title: Reduced immunoreactivity to calcium-binding proteins in Purkinje cells precedes onset of ataxia in spinocerebellar ataxia-1 transgenic mice.
abstract: Earlier we have shown alterations in immunoreactivity (IR) to the calcium-binding proteins parvalbumin (PV) and calbindin D-28k (CaB) in surviving Purkinje cells of patients with spinocerebellar ataxia-1 (SCA-1). In the present study we determined PV and CaB expression (by immunohistochemical and immunoblot analyses) in Purkinje cells of transgenic mice (TM) expressing the human SCA-1 gene with an expanded (line B05) and normal (line A02) CAG tract, as well as in age-matched nontransgenic mice (nTM). Heterozygotes in the B05 line develop progressive ataxia beginning around 12 weeks of age. A02 animals are phenotypically indistinguishable from wild-type (nontransgenic) animals. In the cerebella of 8-, 9-, and 12-week-old TM-B05 there was a progressive decrease in PV IR in Purkinje cells compared with nTM and TM-A02. Parvalbumin immunostaining in interneurons was well preserved in all groups. A progressive decrease was also observed in CaB IR in Purkinje cells of 8-, 9-, and 12-week-old TM-B05. Cerebellar Purkinje cells of 6-week-old TM-B05, which exhibit no ataxia and even lack demonstrable Purkinje cell loss, also revealed reduction in PV IR. This change was matched by a significant decrease in the amount of cerebellar PV in 6-week-old TM-B05 as determined by Western blot analysis. Calbindin D-28K immunohistochemistry did not detect any marked changes in CaB IR within Purkinje cells at 4 weeks. However, at 6 weeks immunostaining and immunoblot analysis revealed a significant decrease in CaB in TM-B05 compared with controls. These data suggest that decreased levels of calcium-binding proteins in Purkinje cells in SCA-1 transgenic mice may cause alteration in Ca2+ homeostasis.
authors.affiliation: Department of Neurology, University of Mississippi Medical Center, Jackson 39216, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Vig
authors.forename: S H
authors.initials: SH
authors.lastname: Subramony
authors.forename: E N
authors.initials: EN
authors.lastname: Burright
authors.forename: J D
authors.initials: JD
authors.lastname: Fratkin
authors.forename: D O
authors.initials: DO
authors.lastname: McDaniel
authors.forename: D
authors.initials: D
authors.lastname: Desaiah
authors.forename: Z
authors.initials: Z
authors.lastname: Qin
mesh_terms: D000483:Alleles; D000818:Animals; D000911:Antibodies, Monoclonal; D064026:Calbindins; D002135:Calcium-Binding Proteins / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D002531:Cerebellum / Q000737:chemistry / Q000378:metabolism; D018076:DNA, Complementary; D004195:Disease Models, Animal; D015870:Gene Expression; D051379:Mice; D008822:Mice, Transgenic; D009410:Nerve Degeneration / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000032:analysis; D010320:Parvalbumins / Q000032:analysis / Q000276:immunology / Q000378:metabolism; D011689:Purkinje Cells / Q000737:chemistry* / Q000201:enzymology; D064030:S100 Calcium Binding Protein G / Q000032:analysis / Q000276:immunology; D013132:Spinocerebellar Degenerations / Q000378:metabolism* / Q000503:physiopathology; D019076:Transgenes
chemical_list: D000911:Antibodies, Monoclonal; D064026:Calbindins; D002135:Calcium-Binding Proteins; D018076:DNA, Complementary; D010320:Parvalbumins; D064030:S100 Calcium Binding Protein G; D019001:Nitric Oxide Synthase