AJP - Cell Physiology, Vol 265, Issue 5 C1220-C1223, Copyright © 1993 by American Physiological Society
Possible specific activation of RNA synthesis in PC-12 cell isolated nuclei by small acidic peptides
E. Castigli, L. Mancinelli, M. A. Mariggio and G. L. Gianfranceschi
Institute of Cell Biology, University of Perugia, Italy.
Three synthetic peptides, pyro-Glu-Ala-Gly-Glu-Ser-Glu-Asp (Pep A),
pyro-Glu-Ala-Gly-Glu-Glu-Glu-Ser-Asn (Pep B), and
pyro-Glu-Asp-Asp-Ser-Asp-Glu-Glu-Asn (Pep C), bear sequences possibly
belonging to components of a naturally occurring family of strongly related
small acidic chromatin peptides involved in regulation of gene expression.
In a crude nuclear fraction and in purified nuclei from PC-12 cells, Pep A
and Pep B activate RNA synthesis, specifically acting on the RNA polymerase
II transcription system. On the other hand, Pep C shows an inhibitory
effect on RNA synthesis in purified nuclei but an activation in the crude
nuclear fraction. Control experiments show that the serum thymic factor
does not affect RNA synthesis in the crude nuclear fraction or in purified
nuclei. A possible regulation by peptide phosphorylation via casein kinase
II (more active in purified nuclei than in the crude nuclear fraction) is
discussed.
