Haruta N et al. (2023) J Cell Sci "Germline-specific role for unconventional components of the γ-tubulin complex in Caenorhabditis elegans."

Kubota Y, Haruta N, Terasawa M, Sumiyoshi E, Honda Y, Toya M, Sugimoto A, Uchiyama C

[J Cell Sci, 2023]

The γ-tubulin complex (γTuC) is a widely conserved microtubule nucleator, but some of its components GCP4-6 have not been detected in Caenorhabditis elegans. Here, we identified two γTuC-associated proteins in C. elegans, namely GTAP-1 and -2, for which apparent orthologs were detected only in the genus Caenorhabditis. They were localized at centrosomes and the plasma membrane of the germline, and their centrosomal localization was interdependent. In early C. elegans embryos, whereas the conserved γTuC component MZT-1/MOZART1 was essential for the localization of centrosomal γ-tubulin, depletion of GTAP-1 and/or -2 caused up to 50% reduction of centrosomal γ-tubulin and precocious disassembly of spindle poles during mitotic telophase. In the adult germline, GTAP-1 and GTP-2 contributed to the efficient recruitment of γTuC to the plasma membrane. Depletion of GTAP-1, but not GTAP-2, severely disrupted both the microtubule array and the honeycomb-like structure in the adult germline. We propose that GTAP-1 and -2 are unconventional components of γTuC that contribute to the organization of both centrosomal and non-centrosomal microtubules by targeting the γTuC to specific subcellular sites in a tissue-specific manner.

Ge YL et al. (2002) Anticancer Res "Effects of adenoviral gene transfer of C. elegans n-3 fatty acid desaturase on the lipid profile and growth of human breast cancer cells."

Kang ZB, Chen Z, Leaf A, Kang JX, Cluette-Brown J, Laposata M, Ge YL

[Anticancer Res, 2002]

Background: Current evidence from both experimental and human studies indicates that omega-6 polyunsaturated fatty acids (n-6 PUFAs) promote breast tumor development, whereas long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs) exert suppressive effects. The ratio of n-6 to n-3 fatty acids appears to be an important factor in controlling tumor development. Human cells usually have a very high n-6/n-3 fatty acid ratio because they cannot convert n-6 PUFAs to n-3 PUFAs due to lack of an n-3 desaturase found in C. elegans. Materials and Methods: Adenoviral strategies were used to introduce the C. elegans fat-1 gene encoding an n-3 fatty acid desaturase into human breast cancer cells followed by examination of the n-6/n-3 fatty acid ratio and growth of the cells. Results: Infection of MCF-7 cells with an adenovirus carrying the fat-1 gene resulted in a high expression of the n-3 fatty acid desaturase. Lipid analysis indicated a remarkable increase in the levels of n-3 PUFAs accompanied with a large decrease in the contents of n-6 PUFAs, leading to a change of the n-6/n-3 ratio from 12.0 to 0.8. Accordingly, production of the eicosanoids derived from n-6 PUFA was reduced significantly in cells expressing the fat-1 gene. Importantly, the gene transfer induced mass cell death and inhibited cell proliferation. Conclusion: The gene transfer of the n-3 fatty acid desaturase, as a novel approach, can effectively modify the n-6/n-3 fatty acid ratio of human tumor cells and provide an anticancer effect, without the need of exogenous n-3 PUFA supplementation. These data also increase the understanding of the effects of n-3 fatty acids and the n-6/n-3 ratio on cancer prevention and treatment.

Seo J et al. (2005) Arch Environ Contam Toxicol "Biodegradation of the insecticide N,N-diethyl-m-toluamide by fungi: identification and toxicity of metabolites."

Kim SD, Cha CJ, Hur HG, Lee YG, Seo J, Ahn JH

[Arch Environ Contam Toxicol, 2005]

Fungi (Cunninghamella elegans ATCC 9245, Mucor ramannianus R-56, Aspergillus niger VKMF-1119, and Phanerochaete chrysosporium BKMF-1767) were tested to elucidate the biologic fate of the topical insect repellent N,N-diethyl-m-toluamide (DEET). The elution profile obtained from analysis by high-pressure liquid chromatography equipped with a reverse-phase C-18 column, showed that three peaks occurred after incubation of C. elegans, with which 1 mM DEET was combined as a final concentration. The peaks were not detected in the control experiments with either DEET alone or tested fungus alone. The metabolites produced by C. elegans exhibited a molecular mass of 207 with a fragment ion (m/z) at 135, a molecular mass of 179 with an m/z at 135, and a molecular mass of 163 with an m/z at 119, all of which correspond to N,N-diethyl-m-toluamide-N-oxide, N-ethyl-m-toluamide-N-oxide, and N-ethyl-m-toluamide, respectively. M. ramannianus R-56 also produced N, N-diethyl-m-toluamide-N-oxide and N-ethyl-m-toluamide but did not produce N-ethyl-m-toluamide-N-oxide. For the biologic toxicity test with DEET and its metabolites, the freshwater zooplankton Daphnia magna was used. The biologic sensitivity in decreasing order was DEET > N-ethyl-m-toluamide > N,N-diethyl-m-toluamide-N-oxide. Although DEET and its fungal metabolites showed relatively low mortality compared with other insecticides, the toxicity was increased at longer exposure periods. These are the first reports of the metabolism of DEET by fungi and of the biologic toxicity of DEET and its fungal metabolites to the freshwater zooplankton D. magna.

Hatanaka R et al. (2024) Genetics "The impact of differential transposition activities of autonomous and non-autonomous hAT transposable elements on genome architecture and gene expression in Caenorhabditis inopinata."

Tamagawa K, Haruta N, Sugimoto A, Hatanaka R

[Genetics, 2024]

Transposable elements (TEs) are DNA sequences capable of moving within genomes and significantly influence genomic evolution. The nematode Caenorhabditis inopinata exhibits a much higher TE copy number than its sister species, C. elegans. In this study, we identified a novel autonomous TE belonging to the hAT superfamily from a spontaneous TE-insertion mutant in C. inopinata and named this transposon Ci-hAT1. Further bioinformatic analyses uncovered three additional autonomous hAT elements-Ci-hAT2, Ci-hAT3, and Ci-hAT4-along with over 1,000 copies of two non-autonomous miniature inverted-repeat transposable elements (MITEs), mCi-hAT1 and mCi-hAT4, likely derived from Ci-hAT1 and Ci-hAT4 through internal deletion. We tracked at least three sequential transpositions of Ci-hAT1 over several years. However, the transposition rates of the other three autonomous hAT elements were lower, suggesting varying activity levels. Notably, the distribution patterns of the two MITE families differed significantly: mCi-hAT1 was primarily located in the chromosome arms, a pattern observed in the TEs of other Caenorhabditis species, whereas mCi-hAT4 was more evenly distributed across chromosomes. Additionally, interspecific transcriptome analysis indicated that C. inopinata genes with upstream or intronic these MITE insertions tend to be more highly expressed than their orthologous genes in C. elegans. These findings highlight the significant role of de-silenced TEs in driving the evolution of genomes and transcriptomes, leading to species-specific genetic diversity.

Kang ZB et al. (2001) Proc Natl Acad Sci U S A "Adenoviral gene transfer of Caenorhabditis elegans n--3 fatty acid desaturase optimizes fatty acid composition in mammalian cells."

Leaf A, Laposata M, Kang ZB, Kang JX, Chen Z, Ge Y, Cluette-Brown J

[Proc Natl Acad Sci U S A, 2001]

Omega-3 polyunsaturated fatty acids (PUFAs) are essential components required for normal cellular function and have been shown to exert many preventive and therapeutic actions. The amount of n-3 PUFAs is insufficient in most Western people, whereas the level of n-6 PUFAs is relatively too high, with an n-6/n-3 ratio of >18. These two classes of PUFAs are metabolically and functionally distinct and often have important opposing physiological functions; their balance is important for homeostasis and normal development. Elevating tissue concentrations of n-3 PUFAs in mammals relies on chronic dietary intake of fat rich in n-3 PUFAs, because mammalian cells lack enzymatic activities necessary either to synthesize the precursor of n-3 PUFAs or to convert n-6 to n-3 PUFAs. Here we report that adenovirus-mediated introduction of the Caenorhabditis elegans fat-1 gene encoding an n-3 fatty acid desaturase into mammalian cells can quickly and effectively elevate the cellular n - 3 PUFA contents and dramatically balance the ratio of n-6/n-3 PUFAs, Heterologous expression of the fat-1 gene in rat cardiac myocytes rendered cells capable of converting various n-6 PUFAs to the corresponding n-3 PUFAs, and changed the n-6/n-3 ratio from about 15:1 to 1:1. In addition, an eicosanoid derived from n-6 PUFA (i.e., arachidonic acid) was reduced significantly in the transgenic cells. This study demonstrates an effective approach to modifying fatty acid composition of mammalian cells and also provides a basis for potential applications of this gene transfer in experimental and clinical settings.

Kang JX et al. (2004) Nature "Transgenic mice: fat-1 mice convert n-6 to n-3 fatty acids."

Kang JX, Wang J, Kang ZB, Wu L

[Nature, 2004]

Mammals cannot naturally produce omega-3 (n-3) fatty acids--beneficial nutrients found mainly in fish oil--from the more abundant omega-6 (n-6) fatty acids and so they must rely on a dietary supply. Here we show that mice engineered to carry a fat-1 gene from the roundworm Caenorhabditis elegans can add a double bond into an unsaturated fatty-acid hydrocarbon chain and convert n-6 to n-3 fatty acids. This results in an abundance of n-3 and a reduction in n-6 fatty acids in the organs and tissues of these mice, in the absence of dietary n-3. As well as presenting an opportunity to investigate the roles played by n-3 fatty acids in the body, our discovery indicates that this technology might be adapted to enrich n-3 fatty acids in animal products such as meat, milk and eggs.

Kang JX (2007) Prostaglandins Leukot Essent Fatty Acids "Fat-1 transgenic mice: a new model for omega-3 research."

Kang JX

[Prostaglandins Leukot Essent Fatty Acids, 2007]

An appropriate animal model that can eliminate confounding factors of diet would be very helpful for evaluation of the health effects of nutrients such as n-3 fatty acids. We recently generated a fat-1 transgenic mouse expressing the Caenorhabditis elegans fat-1 gene encoding an n-3 fatty acid desaturase that converts n-6 to n-3 fatty acids (which is absent in mammals). The fat-1 transgenic mice are capable of producing n-3 fatty acids from the n-6 type, leading to abundant n-3 fatty acids with reduced levels of n-6 fatty acids in their organs and tissues, without the need of a dietary n-3 supply. Feeding an identical diet (high in n-6) to the transgenic and wild-type littermates can produce different fatty acid profiles in these animals. Thus, this model allows well-controlled studies to be performed, without the interference of the potential confounding factors of diet. The transgenic mice are now being used widely and are emerging as a new tool for studying the benefits of n-3 fatty acids and the molecular mechanisms of their action.

Clegg RA et al. (2012) Arch Biochem Biophys "Characterisation of the N'1 isoform of the cyclic AMP-dependent protein kinase (PK-A) catalytic subunit in the nematode, Caenorhabditis elegans."

Bicknell AV, Fisher MJ, Rees HH, Tabish M, Bowen LC, Clegg RA, Prescott MC

[Arch Biochem Biophys, 2012]

Multiple isoforms of the cyclic AMP-dependent protein kinase (PK-A) catalytic (C) subunit, arise as a consequence of the use of alternative splicing strategies during transcription of the kin-1 gene in the nematode, Caenorhabditis elegans. N-myristoylation is a common co-translational modification of mammalian PK-A C-subunits; however, the major isoform (N'3), originally characterised in C. elegans, is not N-myristoylated. Here, we show that N'1 isoforms are targets for N-myristoylation in C. elegans. We have demonstrated the in vivo incorporation of radioactivity into N'1 C-subunit isoforms, following incubation of nematodes with [(3)H]-myristic acid. HPLC and MALDI-TOF MS analysis of proteolytic digests of immunoprecipitates confirmed the presence of myristoyl-glycine in the C-subunit. In order to better understand the impact of the N'1 N-terminal sequence, and its myristoylation, on C-subunit activity, a chimerical C-subunit, consisting of the N'1 N-terminus from C. elegans and a murine core and C-terminal sequence was expressed. Myristoylation had no appreciable effect on the catalytic properties of the chimeric protein. However, the myristoylated chimeric protein did exhibit enhanced apolar targeting compared to the myristoylated wild-type murine polypeptide. This behaviour may reflect the inability of the N'1-encoded N-terminus sequence to correctly dock with a hydrophobic domain on the surface of the C-subunit.

Ge Y et al. (2002) J Neurochem "Gene transfer of the Caenorhabditis elegans n-3 fatty acid desaturase inhibits neuronal apoptosis."

Lo EH, Wang X, Kang JX, Ge Y, Chen Z, Landman N

[J Neurochem, 2002]

Previous studies have shown that n-3 polyunsaturated fatty acids (PUFAs) can exert an antiapoptotic effect on neurons. The present study was designed to investigate whether the Caenorhabditis elegans fat-1 gene encoding an n-3 fatty acid desaturase (an enzyme that converts n-6 PUFAs to corresponding n-3 PUFAs) can be expressed functionally in rat cortical neurons and whether its expression can change the ratio of n-6 : n-3 fatty acids in the cell membrane and exert an effect on neuronal apoptosis. Infection of primary rat cortical cultures with Ad-fat-1 resulted in high expression of the fat-1 gene. Lipid analysis indicated a decrease in the ratio of n-6 : n-3 PUFAs from 5.9 : 1 in control cells, to 1.45 : 1 in cells expressing the n-3 fatty acid desaturase. Accordingly, the levels of prostaglandin E-2, an eicosanoid derived from n-6 PUFA, were significantly lower in cells infected with Ad-fat-1 when compared with control cells. Finally, there was a significant inhibition of growth factor withdrawal-induced apoptotic cell death in neurons expressing the fat-1 gene. These results demonstrate that expression of the fat-1 gene can inhibit apoptotic cell death in neurons and suggest that the change in the n-6 : n-3 fatty acid ratio may play a key role in this protective effect.

Honda Y et al. (2017) J Cell Sci "Tubulin isotype substitution revealed that isotype composition modulates microtubule dynamics in C. elegans embryos."

Sumiyoshi E, Sugimoto A, Haruta N, Tsuchiya K, Honda Y

[J Cell Sci, 2017]

Microtubules (MTs) are polymers composed of - and -tubulin heterodimers, which are generally encoded by multiple gene loci. Despite implications of distinct properties of isotypes, how they contribute to diverse MT dynamics in vivo remains unclear. Here, using genome editing and RNAi depletion of tubulin isotypes, we demonstrate that four tubulin isotypes (hereafter 1, 2, 1 and 2) cooperatively confer distinct MT properties in Caenorhabditis elegans early embryos. GFP insertion into each isotype locus reveals their distinct expression levels and MT incorporation rates. Substitution of isotype coding regions demonstrates that, under the same isotype concentration, 1-composed MTs have higher switching frequency between growth and shrinkage than 2-composed MTs. Lower concentration of -tubulins results in slower growth rates, and the two -tubulins distinctively affect growth rates of 1-composed MTs. Alteration of ratio and concentration of isotypes distinctively modulates both growth rate and switching frequency, and affects the amplitude of mitotic spindle oscillation. Collectively, our findings demonstrate that MT dynamics is modulated by composition (ratio and concentration) of tubulin isotypes with distinct properties, which contributes to create diverse MT behaviors in vivo.