Changes in the chromatin of the brain of developing rats: phosphorylation of chromosomal proteins and modulation of transcription.

In vitro phosphorylation of chromosomal proteins and transcription of chromatin, and their modulation by spermine were studied by incubating slices of cerebral cortex of 3-30 day old developing rats with [32Pi] and [3H]-uridine, respectively. Phosphorylation of histones increases whereas that of nonhistone chromosomal (NHC) proteins decreases during development. Spermine stimulates phosphorylation of both histones and NHC proteins. Transcription of chromatin decreases as development progresses. Phosphorylation of chromosomal proteins stimulates transcription. This is further stimulated by spermine. However, these effects decrease as development proceeds. Such functional alterations in the chromatin may be responsible for the terminal differentiation of neurons, and may have a significant role in differential gene expression during cell differentiation and development.