD, Hakala BE, White C

[J Biol Chem, 1993]

One of the major secreted proteins of human articular chondrocytes in monolayer or explant culture and of synovial fibroblasts is a glycoprotein with an apparent molecular weight of approximately 39,000, referred to as human cartilage glycoprotein-39 (HC gp-39). The protein was purified, and its complete cDNA sequence was determined. It contained an open reading frame coding for a 383-amino acid long peptide. Comparison of the deduced amino acid sequence with known sequences revealed that HC gp-39 contained regions displaying significant homology with a group of bacterial and fungal chitinases and a similar enzyme found in the nematode, Brugia malayi. In addition significant homologies were observed with three mammalian secretory proteins of as yet unknown function, suggesting that a related protein family exists in mammals. The human protein does not possess any glycosidic activity against chitinase substrates, arguing against any function as an endoglycosidase with specificity for N-acetylglucosamine. Analysis by Northern blotting and by reverse transcription/polymerase chain reaction showed mRNA for HC gp-39 to be present in human articular chondrocytes as well is in liver, while mRNA was undetectable in muscle tissues, lung, pancreas, mononuclear cells, or fibroblasts. Neither the protein nor mRNA for HC gp-39 was detectable in normal newborn or adult human articular cartilage obtained at surgery, while mRNA for HC gp-39 was detectable both in synovial specimens and in cartilage obtained from patients with rheumatoid arthritis. These observations suggest that the expression of HC gp-39 may be related to a response of these cells to an altered tissue environment.

Jin MS et al. (2012) Nature "Crystal structure of the multidrug transporter P-glycoprotein from Caenorhabditis elegans."

Jin MS, Chen J, Zhang Q, Oldham ML

[Nature, 2012]

P-glycoprotein (P-gp) is an ATP-binding cassette transporter that confers multidrug resistance in cancer cells. It also affects the absorption, distribution and clearance of cancer-unrelated drugs and xenobiotics. For these reasons, the structure and function of P-gp have been studied extensively for decades. Here we present biochemical characterization of P-gp from Caenorhabditis elegans and its crystal structure at a resolution of 3.4angstroms. We find that the apparent affinities of P-gp for anticancer drugs actinomycinD and paclitaxel are approximately 4,000 and 100 times higher, respectively, in the membrane bilayer than in detergent. This affinity enhancement highlights the importance of membrane partitioning when a drug accesses the transporter in the membrane. Furthermore, the transporter in the crystal structure opens its drug pathway at the level of the membrane's inner leaflet. In the helices flanking the opening to the membrane, we observe extended loops that may mediate drug binding, function as hinges to gate the pathway or both. We also find that the interface between the transmembrane and nucleotide-binding domains, which couples ATP hydrolysis to transport, contains a ball-and-socket joint and salt bridges similar to the ATP-binding cassette importers, suggesting that ATP-binding cassette exporters and importers may use similar mechanisms to achieve alternating access for transport. Finally, a model of human P-gp derived from the structure of C. elegans P-gp not only is compatible with decades of biochemical analysis, but also helps to explain perplexing functional data regarding the Phe335Ala mutant. These results increase our understanding of the structure and function of this important molecule.

Costa JC et al. (2009) Int J Parasitol "Functional characterisation of a cyst nematode acetylcholinesterase gene using Caenorhabditis elegans as a heterologous system."

Costa JC, Atkinson HJ, Lilley CJ, Urwin PE

[Int J Parasitol, 2009]

Migration of plant-parasitic nematode infective larval stages through soil and invasion of roots requires perception and integration of sensory cues culminating in particular responses that lead to root penetration and parasite establishment. Components of the chemoreceptive neuronal circuitry involved in these responses are targets for control measures aimed at preventing infection. Here we report, to our knowledge, the first isolation of cyst nematode ace-2 genes encoding acetylcholinesterase (AChE). The ace-2 genes from Globodera pallida (Gp-ace-2) and Heterodera glycines (Hg-ace-2) show homology to ace-2 of Caenorhabditis elegans (Ce-ace-2). Gp-ace-2 is expressed most highly in the infective J2 stage with lowest expression in the early parasitic stages. Expression and functional analysis of the Globodera gene were carried out using the free-living nematode C. elegans in order to overcome the refractory nature of the obligate parasite G. pallida to many biological studies. Caenorhabditis elegans transformed with a GFP reporter construct under the control of the Gp-ace-2 promoter exhibited specific and restricted GFP expression in neuronal cells in the head ganglia. Gp-ACE-2 protein can functionally complement its C. elegans homologue. A chimeric construct containing the Ce-ace-2 promoter region and the Gp-ace-2 coding region and 3' untranslated region was able to restore a normal phenotype to the uncoordinated C. elegans double mutant ace-1;ace-2. This study demonstrates conservation of AChE function and expression between free-living and plant-parasitic nematode species, and highlights the utility of C. elegans as a heterologous system to study neuronal aspects of plant-parasitic nematode biology.