Identification of PSF, the polypyrimidine tract-binding protein-associatedsplicing factor, as a developmentally regulated neuronal protein

The polypyrimidine tract-binding protein-associated splicing factor (PSF), which plays an essential role in mammalian spliceosomes, has been found to be expressed by differentiating neurons in developing mouse brain. The sequ ence of a fragment of mouse PSF was found to be remarkably similar to that of human PSF, Both the expression of PSF mRNA in cortex and cerebellum and PSF immunoreactivity in all brain areas were high during embryonic and earl y postnatal life and almost disappeared in adult tissue, except in the hipp ocampus and olfactory bulb where various neuronal populations remained PSF- immunopositive, Double-labeling experiments with anti-PSF antibody and anti -neurofilaments or anti-glial fibrillary acidic protein antibodies on secti ons of cortex, hippocampus, and cerebellum indicate that PSF is expressed b y differentiating neurons but not by astrocytic cells. In vitro, mouse PSF was found to be expressed by differentiating cortical and cerebellar neuron s. Radial glia or astrocyte nuclei were not immunopositive; however, oligod endrocytes differentiating in vitro were found to express PSF, The restrict ed expression of PSF suggests that this splicing factor could be involved i n the control of neuronal-specific splicing events occurring at particular stages of neuronal differentiation and maturation. (C) 1999 Wiley-Liss, Inc .