title: Atxn2 Knockout and CAG42-Knock-in Cerebellum Shows Similarly Dysregulated Expression in Calcium Homeostasis Pathway.
abstract: Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominantly inherited neurodegenerative disorder with preferential affection of Purkinje neurons, which are known as integrators of calcium currents. The expansion of a polyglutamine (polyQ) domain in the RNA-binding protein ataxin-2 (ATXN2) is responsible for this disease, but the causal roles of deficient ATXN2 functions versus aggregation toxicity are still under debate. Here, we studied mouse mutants with Atxn2 knockout (KO) regarding their cerebellar global transcriptome by microarray and RT-qPCR, in comparison with data from Atxn2-CAG42-knock-in (KIN) mouse cerebellum. Global expression downregulations involved lipid and growth signaling pathways in good agreement with previous data. As a novel effect, downregulations of key factors in calcium homeostasis pathways (the transcription factor Rora, transporters Itpr1 and Atp2a2, as well as regulator Inpp5a) were observed in the KO cerebellum, and some of them also occurred subtly early in KIN cerebellum. The ITPR1 protein levels were depleted from soluble fractions of cerebellum in both mutants, but accumulated in its membrane-associated form only in the SCA2 model. Coimmunoprecipitation demonstrated no association of ITPR1 with Q42-expanded or with wild-type ATXN2. These findings provide evidence that the physiological functions and protein interactions of ATXN2 are relevant for calcium-mediated excitation of Purkinje cells as well as for ATXN2-triggered neurotoxicity. These insights may help to understand pathogenesis and tissue specificity in SCA2 and other polyQ ataxias like SCA1, where inositol regulation of calcium flux and RORalpha play a role.
authors: Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany.
authors: Melanie Vanessa
authors: MV
authors: Halbach
authors: Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany.
authors: Suzana
authors: S
authors: Gispert
authors: Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany.
authors: Tanja
authors: T
authors: Stehning
authors: Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany.
authors: Ewa
authors: E
authors: Damrath
authors: Institute for Medical Genetics, Eberhard-Karls-University of Tuebingen, 72076, Tuebingen, Germany.
authors: Michael
authors: M
authors: Walter
authors: Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany. auburger@em.uni-frankfurt.de.
authors: Georg
authors: G
authors: Auburger
mesh_terms: D000818:Animals; D000067698:Ataxin-2 / Q000235:genetics* / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002531:Cerebellum / Q000378:metabolism* / Q000473:pathology; D015870:Gene Expression / Q000502:physiology; D055879:Gene Knock-In Techniques; D055786:Gene Knockout Techniques; D006706:Homeostasis / Q000502:physiology*; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011689:Purkinje Cells / Q000378:metabolism / Q000473:pathology; D059467:Transcriptome / Q000502:physiology; D018911:Trinucleotide Repeats
chemical_list: D000067698:Ataxin-2; C000593754:Atxn2 protein, mouse; D053496:Inositol 1,4,5-Trisphosphate Receptors; C025389:Itpr1 protein, mouse; D002118:Calcium
keywords: Atxn2; Calcium; Cerebellum; Homeostasis; Itpr1; Rora; Signaling