Noncovalent binding of poly(ADP-ribose) to nuclear matrix proteins: Developmental changes and tissue specificity

Poly(ADP-ribose) is a nuclear polynucleotide involved in the regulation of chromatin functions via covalent and/or noncovalent modification of nuclear proteins. Using a binding assay on protein blots, we searched for poly(ADP -ribose) binding proteins in nuclear matrices from testes of differently ag ed rats as well as from various adult rat tissues (brain, liver spleen). We found that nuclear matrix proteins represent a significant subset of the n uclear proteins that can establish noncovalent interactions with poly(ADP-r ibose). The profiles of poly(ADP-ribose) binding nuclear matrix proteins ap peared to be tissue-specific and changed during postnatal development in th e testis. The isolation and analysis of endogenous poly(ADP-ribose) from rat testes s howed that the ADP-ribose polymers that bind nuclear matrix proteins in vit ro are also present under physiologic conditions in vivo. These results fur ther substantiate the possibility that poly(ADP-ribose) may affect chromati n functions through noncovalent interaction with specific protein targets, including nuclear matrix components.