Human Molecular Genetics Advance Access originally published online on July 19, 2009
Human Molecular Genetics 2009 18(20):3851-3863; doi:10.1093/hmg/ddp329
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Dysbindin-1 in dorsolateral prefrontal cortex of schizophrenia cases is reduced in an isoform-specific manner unrelated to dysbindin-1 mRNA expression
1 Center for Neurobiology and Behavior in the Department of Psychiatry, University of Pennsylvania, Philadelphia, PA 19104-3403, USA and 2 MRC Centre for Neuropsychiatric Genetics and Genomics and Department of Psychological Medicine and Neurology, Cardiff University, Cardiff, Wales CF14 4XN, UK
* To whom correspondence should be addressed at: Center for Neurobiology and Behavior, Translational Research Laboratories, 125 South 31st Street, Philadelphia, PA 19104-3403, USA. Tel: +1 2157463647; Fax: +1 2155732041; Email: talbotk2{at}mail.med.upenn.edu
Received February 4, 2009; Revised July 10, 2009; Accepted July 16, 2009
DTNBP1 (dystrobrevin binding protein 1) remains a top candidate gene in schizophrenia. Reduced expression of this gene and of its encoded protein, dysbindin-1, have been reported in the brains of schizophrenia cases. It has not been established, however, if the protein reductions encompass all dysbindin-1 isoforms or if they are associated with decreased DTNBP1 gene expression. Using a matched pairs design in which each of 28 Caucasian schizophrenia cases was matched in age and sex to a normal Caucasian control, Western blotting of whole-tissue lysates of dorsolateral prefrontal cortex (DLPFC) revealed significant reductions in dysbindin-1C (but not in dysbindin-1A or -1B) in schizophrenia (P = 0.022). These reductions occurred without any significant change in levels of the encoding transcript in the same tissue samples and in the absence of the only DTNBP1 risk haplotype for schizophrenia reported in the USA. Indeed, no significant correlations were found between case–control differences in any dysbindin-1 isoform and the case–control differences in its encoding mRNA. Consequently, the mean 60% decrease in dysbindin-1C observed in 71% of our case–control pairs appears to reflect abnormalities in mRNA translation and/or processes promoting dysbindin-1C degradation (e.g. oxidative stress, phosphorylation and/or ubiquitination). Given the predominantly post-synaptic localization of dysbindin-1C and known post-synaptic effects of dysbindin-1 reductions in the rodent equivalent of the DLPFC, the present findings suggest that decreased dysbindin-1C in the DLPFC may contribute to the cognitive deficits of schizophrenia by promoting NMDA receptor hypofunction in fast-spiking interneurons.