Luo Y et al. (2011) Sci China Life Sci "Copper ions influence the toxicity of -amyloid(1-42) in a concentration-dependent manner in a Caenorhabditis elegans model of Alzheimer's disease."

Zhao B, Zhang J, Liu N, Luo Y

[Sci China Life Sci, 2011]

-amyloid (A) and copper play important roles in the pathogenesis of Alzheimer's disease (AD). However, the behavioral correlativity and molecular mechanisms of A and copper toxicity have been investigated less often. In the present study, we investigated the interaction and toxicity of A1-42 and copper in the A1-42 transgenic Caenorhabditis elegans worm model CL2006. Our data show that the paralysis behavior of CL2006 worms significantly deteriorated after exposure to 10(-3) mol L(-1) copper ions. However, the paralysis behavior was dramatically attenuated with exposure to 10(-4) mol L(-1) copper ions. The exogenous copper treatment also partially changed the homeostatic balance of zinc, manganese, and iron. Our data suggest that the accumulation of reactive oxygen species (ROS) was responsible for the paralysis induced by A and copper in CL2006. The ROS generation induced by A and copper appear to be through sod-1, prdx-2, skn-1, hsp-60 and hsp-16.2 genes.

Luo Y et al. (2015) Free Radic Biol Med "Asymmetric dimethylarginine exacerbates A-induced toxicity and oxidative stress in human cell and Caenorhabditis elegans models of Alzheimer disease."

Wang Y, Luo Y, Lu Z, Quan X, Zhao B, Yue W

[Free Radic Biol Med, 2015]

Growing evidence suggests a strong association between cardiovascular risk factors and incidence of Alzheimer disease (AD). Asymmetric dimethylarginine (ADMA), the endogenous nitric oxide synthase inhibitor, has been identified as an independent cardiovascular risk factor and is also increased in plasma of patients with AD. However, whether ADMA is involved in the pathogenesis of AD is unknown. In this study, we found that ADMA content was increased in a transgenic Caenorhabditis elegans -amyloid (A) overexpression model, strain CL2006, and in human SH-SY5Y cells overexpressing the Swedish mutant form of human A precursor protein (APPsw). Moreover, ADMA treatment exacerbated A-induced paralysis and oxidative stress in CL2006 worms and further elevated oxidative stress and A secretion in APPsw cells. Knockdown of type 1 protein arginine N-methyltransferase to reduce ADMA production failed to show a protective effect against A toxicity, but resulted in more paralysis in CL2006 worms as well as increased oxidative stress and A secretion in APPsw cells. However, overexpression of dimethylarginine dimethylaminohydrolase 1 (DDAH1) to promote ADMA degradation significantly attenuated oxidative stress and A secretion in APPsw cells. Collectively, our data support the hypothesis that elevated ADMA contributes to the pathogenesis of AD. Our findings suggest that strategies to increase DDAH1 activity in neuronal cells may be a novel approach to attenuating AD development.

Wu Y et al. (2010) Neurobiol Aging "Heat shock treatment reduces beta amyloid toxicity in vivo by diminishing oligomers."

Cao Z, Klein WL, Luo Y, Wu Y

[Neurobiol Aging, 2010]

Heat shock response, mediated by heat shock proteins, is a highly conserved physiological process in multicellular organisms for reestablishment of cellular homeostasis. Expression of heat shock factors and subsequent heat shock protein plays a role in protection against proteotoxicity in invertebrate and vertebrate models. Proteotoxicity due to beta-amyloid peptide (Abeta) oligomerization has been linked to the pathogenesis of Alzheimer's disease. Previously, we demonstrated that progressive paralysis induced by expression of human Abeta(1-42) in transgenic Caenorhabditis elegans was alleviated by Abeta oligomer inhibitors Ginkgo biloba extract and its constituents [Wu, Y., Wu, Z., Butko, P., Christen, Y., Lambert, M.P., Klein, W.L., Link, C.D., Luo, Y., 2006. Amyloid-beta-induced pathological behaviors are suppressed by Ginkgo biloba extract EGb 761 and ginkgolides in transgenic Caenorhabditis elegans. J. Neurosci. 26(50): 13102-13113]. In this study, we apply a protective heat shock to the transgenic C. elegans and demonstrate: (1) a delay in paralysis, (2) increased expression of small heat shock protein HSP16.2, and (3) significant reduction of Abeta oligomers in a heat shock time-dependent manner. These results suggest that transient heat shock lessens Abeta toxicity by diminishing Abeta oligomerization, which provides a link between up regulation of endogenous chaperone proteins and protection against Abeta proteotoxicity in vivo.

Perreault J et al. (2007) Mol Biol Evol "Ro-associated Y RNAs in metazoans: evolution and diversification."

Perreault J, Perreault JP, Boire G

[Mol Biol Evol, 2007]

The Y genes encode small non-coding RNAs whose functions remain elusive, whose numbers vary between species, and whose major property is to be bound by the Ro60 protein (or its ortholog in other species). To better understand the evolution of the Y gene family, we performed a homology search in 27 different genomes along with a structural search using Y RNA specific motifs. These searches confirmed that Y RNAs are well conserved in the animal kingdom and resulted in the detection of several new Y RNA genes, including the first Y RNAs in insects and a second Y RNA detected in Caenorhabditis elegans. Unexpectedly, Y5 genes were retrieved almost as frequently as Y1 and Y3 genes, and, consequently are not the result of a relatively recent apparition as is generally believed. Investigation of the organization of the Y genes demonstrated that the synteny was conserved among species. Interestingly, it revealed the presence of six putative "fossil" Y genes, all of which were Y4 and Y5 related. Sequence analysis led to inference of the ancestral sequences for all Y RNAs. In addition, the evolution of existing Y RNAs was deduced for many families, orders and classes. Moreover, a consensus sequence and secondary structure for each Y species was determined. Further evolutionary insight was obtained from the analysis of several thousand Y retropseudogenes among various species. Taken together, these results confirm the rich and diversified evolution history of Y RNAs.

Gardiner TJ et al. (2009) RNA "A conserved motif of vertebrate Y RNAs essential for chromosomal DNA replication."

Langley AR, Gardiner TJ, Krude T, Christov CP

[RNA, 2009]

Noncoding Y RNAs are required for the reconstitution of chromosomal DNA replication in late G1 phase template nuclei in a human cell-free system. Y RNA genes are present in all vertebrates and in some isolated nonvertebrates, but the conservation of Y RNA function and key determinants for its function are unknown. Here, we identify a determinant of Y RNA function in DNA replication, which is conserved throughout vertebrate evolution. Vertebrate Y RNAs are able to reconstitute chromosomal DNA replication in the human cell-free DNA replication system, but nonvertebrate Y RNAs are not. A conserved nucleotide sequence motif in the double-stranded stem of vertebrate Y RNAs correlates with Y RNA function. A functional screen of human Y1 RNA mutants identified this conserved motif as an essential determinant for reconstituting DNA replication in vitro. Double-stranded RNA oligonucleotides comprising this RNA motif are sufficient to reconstitute DNA replication, but corresponding DNA or random sequence RNA oligonucleotides are not. In intact cells, wild-type hY1 or the conserved RNA duplex can rescue an inhibition of DNA replication after RNA interference against hY3 RNA. Therefore, we have identified a new RNA motif that is conserved in vertebrate Y RNA evolution, and essential and sufficient for Y RNA function in human chromosomal DNA replication.

Erickson DL et al. (2006) J Bacteriol "Serotype differences and lack of biofilm formation characterize Yersinia pseudotuberculosis infection of the Xenopsylla cheopis flea vector of Yersinia pestis."

Hinnebusch BJ, Erickson DL, Wren BW, Jarrett CO

[J Bacteriol, 2006]

Yersinia pestis, the agent of plague, is usually transmitted by fleas. To produce a transmissible infection, Y. pestis colonizes the flea midgut and forms a biofilm in the proventricular valve, which blocks normal blood feeding. The enteropathogen Yersinia pseudotuberculosis, from which Y. pestis recently evolved, is not transmitted by fleas. However, both Y. pestis and Y. pseudotuberculosis form biofilms that adhere to the external mouthparts and block feeding of Caenorhabditis elegans nematodes, which has been proposed as a model of Y. pestis-flea interactions. We compared the ability of Y. pestis and Y. pseudotuberculosis to infect the rat flea Xenopsylla cheopis and to produce biofilms in the flea and in vitro. Five of 18 Y. pseudotuberculosis strains, encompassing seven serotypes, including all three serotype O3 strains tested, were unable to stably colonize the flea midgut. The other strains persisted in the flea midgut for 4 weeks but did not increase in numbers, and none of the 18 strains colonized the proventriculus or produced a biofilm in the flea. Y. pseudotuberculosis strains also varied greatly in their ability to produce biofilms in vitro, but there was no correlation between biofilm phenotype in vitro or on the surface of C. elegans and the ability to colonize or block fleas. Our results support a model in which a genetic change in the Y. pseudotuberculosis progenitor of Y. pestis extended its pre-existing ex vivo biofilm-forming ability to the flea gut environment, thus enabling proventricular blockage and efficient flea-borne transmission.

Georgieva S et al. (2001) Mol Cell Biol "The novel transcription factor e(y)2 interacts with TAF(II)40 and potentiates transcription activation on chromatin templates."

Soldatov A, Georgieva S, Eickhoff H, Tora L, Becker P, Dilworth FJ, Georgiev P, Nabirochkina E

[Mol Cell Biol, 2001]

Weak hypomorph mutations in the enhancer of yellow genes, e(y)1 and e(y)2, of Drosophila melanogaster were discovered during the search for genes involved in the organization of interaction between enhancers and promoters. Previously, the e(y)1 gene was cloned and found to encode TAF(II)40 protein. Here we cloned the e(y)2 gene and demonstrated that it encoded a new ubiquitous evolutionarily conserved transcription factor. The e(y)2 gene is located at 10C3 (36.67) region and is expressed at all stages of Drosophila development. It encodes a 101-amino-acid protein, e(y)2. Vertebrates, insects, protozoa, and plants have proteins which demonstrate a high degree of homology to e(y)2. The e(y)2 protein is localized exclusively to the nuclei and is associated with numerous sites along the entire length of the salivary gland polytene chromosomes. Both genetic and biochemical experiments demonstrate an interaction between e(y)2 and TAF(II)40, while immunoprecipitation studies demonstrate that the major complex, including both proteins, appears to be distinct from TFIID. Furthermore, we provide genetic evidence suggesting that the carboxy terminus of dTAF(II)40 is important for mediating this interaction. Finally, using an in vitro transcription system, we demonstrate that recombinant e(y)2 is able to enhance transactivation by GAL4-VP16 on chromatin but not on naked DNA templates, suggesting that this novel protein is involved in the regulation of transcription.

Styer KL et al. (2005) EMBO Rep "Yersinia pestis kills Caenorhabditis elegans by a biofilm-independent process that involves novel virulence factors."

Plano GV, Aballay A, Frothingham R, Bartra SS, Hopkins GW, Styer KL

[EMBO Rep, 2005]

It is known that Yersinia pestis kills Caenorhabditis elegans by a biofilm-dependent mechanism that is similar to the mechanism used by the pathogen to block food intake in the flea vector. Using Y. pestis KIM 5, which lacks the genes that are required for biofilm formation, we show that Y. pestis can kill C. elegans by a biofilm-independent mechanism that correlates with the accumulation of the pathogen in the intestine. We used this novel Y. pestis-C. elegans pathogenesis system to show that previously known and unknown virulence-related genes are required for full virulence in C. elegans. Six Y. pestis mutants with insertions in genes that are not related to virulence before were isolated using C. elegans. One of the six mutants carried an insertion in a novel virulence gene and showed significantly reduced virulence in a mouse model of Y. pestis pathogenesis. Our results indicate that the Y. pestis-C. elegans pathogenesis system that is described here can be used to identify and study previously uncharacterized Y. pestis gene products required for virulence in mammalian systems.

Kurshakova M et al. (2007) Mol Cell "Evolutionarily conserved E(y)2/Sus1 protein is essential for the barrier activity of Su(Hw)-dependent insulators in Drosophila."

Georgiev P, Golovnin A, Kurshakova M, Georgieva S, Maksimenko O, Pulina M, Krasnov A

[Mol Cell, 2007]

Chromatin insulators affect interactions between promoters and enhancers/silencers and function as barriers for spreading of repressive chromatin. The Su(Hw) protein is responsible for activity of the best-studied Drosophila insulators. Here we demonstrate that an evolutionarily conserved protein, E(y)2/Sus1, is recruited to the Su(Hw) insulators via binding to the zinc-finger domain of Su(Hw). Partial inactivation of E(y)2 in a weak mutation, e(y)2(u1), impairs only the barrier, but not the enhancer-blocking, activity of the Su(Hw) insulators. Whereas neither su(Hw)(-) nor e(y)2(u1) affects fly viability, their combination proves lethal, testifying to functional interaction between Su(Hw) and E(y)2 in vivo. Apparently, different domains of Su(Hw) recruit proteins responsible for enhancer-blocking and for the barrier activity.

Smith JV et al. (2003) J Alzheimers Dis "Elevation of oxidative free radicals in Alzheimer's disease models can be attenuated by Ginkgo biloba extract EGb 761."

Luo Y, Smith JV

[J Alzheimers Dis, 2003]

The role of amyloid beta-peptide (Abeta) in the free-radical oxidative-stress model of neurotoxicity in Alzheimer's disease (AD) has received much attention recently. In this study, we have employed both in vitro and in vivo models displaying endogenous Abeta production to study the effects of Abeta on intracellular free radical levels. We employed a neuroblastoma cell line stably expressing an AD-associated double mutation, which exhibits both increased secretion and intracellular accumulation of Abeta when stimulated, as well as transgenic Caenorhabditis elegans constitutively expressing human Abeta. A rise in levels of hydrogen peroxide (H2O2) was observed in both in vitro and in vivo AD-associated transgenic models expressing the Abeta peptide compared with the wild type controls. Treatment of the cells or C. elegans with Ginkgo biloba extract EGb 761 significantly attenuated the basal as well as the induced levels of H2O2-related reactive oxygen species (ROS). Among individual EGb 761 components tested, kaempferol and quercetin provided maximum attenuation in both models. Furthermore, an age-dependent increase in H2O2-related ROS was observed in wild type C. elegans, which is accelerated in the AD-associated C. elegans mutant. These results support the hypothesis of the involvement of Abeta and ROS in association with AD.