Caenorhabditis Elegans Strains Research Articles

Cholinesterase inhibitory potential of Dillenia suffruticosa chemical constituents and protective effect against Aβ−induced toxicity in transgenic Caenorhabditis elegans model

BackgroundThe Dillenia suffruticosa leaves have been used in African tribal herbal medicine to relieve inflammatory conditions and memory loss. However, little is known about the phytoconstituents and their potential against cholinergic dysfunction and β-amyloid accumulation related to neurodegenerative disorder. PurposeThree triterpenoids and three flavonoids were isolated and investigated for acetylcholinesterase and butyrylcholinesterase inhibitions, including molecular docking mechanisms underlying the effects. The effect of the bioactive triterpenoids to delay the β-amyloid (Aβ)-induced paralysis of transgenic Caenorhabditis elegans strain GMC101 was also studied. MethodologyThe extraction, fractionation, and isolation of the phytoconstituents from D. suffruticosa leaves followed the results of cholinesterase inhibitory activities determined using the modified Ellman's method. The in silico molecular docking simulation studies investigated the mode of interactions of the phytoconstituents on Torpedo californica acetylcholinesterase (TcAChE) and human butyrylcholinesterase (huBuChE) enzymes. The transgenic C. elegans strain GMC101 was tested with and without betulinic acid (1) or koetjapic acid (2) on their potential to delay paralysis. ResultsBetulinic acid (1) had the highest potency in acetylcholinesterase inhibition (AChEI) and butyrylcholinesterase inhibition (BuChEI), followed by koetjapic acid (2), whereas stigmasterol glycoside (3) displayed the least potency. Vitexin (4), a C-glycoside displayed a higher potency than tiliroside (5), the O-glycosidic flavonoid against BuChE and AChE. Kaempferol (6), compared to its aglycone (5), was about 4 and 1.4 times more potent on AChEI and BuChEI, respectively. The selectivity indices suggested that the isolated phytoconstituents were dual AChE-BuChE inhibitors, more selective against BuChE than AChE, except 5. The molecular docking studies supported that small molecule like 6 only required very low binding energy unlike its glycoside (5), to dock fully at the overcrowded catalytic sites of AChE. Bulkier ligands docked more easily at lesser crowded BuChE active sites instead. For the first time, 2 was reported to delay Aβ-induced paralysis of transgenic C. elegans strain GMC101 and produced significantly longer survival time (p < 0.001) than 1. ConclusionThe studies demonstrated that bulky phytoconstituents from D. suffruticosa are more likely inhibitors of BuChE than AChE. Koetjapic acid (2) and betulinic acid (1) may possess protective potential against neurodegenerative disorders, related to their anti-cholinesterase and β-amyloid mechanisms.Significance statement:The bulkier phytoconstituents of D. suffruticosa are mainly triterpenoids and flavonoid glycosides which may have potential protective activity against memory loss and cognitive decline related to Alzheimer's disease.

A single copy transgenic mutant FUS strain reproduces age-dependent ALS phenotypes in C. elegans.

Mutations in the human DNA/RNA binding protein FUS are associated with amyotrophic lateral sclerosis and frontotemporal lobar degeneration, including some aggressive and juvenile onset forms. Cytoplasmic inclusions of human FUS proteins are observed in various neurodegenerative disorders, such as Huntington’s disease or spinocerebellar ataxia, suggesting that FUS proteinopathy may be a key player in neurodegeneration. To better understand the pathogenic mechanisms of FUS, we created single copy transgenic Caenorhabditis elegans strains expressing full-length, untagged human FUS in the worm’s GABAergic neurons. These transgenic worms expressing human mutant FUS (mFUS) display the same ALS-associated phenotypes than our previous multiple copy transgenic model, including adult-onset age-dependent loss of motility, progressive paralysis and GABAergic neurodegeneration. These phenotypes are distinct from the transgenic worms expressing human wild-type FUS (wtFUS). We introduce here our C. elegans single copy transgenic for human mutant FUS motor neuron toxicity that may be used for rapid genetic and pharmacological suppressor screening.

Whole Genome Sequencing identifies reciprocal translocation hT2(I;III) breakpoints.

We used whole-genome sequencing (WGS) data from a Caenorhabditis elegans strain homozygous for the reciprocal translocation hT2(I;III) to identify its breakpoints molecularly. The translocation structure is fairly straightforward, with only minor secondary rearrangement in addition to the primary breakpoints. The graphical representation below depicts the two hT2 half-translocations for ease of conceptualization.

Fenchol ameliorates Alzheimer’s disease like phenotypes by modulating microbiome/proteolysis/senescence axis

AbstractBackgroundAlzheimer’s disease (AD) is progressive debilitating public health problem, with no successful preventive and therapeutic strategy. Emerging evidence indicate that the gut microbiome and its metabolites like short chain fatty acids (SCFAs; such as acetate, propionate, butyrate) contribute in AD pathology. SCFAs function as gut microbiome sensors on distinct cell types including neurons through activating G‐couple protein receptors like free fatty acid receptor 2/3 (FFAR2/3). Therefore, targeting this signaling can be a novel strategy to ameliorate AD pathology.MethodUpon screening of &gt;144,000 natural compounds library with human FFAR2 docking patterns, and selected 14 compounds were further studied for FFAR2 signaling agonism by measuring phosph‐ERK1/2, cAMP and calcium levels in SK‐N‐SH cells that express FFAR2. In addition, selected compound (Fenchol) investigated for its beneficial effects on life‐span, Aβ accumulation, neurodegeneration and cognitive functions in Caenorhabditis (C.) elegans and cells.ResultWe demonstrated that FFAR2 expressed in neuronal cells, and its inhibition aggravates Aβ‐induced neuronal cell death. We screened &gt;144,000 natural compound library with human FFAR2 docking patterns, and selected 14 compounds, based on higher binding energy. Further, among them, Fenchol shows highest FFAR2 signaling activation in terms of phospho‐ERK1/2, inhibition in cAMP and increase in intracellular calcium in SK‐N‐SH cells. Interestingly, Fenchol enhanced longevity in wild‐type (N2), and human Aβ42 over‐expressing CL2600 Caenorhabditis (C.) elegans strains. Fenchol also reduced Aβ aggregates, neurodegeneration induced paralysis and cognitive memory (by chemotaxis assay) in C. elegans. In addition, Fenchol induced reduction in Aβ aggregates are linked with significantly increased proteolysis and reduced senescence (β‐galactosidase staining) in C. elegans and neuronal cells.ConclusionOverall, results demonstrate that Fenchol (a microbiome sensor through FFAR2 agonist) ameliorates Aβ aggregation in neuronal cells through activation of proteolysis and reduces senescence which ultimately can ameliorate AD pathology.

ATP13A2-mediated endo-lysosomal polyamine export counters mitochondrial oxidative stress

Recessive loss-of-function mutations in ATP13A2 (PARK9) are associated with a spectrum of neurodegenerative disorders, including Parkinson's disease (PD). We recently revealed that the late endo-lysosomal transporter ATP13A2 pumps polyamines like spermine into the cytosol, whereas ATP13A2 dysfunction causes lysosomal polyamine accumulation and rupture. Here, we investigate how ATP13A2 provides protection against mitochondrial toxins such as rotenone, an environmental PD risk factor. Rotenone promoted mitochondrial-generated superoxide (MitoROS), which was exacerbated by ATP13A2 deficiency in SH-SY5Y cells and patient-derived fibroblasts, disturbing mitochondrial functionality and inducing toxicity and cell death. Moreover, ATP13A2 knockdown induced an ATF4-CHOP-dependent stress response following rotenone exposure. MitoROS and ATF4-CHOP were blocked by MitoTEMPO, a mitochondrial antioxidant, suggesting that the impact of ATP13A2 on MitoROS may relate to the antioxidant properties of spermine. Pharmacological inhibition of intracellular polyamine synthesis with α-difluoromethylornithine (DFMO) also increased MitoROS and ATF4 when ATP13A2 was deficient. The polyamine transport activity of ATP13A2 was required for lowering rotenone/DFMO-induced MitoROS, whereas exogenous spermine quenched rotenone-induced MitoROS via ATP13A2. Interestingly, fluorescently labeled spermine uptake in the mitochondria dropped as a consequence of ATP13A2 transport deficiency. Our cellular observations were recapitulated in vivo, in a Caenorhabditis elegans strain deficient in the ATP13A2 ortholog catp-6 These animals exhibited a basal elevated MitoROS level, mitochondrial dysfunction, and enhanced stress response regulated by atfs-1, the C. elegans ortholog of ATF4, causing hypersensitivity to rotenone, which was reversible with MitoTEMPO. Together, our study reveals a conserved cell protective pathway that counters mitochondrial oxidative stress via ATP13A2-mediated lysosomal spermine export.

Vitexin prevents Aβ proteotoxicity in transgenic Caenorhabditis elegans model of Alzheimer's disease by modulating unfolded protein response.

Alzheimer's disease (AD) accounts for an estimated 60% to 80% of all dementia cases. The present study is aimed at evaluating the neuroprotective efficacy of vitexin, an apigenin flavone glycoside using transgenic Caenorhabditis elegans strain (CL2006) of AD. The neuroprotective effect of vitexin was determined using physiological assays, quantitative polymerase chain reaction, and Western blotting. The results of survival and paralysis assay indicate that vitexin (200 μM) significantly extended the lifespan of the nematodes. Vitexin-treated nematodes showed a significant reduction in the expression of Aβ, ace-1, and ace-2 genes when compared to control. Further, vitexin significantly upregulated the expression of acr-8 and dnj-14, and increased the lifespan of the nematodes. Vitexin was also found to modulate the unfolded protein response genes (hsp-4, pek-1, ire-1, and xbp-1) and suppress the expression of Aβ. Overall, the results show that vitexin acts as a neuroprotective agent and protects transgenic C. elegans strains from Aβ proteotoxicity.

Quercetin enhances motility in aged and heat-stressed Caenorhabditis elegans nematodes by modulating both HSF-1 activity, and insulin-like and p38-MAPK signalling.

Quercetin is a yellow pigment that is found in many common dietary plants, and that protects against oxidative stress, inflammation, and arteriosclerosis. It has also been suggested to prolong the lifespan of, and enhance heat-stress tolerance in nematodes; thus, the present study investigated its effects on both the nematode life- and health span by assessing its capacity to promote nematode motility after aging and/or heat stress, as well as the mechanisms underlying these effects. The results of the conducted analyses showed that quercetin feeding prolonged lifespan, suppressed age-related motility retardation, improved motility recovery after heat stress, and decreased the production of both intercellular and mitochondrial reactive oxygen species in the analysed Caenorhabditis elegans strains, likely by modulating the insulin-like signalling (ILS) pathway and p38-mitogen-activated protein kinase (MAPK) pathway. In particular, the transcription factors DAF-16 and SKN-1 were found to mediate the observed quercetin-induced effects, consistent with their previously demonstrated roles as regulators of aging. Furthermore, we demonstrated, for the first time, that quercetin induced heat-stress tolerance in C. elegans by modulating HSF-1 expression and/or activity. Thus, the present study provides valuable insights into the mechanisms by which quercetin inhibit aging and enhance heat-stress tolerance via ILS and MAPK pathway in C. elegans.

Mating Affects Lifespan Differently in Two Strains of Pseudo-female Caenorhabditis elegans

Mating is vital for sexually reproducing species, yet the ideal mating strategy for males and females can differ. The ensuing conflict between the sexes – namely, sexual conflict – results in a decrease in population level fitness. The degree of sexual conflict can be affected by the behavior, physiology, and life history of a population. Previous studies in the nematode Caenorhabditis elegans have shown that mating causes lifespan to decrease in pseudo-females and hermaphrodites, which was interpreted as evidence of sexual conflict. However, it is still an open question whether variations in mating condition and strain type can affect the degree of sexual conflict and lifespan decrease. Here, I investigate whether lifespan is affected by mating in conditions other than sex- skewed individual mating scenarios used in previous work. I conducted population-based mating assays in two different strains of C. elegans using both natural and male-skewed sex ratios. Counter to expectations, I found no effect of mating on lifespan in a wild isolate of C. elegans, while virgins from a canonical laboratory strain had a decreased lifespan relative to their counterparts mated in groups. My data offers a counterpoint to the literature, which agrees that mating universally decreases the lifespan of C. elegans pseudo-females and hermaphrodites. These results highlight the flexibility of reproductive costs and the importance of life histories in experimental populations.

Genetically modified Caenorhabditis elegans may lead to inaccurate toxicity evaluation of mixtures

BackgroundOne of the major challenges in environmental science is how to assess the toxicity and risk of complex pollutant mixtures. However, only a few studies have pointed out that there is a significant difference between the toxicities of chemicals on genetically modified strains and wild-type organisms and there are few reports of the differences in the toxicity of chemical mixtures. Therefore, six chemicals, two substituted phenols (4-chlorophenol and 4-nitrophenol), two pesticides (dichlorvos and glyphosate) and two ionic liquids (1-butylpyridinium chloride and 1-butylpyridinium bromide), were selected to construct a six-component mixture system, the lethality of various mixtures on the genetically modified Caenorhabditis elegans strain mtl-2::GFP (MTL-2) at 12 and 24 h were determined, and differences in toxicity to other strains were compared.ResultsAlthough the toxicity of 4-chlorophenol on MTL-2 was not significantly different from that on N2 wild-type Caenorhabditis elegans (N2), the toxicities of the other five chemicals on MTL-2 were greater than those on N2. The toxicities of six single chemicals and nine mixture rays on MTL-2 increased with time, which is consistent with the effect on N2 and on the genetically modified strain sod-3::GFP Caenorhabditis elegans (SOD-3). The toxicological interactions of various mixtures in MTL-2 at 12 h were half antagonistic (ANT) and half additive (ADD), while at 24 h, they were mainly synergistic (SYN). The toxicological interactions of various mixtures in MTL-2 change from ANT/ADD to primarily SYN with time, which is different from the change from ANT to ADD in SOD-3 and from SYN to ADD in N2.ConclusionsThe toxicity and toxicity interactions of chemical mixtures on different Caenorhabditis elegans strains are different. Therefore, it is necessary to examine the effect of genetic factors on the toxicological interaction of mixtures to avoid underestimating or overestimating the mixture risk.

Single Amino Acid Changes in the Ryanodine Receptor in the Human Population Have Effects In Vivo on Caenorhabditis elegans Neuro-Muscular Function.

The ryanodine receptor mediates intracellular calcium ion release with excitation of nerve and muscle cells. Ryanodine receptor missense variants cause a number of myopathologies, such as malignant hyperthermia, and have been linked with various neuropathologies, including Alzheimer’s disease. We characterized the consequences of ryanodine receptor variants in vivo. Eight Caenorhabditis elegans strains, with ryanodine receptor modifications equivalent to human myopathic RYR1 variants, were generated by genome editing. In humans, these variants are rare and confer sensitivity to the inhalational anaesthetic halothane when heterozygous. Increased sensitivity to halothane was found in both homozygous and heterozygous C. elegans. Close analysis revealed distinct subtle locomotion defects, due to the different single amino acid residue changes, even in the absence of the external triggering agent. Distinct pre- and postsynaptic consequences of the variants were characterized through the responses to cholinergic pharmacological agents. The range of phenotypes reflects the complexity of the regulatory inputs to the ryanodine receptor and the criticality of the calcium ion channel opening properties, in different cell types and with age. Ryanodine receptors with these single amino acid residue changes still function as calcium ion channels, but with altered properties which are likely to have subtle consequences for human carriers of such variants. The long-term consequences of subtly altered calcium ion signalling could be cumulative and may be focussed in the smaller nerve cells rather than the more robust muscle cells. It was important to assess phenotypes in vivo to properly appreciate consequences for a whole organism.

Caffeine reduces deficits in mechanosensation and locomotion induced by L-DOPA and protects dopaminergic neurons in a transgenic Caenorhabditis elegans model of Parkinson’s disease

Context L-DOPA is the first-line drug for Parkinson’s disease (PD). However, chronic use can lead to dyskinesia. Caffeine, which is a known neuroprotectant, can potentially act as an adjunct to minimise adverse effects of L-DOPA. Objectives This study determined changes in terms of neurodegeneration, locomotion and mechanosensation in Caenorhabditis elegans (Rhabditidae) strain UA57 overexpressing tyrosine hydroxylase (CAT-2) when treated with caffeine, L-DOPA or their combinations. Materials and methods Neurodegeneration was monitored via fluorescence microscopy of GFP-tagged dopaminergic neurons in the head and tail regions of C. elegans. Meanwhile, mechanosensation and locomotion under vehicle (0.1% DMSO), L-DOPA (60 mM), caffeine (10 mM) or 60 mM L-DOPA + 10 or 20 mM caffeine (60LC10 and 60LC20) treatments were scored for 3 days (n = 20). Results L-DOPA (60 mM) reduced CEP and ADE neurons by 4.3% on day 3, with a concomitant decrease in fluorescence by 44.6%. This correlated with reductions in gentle head (−35%) and nose touch (−40%) responses, but improved locomotion (20–75%) compared with vehicle alone. CEP and ADE neuron counts were preserved with caffeine (10 mM) or 60LC10 (98–100%), which correlated with improved mechanosensation (10–23%) and locomotion (18–76%). However, none of the treatments was able to preserve PDE neuron count, reducing the basal slowing response. Discussion and conclusions Taken together, we show that caffeine can protect DAergic neurons and can reduce aberrant locomotion and loss of sensation when co-administered with L-DOPA, which can potentially impact PD treatment and warrants further investigation.

Evaluation of anticancer potential of Eleusine indica methanolic leaf extract through Ras- and Wnt-related pathways using transgenic Caenorhabditis elegans strains

Background: In the Philippines, many accounts have resurfaced claiming different herbal and therapeutic advantages of Eleusine indica. One of these advantages is its anticancer potential. Despite some studies showing that the crude extract has cytotoxic and radical scavenging activity, it is still insufficient and further scientific evidence is needed to support this claim. Aim: Hence, we evaluate the anticancer potential of E. indic a methanolic leaf extract (EMLE) by focusing on two cancer-related pathways, Ras and Wnt pathways. Subjects and Methods: We used wild-type and transgenic Caenorhabditis elegans strains which have an irregular Ras or Wnt signaling. We determined the average number of eggs laid of each strain and the multivulva development of the Ras-mutant strain. Results: Our experiments show that EMLE does not affect the number of eggs laid of the wild-type, Ras-mutant-and Wnt-mutant worms. Furthermore, EMLE was not able to reduce Ras-mutant population demonstrating multi-vulva. Conclusion: Taken together, our data suggest that the anticancer potential of EMLE may be independent of Ras and Wnt signaling pathways.

A Novel Microtubule-Binding Drug Attenuates and Reverses Protein Aggregation in Animal Models of Alzheimer's Disease.

Age-progressive neurodegenerative pathologies, including Alzheimer’s disease (AD), are distinguished and diagnosed by disease-specific components of intra- or extra-cellular aggregates. Increasing evidence suggests that neuroinflammation promotes protein aggregation, and is involved in the etiology of neurological diseases. We synthesized and tested analogs of the naturally occurring tubulin-binding compound, combretastatin A-4. One such analog, PNR502, markedly reduced the quantity of Alzheimer-associated amyloid aggregates in the BRI-Aβ1–42 mouse model of AD, while blunting the ability of the pro-inflammatory cytokine IL-1β to raise levels of amyloid plaque and its protein precursors in a neuronal cell-culture model. In transgenic Caenorhabditis elegans (C. elegans) strains that express human Aβ1–42 in muscle or neurons, PNR502 rescued Aβ-induced disruption of motility (3.8-fold, P < 0.0001) or chemotaxis (1.8-fold, P < 0.05), respectively. Moreover, in C. elegans with neuronal expression of Aβ1–42, a single day of PNR502 exposure reverses the chemotaxis deficit by 54% (P < 0.01), actually exceeding the protection from longer exposure. Moreover, continuous PNR502 treatment extends nematode lifespan 23% (P ≤ 0.001). Given that PNR502 can slow, prevent, or reverse Alzheimer-like protein aggregation in human-cell-culture and animal models, and that its principal predicted and observed binding targets are proteins previously implicated in Alzheimer’s, we propose that PNR502 has therapeutic potential to inhibit cerebral Aβ1–42 aggregation and prevent or reverse neurodegeneration.

Development and validation of rapid environmental DNA (eDNA) detection methods for bog turtle (Glyptemys muhlenbergii).

Bog turtles (Glyptemys muhlenbergii) are listed as Species of Greatest Conservation Need (SGCN) for wildlife action plans in every state it occurs and multi-state efforts are underway to better characterize extant populations and prioritize restoration efforts. However, traditional sampling methods can be ineffective due to the turtle’s wetland habitat, small size, and burrowing nature. Molecular methods, such as qPCR, provide the ability to overcome this challenge by effectively quantifying minute amounts of turtle DNA left behind in its environment (eDNA). Developing such methods for bog turtles has proved difficult partly because of the high sequence similarity between bog turtles and closely-related, cohabitating species, most often wood turtles (Glyptemys insculpta). Additionally, substrates containing bog turtle eDNA are often rich in organics or other substances that frequently inhibit both DNA extraction and qPCR amplification. Here, we describe the development and validation of a qPCR assay, BT3, targeting the mitochondrial cytochrome oxidase I gene that correctly identifies bog turtles with 100% specificity and sensitivity when tested on 201 blood samples collected from six species over a wide geographic range. We also developed a full-process internal control employing a genetically modified strain of Caenorhabditis elegans to improve DNA extraction methods, limit false negative results due to qPCR inhibition, and measure total DNA recovery from each sample. Using the internal control, we found that DNA recovery varied by over an order of magnitude between samples and likely explains the lack of bog turtle detection in some cases. Methods presented herein are highly-specific and may offer a more cost effective, non-invasive tool to supplement bog turtle population assessments in the Eastern United States. Poor or differential DNA recovery, which remains unmeasured in the vast majority of eDNA studies, significantly reduced the ability to detect bog turtle in their natural environment.

Caenorhabditis elegans strain sensitivity to sodium arsenite exposure is varied based on age and outcome measured.

Caenorhabditis elegans strain sensitivity to sodium arsenite exposure is varied based on age and outcome measured.

Metabolic stress is a primary pathogenic event in transgenic Caenorhabditis elegans expressing pan-neuronal human amyloid beta.

Alzheimer's disease (AD) is the most common neurodegenerative disease affecting the elderly worldwide. Mitochondrial dysfunction has been proposed as a key event in the etiology of AD. We have previously modeled amyloid-beta (Aβ)-induced mitochondrial dysfunction in a transgenic Caenorhabditis elegans strain by expressing human Aβ peptide specifically in neurons (GRU102). Here, we focus on the deeper metabolic changes associated with this Aβ-induced mitochondrial dysfunction. Integrating metabolomics, transcriptomics and computational modeling, we identify alterations in Tricarboxylic Acid (TCA) cycle metabolism following even low-level Aβ expression. In particular, GRU102 showed reduced activity of a rate-limiting TCA cycle enzyme, alpha-ketoglutarate dehydrogenase. These defects were associated with elevation of protein carbonyl content specifically in mitochondria. Importantly, metabolic failure occurred before any significant increase in global protein aggregate was detectable. Treatment with an anti-diabetes drug, Metformin, reversed Aβ-induced metabolic defects, reduced protein aggregation and normalized lifespan of GRU102. Our results point to metabolic dysfunction as an early and causative event in Aβ-induced pathology and a promising target for intervention.

Fecundity compensation is dependent on the generalized stress response in a nematode host.

BackgroundFecundity compensation, increased offspring output following parasite exposure, is widely reported, but the underlying mechanisms remain unclear. General stress responses are linked to other indirect defenses against parasites, and therefore may be responsible. We challenged strains of Caenorhabditis elegans (wild type and mutants with compromised or strengthened stress responses) with Staphylococcus aureus.ResultsIn all strains except the compromised stress response mutant, we saw elevated offspring production if hosts survived initial parasite exposure.ConclusionWe infer that general stress responses are linked with fecundity compensation. These results may explain why trade‐offs are not always observed among parasite defense mechanisms.

Restoration of Proteostasis in the Endoplasmic Reticulum Reverses an Inflammation-Like Response to Cytoplasmic DNA in Caenorhabditis elegans.

Innate immune responses protect organisms against various insults, but may lead to tissue damage when aberrantly activated. In higher organisms, cytoplasmic DNA can trigger inflammatory responses that can lead to tissue degeneration. Simpler metazoan models could shed new mechanistic light on how inflammatory responses to cytoplasmic DNA lead to pathologies. Here, we show that in a DNase II-defective Caenorhabditis elegans strain, persistent cytoplasmic DNA leads to systemic tissue degeneration and loss of tissue functionality due to impaired proteostasis. These pathological outcomes can be therapeutically alleviated by restoring protein homeostasis, either via ectopic induction of the ER unfolded protein response or N-acetylglucosamine treatment. Our results establish C. elegans as an ancestral metazoan model for studying the outcomes of inflammation-like conditions caused by persistent cytoplasmic DNA and provide insight into potential therapies for human conditions involving chronic inflammation.

The human ABCB6 protein is the functional homologue of HMT-1 proteins mediating cadmium detoxification

ABCB6 belongs to the family of ATP-binding cassette (ABC) transporters, which transport various molecules across extra- and intra-cellular membranes, bearing significant impact on human disease and pharmacology. Although mutations in the ABCB6 gene have been linked to a variety of pathophysiological conditions ranging from transfusion incompatibility to pigmentation defects, its precise cellular localization and function is not understood. In particular, the intracellular localization of ABCB6 has been a matter of debate, with conflicting reports suggesting mitochondrial or endolysosomal expression. ABCB6 shows significant sequence identity to HMT-1 (heavy metal tolerance factor 1) proteins, whose evolutionarily conserved role is to confer tolerance to heavy metals through the intracellular sequestration of metal complexes. Here, we show that the cadmium-sensitive phenotype of Schizosaccharomyces pombe and Caenorhabditis elegans strains defective for HMT-1 is rescued by the human ABCB6 protein. Overexpression of ABCB6 conferred tolerance to cadmium and As(III) (As2O3), but not to As(V) (Na2HAsO4), Sb(V), Hg(II), or Zn(II). Inactivating mutations of ABCB6 abolished vacuolar sequestration of cadmium, effectively suppressing the cadmium tolerance phenotype. Modulation of ABCB6 expression levels in human glioblastoma cells resulted in a concomitant change in cadmium sensitivity. Our findings reveal ABCB6 as a functional homologue of the HMT-1 proteins, linking endolysosomal ABCB6 to the highly conserved mechanism of intracellular cadmium detoxification.

The Secrets in the Leaves: Memory Retention in C. elegans

A mutant strain of Caenorhabditis elegans overexpresses a protein, amyloid precursor‐like protein (APL‐1), that is similar to the human amyloid precursor protein (APP) linked to early‐onset Alzheimer's disease (AD). AD is characterized by amyloid plaques which accumulate and contribute to the progressive neurodegeneration. The mutant strain of C. elegans (ynIs‐79) overexpresses APL‐1 specifically in neurons. Overexpression in C. elegans causes molting issues, motor dysfunction, and disrupts morphogenesis in the nematode. Ginkgo biloba (GB) extract is a popular herbal supplement which may delay or improve the memory problems associated with AD. We hypothesize that individual flavonoids, like quercetin, are likely to be the positive contributing factors because of known protective roles in preventing oxidative stress. After purifying an extract from GB leaves, we determined the concentration of quercetin using HPLC analysis and then using a standard analytical grade solution of quercetin we applied a similar concentration to both the mutant and wild type C. elegans strains. Anterior and posterior tap habituation was used to determine the ability of each stain to recognize a nonthreatening stimulus. We expected that exposing the mutant nematodes to quercetin would decrease the number of taps needed for habituation, and our results show a significant decrease, suggesting increased memory retention and rescue of neurodegenerative dysfunction for the ynIs‐79 strain.Support or Funding InformationGail Dillard Faculty Development FundThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.