title: Systemic application of AAV vectors targeting GFAP-expressing astrocytes in Z-Q175-KI Huntington's disease mice.
abstract: Huntington's disease (HD) affects both neurons and astrocytes. To target the latter and to ensure brain-wide transgene expression, adeno-associated viral (AAV) vectors can be administered intravenously, as AAV vectors cross the blood-brain barrier (BBB) and enable preferential transduction of astrocytes due to their close association with blood vessels. However, there is a possibility that the subclass of GFAP-expressing astrocytes performs a distinct role in HD and reacts differently to therapeutic measures than the rest of the astrocytes. The gfaABC1D promoter allows specific targeting of the GFAP-expressing astrocytes (~25% of S100β-expressing astrocytes). We have examined the expression of three different transgenes (GCaMP6f, Kir4.1 and GLT1) and tested the effects of the AAV serotypes 9 and rh8. The AAV vectors were injected into the tail vein of 1-year-old homozygous Z-Q175-KI HD mice and their wild-type (WT) littermates. At this age, HD mice exhibit motor symptoms, including pronounced hypokinesia and circling behaviour. The expression times ranged from 3 to 6weeks. The target cell population was defined as the cells expressing S100β in addition to GFAP. Viewfields in the dorsal striatum and the overlaying cortex were evaluated and the transduction rate was defined as the percentage of target cells that expressed the reporter transgene (enhanced green fluorescent protein, EGFP, or Tomato). In all cases, the transduction rate was higher in the cortex than in the striatum. AAV9 was more efficient than AAVrh8. One of the injected constructs (AAV9-gfaABC1D-GLT1-Tomato) was tested for the first time. GLT1, the principal astrocytic glutamate transporter, is deficient in HD and therefore considered as a potential target for gene therapy. At a dose of 1.86×1011vector genome (vg) per animal, the fraction of GLT1-Tomato+ cells in the striatum and the cortex amounted to 30% and 49%, respectively. In individual Tomato+ HD astrocytes, treatment with the GLT1 vector increased the level of GLT1 immunofluorescence by 21% compared to the HD control. The described approach offers new and interesting opportunities to examine the pathophysiological consequences of brain-wide transgene expression in a specific astrocyte subpopulation.
authors.affiliation: Cluster of Excellence NeuroCure, University Medicine Charitè, Berlin, Germany. Electronic address: tatyana.vagner@charite.de.
authors.forename: Tatyana
authors.initials: T
authors.lastname: Vagner
authors.affiliation: Cluster of Excellence NeuroCure, University Medicine Charitè, Berlin, Germany.
authors.forename: Anton
authors.initials: A
authors.lastname: Dvorzhak
authors.affiliation: Cluster of Excellence NeuroCure, University Medicine Charitè, Berlin, Germany.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Wójtowicz
authors.affiliation: Department of Experimental Neurology, University Medicine Charité, Berlin, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Harms
authors.affiliation: Cluster of Excellence NeuroCure, University Medicine Charitè, Berlin, Germany; Department of Experimental Neurology, University Medicine Charité, Berlin, Germany.
authors.forename: Rosemarie
authors.initials: R
authors.lastname: Grantyn
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D003342:Corpus Striatum / Q000378:metabolism; D000229:Dependovirus / Q000235:genetics*; D027342:Excitatory Amino Acid Transporter 2 / Q000235:genetics / Q000378:metabolism; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics / Q000378:metabolism*; D006816:Huntington Disease / Q000628:therapy*; D008297:Male; D051379:Mice; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D064568:S100 Calcium Binding Protein beta Subunit / Q000235:genetics / Q000378:metabolism; D019076:Transgenes; D000098854:Kcnj10 Channel
chemical_list: D027342:Excitatory Amino Acid Transporter 2; D005904:Glial Fibrillary Acidic Protein; D000098854:Kcnj10 Channel; D024661:Potassium Channels, Inwardly Rectifying; D064568:S100 Calcium Binding Protein beta Subunit; C493396:Slc1a2 protein, mouse; C528900:glial fibrillary astrocytic protein, mouse
keywords: AAV9; Astrocytes; Cerebral cortex; GFAP; GLT1; Huntington's disease; Kir4.1; Striatum