Immunohistochemical localization of the nucleosome-binding protein HMGN3 in mouse brain.

HMGN3 (Trip7) is a member of the high-mobility group N (HMGN) nucleosome-binding protein family, which binds specifically to nucleosomes, reduces the compactness of the chromatin fiber, and enhances transcription from chromatin templates. By Western blotting and Northern blotting analysis, we showed that HMGN3 is expressed in a tissue-specific manner, with the strongest expression in mouse brain. Here we analyzed the expression of HMGN3 in various regions of the mouse brain by histological techniques. Enhanced expression of HMGN3 was observed in the lateral olfactory tract, anterior commissure, corpus callosum, internal capsule, fornix, stria medullans, optic tract, and axon bundles. The expression patterns of HMGN3 in the mouse brain was significantly different from that of the related protein HMGN2 and was very similar to that of the glial fibrillary acidic protein (GFAP). We suggest that HMGN3 might play a role in astrocyte function.