| Autor: |
Wenzel HJ; Department of Neurological Surgery, University of California, Davis, Davis, CA, USA., Murray KD; Department of Psychiatry and Behavioral Sciences, University of California, Davis, Davis, CA, USA., Haify SN; Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands., Hunsaker MR; Graduate Program in Neuroscience, University of California, Davis, Davis, CA, USA., Schwartzer JJ; Program in Neuroscience and Behavior, Department of Psychology and Education, Mount Holyoke College, South Hadley, MA, USA., Kim K; Division of Biostatistics, Department of Public Health Sciences, University California Davis, Davis, CA, USA., La Spada AR; Departments of Neurology, Neurobiology, and Cell Biology, and the Duke Center for Neurodegeneration & Neurotherapeutics, Duke University School of Medicine, Durham, NC, USA., Sopher BL; Department of Neurology, University of Washington School of Medicine, Seattle, WA, USA., Hagerman PJ; Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, CA, USA., Raske C; Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, CA, USA., Severijnen LWFM; Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands., Willemsen R; Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands., Hukema RK; Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands., Berman RF; Department of Neurological Surgery, University of California, Davis, Davis, CA, USA. rfberman@ucdavis.edu. |
| Abstrakt: |
The fragile X premutation is a CGG trinucleotide repeat expansion between 55 and 200 repeats in the 5'-untranslated region of the fragile X mental retardation 1 (FMR1) gene. Human carriers of the premutation allele are at risk of developing the late-onset neurodegenerative disorder, fragile X-associated tremor/ataxia syndrome (FXTAS). Characteristic neuropathology associated with FXTAS includes intranuclear inclusions in neurons and astroglia. Previous studies recapitulated these histopathological features in neurons in a knock-in mouse model, but without significant astroglial pathology. To determine the role of astroglia in FXTAS, we generated a transgenic mouse line (Gfa2-CGG99-eGFP) that selectively expresses a 99-CGG repeat expansion linked to an enhanced green fluorescent protein (eGFP) reporter in astroglia throughout the brain, including cerebellar Bergmann glia. Behaviorally these mice displayed impaired motor performance on the ladder-rung test, but paradoxically better performance on the rotarod. Immunocytochemical analysis revealed that CGG99-eGFP co-localized with GFAP and S-100ß, but not with NeuN, Iba1, or MBP, indicating that CGG99-eGFP expression is specific to astroglia. Ubiquitin-positive intranuclear inclusions were found in eGFP-expressing glia throughout the brain. In addition, intracytoplasmic ubiquitin-positive inclusions were found outside the nucleus in distal astrocyte processes. Intriguingly, intranuclear inclusions, in the absence of eGFP mRNA and eGFP fluorescence, were present in neurons of the hypothalamus and neocortex. Furthermore, intranuclear inclusions in both neurons and astrocytes displayed immunofluorescent labeling for the polyglycine peptide FMRpolyG, implicating FMRpolyG in the pathology found in Gfa2-CGG99 mice. Considered together, these results show that Gfa2-CGG99 expression in mice is sufficient to induce key features of FXTAS pathology, including formation of intranuclear inclusions, translation of FMRpolyG, and deficits in motor function. |
