C9orf10 Protein, a Novel Protein Component of Purα-containing mRNA-protein Particles (Purα-mRNPs): Characterization of Developmental and Regional Expressions in the Mouse Brain

摘要

Purα has been implicated in mRNA transport and translation in neurons. We previously reported that Purα is a component of mRNA/protein complexes (Purα-mRNPs) with several other proteins. Among them, we found the C9orf10 (Homo sapiens chromosome 9 open reading frame 10) protein, which was recently characterized as a component of RNA-containing structures. However, C9orf10 itself remains poorly understood. To characterize C9orf10 expression at the protein level, we raised an antibody against C9orf10 and compared the spatial and developmental expressions of this protein and Purα in the mouse brain. C9orf10 was expressed as early as embryo stage 12, whereas Purα was expressed from 5 days after birth. In adults, C9orf10 expression was most prominent in the hippocampus, caudate putamen, cerebral cortex, and cerebellum, unlike the uniform distribution of Purα. C9orf10-positive cells also showed immunoreactivity to Purα. C9orf10 expression was restricted to neurons, judging by the immunoreactivity to neuron-specific nuclear protein or CaM kinase II. These observations suggest an accessory role of C9orf10 for Purα in a limited brain region in addition to other possible functions that have not yet been determined. (J Histochem Cytochem 56:723–731, 2008)