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Search Results: 1 - 10 of 50894 matches for " Huda Y. Zoghbi "
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Genomic organization of Tropomodulins 2 and 4 and unusual intergenic and intraexonic splicing of YL-1 and Tropomodulin 4
Patrick R Cox, Teepu Siddique, Huda Y Zoghbi
BMC Genomics , 2001, DOI: 10.1186/1471-2164-2-7
Abstract: In this study, we determined the genomic structure of TMOD2 and TMOD4 and found the organization of both genes to be similar. Sequence analysis of TMOD2 revealed no mutations or polymorphisms in ALS5 patients or controls. Interestingly, we discovered that another gene, YL-1, intergenically splices into TMOD4. YL-1 encodes six exons, the last of which is 291 bp from a 5' untranslated exon of TMOD4. We used 5' RACE and RT-PCR from TMOD4 to identify several intergenic RACE products. YL-1 was also found to undergo unconventional splicing using non-canonical splice sites within exons (intraexonic splicing) to produce several alternative transcripts.The genomic structure of TMOD2 and TMOD4 have been delineated. This should facilitate future mutational analysis of these genes. In addition, intergenic splicing at TMOD4/YL-1 was discovered, demonstrating yet another level of complexity of gene organization and regulation.Tropomodulins are the vertebrate proteins that cap the pointed ends of filamentous actin [1]. The first tropomodulin (TMOD) gene was cloned by Sung and colleagues (1992) from a fetal liver library. Three additional family members have been identified in humans, and TMOD homologs have been identified in mouse, rat, chick, Drosophila, and C. elegans[2-8]. Expression patterns vary extensively: Tropomodulin 3 (TMOD3) is ubiquitous; Tropomodulin 1 (TMOD1) is widespread in heart, muscle, brain, lens, erythrocytes, and arterioles; Tropomodulin 2 (TMOD2) is restricted to neuronal tissue; Tropomodulin 4 (TMOD4). is expressed in skeletal muscle, with a less abundant ~7 kb transcript expressed in both skeletal and cardiac muscle [8]. Whereas tropomodulins or the Arp 2/3 complex cap the pointed end of actin filaments, the barbed end can be capped by CapZ, α, β, and γ adducins as well as gelsolin [9-11]. Control of thin filament length is critical for maintaining proper sarcomere function and length[12]. Inhibition of Tmod1's capping activity – either by using an antibod
Genetic Modifiers of MeCP2 Function in Drosophila
Holly N. Cukier,Alma M. Perez,Ann L. Collins,Zhaolan Zhou,Huda Y. Zoghbi,Juan Botas
PLOS Genetics , 2008, DOI: 10.1371/journal.pgen.1000179
Abstract: The levels of methyl-CpG–binding protein 2 (MeCP2) are critical for normal post-natal development and function of the nervous system. Loss of function of MeCP2, a transcriptional regulator involved in chromatin remodeling, causes classic Rett syndrome (RTT) as well as other related conditions characterized by autism, learning disabilities, or mental retardation. Increased dosage of MeCP2 also leads to clinically similar neurological disorders and mental retardation. To identify molecular mechanisms capable of compensating for altered MeCP2 levels, we generated transgenic Drosophila overexpressing human MeCP2. We find that MeCP2 associates with chromatin and is phosphorylated at serine 423 in Drosophila, as is found in mammals. MeCP2 overexpression leads to anatomical (i.e., disorganized eyes, ectopic wing veins) and behavioral (i.e., motor dysfunction) abnormalities. We used a candidate gene approach to identify genes that are able to compensate for abnormal phenotypes caused by MeCP2 increased activity. These genetic modifiers include other chromatin remodeling genes (Additional sex combs, corto, osa, Sex combs on midleg, and trithorax), the kinase tricornered, the UBE3A target pebble, and Drosophila homologues of the MeCP2 physical interactors Sin3a, REST, and N-CoR. These findings demonstrate that anatomical and behavioral phenotypes caused by MeCP2 activity can be ameliorated by altering other factors that might be more amenable to manipulation than MeCP2 itself.
Partial Loss of Ataxin-1 Function Contributes to Transcriptional Dysregulation in Spinocerebellar Ataxia Type 1 Pathogenesis
Juan Crespo-Barreto,John D. Fryer,Chad A. Shaw,Harry T. Orr,Huda Y. Zoghbi
PLOS Genetics , 2010, DOI: 10.1371/journal.pgen.1001021
Abstract: Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited neurodegenerative disease caused by expansion of a CAG repeat that encodes a polyglutamine tract in ATAXIN1 (ATXN1). Molecular and genetic data indicate that SCA1 is mainly caused by a gain-of-function mechanism. However, deletion of wild-type ATXN1 enhances SCA1 pathogenesis, whereas increased levels of an evolutionarily conserved paralog of ATXN1, Ataxin 1-Like, ameliorate it. These data suggest that a partial loss of ATXN1 function contributes to SCA1. To address this possibility, we set out to determine if the SCA1 disease model (Atxn1154Q/+ mice) and the loss of Atxn1 function model (Atxn1?/? mice) share molecular changes that could potentially contribute to SCA1 pathogenesis. To identify transcriptional changes that might result from loss of function of ATXN1 in SCA1, we performed gene expression microarray studies on cerebellar RNA from Atxn1?/? and Atxn1154Q/+ cerebella and uncovered shared gene expression changes. We further show that mild overexpression of Ataxin-1-Like rescues several of the molecular and behavioral defects in Atxn1?/? mice. These results support a model in which Ataxin 1-Like overexpression represses SCA1 pathogenesis by compensating for a partial loss of function of Atxn1. Altogether, these data provide evidence that partial loss of Atxn1 function contributes to SCA1 pathogenesis and raise the possibility that loss-of-function mechanisms contribute to other dominantly inherited neurodegenerative diseases.
Lithium Therapy Improves Neurological Function and Hippocampal Dendritic Arborization in a Spinocerebellar Ataxia Type 1 Mouse Model
Kei Watase,Jennifer R Gatchel,Yaling Sun,Effat Emamian,Richard Atkinson,Ronald Richman,Hidehiro Mizusawa,Harry T Orr,Chad Shaw,Huda Y Zoghbi
PLOS Medicine , 2007, DOI: 10.1371/journal.pmed.0040182
Abstract: Background Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited neurodegenerative disorder characterized by progressive motor and cognitive dysfunction. Caused by an expanded polyglutamine tract in ataxin 1 (ATXN1), SCA1 pathogenesis involves a multifactorial process that likely begins with misfolding of ATXN1, which has functional consequences on its interactions, leading to transcriptional dysregulation. Because lithium has been shown to exert neuroprotective effects in a variety of conditions, possibly by affecting gene expression, we tested the efficacy of lithium treatment in a knock-in mouse model of SCA1 (Sca1154Q/2Q mice) that replicates many features of the human disease. Methods and Findings Sca1154Q/2Q mice and their wild-type littermates were fed either regular chow or chow that contained 0.2% lithium carbonate. Dietary lithium carbonate supplementation resulted in improvement of motor coordination, learning, and memory in Sca1154Q/2Q mice. Importantly, motor improvement was seen when treatment was initiated both presymptomatically and after symptom onset. Neuropathologically, lithium treatment attenuated the reduction of dendritic branching in mutant hippocampal pyramidal neurons. We also report that lithium treatment restored the levels of isoprenylcysteine carboxyl methyltransferase (Icmt; alternatively, Pccmt), down-regulation of which is an early marker of mutant ATXN1 toxicity. Conclusions The effect of lithium on a marker altered early in the course of SCA1 pathogenesis, coupled with its positive effect on multiple behavioral measures and hippocampal neuropathology in an authentic disease model, make it an excellent candidate treatment for human SCA1 patients.
dAtaxin-2 Mediates Expanded Ataxin-1-Induced Neurodegeneration in a Drosophila Model of SCA1
Ismael Al-Ramahi,Alma M Pérez,Janghoo Lim,Minghang Zhang,Rie Sorensen,Maria de Haro,Joana Branco,Stefan M Pulst,Huda Y Zoghbi,Juan Botas
PLOS Genetics , 2007, DOI: 10.1371/journal.pgen.0030234
Abstract: Spinocerebellar ataxias (SCAs) are a genetically heterogeneous group of neurodegenerative disorders sharing atrophy of the cerebellum as a common feature. SCA1 and SCA2 are two ataxias caused by expansion of polyglutamine tracts in Ataxin-1 (ATXN1) and Ataxin-2 (ATXN2), respectively, two proteins that are otherwise unrelated. Here, we use a Drosophila model of SCA1 to unveil molecular mechanisms linking Ataxin-1 with Ataxin-2 during SCA1 pathogenesis. We show that wild-type Drosophila Ataxin-2 (dAtx2) is a major genetic modifier of human expanded Ataxin-1 (Ataxin-1[82Q]) toxicity. Increased dAtx2 levels enhance, and more importantly, decreased dAtx2 levels suppress Ataxin-1[82Q]-induced neurodegeneration, thereby ruling out a pathogenic mechanism by depletion of dAtx2. Although Ataxin-2 is normally cytoplasmic and Ataxin-1 nuclear, we show that both dAtx2 and hAtaxin-2 physically interact with Ataxin-1. Furthermore, we show that expanded Ataxin-1 induces intranuclear accumulation of dAtx2/hAtaxin-2 in both Drosophila and SCA1 postmortem neurons. These observations suggest that nuclear accumulation of Ataxin-2 contributes to expanded Ataxin-1-induced toxicity. We tested this hypothesis engineering dAtx2 transgenes with nuclear localization signal (NLS) and nuclear export signal (NES). We find that NLS-dAtx2, but not NES-dAtx2, mimics the neurodegenerative phenotypes caused by Ataxin-1[82Q], including repression of the proneural factor Senseless. Altogether, these findings reveal a previously unknown functional link between neurodegenerative disorders with common clinical features but different etiology.
Glutamine-Expanded Ataxin-7 Alters TFTC/STAGA Recruitment and Chromatin Structure Leading to Photoreceptor Dysfunction
Dominique Helmlinger,Sara Hardy,Gretta Abou-Sleymane,Adrien Eberlin,Aaron B. Bowman,Anne Gansmüller,Serge Picaud,Huda Y. Zoghbi,Yvon Trottier,Làszlò Tora,Didier Devys
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0040067
Abstract: Spinocerebellar ataxia type 7 (SCA7) is one of several inherited neurodegenerative disorders caused by a polyglutamine (polyQ) expansion, but it is the only one in which the retina is affected. Increasing evidence suggests that transcriptional alterations contribute to polyQ pathogenesis, although the mechanism is unclear. We previously demonstrated that theSCA7 gene product, ataxin-7 (ATXN7), is a subunit of the GCN5 histone acetyltransferase–containing coactivator complexes TFTC/STAGA. We show here that TFTC/STAGA complexes purified from SCA7 mice have normal TRRAP, GCN5, TAF12, and SPT3 levels and that their histone or nucleosomal acetylation activities are unaffected. However, rod photoreceptors from SCA7 mouse models showed severe chromatin decondensation. In agreement, polyQ-expanded ataxin-7 induced histone H3 hyperacetylation, resulting from an increased recruitment of TFTC/STAGA to specific promoters. Surprisingly, hyperacetylated genes were transcriptionally down-regulated, and expression analysis revealed that nearly all rod-specific genes were affected, leading to visual impairment in SCA7 mice. In conclusion, we describe here a set of events accounting for SCA7 pathogenesis in the retina, in which polyQ-expanded ATXN7 deregulated TFTC/STAGA recruitment to a subset of genes specifically expressed in rod photoreceptors, leading to chromatin alterations and consequent progressive loss of rod photoreceptor function.
Inactivation of hnRNP K by Expanded Intronic AUUCU Repeat Induces Apoptosis Via Translocation of PKCδ to Mitochondria in Spinocerebellar Ataxia 10
Misti C. White equal contributor,Rui Gao equal contributor,Weidong Xu,Santi M. Mandal,Jung G. Lim,Tapas K. Hazra,Maki Wakamiya,Sharon F. Edwards,Salmo Raskin,Hélio A. G. Teive,Huda Y. Zoghbi,Partha S. Sarkar,Tetsuo Ashizawa
PLOS Genetics , 2010, DOI: 10.1371/journal.pgen.1000984
Abstract: We have identified a large expansion of an ATTCT repeat within intron 9 of ATXN10 on chromosome 22q13.31 as the genetic mutation of spinocerebellar ataxia type 10 (SCA10). Our subsequent studies indicated that neither a gain nor a loss of function of ataxin 10 is likely the major pathogenic mechanism of SCA10. Here, using SCA10 cells, and transfected cells and transgenic mouse brain expressing expanded intronic AUUCU repeats as disease models, we show evidence for a key pathogenic molecular mechanism of SCA10. First, we studied the fate of the mutant repeat RNA by in situ hybridization. A Cy3-(AGAAU)10 riboprobe detected expanded AUUCU repeats aggregated in foci in SCA10 cells. Pull-down and co-immunoprecipitation data suggested that expanded AUUCU repeats within the spliced intronic sequence strongly bind to hnRNP K. Co-localization of hnRNP K and the AUUCU repeat aggregates in the transgenic mouse brain and transfected cells confirmed this interaction. To examine the impact of this interaction on hnRNP K function, we performed RT–PCR analysis of a splicing-regulatory target of hnRNP K, and found diminished hnRNP K activity in SCA10 cells. Cells expressing expanded AUUCU repeats underwent apoptosis, which accompanied massive translocation of PKCδ to mitochondria and activation of caspase 3. Importantly, siRNA–mediated hnRNP K deficiency also caused the same apoptotic event in otherwise normal cells, and over-expression of hnRNP K rescued cells expressing expanded AUUCU repeats from apoptosis, suggesting that the loss of function of hnRNP K plays a key role in cell death of SCA10. These results suggest that the expanded AUUCU–repeat in the intronic RNA undergoes normal transcription and splicing, but causes apoptosis via an activation cascade involving a loss of hnRNP K activities, massive translocation of PKCδ to mitochondria, and caspase 3 activation.
Glutamine-Expanded Ataxin-7 Alters TFTC/STAGA Recruitment and Chromatin Structure Leading to Photoreceptor Dysfunction
Dominique Helmlinger,Sara Hardy equal contributor,Gretta Abou-Sleymane equal contributor,Adrien Eberlin,Aaron B Bowman,Anne Gansmüller,Serge Picaud,Huda Y Zoghbi,Yvon Trottier,Làszlò Tora ,Didier Devys
PLOS Biology , 2006, DOI: 10.1371/journal.pbio.0040067
Abstract: Spinocerebellar ataxia type 7 (SCA7) is one of several inherited neurodegenerative disorders caused by a polyglutamine (polyQ) expansion, but it is the only one in which the retina is affected. Increasing evidence suggests that transcriptional alterations contribute to polyQ pathogenesis, although the mechanism is unclear. We previously demonstrated that theSCA7 gene product, ataxin-7 (ATXN7), is a subunit of the GCN5 histone acetyltransferase–containing coactivator complexes TFTC/STAGA. We show here that TFTC/STAGA complexes purified from SCA7 mice have normal TRRAP, GCN5, TAF12, and SPT3 levels and that their histone or nucleosomal acetylation activities are unaffected. However, rod photoreceptors from SCA7 mouse models showed severe chromatin decondensation. In agreement, polyQ-expanded ataxin-7 induced histone H3 hyperacetylation, resulting from an increased recruitment of TFTC/STAGA to specific promoters. Surprisingly, hyperacetylated genes were transcriptionally down-regulated, and expression analysis revealed that nearly all rod-specific genes were affected, leading to visual impairment in SCA7 mice. In conclusion, we describe here a set of events accounting for SCA7 pathogenesis in the retina, in which polyQ-expanded ATXN7 deregulated TFTC/STAGA recruitment to a subset of genes specifically expressed in rod photoreceptors, leading to chromatin alterations and consequent progressive loss of rod photoreceptor function.
Pharmacometabolomic Signature of Ataxia SCA1 Mouse Model and Lithium Effects
Bertrand Perroud, Paymaan Jafar-Nejad, William R. Wikoff, Jennifer R. Gatchel, Lu Wang, Dinesh K. Barupal, Juan Crespo-Barreto, Oliver Fiehn, Huda Y. Zoghbi, Rima Kaddurah-Daouk
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0070610
Abstract: We have shown that lithium treatment improves motor coordination in a spinocerebellar ataxia type 1 (SCA1) disease mouse model (Sca1154Q/+). To learn more about disease pathogenesis and molecular contributions to the neuroprotective effects of lithium, we investigated metabolomic profiles of cerebellar tissue and plasma from SCA1-model treated and untreated mice. Metabolomic analyses of wild-type and Sca1154Q/+ mice, with and without lithium treatment, were performed using gas chromatography time-of-flight mass spectrometry and BinBase mass spectral annotations. We detected 416 metabolites, of which 130 were identified. We observed specific metabolic perturbations in Sca1154Q/+ mice and major effects of lithium on metabolism, centrally and peripherally. Compared to wild-type, Sca1154Q/+ cerebella metabolic profile revealed changes in glucose, lipids, and metabolites of the tricarboxylic acid cycle and purines. Fewer metabolic differences were noted in Sca1154Q/+ mouse plasma versus wild-type. In both genotypes, the major lithium responses in cerebellum involved energy metabolism, purines, unsaturated free fatty acids, and aromatic and sulphur-containing amino acids. The largest metabolic difference with lithium was a 10-fold increase in ascorbate levels in wild-type cerebella (p<0.002), with lower threonate levels, a major ascorbate catabolite. In contrast, Sca1154Q/+ mice that received lithium showed no elevated cerebellar ascorbate levels. Our data emphasize that lithium regulates a variety of metabolic pathways, including purine, oxidative stress and energy production pathways. The purine metabolite level, reduced in the Sca1154Q/+ mice and restored upon lithium treatment, might relate to lithium neuroprotective properties.
Chemical Composition, Colour and Sensory Characteristics of Commercial Serunding (Shredded Meat) in Malaysia
N. Huda,Y. Fatma,A. Fazillah,F. Adzitey
Pakistan Journal of Nutrition , 2012,
Abstract: Serunding (shredded meat) is one of the traditional meat based-product popular among Malaysians. Eight commercial serunding prepared using beef, chicken and fish as raw material were collected from markets and analyzed to determine their chemical composition, colour and sensory characteristics. The results showed that moisture, fat and protein contents were within the range of 8.60-13.56, 3.20-31.14 and 19.86-30.15%, respectively. Serunding ayam or shredded chicken was the lightest in colour followed by serunding daging or shredded meat and serunding ikan or shredded fish. Sensory evaluation showed that panelists preferred shredded fish with darker colour. However there was no significant difference between the overall acceptability for shredded meat and chicken.
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