title: Cellular and circuit mechanisms underlying spinocerebellar ataxias.
abstract: Degenerative ataxias are a common form of neurodegenerative disease that affect about 20 individuals per 100,000. The autosomal dominant spinocerebellar ataxias (SCAs) are caused by a variety of protein coding mutations (single nucleotide changes, deletions and expansions) in single genes. Affected genes encode plasma membrane and intracellular ion channels, membrane receptors, protein kinases, protein phosphatases and proteins of unknown function. Although SCA-linked genes are quite diverse they share two key features: first, they are highly, although not exclusively, expressed in cerebellar Purkinje neurons (PNs), and second, when mutated they lead ultimately to the degeneration of PNs. In this review we summarize ataxia-related changes in PN neurophysiology that have been observed in various mouse knockout lines and in transgenic models of human SCA. We also highlight emerging evidence that altered metabotropic glutamate receptor signalling and disrupted calcium homeostasis in PNs form a common, early pathophysiological mechanism in SCAs. Together these findings indicate that aberrant calcium signalling and profound changes in PN neurophysiology precede PN cell loss and are likely to lead to cerebellar circuit dysfunction that explains behavioural signs of ataxia characteristic of the disease.
authors.affiliation: Department of Neurobiology, Geffen School of Medicine, University of California, 650 Charles Young Drive, Los Angeles, CA, 90095, USA.
authors.forename: Pratap
authors.initials: P
authors.lastname: Meera
authors.affiliation: Department of Neurology, University of Utah, 175 N Medical Drive E, Salt Lake City, UT, 84132, USA.
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Pulst
authors.affiliation: Department of Neurobiology, Geffen School of Medicine, University of California, 650 Charles Young Drive, Los Angeles, CA, 90095, USA.|Roche Pharmaceutical Research and Early Development (pRED), Neuroscience, Ophthalmology and Rare Diseases (NORD), Grenzacherstrasse 124, CH-4070, Basel, Switzerland.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Otis
mesh_terms: D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000502:physiology; D006801:Humans; D011689:Purkinje Cells / Q000502:physiology; D018094:Receptors, Metabotropic Glutamate / Q000502:physiology; D015398:Signal Transduction; D020754:Spinocerebellar Ataxias / Q000503:physiopathology*
chemical_list: D018094:Receptors, Metabotropic Glutamate; D002118:Calcium