Paul J Hagerman

Publications (113)629.59 Total impact

• Article: Enhanced Asynchronous Ca2+ Oscillations Associated with Impaired Glutamate Transport In Cortical Astrocytes Expressing Fmr1 Premutation Expansion.

  Zhengyu Cao, Susan Hulsizer, Yanjun Cui, Dalyir L Pretto, Kyung Ho Kim, Paul J Hagerman, Flora Tassone, Isaac N Pessah
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  ABSTRACT: Premutation CGG repeat expansions (55-200 CGG repeats; preCGG) within the fragile X mental retardation 1 (FMR1) gene can cause fragile X-associated tremor/ataxia syndrome (FXTAS). Defects in early neuronal migration and morphology, electrophysiological activity and mitochondria trafficking have been described in a premutation mouse model, but whether preCGG mutations also affect astrocyte function remains unknown. PreCGG cortical astrocytes (~170 CGG repeats) displayed 3-fold higher Fmr1 mRNA and 30% lower FMRP compared to WT. PreCGG astrocytes showed modest reductions in expression of glutamate (Glu) transporters GLT-1 and GLAST and attenuated Glu uptake (p<0.01). Consistent with astrocyte cultures in vitro, aged preCGG mice cerebral cortex also displayed reduced GLAST and GLT-1 expression. Approximately 65% of the WT and preCGG cortical astrocytes displayed spontaneous asynchonous Ca(2+) oscillations. PreCGG astrocytes exhibited nearly 50% higher frequency of asynchronous Ca(2+) oscillations (p<0.01) than WT, a difference mimicked by chronic exposure of WT astrocytes to l-trans-PDC or by partial suppression of GLAST using siRNA interference. Acute challenge with Glu augmented the frequency of Ca(2+) oscillations in both genotypes. Additionally, 10 μM Glu elicited a sustained intracellular Ca(2+) rise in a higher portion of preCGG astrocytes compared to WT. Pharmacological studies showed that mGluR5, but not NMDA receptor, contributed to Glu hypersensitivity in preCGG astrocytes. These functional defects in preCGG astrocytes, especially in Glu signaling, may contribute to FXTAS neuropathology.
  Journal of Biological Chemistry 04/2013; · 4.77 Impact Factor
• Article: Sequestration of DROSHA and DGCR8 by Expanded CGG RNA Repeats Alters MicroRNA Processing in Fragile X-Associated Tremor/Ataxia Syndrome.

  Chantal Sellier, Fernande Freyermuth, Ricardos Tabet, Tuan Tran, Fang He, Frank Ruffenach, Violaine Alunni, Herve Moine, Christelle Thibault, Adeline Page, Flora Tassone, Rob Willemsen, Matthew D Disney, Paul J Hagerman, Peter K Todd, Nicolas Charlet-Berguerand
  [show abstract] [hide abstract]
  ABSTRACT: Fragile X-associated tremor/ataxia syndrome (FXTAS) is an inherited neurodegenerative disorder caused by the expansion of 55-200 CGG repeats in the 5' UTR of FMR1. These expanded CGG repeats are transcribed and accumulate in nuclear RNA aggregates that sequester one or more RNA-binding proteins, thus impairing their functions. Here, we have identified that the double-stranded RNA-binding protein DGCR8 binds to expanded CGG repeats, resulting in the partial sequestration of DGCR8 and its partner, DROSHA, within CGG RNA aggregates. Consequently, the processing of microRNAs (miRNAs) is reduced, resulting in decreased levels of mature miRNAs in neuronal cells expressing expanded CGG repeats and in brain tissue from patients with FXTAS. Finally, overexpression of DGCR8 rescues the neuronal cell death induced by expression of expanded CGG repeats. These results support a model in which a human neurodegenerative disease originates from the alteration, in trans, of the miRNA-processing machinery.
  Cell reports. 03/2013;
• Source

  Available from: Anna L Ludwig

  Dataset: Ludwig-2011-Initiation of Translation of the FMR1 mRNA Occurs Predominantly through-SUPP

  Anna L Ludwig, John W B Hershey, Paul J Hagerman
• Article: Influence of the fragile X mental retardation (FMR1) gene on the brain and working memory in men with normal FMR1 alleles.

  Jun Yi Wang, David Hessl, Christine Iwahashi, Katherine Cheung, Andrea Schneider, Randi J Hagerman, Paul J Hagerman, Susan M Rivera
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  ABSTRACT: The fragile X mental retardation 1 (FMR1) gene plays an important role in the development and maintenance of neuronal circuits that are essential for cognitive functioning. We explored the functional linkage(s) among lymphocytic FMR1 gene expression, brain structure, and working memory in healthy adult males. We acquired T1-weighted and diffusion tensor imaging from 34 males (18-80years, mean±SD=43.6±18.4years) with normal FMR1 alleles and performed genetic and working memory assessments. Brain measurements were obtained from fiber tracts important for working memory (i.e. the arcuate fasciculus, anterior cingulum bundle, inferior longitudinal fasciculus, and the genu and anterior body of the corpus callosum), individual voxels, and whole brain. Both FMR1 mRNA and protein (FMRP) levels exhibited significant associations with brain measurements, with FMRP correlating positively with gray matter volume and white matter structural organization, and FMR1 mRNA negatively with white matter structural organization. The correlation was widespread, impacting rostral white matter and 2 working-memory fiber tracts for FMRP, and all cerebral white matter areas except the fornix and cerebellar peduncles and all 4 fiber tracts for FMR1 mRNA. In addition, the levels of FMR1 mRNA as well as the fiber tracts demonstrated a significant correlation with working memory performance. While FMR1 mRNA exhibited a negative correlation with working memory, fiber tract structural organization showed a positive correlation. These findings suggest that the FMR1 gene is a genetic factor common for both working memory and brain structure, and has implications for our understanding of the transmission of intelligence and brain structure.
  NeuroImage 10/2012; · 5.89 Impact Factor
• Article: Sequencing the unsequenceable: Expanded CGG-repeat alleles of the fragile X gene.

  Erick W Loomis, John S Eid, Paul Peluso, Jun Yin, Luke Hickey, David Rank, Sarah McCalmon, Randi J Hagerman, Flora Tassone, Paul J Hagerman
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  ABSTRACT: The human fragile X mental retardation 1 (FMR1) gene contains a (CGG)(n) trinucleotide repeat in its 5' untranslated region (5'UTR). Expansions of this repeat result in a number of clinical disorders with distinct molecular pathologies, including fragile X syndrome (FXS; full mutation range, > 200 CGG repeats) and fragile X-associated tremor/ataxia syndrome (FXTAS; premutation range, 55-200 repeats). Study of these diseases has been limited by an inability to sequence expanded CGG repeats, particularly in the full mutation range, with existing DNA sequencing technologies. Single molecule real time (SMRT) sequencing provides an approach to sequencing that is fundamentally different from other "next-generation" sequencing platforms, and is well suited for long, repetitive DNA sequences. We report the first sequence data for expanded CGG-repeat FMR1 alleles in the full mutation range that reveal the confounding effects of CGG-repeat tracts on both cloning and PCR. A unique feature of SMRT sequencing is its ability to yield real-time information on the rates of nucleoside addition by the tethered DNA polymerase; for the CGG-repeat alleles, we find a strand-specific effect of CGG-repeat DNA on the inter-pulse distance. This kinetic signature reveals a novel aspect of the repeat element; namely, that the particular G bias within the CGG/CCG-repeat element influences polymerase activity in a manner that extends beyond simple nearest-neighbor effects. These observations provide a baseline for future kinetic studies of repeat elements, as well as for studies of epigenetic and other chemical modifications thereof.
  Genome Research 10/2012; · 13.61 Impact Factor
• Article: Early mitochondrial abnormalities in hippocampal neurons cultured from Fmr1 pre-mutation mouse model.

  Eitan S Kaplan, Zhengyu Cao, Susan Hulsizer, Flora Tassone, Robert F Berman, Paul J Hagerman, Isaac N Pessah
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  ABSTRACT: Pre-mutation CGG repeat expansions (55-200 CGG repeats; pre-CGG) within the fragile-X mental retardation 1 (FMR1) gene cause fragile-X-associated tremor/ataxia syndrome in humans. Defects in neuronal morphology, early migration, and electrophysiological activity have been described despite appreciable expression of fragile-X mental retardation protein (FMRP) in a pre-CGG knock-in (KI) mouse model. The triggers that initiate and promote pre-CGG neuronal dysfunction are not understood. The absence of FMRP in a Drosophila model of fragile-X syndrome was shown to increase axonal transport of mitochondria. In this study, we show that dissociated hippocampal neuronal culture from pre-CGG KI mice (average 170 CGG repeats) express 42.6% of the FMRP levels and 3.8-fold higher Fmr1 mRNA than that measured in wild-type neurons at 4 days in vitro. Pre-CGG hippocampal neurons show abnormalities in the number, mobility, and metabolic function of mitochondria at this early stage of differentiation. Pre-CGG hippocampal neurites contained significantly fewer mitochondria and greatly reduced mitochondria mobility. In addition, pre-CGG neurons had higher rates of basal oxygen consumption and proton leak. We conclude that deficits in mitochondrial trafficking and metabolic function occur despite the presence of appreciable FMRP expression and may contribute to the early pathophysiology in pre-CGG carriers and to the risk of developing clinical fragile-X-associated tremor/ataxia syndrome.
  Journal of Neurochemistry 08/2012; 123(4):613-21. · 4.06 Impact Factor
• Article: Neural Substrates of Executive Dysfunction in Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS): a Brain Potential Study.

  Jin-Chen Yang, Shiao-Hui Chan, Sara Khan, Andrea Schneider, Rawi Nanakul, Sara Teichholtz, Yu-Qiong Niu, Andreea Seritan, Flora Tassone, Jim Grigsby, Paul J Hagerman, Randi J Hagerman, John M Olichney
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  ABSTRACT: Executive dysfunction in fragile X-associated tremor/ataxia syndrome (FXTAS) has been suggested to mediate other cognitive impairments. In the present study, event-related potentials and neuropsychological testing were combined to investigate the brain mechanisms underlying the executive dysfunction in FXTAS. Thirty-two-channel electroencephalography was recorded during an auditory "oddball" task requiring dual responses. FXTAS patients (N= 41, mean age= 62) displayed prolonged latencies of N1 and P3 and reduced amplitudes of P2 and P3, whereas their N2 measures remained within the normal range, indicating relatively preserved early-stage auditory attention but markedly impaired late-stage attention and working memory updating processes (as indexed by P3). Topographical mapping revealed a typical parietal P3 peak preceded by a prominent fronto-central P3 in normal control subjects (N= 32), whereas FXTAS patients had decreased parietal P3 amplitude and diminished fronto-central positivities with a delayed onset (∼50 ms later than controls, P < 0.002). The P3 abnormalities were associated with lower executive function test (e.g., BDS-2) scores. Smaller P3 amplitudes also correlated with increased CGG repeat length of fragile X mental retardation 1 (FMR1) gene and higher FMR1 mRNA levels. These results indicate that abnormal fronto-parietal attentional network dynamics underlie executive dysfunction, the cardinal feature of cognitive impairment in FXTAS.
  Cerebral Cortex 08/2012; · 6.54 Impact Factor
• Article: Immune-mediated disorders among women carriers of fragile X premutation alleles.

  Tri Indah Winarni, Weerasak Chonchaiya, Tanjung Ayu Sumekar, Paul Ashwood, Guadalupe Mendoza Morales, Flora Tassone, Danh V Nguyen, Sultana M H Faradz, Judy Van de Water, Kylee Cook, Alyssa Hamlin, Yi Mu, Paul J Hagerman, Randi J Hagerman
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  ABSTRACT: The relative risk of immune-mediated disorders (IMDs) among women carriers of premutation alleles is estimated by a survey for IMDs among 344 carrier women (age 19-81 years; mean 46.35 and SD 12.60) and 72 controls (age 18-87 years; mean 52.40 and SD 15.40). One hundred fifty four (44.77%) women carrier had at least one IMD, as did 20 controls (27.78%). Among women carriers, autoimmune thyroid disorder was the most common (24.4%), then fibromyalgia (10.2%), irritable bowel syndrome (IBS; 9.9%), Raynaud's phenomenon (7.6%), rheumatoid arthritis (RA; 3.8%), Sjögren syndrome (2.6%), systemic lupus erythematosus (SLE; 2.03%), multiple sclerosis (1.74%). Of 55 carriers age 40 or older with FXTAS, 72.73% had at least one IMD, compared to 46.54% of those without FXTAS (n = 159), and 31.58% of controls (n = 57). The estimated odds ratio (OR) for IMD is 2.6 (95% CI 1.2-5.6, P = 0.015) for women with FXTAS relative to those without FXTAS; the likelihood of IMD in carriers without or with FXTAS was also significantly higher than for controls (OR 2.1, 95% CI 1.1-4.2, P = 0.034; OR 5.5, 95% CI 2.4-12.5, P < 0.001, respectively). Similarly, the odds of having an IMD among carriers with FXPOI is about 2.4 times higher when compared to carriers without FXPOI (95% CI 1.1-5.0; P = 0.021). The likelihood of IMD in carriers with or without FXPOI is greater (OR 2.4, 95% CI 1.1-5.0; P = 0.021) compared to that of controls. © 2012 Wiley Periodicals, Inc.
  American Journal of Medical Genetics Part A 08/2012; 158A(10):2473-81. · 2.39 Impact Factor
• Article: Signaling defects in iPSC-derived fragile X premutation neurons.

  Jing Liu, Katarzyna A Koscielska, Zhengyu Cao, Susan Hulsizer, Natalie Grace, Gaela Mitchell, Catherine Nacey, Jackline Githinji, Jeannine McGee, Dolores Garcia-Arocena, Randi J Hagerman, Jan Nolta, Isaac N Pessah, Paul J Hagerman
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  ABSTRACT: Fragile X-associated tremor/ataxia syndrome (FXTAS) is a leading monogenic neurodegenerative disorder affecting premutation carriers of the fragile X (FMR1) gene. To investigate the underlying cellular neuropathology, we produced induced pluripotent stem cell-derived neurons from isogenic subclones of primary fibroblasts of a female premutation carrier, with each subclone bearing exclusively either the normal or the expanded (premutation) form of the FMR1 gene as the active allele. We show that neurons harboring the stably-active, expanded allele (EX-Xa) have reduced postsynaptic density protein 95 protein expression, reduced synaptic puncta density and reduced neurite length. Importantly, such neurons are also functionally abnormal, with calcium transients of higher amplitude and increased frequency than for neurons harboring the normal-active allele. Moreover, a sustained calcium elevation was found in the EX-Xa neurons after glutamate application. By excluding the individual genetic background variation, we have demonstrated neuronal phenotypes directly linked to the FMR1 premutation. Our approach represents a unique isogenic, X-chromosomal epigenetic model to aid the development of targeted therapeutics for FXTAS, and more broadly as a model for the study of common neurodevelopmental (e.g. autism) and neurodegenerative (e.g. Parkinsonism, dementias) disorders.
  Human Molecular Genetics 05/2012; 21(17):3795-805. · 7.64 Impact Factor
• Article: AGG interruptions within the maternal FMR1 gene reduce the risk of offspring with fragile X syndrome.

  Carolyn M Yrigollen, Blythe Durbin-Johnson, Louise Gane, David L Nelson, Randi Hagerman, Paul J Hagerman, Flora Tassone
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  ABSTRACT: The ability to accurately predict the likelihood of expansion of the CGG repeats in the FMR1 gene to a full mutation is of critical importance for genetic counseling of women who are carriers of premutation alleles (55-200 CGG repeats) and who are weighing the risk of having a child with fragile X syndrome. The presence of AGG interruptions within the CGG repeat tract is thought to decrease the likelihood of expansion to a full mutation during transmission, thereby reducing risk, although their contribution has not been quantified. We retrospectively analyzed 267 premutation alleles for number and position of AGG interruptions, length of pure CGG repeats, and CGG repeat lengths present in the offspring of the maternal transmissions. In addition, we determined the haplotypes of four markers flanking the 5'-UTR locus in the premutation mothers. We found that the presence of AGG interruptions significantly increased genetic stability, whereas specific haplotypes had a marginal association with transmission instability. The presence of AGG interruptions reduced the risk of transmission of a full mutation for all maternal (premutation) repeat lengths below ~100 CGG repeats, with a differential risk (0 vs. 2 AGG) exceeding 60% for alleles in the 70- to 80-CGG repeat range.
  Genetics in medicine: official journal of the American College of Medical Genetics 04/2012; 14(8):729-36. · 3.92 Impact Factor
• Article: Reduced telomere length in individuals with FMR1 premutations and full mutations.

  Edmund C Jenkins, Flora Tassone, Lingling Ye, André T Hoogeveen, W Ted Brown, Randi J Hagerman, Paul J Hagerman
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  ABSTRACT: We reported previously that 10 older men (66.4 ± 4.6 years) with premutation alleles (55-200 CGG repeats) of the FMR1 gene, with or without FXTAS, had decreased telomere length when compared to sex- and age-matched controls. Extending our use of light intensity measurements from a telomere probe hybridized to interphase preparations, we have now found shortened telomeres in 9 younger male premutation carriers (31.7 ± 17.6 years). We have also shown decreased telomere length in T lymphocytes from 6 male individuals (12.0 ± 1.8 years) with full mutation FMR1 alleles (>200 CGG repeats). These findings support our hypothesis that reduced telomere length is a component of the sub-cellular pathology of FMR1-associated disorders. The experimental approach involved pair-wise comparisons of light intensity values of 20 cells from an individual with either premutation or full mutation CGG-repeat expansions relative to an equivalent number of cells from a sex- and age-matched control. In addition, we demonstrated reduced telomere size in T-lymphocyte cultures from eight individuals with the FMR1 premutation using six different measures. Four relied on detection of light intensity differences, and two involved measuring the whole chromosome, including the telomere, in microns. This new approach confirmed our findings with light intensity measurements and demonstrated the feasibility of direct linear measurements for detecting reductions in telomere size. We have thus confirmed our hypothesis that reduced telomere length is associated with both premutation and full mutation-FMR1 alleles and have demonstrated that direct measurements of telomere length can reliably detect such reductions.
  American Journal of Medical Genetics Part A 04/2012; 158A(5):1060-5. · 2.39 Impact Factor
• Article: Clustered burst firing in FMR1 premutation hippocampal neurons: amelioration with allopregnanolone.

  Zhengyu Cao, Susan Hulsizer, Flora Tassone, Hiu-tung Tang, Randi J Hagerman, Michael A Rogawski, Paul J Hagerman, Isaac N Pessah
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  ABSTRACT: Premutation CGG repeat expansions (55-200 CGG repeats; preCGG) within the fragile X mental retardation 1 (FMR1) gene cause fragile X-associated tremor/ataxia syndrome (FXTAS). Defects in neuronal morphology and migration have been described in a preCGG mouse model. Mouse preCGG hippocampal neurons (170 CGG repeats) grown in vitro develop abnormal networks of clustered burst (CB) firing, as assessed by multielectrode array recordings and clustered patterns of spontaneous Ca(2+) oscillations, neither typical of wild-type (WT) neurons. PreCGG neurons have reduced expression of vesicular GABA and glutamate (Glu) transporters (VGAT and VGLUT1, respectively), and preCGG hippocampal astrocytes display a rightward shift on Glu uptake kinetics, compared with WT. These alterations in preCGG astrocytes and neurons are associated with 4- to 8-fold elevated Fmr1 mRNA and occur despite consistent expression of fragile X mental retardation protein levels at ∼50% of WT levels. Abnormal patterns of activity observed in preCGG neurons are pharmacologically mimicked in WT neurons by addition of Glu or the mGluR1/5 agonist, dihydroxyphenylglycine, to the medium, or by inhibition of astrocytic Glu uptake with dl-threo-β-benzyloxyaspartic acid, but not by the ionotropic Glu receptor agonists, α-2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl) propanoic acid or N-methyl-d-aspartic acid. The mGluR1 (7-(hydroxyimino)cyclopropa [b]chromen-1a-carboxylate ethyl ester) or mGluR5 (2-methyl-6-(phenylethynyl)pyridine hydrochloride) antagonists reversed CB firing. Importantly, the acute addition of the neurosteroid allopregnanolone mitigated functional impairments observed in preCGG neurons in a reversible manner. These results demonstrate abnormal mGluR1/5 signaling in preCGG neurons, which is ameliorated by mGluR1/5 antagonists or augmentation of GABA(A) receptor signaling, and identify allopregnanolone as a candidate therapeutic lead.
  Human Molecular Genetics 04/2012; 21(13):2923-35. · 7.64 Impact Factor
• Source

  Available from: Kami Koldewyn

  Article: Investigation of amygdala volume in men with the fragile X premutation.

  Diana Selmeczy, Kami Koldewyn, John M Wang, Aaron Lee, Danielle Harvey, David R Hessl, Flora Tassone, Patrick Adams, Randi J Hagerman, Paul J Hagerman, Susan M Rivera
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  ABSTRACT: Premutation fragile X carriers have a CGG repeat expansion (55 to 200 repeats) in the promoter region of the fragile X mental retardation 1 (FMR1) gene. Amygdala dysfunction has been observed in premutation symptomatology, and recent research has suggested the amygdala as an area susceptible to the molecular effects of the premutation. The current study utilizes structural magnetic resonance imaging (MRI) to examine the relationship between amygdala volume, CGG expansion size, FMR1 mRNA, and psychological symptoms in male premutation carriers without FXTAS compared with age and IQ matched controls. No significant between group differences in amygdala volume were found. However, a significant negative correlation between amygdala volume and CGG was found in the lower range of CGG repeat expansions, but not in the higher range of CGG repeat expansions.
  Brain Imaging and Behavior 07/2011; 5(4):285-94. · 1.66 Impact Factor
• Article: Widespread non-central nervous system organ pathology in fragile X premutation carriers with fragile X-associated tremor/ataxia syndrome and CGG knock-in mice.

  Michael R Hunsaker, Claudia M Greco, Marian A Spath, Arie P T Smits, Celestine S Navarro, Flora Tassone, Johan M Kros, Lies-Anne Severijnen, Elizabeth M Berry-Kravis, Robert F Berman, Paul J Hagerman, Rob Willemsen, Randi J Hagerman, Renate K Hukema
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  ABSTRACT: Fragile X-associated tremor/ataxia syndrome (FXTAS) is an adult-onset neurodegenerative disorder generally presenting with intention tremor and gait ataxia, but with a growing list of co-morbid medical conditions including hypothyroidism, hypertension, peripheral neuropathy, and cognitive decline. The pathological hallmark of FXTAS is the presence of intranuclear inclusions in both neurons and astroglia. However, it is unknown to what extent such inclusions are present outside the central nervous system (CNS). To address this issue, we surveyed non-CNS organs in ten human cases with FXTAS and in a CGG repeat knock-in (CGG KI) mouse model known to possess neuronal and astroglial inclusions. We find inclusions in multiple tissues from FXTAS cases and CGG KI mice, including pancreas, thyroid, adrenal gland, gastrointestinal, pituitary gland, pineal gland, heart, and mitral valve, as well as throughout the associated autonomic ganglia. Inclusions were observed in the testes, epididymis, and kidney of FXTAS cases, but were not observed in mice. These observations demonstrate extensive involvement of the peripheral nervous system and systemic organs. The finding of intranuclear inclusions in non-CNS somatic organ systems, throughout the PNS, and in the enteric nervous system of both FXTAS cases as well as CGG KI mice suggests that these tissues may serve as potential sites to evaluate early intervention strategies or be used as diagnostic factors.
  Acta Neuropathologica 07/2011; 122(4):467-79. · 9.32 Impact Factor
• Article: Decreased fragile X mental retardation protein expression underlies amygdala dysfunction in carriers of the fragile X premutation.

  David Hessl, John M Wang, Andrea Schneider, Kami Koldewyn, Lien Le, Christine Iwahashi, Katherine Cheung, Flora Tassone, Paul J Hagerman, Susan M Rivera
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  ABSTRACT: The fragile X premutation provides a unique opportunity for the study of genetic and brain mechanisms of behavior and cognition in the context of neurodevelopment and neurodegeneration. Although the neurodegenerative phenotype, fragile X-associated tremor/ataxia syndrome, is well described, evidence of a causal link between the premutation and psychiatric disorder earlier in life, clear delineation of a behavioral/cognitive phenotype, and characterization of the physiological basis of observed symptoms have been elusive. We completed functional magnetic resonance imaging targeting the amygdala with an emotion-matching task and concurrent infrared eye tracking, FMR1 molecular genetic testing, and neuropsychological assessment in 23 men with the premutation (mean age = 32.9 years) and 25 male control subjects (mean age = 30.1 years). Premutation carriers had significantly smaller left and right amygdala volume and reduced right amygdala activation during the task relative to control subjects. Although both elevated FMR1 messenger RNA and reduced fragile X mental retardation protein (FMRP) were associated with the reduced activation, multiple regression analysis suggested that reduced FMRP is the primary factor. Premutation carriers also had higher ratings of autism spectrum symptoms than control subjects, which were associated with the reduced amygdala response. Although prior studies have emphasized a toxic gain-of-function effect of elevated messenger RNA associated with the premutation, the current results point to the role of reduced FMRP in alterations of brain activity and behavior.
  Biological psychiatry 07/2011; 70(9):859-65. · 8.93 Impact Factor
• Article: Rare intranuclear inclusions in the brains of 3 older adult males with fragile x syndrome: implications for the spectrum of fragile x-associated disorders.

  Michael R Hunsaker, Claudia M Greco, Flora Tassone, Robert F Berman, Rob Willemsen, Randi J Hagerman, Paul J Hagerman
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  ABSTRACT: The FMR1 gene is polymorphic for the length of CGG trinucleotide repeat expansions in the 5' untranslated region. Premutation (55-200 CGG repeats) and full-mutation (>200 CGG repeats) alleles give rise to their respective disorders by different pathogenic mechanisms: RNA gain-of-function toxicity leads to fragile X-associated tremor/ataxia syndrome in the premutation range, and transcriptional silencing and absence of fragile X mental retardation protein (FMRP) lead to fragile X syndrome in the full-mutation range. However, for the latter, incomplete silencing and/or size-mosaicism might result in some contribution to the disease process from residual messenger RNA production. To address this possibility, we examined the brains of 3 cases of fragile X syndrome for the presence of intranuclear inclusions in the hippocampal dentate gyrus. We identified low levels (0.1%-1.3%) of intranuclear inclusions in all 3 cases. Quantitative reverse transcription-polymerase chain reaction for FMR1 messenger RNA and immunofluorescence for FMRP revealed low but detectable levels of both RNA and protein in the 3 cases, consistent with the presence of small numbers of inclusions. The intranuclear inclusions were only present in FMRP-immunoreactive cells. The small numbers of inclusions and very low levels of both FMR1 RNA and protein suggest that the clinical course in these 3 subjects would not have been influenced by contributions from RNA toxicity.
  Journal of Neuropathology and Experimental Neurology 06/2011; 70(6):462-9. · 4.26 Impact Factor
• Source

  Available from: Eleonora Napoli

  Article: Altered zinc transport disrupts mitochondrial protein processing/import in fragile X-associated tremor/ataxia syndrome.

  Eleonora Napoli, Catherine Ross-Inta, Sarah Wong, Alicja Omanska-Klusek, Cedrick Barrow, Christine Iwahashi, Dolores Garcia-Arocena, Danielle Sakaguchi, Elizabeth Berry-Kravis, Randi Hagerman, Paul J Hagerman, Cecilia Giulivi
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  ABSTRACT: Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder that affects individuals who are carriers of small CGG premutation expansions in the fragile X mental retardation 1 (FMR1) gene. Mitochondrial dysfunction was observed as an incipient pathological process occurring in individuals who do not display overt features of FXTAS (1). Fibroblasts from premutation carriers had lower oxidative phosphorylation capacity (35% of controls) and Complex IV activity (45%), and higher precursor-to-mature ratios (P:M) of nDNA-encoded mitochondrial proteins (3.1-fold). However, fibroblasts from carriers with FXTAS symptoms presented higher FMR1 mRNA expression (3-fold) and lower Complex V (38%) and aconitase activities (43%). Higher P:M of ATPase β-subunit (ATPB) and frataxin were also observed in cortex from patients that died with FXTAS symptoms. Biochemical findings observed in FXTAS cells (lower mature frataxin, lower Complex IV and aconitase activities) along with common phenotypic traits shared by Friedreich's ataxia and FXTAS carriers (e.g. gait ataxia, loss of coordination) are consistent with a defective iron homeostasis in both diseases. Higher P:M, and lower ZnT6 and mature frataxin protein expression suggested defective zinc and iron metabolism arising from altered ZnT protein expression, which in turn impairs the activity of mitochondrial Zn-dependent proteases, critical for the import and processing of cytosolic precursors, such as frataxin. In support of this hypothesis, Zn-treated fibroblasts showed a significant recovery of ATPB P:M, ATPase activity and doubling time, whereas Zn and desferrioxamine extended these recoveries and rescued Complex IV activity.
  Human Molecular Genetics 05/2011; 20(15):3079-92. · 7.64 Impact Factor
• Article: FMR1 gray-zone alleles: association with Parkinson's disease in women?

  Deborah A Hall, Elizabeth Berry-Kravis, Wenting Zhang, Flora Tassone, Elaine Spector, Gary Zerbe, Paul J Hagerman, Bichun Ouyang, Maureen A Leehey
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  ABSTRACT: Carriers of fragile X mental retardation 1 repeat expansions in the premutation range (55-200 CGG repeats), especially males, often develop tremor, ataxia, and parkinsonism. These neurological signs are believed to be a result of elevated levels of expanded CGG-repeat fragile X mental retardation 1 mRNA. The purpose of this study was to determine the prevalence of fragile X mental retardation 1 repeat expansions in a movement disorder population comprising subjects with all types of tremor, ataxia, and parkinsonism. We screened 335 consecutive patients with tremor, ataxia, or parkinsonism and 273 controls confirmed to have no movement disorders. There was no difference in fragile X mental retardation 1 premutation size expansions in the cases compared with controls. Eleven percent of the women with Parkinson's disease had fragile X mental retardation 1 gray-zone expansions compared with 4.4% of female controls (odds ratio of 3.2; 95% confidence interval, 1.2-8.7). Gray-zone expansions in patients with other phenotypes were not overrepresented in comparison with controls. Fragile X mental retardation 1 premutation range expansions are not more common in a mixed movement disorder population compared with controls. Our results, however, suggest that fragile X mental retardation 1 gray-zone alleles may be associated with Parkinson's disease in women.
  Movement Disorders 05/2011; 26(10):1900-6. · 4.51 Impact Factor
• Source

  Available from: Chiara Carosi

  Article: Differential usage of transcriptional start sites and polyadenylation sites in FMR1 premutation alleles.

  Flora Tassone, Silvia De Rubeis, Chiara Carosi, Giorgio La Fata, Gisele Serpa, Christopher Raske, Rob Willemsen, Paul J Hagerman, Claudia Bagni
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  ABSTRACT: 5'- and 3'-untranslated regions (UTRs) are important regulators of gene expression and play key roles in disease progression and susceptibility. The 5'-UTR of the fragile X mental retardation 1 (FMR1) gene contains a CGG repeat element that is expanded (>200 CGG repeats; full mutation) and methylated in fragile X syndrome (FXS), the most common form of inherited intellectual disability (ID) and known cause of autism. Significant phenotypic involvement has also emerged in some individuals with the premutation (55-200 CGG repeats), including fragile X-associated premature ovarian insufficiency (FXPOI) in females, and the neurodegenerative disorder, fragile X-associated tremor/ataxia syndrome (FXTAS), in older adult carriers. Here, we show that FMR1 mRNA in human and mouse brain is expressed as a combination of multiple isoforms that use alternative transcriptional start sites and different polyadenylation sites. Furthermore, we have identified a novel human transcription start site used in brain but not in lymphoblastoid cells, and have detected FMR1 isoforms generated through the use of both canonical and non-canonical polyadenylation signals. Importantly, in both human and mouse, a specific regulation of the UTRs is observed in brain of FMR1 premutation alleles, suggesting that the transcript variants may play a role in premutation-related pathologies.
  Nucleic Acids Research 04/2011; 39(14):6172-85. · 8.03 Impact Factor
• Article: High-resolution methylation polymerase chain reaction for fragile X analysis: evidence for novel FMR1 methylation patterns undetected in Southern blot analyses.

  Liangjing Chen, Andrew G Hadd, Sachin Sah, Jeffrey F Houghton, Stela Filipovic-Sadic, Wenting Zhang, Paul J Hagerman, Flora Tassone, Gary J Latham
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  ABSTRACT: Fragile X syndrome is associated with the expansion of CGG trinucleotide repeats and subsequent methylation of the FMR1 gene. Molecular diagnosis of fragile X currently requires Southern blot analysis to assess methylation. This study describes the evaluation of a polymerase chain reaction-only workflow for the determination of methylation status across a broad range of FMR1 genotypes in male and female specimens. We evaluated a novel method that combines allele-specific methylation polymerase chain reaction and capillary electrophoresis with eight cell line and 80 clinical samples, including 39 full mutations. Methylation status was determined using a three-step workflow: (1) differential treatment of genomic DNA using a methylation-sensitive restriction enzyme; (2) polymerase chain reaction with two sets of dye-tagged primers; and (3) amplicon sizing by capillary electrophoresis. All samples were analyzed by both methylation polymerase chain reaction and Southern blot analysis. FMR1 methylation status and CGG repeat sizing were accurately and reproducibly determined in a set of methylation controls and genomic DNA samples representing a spectrum of CGG repeat lengths and methylation states. Moreover, methylation polymerase chain reaction revealed allele-specific methylation patterns in premutation alleles that were unobtainable using Southern blot analysis. Methylation polymerase chain reaction enabled high throughput, high resolution, and semiquantitative methylation assessments of FMR1 alleles, as well as determinations of CGG repeat length. Results for all samples were concordant with corresponding Southern blot analyses. As a result, this study presents a polymerase chain reaction-based method for comprehensive FMR1 analysis. In addition, the identification of novel methylation mosaic patterns revealed after polymerase chain reaction and capillary electrophoresis may be relevant to several FMR1 disorders.
  Genetics in medicine: official journal of the American College of Medical Genetics 03/2011; 13(6):528-38. · 3.92 Impact Factor