Naim, N. et al. (2019) International Worm Meeting "The tissue-specific role of NHR-49 in immunity versus longevity."

Naim, N., Gandhi, F. A., Ghazi, A.

[International Worm Meeting, 2019]

Germline-less animals are a well-established longevity model that recognizes a trade-off between lifespan and reproduction. Expression of the nuclear hormone receptor NHR-49 (functional homolog of vertebrate lipid metabolism regulator PPAR?) has been noted as essential to glp-1 mutant longevity, as it is thought to repurpose fats for reproduction in favor of a lifespan-extending lipid profile. Yet, as long-lived animals often exhibit other improved aspects of healthspan, our laboratory has seen glp-1 mutants have increased resistance to pathogen that additionally depends on NHR-49. Interestingly, NHR-49 is also needed for the immune resistance of fertile wild-type worms in this same experimental paradigm (slow-killing) which exposes worms to P. aeruginosa. This suggests the immunity benefit given to glp-1 worms by NHR-49 is not due to the resources gained from forgoing reproduction. We have identified tissues where NHR-49 acts to (1) promote longevity and (2) confer immune resistance to PA14. These will be discussed along with our data on the molecular mechanisms by which NHR-49 impacts immunity versus longevity.

Rehain K et al. (2015) Curr Biol "Neuron migration: anillin protects leading edge actin."

Maddox AS, Rehain K

[Curr Biol, 2015]

Establishment of a neuronal system requires proper regulation of the F-actin-rich leading edges of migrating neurons and neurite growth cones. A new study shows that RhoG signals through the multi-domain protein anillin to stabilize F-actin in these structures.

Bennett JL et al. (1988) Parasitol Today "Pharmacology of ivermectin."

Williams JF, Bennett JL, Dave V

[Parasitol Today, 1988]

Ivermectin is a semi-synthetic macrocyclic lactone (Fig. I) active in single low doses against many parasites - particularly nematodes and arthropods. It has been registered for animal health use since early 1985, and was earlier this year approved for human use by the French Directorate o f Pharmacy and Drugs. Of particular interest is ivermectin's potential as a micro filaricide for treatment o f onchocerciasis. Clinical trials leave little doubt about the potential o f ivermectin as a therapeutic tool for symptomatic relief from the effects o f infection with Onchocerca volvulus, and the drug is also recognized to have potential in reducing transmission o f the parasite. The manufacturers (Merck, Sharp and Dohme) recently arranged to provide the drug free o f charge to the WHO for mass trials against onchocerciasis in 12 African and Central American countries. In this article we focus on the pharmacological properties o f ivermectin, with a brief consideration of its absorption, fate, excretion and side-effects, and a discussion o f its micro filaricidal action.

Kipreos ET et al. (2000) Genome Biol "The F-box protein family."

Kipreos ET, Pagano M

[Genome Biol, 2000]

SUMMARY: The F-box is a protein motif of approximately 50 amino acids that functions as a site of protein-protein interaction. F-box proteins were first characterized as components of SCF ubiquitin-ligase complexes (named after their main components, Skp I, Cullin, and an F-box protein), in which they bind substrates for ubiquitin-mediated proteolysis. The F-box motif links the F-box protein to other components of the SCF complex by binding the core SCF component Skp I. F-box proteins have more recently been discovered to function in non-SCF protein complexes in a variety of cellular functions. There are 11 F-box proteins in budding yeast, 326 predicted in Caenorhabditis elegans, 22 in Drosophila, and at least 38 in humans. F-box proteins often include additional carboxy-terminal motifs capable of protein-protein interaction; the most common secondary motifs in yeast and human F-box proteins are WD repeats and leucine-rich repeats, both of which have been found to bind phosphorylated substrates to the SCF complex. The majority of F-box proteins have other associated motifs, and the functions of most of these proteins have not yet been defined.

Kwiatkowski AV et al. (2010) Proc Natl Acad Sci U S A "In vitro and in vivo reconstitution of the cadherin-catenin-actin complex from Caenorhabditis elegans."

Hardin J, Weis WI, Nelson WJ, Choi HJ, Lynch AM, Kwiatkowski AV, Benjamin JM, Pokutta S, Maiden SL

[Proc Natl Acad Sci U S A, 2010]

The ternary complex of cadherin, beta-catenin, and alpha-catenin regulates actin-dependent cell-cell adhesion. alpha-Catenin can bind beta-catenin and F-actin, but in mammals alpha-catenin either binds beta-catenin as a monomer or F-actin as a homodimer. It is not known if this conformational regulation of alpha-catenin is evolutionarily conserved. The Caenorhabditis elegans alpha-catenin homolog HMP-1 is essential for actin-dependent epidermal enclosure and embryo elongation. Here we show that HMP-1 is a monomer with a functional C-terminal F-actin binding domain. However, neither full-length HMP-1 nor a ternary complex of HMP-1-HMP-2(beta-catenin)-HMR-1(cadherin) bind F-actin in vitro, suggesting that HMP-1 is auto-inhibited. Truncation of either the F-actin or HMP-2 binding domain of HMP-1 disrupts C. elegans development, indicating that HMP-1 must be able to bind F-actin and HMP-2 to function in vivo. Our study defines evolutionarily conserved properties of alpha-catenin and suggests that multiple mechanisms regulate alpha-catenin binding to F-actin.

Jayamani E et al. (2017) Antimicrob Agents Chemother "Characterization of a Francisella tularensis-Caenorhabditis elegans pathosystem for the evaluation of therapeutic compounds."

Ausubel FM, Nau GJ, Kim W, Mylonakis E, Coleman JJ, Okoli I, Lee K, RajaMuthiah R, Tharmalingam N, Hernandez AM, Jayamani E

[Antimicrob Agents Chemother, 2017]

Francisella tularensis is a highly infectious Gram-negative intracellular pathogen that causes tularemia. Because of its potential as a bioterrorism agent, there is a need for new therapeutic agents. We therefore developed a whole animal Caenorhabditis elegans-F. tularensis pathosystem for high throughput screening to identify and characterize potential therapeutic compounds. We found that the C. elegans p38 MAP kinase cascade is involved in the immune response to F. tularensis and we developed a robust F. tularensis-mediated C. elegans killing assay with a Z'-factor consistently >0.5, which was then utilized to screen a library of FDA approved compounds that included 1,760 small molecules. In addition to clinically used antibiotics, 5 FDA-approved drugs were also identified as potential hits, including the anti-inflammatory drug diflunisal that showed anti-F. tularensis activity in vitro Moreover, the NSAID diflunisal, at 4X MIC, blocked the replication of a F. tularensis live vaccine strain (LVS) in primary human macrophages and non-phagocytic cells. Diflunisal was non-toxic to human erythrocytes and HepG2 human liver cells at concentrations 32-g/ml. Finally, diflunisal exhibited synergetic activity with the antibiotic ciprofloxacin in both a checkerboard assay and a macrophage infection assay. In conclusion, the liquid C. elegans - F. tularensis LVS assay described here allows screening for anti-F. tularensis compounds and suggests that diflunisal could potentially be repurposed for the management of tularemia.

Ono S et al. (2001) J Biol Chem "The C-terminal tail of UNC-60B (actin depolymerizing factor/cofilin) is critical for maintaining its stable association with F-actin and is implicated in the second actin-binding site."

Gernert KM, Weeds AG, McGough A, Bui A, Pope BJ, Benian GM, Ono S, Tolbert VT, Pohl J

[J Biol Chem, 2001]

Actin depolymerizing factor (ADF)/cofilin changes the twist of actin filaments by binding two longitudinally associated actin subunits, In the absence of an atomic model of the ADF/cofilin-F-actin complex, we have identified residues in ADF/cofilin that are essential for filament binding. Here, we have characterized the C-terminal tail of UNC-60B (a nematode ADF/cofilin isoform) as a novel determinant for its association with F-actin, Removal of the C-terminal isoleucine (Ile(152)) by carboxypeptidase A or truncation by mutagenesis eliminated F-actin binding activity but strongly enhanced actin depolymerizing activity, Replacement of Ile(152) by Ala had a similar but less marked effect; F-actin binding was weakened and depolymerizing activity slightly enhanced. Truncation of both Arg(151) and Ile(152) or replacement of Arg(151) with Ala also abolished F-actin binding and enhanced depolymerizing activity. Loss of F-actin binding in these mutants was accompanied by loss or greatly decreased severing activity. All of the variants of UNC-60B interacted with G-actin in an indistinguishable manner from wild type. Cryoelectron microscopy showed that UNC-60B changed the twist of F-actin to a similar extent to vertebrate ADF/cofilins. Helical reconstruction and structural modeling of UNC-60B-F-actin complex reveal how the C terminus of UNC-60B might be involved in one of the two actin-binding sites.

Wang A et al. (2021) BMC Genomics "Genome-wide characterization, evolution, structure, and expression analysis of the F-box genes in Caenorhabditis."

Chen W, Tao S, Wang A

[BMC Genomics, 2021]

Background: F-box proteins represent a diverse class of adaptor proteins of the ubiquitin-proteasome system (UPS) that play critical roles in the cell cycle, signal transduction, and immune response by removing or modifying cellular regulators. Among closely related organisms of the Caenorhabditis genus, remarkable divergence in F-box gene copy numbers was caused by sizeable species-specific expansion and contraction. Although F-box gene number expansion plays a vital role in shaping genomic diversity, little is known about molecular evolutionary mechanisms responsible for substantial differences in gene number of F-box genes and their functional diversification in Caenorhabditis. Here, we performed a comprehensive evolution and underlying mechanism analysis of F-box genes in five species of Caenorhabditis genus, including C. brenneri, C. briggsae, C. elegans, C. japonica, and C. remanei.Results: Herein, we identified and characterized 594, 192, 377, 39, 1426 F-box homologs encoding putative F-box proteins in the genome of C. brenneri, C. briggsae, C. elegans, C. japonica, and C. remanei, respectively. Our work suggested that extensive species-specific tandem duplication followed by a small amount of gene loss was the primary mechanism responsible for F-box gene number divergence in Caenorhabditis genus. After F-box gene duplication events occurred, multiple mechanisms have contributed to gene structure divergence, including exon/intron gain/loss, exonization/pseudoexonization, exon/intron boundaries alteration, exon splits, and intron elongation by tandem repeats. Based on high-throughput RNA sequencing data analysis, we proposed that F-box gene functions have diversified by sub-functionalization through highly divergent stage-specific expression patterns in Caenorhabditis species.Conclusions: Massive species-specific tandem duplications and occasional gene loss drove the rapid evolution of the F-box gene family in Caenorhabditis, leading to complex gene structural variation and diversified functions affecting growth and development within and among Caenorhabditis species. In summary, our findings outline the evolution of F-box genes in the Caenorhabditis genome and lay the foundation for future functional studies.

Bonnie Kaas et al. (2008) C.elegans Neuronal Development Meeting "Regulation of Levels of UNC-13 at Synapses"

Rebecca Lawson, Rebecca Kohn, Thomas Limouze, Ryan Wennell, Bonnie Kaas

[C.elegans Neuronal Development Meeting, 2008]

Release of neurotransmitters from neurons is highly regulated. Several proteins play roles in this process, including UNC-13, and decreased release of neurotransmitters in unc-13 mutants results in paralysis. We identified an F-box protein that interacts with UNC-13. F-box proteins participate in ubiquitin ligase complexes and in Drosophila, DUNC-13 is degraded via the ubiquitin proteasome pathway. This UNC-13/F-box interaction may therefore indicate that UNC-13 is tagged for proteasomal degradation with ubiquitin by the ligase complex in C. elegans. The C. elegans knockout consortium isolated a strain with a large deletion in the coding region of the gene that codes for the F-box protein. If the F-box protein is indeed involved in the degradation of UNC-13, this strain would be expected to have higher levels of UNC-13, which could result in changes in phenotypes. We characterized the F-box deletion mutant by assaying brood size, developmental rate, and body bends per minute. Aldicarb assays were used to determine whether a deletion in the gene coding for the F-box protein alters the response to inhibitors of acetylcholinesterase. We found that the deletion resulted in some changes in developmental rate and in aldicarb sensitivity. We are continuing to study strains with mutations in both the gene coding for the F-box protein and in unc-13.

Chamberlin HM et al. (1995) Worm Breeder's Gazette "lin-49, An Essential Gene Required For Normal F and U Cells."

Chamberlin HM, Sternberg PW, Baillie DL

[Worm Breeder's Gazette, 1995]

lin-49, an essential gene required for normal F and U cells