Dysbindin-1, a schizophrenia-related protein, functionally interacts with the DNA- dependent protein kinase complex in an isoform-dependent manner.
DTNBP1 has been recognized as a schizophrenia susceptible gene, and its protein product, dysbindin-1, is down-regulated in the brains of schizophrenic patients. However, little is known about the physiological role of dysbindin-1 in the central nervous system. We hypothesized that disruption of dysbindin-1 with unidentified proteins could contribute to pathogenesis and the symptoms of schizophrenia. GST pull-down from human neuroblastoma lysates showed an association of dysbindin-1 with the DNA-dependent protein kinase (DNA-PK) complex. The DNA-PK complex interacts only with splice isoforms A and B, but not with C. We found that isoforms A and B localized in nucleus, where the kinase complex exist, whereas the isoform C was found exclusively in cytosol. Furthermore, results of phosphorylation assay suggest that the DNA-PK complex phosphorylated dysbindin-1 isoforms A and B in cells. These observations suggest that DNA-PK regulates the dysbindin-1 isoforms A and B by phosphorylation in nucleus. Isoform C does not contain exons from 1 to 6. Since schizophrenia-related single nucleotide polymorphisms (SNPs) occur in these introns between exon 1 and exon 6, we suggest that these SNPs might affect splicing of DTNBP1, which leads to impairment of the functional interaction between dysbindin-1 and DNA-PK in schizophrenic patients.
Oyama
Satoko
S
Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, Tokyo, Japan.
Yamakawa
Hidekuni
H
Sasagawa
Noboru
N
Hosoi
Yoshio
Y
Futai
Eugene
E
Ishiura
Shoichi
S
D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D002467:Cell Nucleus; D002490:Central Nervous System; D051747:DNA-Activated Protein Kinase / Q000378:metabolism*; D000074765:Dysbindin; D049029:Dystrophin-Associated Proteins; D006801:Humans; D010766:Phosphorylation; D020641:Polymorphism, Single Nucleotide; D020033:Protein Isoforms / Q000378:metabolism; D012559:Schizophrenia / Q000209:etiology*
D002352:Carrier Proteins; C432416:DTNBP1 protein, human; D000074765:Dysbindin; D049029:Dystrophin-Associated Proteins; D020033:Protein Isoforms; D051747:DNA-Activated Protein Kinase