KAPPA-B ENHANCER-BINDING COMPLEXES THAT DO NOT CONTAIN NF-KAPPA-B ARE DEVELOPMENTALLY-REGULATED IN MAMMALIAN BRAIN

DNA-binding complexes which are temporally regulated in developing rat brain have been identified by their ability to interact with the kappaB enhancer sequence in electrophoretic mobility-shift assays. These complexes, referred to as developing-brain factors (DBFs) 1 and 2, are abundant in nuclear extracts from developing rat brain through postnatal day 2 and decline to nearly undetectable levels by postnatal day 7. DBFs were not detected in extracts from cultured cell lines or in tissues other than the developing brain. The highest level of DBF DNA-binding activity was observed in developing cortex, and the lowest in cerebellum. In UV crosslinking experiments, a labeled kappaB oligonucleotide probe crosslinked 110- and 115-kDa proteins from DBF complexes. DBFs are likely to be involved in the regulation of transcriptional events which take place during brain development.