Disrupted-In-Schizophrenia 1 (DISC1) is a promising candidate gene for susceptibility to psychiatric disorders, including schizophrenia. DISC1 appears to be involved in neurogenesis, neuronal migration, axon/dendrite formation and synapse formation; during these processes, DISC1 acts as a scaffold protein by interacting with various partners. However, the lack of Disc1 knockout mice and a well-characterized antibody to DISC1 has made it difficult to determine the exact role of DISC1 in vivo. In this study, we generated mice lacking exons 2 and 3 of the Disc1 gene and prepared specific antibodies to the N- and C-termini of DISC1. The Disc1 mutant mice are viable and fertile, and no gross phenotypes, such as disorganization of the brain's cytoarchitecture, were observed. Western blot analysis revealed that the DISC1-specific antibodies recognize a protein with an apparent molecular mass of ~100 kDa in brain extracts from wild-type mice but not in brain extracts from DISC1 mutant mice. Immunochemical studies demonstrated that DISC1 is mainly localized to the vicinity of the Golgi apparatus in hippocampal neurons and astrocytes. A deficiency of full-length Disc1 induced a threshold shift in the induction of long-term potentiation in the dentate gyrus. The Disc1 mutant mice displayed abnormal emotional behavior as assessed by the elevated plus-maze and cliff-avoidance tests, thereby suggesting that a deficiency of full-length DISC1 may result in lower anxiety and/or higher impulsivity. Based on these results, we suggest that full-length Disc1-deficient mice and DISC1-specific antibodies are powerful tools for dissecting the pathophysiological functions of DISC1.

Disrupted-in-schizophrenia 1 (DISC1) is a susceptibility gene for major psychiatric disorders, including schizophrenia. DISC1 has been implicated in neurodevelopment in relation to scaffolding signal complexes. Here we used proteomic analysis to screen for DISC1 interactors and identified several RNA-binding proteins, such as hematopoietic zinc finger (HZF), that act as components of RNA-transporting granules. HZF participates in the mRNA localization of inositol-1,4,5-trisphosphate receptor type 1 (ITPR1), which plays a key role in synaptic plasticity. DISC1 colocalizes with HZF and ITPR1 mRNA in hippocampal dendrites and directly associates with neuronal mRNAs, including ITPR1 mRNA. The binding potential of DISC1 for ITPR1 mRNA is facilitated by HZF. Studies of Disc1-knockout mice have revealed that DISC1 regulates the dendritic transport of Itpr1 mRNA by directly interacting with its mRNA. The DISC1-mediated mRNA regulation is involved in synaptic plasticity. We show that DISC1 binds ITPR1 mRNA with HZF, thereby regulating its dendritic transport for synaptic plasticity.

ABSTRACT. The small GTP-binding protein Rho plays a crucial role in a wide variety of cellular functions through various effector proteins. Rho-kinase is a key effector protein of Rho, which is composed of two isoforms, ROCK1 and ROCK2. To clarify the site of action of ROCK1 and ROCK2, we performed immunofluorescence and immunoelectron microscopic analyses using isoform-specific antibodies in mouse tissues. In the large and small intestines, ROCK1 immunoreactivity was predominantly identified in epithelial cells, and ROCK2 immunoreactivity was negligible. In these epithelial cells, ROCK1 immunoreactivity was distributed on plasma membranes, while ROCK1 immunogold signals were localized at cell-cell contacts and cell adhesion sites, especially at the adherens junctions at the ultrastructural level. In the bladder epithelium, however, ROCK1 and ROCK2 signals were identified at intermediate filaments, and ROCK2 signals were also observed in nuclei. In the three types of muscular cells-smooth, cardiac, and skeletal muscle cells-ROCK1 and ROCK2 also showed differential distribution. ROCK1 signals were localized at actin filaments, plasma membranes, and vesicles near plasma membranes in smooth muscle cells; at the lysosomes in skeletal muscle cells; and were undetectable in cardiac muscle cells. ROCK2 signals were localized at actin filaments and centrosomes in smooth muscle cells, at intercalated discs in cardiac muscle cells, and at Z-discs and sarcoplasmic reticulum in skeletal muscle cells. In the brain, ROCK1 immunoreactivity was distributed in glia, whereas ROCK2 immunoreactivity was observed in neurons. These results indicate that the two isoforms of Rho-kinase distribute differentially to accomplish their specific functions.

Regenerative medicine using umbilical cord blood (UCB) cells shows promise for the treatment of cerebral palsy. Although the efficacy of this therapy has been seen in the clinic, the mechanisms by which UCB cells interact and aid in the improvement of symptoms are not clear. We explored the chemokine expression profile in damaged brain tissue in the neonatal mouse ischemia-reperfusion (IR) brain injury model that was infused with human UCB (hUCB) cells. IR brain injury was induced in 9-day-old NOD/SCID mice. hUCB cells were administered 3 weeks post brain injury. Chemokine expression profiles in the brain extract were determined at various time points. Inflammatory chemokines such as CCL1, CCL17, and CXCL12 were transiently upregulated by 24 hours post brain injury. Upregulation of other chemokines, including CCL5, CCL9, and CXCL1 were prolonged up to 3 weeks post brain injury, but most chemokines dissipated over time. There were marked increases in levels of CCL2, CCL12, CCL20, and CX3CL1 in response to hUCB cell treatment, which might be related to the new recruitment and differentiation of neural stem cells, leading to the induction of tissue regeneration. We propose that the chemokine expression profile in the brain shifted from responding to tissue damage to inducing tissue regeneration. hUCB cell administration further enhanced the production of chemokines, and chemokine networks may play an active role in tissue regeneration in neonatal hypoxic-ischemic brain injury.