[
MicroPubl Biol,
2022]
Vehicular air pollution is an environmental toxicant that can have several health consequences, such as decreased respiratory and cardiovascular function and an increased incidence of age-related dementia and neurodegenerative diseases such as Alzheimer's disease. C. elegans has been previously shown to be a valuable animal model to study the effects of air pollution due to its tendency to respond to acute exposure to nano-sized particulate matter (nPM) produced by vehicular emissions. Specifically, nPM causes delayed development resulting in smaller animal size and induction of the SKN-1-mediated oxidative stress response. Here we show that various wild isolates demonstrate differential susceptibility to nPM, as measured by body size. Specifically, the Hawaiian isolate, CB4856, displayed the highest sensitivity, equivalent to its sensitivity to the potent oxidant paraquat. The findings described herein suggest that C. elegans may be a useful genetic tool for identifying nPM-susceptibility loci.
[
International Worm Meeting,
2019]
Polyglutamine (polyQ) expansions in specific proteins are the genetic determinants of nine different neurodegenerative disorders including Huntington's disease (HD), which causes cognitive and motor impairment in mid-late life and is ultimately fatal. We are interested in understanding the molecular and cell biological processes that are affected by the presence of disease-associated variants of the human huntingtin protein (htt). To this end, we generated a novel model of huntingtin protein aggregation by expressing a disease-associated polyQ-containing N-terminal fragment of 513 amino acids of the htt protein with 128 glutamines (Htt513Q128) in C. elegans body wall muscle cells. As a control, we also expressed a non-disease associated tract of 15 glutamines (Htt513Q15). The animals exhibited polyQ length-dependent aggregation and toxicity. To identify genetic modifiers of htt-associated aggregation and toxicity, we performed ethyl methanesulfonate (EMS) mutagenesis on animals with expanded polyQ in the context of the human htt protein and identified three mutants having either a below or above average aggregate count. Western blot analysis revealed that all mutants had significantly higher levels of polyQ protein in comparison to Htt513Q128-expressing animals. This was true even for animals in which we detected less Htt aggregation, meaning that the normal function of certain genes (or QTLs) exacerbates the aggregation and toxicity of the Htt513Q128 protein.
[
MicroPubl Biol,
2020]
Huntingtons disease (HD) is an autosomal dominant monogenic neurodegenerative disorder caused by a CAG trinucleotide repeat expansion in the gene encoding the protein huntingtin (Htt) (MacDonald et al., 1993). The resultant disease-associated Htt protein harbors a polyglutamine (polyQ) repeat that renders it metastable with respect to folding (Carrell and Lomas, 1997). Htt protein misfolding, characterized by the accumulation of misfolded protein aggregates and neurotoxicity, is first observed in mid- to late-life for most HD patients (Becher et al., 1998). The age-of-onset for HD is inversely proportional to CAG repeat length (Becher et al., 1998). Nonetheless, genetic variation between HD patients is attributed to slight differences in age-of-onset, even when repeat length is the same (Gusella and MacDonald, 2000). Thus, genetic background seems to be an important modifier of Htt protein aggregation and toxicity. We are interested in identifying genes/proteins that enhance or suppress the folding defect of human Htt.To model Htt toxic-gain-of-function in the genetically tractable Caenorhabditis elegans, we previously characterized transgenic animals expressing a YFP-tagged polyQ-expanded disease-associated fragment of human Htt in C. elegans body wall muscle cells (Lee et al., 2017). More specifically, the first 513 amino acids of the human Htt protein were fused to YFP for visualization. Two different polyQ tract lengths (Q15 and Q128) were utilized, resulting in the proteins Htt513(Q15)::YFP and Htt513(Q128)::YFP, corresponding to the strains EAK102 and EAK103, respectively (Lee et al., 2017). For simplicity, these proteins are referred to herein as Htt513(Q15) or Htt513(Q128). As reported, only Htt513(Q128), not Htt513(Q15), formed protein aggregates in body wall muscle cells (Lee et al., 2017), consistent with only longer polyQ tracts being associated with disease.Here, we describe the identification and characterization of genetic modifiers of Htt aggregation (mha). To this end, EAK103 animals expressing Htt513(Q128) were grown to the L4 larval stage and exposed to the alkylating agent ethyl methanesulfonate (EMS) at a final concentration of 50mM for 4hrs, according to established protocols (Brenner, 1974). In short, F1 individuals derived from the mutagenized parents were allowed to self-fertilize for one generation, yielding an F2 population, for the purpose of homozygosing recessive alleles and thereby uncovering mutant phenotypes. Screening of the F2 animals for those with increased or decreased aggregation was performed by eye with a fluorescent stereomicroscope.
Rajasekeran, Prisha, Ryou, Hayeon, Garcia Manriquez, Bailey, Papapanagiotou, Julia, Strysick, Claire, Kikis, Elise, Green, Emily
[
International Worm Meeting,
2021]
Environmental degradation caused by human behavior is of great concern for human health and the health of Earth's ecosystems. Air pollution, and, especially, traffic-associated particulate matter (TRAP) is a significant health concern. Epidemiological studies have shown that exposure to TRAP triggers Alzheimer's disease (AD) symptoms. Likewise, controlled laboratory studies in which AD mice were continuously exposed to TRAP revealed an increase in amyloid beta (Abeta) plaques. Abeta plaques are composed of misfolded protein. Their increase could be a direct consequence of the disruption of the proteostasis network or an indirect consequence of neuroinflammation. To determine whether TRAP directly impairs the folding of disease-associated proteins, we utilized C. elegans as a model that lacks a canonical inflammatory response. To this end, we exposed animals expressing Abeta or Huntington's disease-associated polyQ protein to nano-sized traffic-derived particulate matter. We found that TRAP triggered polyQ protein misfolding and increased Abeta toxicity. Together, our data suggest that TRAP may act, at least in part, to trigger disease by disrupting the proteostasis balance.