139 Papers found (0.011 seconds)

Bond, Michelle R et al. (2011) International Worm Meeting "O-GlcNAc cycling is a regulator of innate immunity in Caenorhabditis elegans."

Krause, Michael W, Hanover, John A, Bond, Michelle R

[

International Worm Meeting,

2011]

Playing critical roles in biological process including signaling and gene transcription, the O-linked N-acetylglucosamine (O-GlcNAc) post-translational modification of serine and threonine residues is dynamic. Modifying and/or regulating over 600 proteins, O-GlcNAc has been implicated in a variety of human conditions including Diabetes mellitus, cancer, and neurodegenerative diseases. O-GlcNAc cycling is governed by two proteins, O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) that add and remove the modification, respectively. OGT interacts with evolutionarily conserved proteins that are key for the innate immune response: it interacts with components in the beta-catenin, p38 MAPK, and insulin signaling pathways. Given its role as a key signaling molecule and the pathways with which OGT interacts, we hypothesize that O-GlcNAc cycling plays a role in "fine-tuning" the innate immune response. Bacterial infections, especially those that are drug resistant, are of growing health concern in the USA. Although significant progress has been made in understanding organisms' responses to bacterial infections, the complexity of the mammalian system leaves in-depth characterization of immune pathways at the whole-organism level wanting. The bacteriovore C. elegans is an attractive candidate for studying the innate immune response: it is susceptible to many human pathogens, the animal's transparency allows real-time observation of bacterial accumulation and its short life span permits characterization of susceptibility by scoring longevity. Importantly, although the removal of OGT and OGA yields lethality in most organisms, null mutants of OGT and OGA are viable and fertile in C. elegans. The innate immune response was examined for wild type (WT), ogt-1 mutant, or oga-1 mutant worms to heat-killed S. aureus (HKSA). While the WT worms had similar longevity profiles regardless of the bacterial strain they were fed, ogt-1 and oga-1 mutant worms had an increased lifespan on HKSA in comparison to WT. These data suggest that defects in O-GlcNAc cycling may influence the animals' sensitivity to bacteria by changing the proteins modified by O-GlcNAc. In order to understand the implications of these data, we study the C. elegans innate immune response to live S. aureus and profile the proteins modified by O-GlcNAc in each case by immunoblot and mass spectrometry. The susceptibility of both O-GlcNAc cycling mutants and other innate immunity mutants is currently under investigation.

Duret L et al. (1998) Genome Res "New insulin-like proteins with atypical disulfide bond pattern characterized in Caenorhabditis elegans by comparative sequence analysis and homology modeling."

Bairoch A, Duret L, Guex N, Peitsch MC

[

Genome Res,

1998]

We have identified three new families of insulin homologs in Caenorhabditis elegans. In two of these families, concerted mutations suggest that an additional disulfide bond links B and A domains, and that the A-domain internal disulfide bond is substituted by a hydrophobic interaction. Homology modeling remarkably confirms these predictions and shows that despite this atypical disulfide bond pattern and the absence of C-like peptide, all these proteins may adopt the same fold as the insulin. Interestingly, whereas we identified 10 insulin-like peptides, only one insulin-like-receptor (daf-2) has been found. We propose that these insulin-related peptides may correspond to different activators or inhibitors of the daf-2 insulin-regulating pathway.

Konzman, Daniel et al. (2019) International Worm Meeting "Defining the impact of O-GlcNAc on fertility of C. elegans males."

Konzman, Daniel, Krause, Michael, Fukushige, Tetsu, Hanover, John, Bond, Michelle

[

International Worm Meeting,

2019]

Fertility is critically impacted by environmental factors including diet, xenobiotics, and stress. O-GlcNAc is an important post-translational modification that is involved diverse biological pathways including nutrient signaling, stress response, and stem cell maintenance. Our lab has found that disruption of O-GlcNAcylation affects fertility across evolution from nematodes to mice. Though lethal in most metazoans, loss of function of O-GlcNAc transferase (ogt-1) animals are viable in C. elegans, allowing genetic analysis of the biological roles of this modification. Though hermaphrodite ogt-1 mutants appear generally healthy and their fertility is not greatly compromised, ogt-1 males have a three-fold reduction in mating success compared to control. Despite what is known about C. elegans male biology, the mechanistic link between O-GlcNAc and fertility is unclear. A significant increase in developmental defects at a low penetrance suggests ogt-1 may play a role in the development of the male copulatory organ. Also, sperm tracking assays demonstrated that ogt-1 males transfer a reduced number of sperm to their mates, which may be caused by aberrant sperm motility or defective mating behavior. These data suggest that developmental, behavioral, and spermatogenesis defects may be factors contributing to ogt-1 males' poor fertility. As the male and hermaphrodite germlines have distinct gene expression, and cues from several somatic tissues have been shown to impact sperm function, the described phenotype may involve cell-autonomous and non-autonomous mechanisms. Given the established role of O-GlcNAc cycling in development, we hypothesize O-GlcNAc influences fertility by regulating spermatogenesis and copulatory behavior. A fosmid containing a wild-type copy of ogt-1 is sufficient to rescue both the lost enzymatic activity and male infertility associated with ogt-1 deletion. Further rescue experiments using tissue-specific promoters to express an ogt-1 transgene will be used to test the contributions of different candidate tissues to the fertility defect. To test if behavioral problems contribute to the phenotype, we will conduct assays of the well-characterized, stereotypic behaviors of mating. Further experiments will define the role of nutrient-sensing O-GlcNAc and how it influences fertility.

Gallego-Garcia A et al. (2019) Science "A bacterial light response reveals an orphan desaturase for human plasmalogen synthesis."

Padmanabhan S, Elias-Arnanz M, Monera-Girona AJ, Pajares-Martinez E, Gallego-Garcia A, Iniesta AA, Bastida-Martinez E, Fontes M, Perez-Castano R

[

Science,

2019]

Plasmalogens are glycerophospholipids with a hallmark sn-1 vinyl ether bond. These lipids are found in animals and some bacteria and have proposed membrane organization, signaling, and antioxidant roles. We discovered the plasmanylethanolamine desaturase activity that is essential for vinyl ether bond formation in a bacterial enzyme, CarF, which is a homolog of the human enzyme TMEM189. CarF mediates light-induced carotenogenesis in Myxococcus xanthus, and plasmalogens participate in sensing photooxidative stress through singlet oxygen. TMEM189 and other animal homologs could functionally replace CarF in M. xanthus, and knockout of TMEM189 in a human cell line eliminated plasmalogens. Discovery of the human plasmanylethanolamine desaturase will spur further study of plasmalogen biogenesis, functions, and roles in disease.

Zhu L et al. (2008) Mol Biol Cell "The torsin-family AAA+ protein OOC-5 contains a critical disulfide adjacent to Sensor-II that couples redox state to nucleotide binding."

Rose LS, Thomas PJ, Hayashi AP, Zhu L, Wrabl JO

[

Mol Biol Cell,

2008]

Monitoring Editor: Jeffrey L. Brodsky A subgroup of the AAA+ proteins that reside in the endoplasmic reticulum and the nuclear envelope including human torsinA, a protein mutated in hereditary dystonia, is called the torsin family of AAA+ proteins. A multiple-sequence-alignment of this family with Hsp100 proteins of known structure reveals a conserved cysteine in the C-terminus of torsin proteins within the Sensor-II motif. A structural model predicts this cysteine to be a part of an intramolecular disulfide bond, suggesting that it may function as a redox sensor to regulate ATPase activity. In vitro experiments with OOC-5, a torsinA homolog from C. elegans, demonstrate that redox changes that reduce this disulfide bond affect the binding of ATP and ADP and cause an attendant local conformational change detected by limited proteolysis. Transgenic worms expressing an ooc-5 gene with cysteine to serine mutations that disrupt the disulfide bond have a very low embryo hatch rate compared with wild type controls, indicating these two cysteines are essential for OOC-5 function. We propose that the Sensor-II in torsin family proteins is a redox-regulated sensor (RRS). This regulatory mechanism may be central to the function of OOC-5 and human torsinA.

Aspbury RA et al. (1995) Biochem Soc Trans "Fatty acylation of polypeptides in the free-living nematode Caenorhabditis elegans."

Aspbury RA, Fisher MJ, Rees HH

[

Biochem Soc Trans,

1995]

Modification, by the addition of lipid-derived groups, is an important determinant of the correct expression of a variety of polypeptides involved in signal transduction. Myristic and palmitic acid are the predominant fatty acids attached to proteins in eucaryotes. Myristic acid is normally linked, cotranslationally, via an amide bond to an N-terminal glycine. In contrast, palmitic acid attachment occurs post-translationally via an alkali-labile ester or thioester linkage...

Zhao J et al. (2022) Nat Commun "Bond-selective intensity diffraction tomography."

Zhan Y, Chen Z, Wang B, Matlock A, Chen F, Song Z, Xu Y, Zhao J, Cheng JX, Lin X, Zhu J, Zhu H, Tian L

[

Nat Commun,

2022]

Recovering molecular information remains a grand challenge in the widely used holographic and computational imaging technologies. To address this challenge, we developed a computational mid-infrared photothermal microscope, termed Bond-selective Intensity Diffraction Tomography (BS-IDT). Based on a low-cost brightfield microscope with an add-on pulsed light source, BS-IDT recovers both infrared spectra and bond-selective 3D refractive index maps from intensity-only measurements. High-fidelity infrared fingerprint spectra extraction is validated. Volumetric chemical imaging of biological cells is demonstrated at a speed of ~20 s per volume, with a lateral and axial resolution of ~350 nm and ~1.1 µm, respectively. BS-IDT's application potential is investigated by chemically quantifying lipids stored in cancer cells and volumetric chemical imaging on Caenorhabditis elegans with a large field of view (~100 µm x 100 µm).

Bouyanfif A et al. (2017) Analyst "FTIR imaging detects diet and genotype-dependent chemical composition changes in wild type and mutant C. elegans strains."

Vanapalli SA, Bouyanfif A, Moustaid-Moussa N, Hequet E, Hewitt JE, Liyanage S, Abidi N

[

Analyst,

2017]

This study focuses on the use of Fourier Transform Infrared (FTIR) microspectroscopy to determine chemical changes induced in the nematode Caenorhabditis elegans by supplementation of C. elegans maintenance media (CeMM) by Eicosapentaenoic acid (EPA). Wild-type C. elegans (N2) and mutant strains (tub-1 and fat-3) were grown in CeMM alone, and CeMM supplemented with EPA at 25 or 100 M. Feeding was performed for 72 h. FTIR imaging was performed in transmission mode on individual worms. The FTIR imaging analysis of wild-type animals revealed the presence of vibrations assigned to unsaturated fatty acids, specifically bands at 3008 cm(-1) ([double bond, length as m-dash]C-H, olefinic stretch) and 1744 cm(-1) (C[double bond, length as m-dash]O, unsaturated fatty acids). It confirmed previously reported synthesis of unsaturated fatty acids in wild-type C. elegans. For the FTIR spectra of mutant strains, these vibrations were absent or present only as very small shoulder, which indicates that tub-1 and fat-3 synthesize essentially saturated fatty acids as indicated by the presence of -CH2 and C[double bond, length as m-dash]O vibrations. These results are in agreement with previous studies which reported that these mutants have altered lipid compositions. Principal component analysis showed differences in chemical composition between wild-type and mutant strains as well as between mutant strains cultured in normal CeMM and those cultured in CeMM supplemented with EPA. This study demonstrated the usefulness of FTIR microspectroscopy to investigate fat metabolism in C. elegans.

Lozano R et al. (1985) Lipids "Dealkylation of various 24-alkylsterols by the nematode C. elegans."

Svoboda JA, Chitwood DJ, Lozano R, Lusby WR

[

Lipids,

1985]

The metabolism of 4 dietary 24-alkylsterols was investigated in the free-living nematode Caenorhabditis elegans. The major unesterified sterols of C. elegans in media supplemented with either campesterol, 22-dihydrobrassicasterol or stigmasterol included cholesta-5,7-dienol, cholesterol, cholest-7-enol, and 4a-methylcholest-8(14)-enol. Dietary stigmastanol yielded cholest-7-enol, cholestanol, cholest-8(14)-enol, and 4a-methylcholest-8(14)-enol as major unesterified sterols. Esterified sterols comprised less than 22% of the total sterol. Removal of a C-24 ethyl substituent of sterols was neither hindered by the presence of a delta22-bond in the sterol side chain nor was it dependent on unsaturation in ring B of the steroid nucleus. C. elegans reduced a delta22-bond during its metabolism of stigmasterol; it did not introduce a delta5-bond during stigmastanol metabolism. C. elegans was capable of removing a C-24 methyl substituent regardless of it stereochemical orientation. Metabolic processes involving the steroid ring system of cholesterol (C-7 dehydrogenation, delta5-reduction, 4a-methylation, delta8(14)-isomerization) in C. elegans were not hindered by the presence of a 24-methyl group; various 24-methylsterol metabolites from campesterol were detected, mostly 24-methylcholesta-5,7-dienol. In contrast, no 24-ethylsterol metabolites from the dietary ethylsterols were found. More dietary 24-methylsterol remained unmetabolized than did dietary 24-ethylsterol. A 24a-ethyl group and a 24B-methyl group were dealkylated to a greater extent by C. elegans than was a 24a-methyl group, perhaps reflecting the substrate specificity of the dealkylation enzyme system, or suggesting different enzymes

Wang C et al. (2018) Chem Sci "Reductive cleavage of C[double bond, length as m-dash]C bonds as a new strategy for turn-on dual fluorescence in effective sensing of H₂S."

Zhang X, Ding Z, Li G, Zhang H, Yuan D, Wang C, Tan J, Wang W, Cheng X

[

Chem Sci,

2018]

Reductive cleavage of alkenes is rarely reported in synthetic chemistry. Here we report a unique H2S-mediated reductive cleavage of C[double bond, length as m-dash]C bonds under mild conditions, which is a successful new strategy for the design of probes for effective sensing of H2S with turn-on dual-color fluorescence. A short series of phenothiazine ethylidene malononitrile derivatives were shown to react with H2S, via reductive cleavage of C[double bond, length as m-dash]C bonds with intramolecular cyclization reactions to form thiophene rings. Enlightened by this new reaction mechanism, four effective probes with turn-off to turn-on fluorescence switches were successfully applied for sensing H2S, an important gaseous signalling molecule in living systems, among which PTZ-P4 exhibited two fluorescent colors after reductive cleavage. The dual-color probe was applied for imaging endogenous H2S and showed distinct differences in brightness in living C. elegans for wild type N2, glp-1 (e2144) mutants (higher levels of endogenous H2S), and cth-1 (ok3319) mutants (lower levels of endogenous H2S). The discovery of H2S-mediated reductive cleavage of C[double bond, length as m-dash]C bonds is expected to be valuable for chemical synthesis, theoretical studies, and the design of new fluorescent H2S probes.

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