Satoshi Hirakawa

Bral1, a brain-specific link protein, colocalizing with the versican V2 isoform at the nodes of Ranvier in developing and adult, mouse central nervous systems

Bral1, a brain-specific hyaluronan-binding protein, has been cloned recently. To gain insight into the role of Bral1, we generated a specific antibody against this protein. We have examined the detailed localization pattern of Bral1 protein and compared it with that of other members of the lectican proteoglycan family, such as brevican and versican, with which Bral1 is predicted to interact. The immunoreactivity of Bral1 antibody was predominantly observed in myelinated fiber tracts in the adult brain and could be detected at P20 in the white matter of the developing cerebellum, suggesting that expression starts when axonal myelination takes place. Furthermore, immunostaining demonstrated that Bral1 colocalized with the versican V2 isoform at the nodes of Ranvier. The present data suggest that Bral1 may play a pivotal role in the formation of the hyaluronan-associated matrix in the CNS that facilitates neuronal conduction by forming an ion diffusion barrier at the nodes.

Molecular cloning of Bral2, a novel brain-specific link protein, and immunohistochemical colocalization with brevican in perineuronal nets

The hyaluronan binding chondroitin sulphate proteoglycans, called lecticans, are the abundant extracellular matrix molecules in the developing and/or adult brain. The link proteins (LPs) are also known to be coordinately present in brain. We report here the molecular cloning and expression analysis of a novel member of LPs: Bral2, predominantly expressed in brain. The Bral2 mRNA expression is first detected at P20 and continued through adulthood, suggesting its functional importance and association with adult-type lecticans. The substantial immunoreactivity of Bral2 is found in several nuclei throughout the midbrain and hindbrain in a perineuronal net pattern. In situ hybridization revealed that Bral2 is synthesized by these neurons themselves, especially by the GABAergic neurons in the cerebellar cortex. Interestingly, the colocalization and synergic importance of Bral2 and brevican in the perineuronal nets is indicated by the comparative immunohistochemical analysis using wild-type and brevican-deficient mouse brain. Our results suggest that Bral2 is involved in the formation of extracellular matrix contributing to perineuronal nets and facilitate the understanding of a functional role of these extracellular matrices.

Nasal and nasal-type natural killer/ T–cell lymphoma☆☆☆

Nasal and nasal-type natural killer (NK)/T-cell lymphomas follow an aggressive course and have a poor prognosis. Recent pathologic studies suggest that the disease is a malignant proliferation of NK cells, which often express CD56. An association with the Epstein-Barr virus has also been reported. Skin involvement occurred in each of the 3 patients studied. Radiation therapy provided some benefit to the patients in the early stages. Conventional chemotherapies were not effective. To overcome this multiple-drug resistance of the tumor cells, cyclosporine and high-dose chemotherapy was combined with peripheral-blood stem-cell transplantation. The average life span from the onset of the disease for our patients was 9.6 months. Further improvement in the management of nasal and nasal-type NK/T-cell lymphomas is necessary.