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W R Kinney

Publications and source records attributed to W R Kinney.

3 recordsLinked to original sources
PubMed1996

Gene expression of the transcription factor NF-kappa B in hippocampus: regulation by synaptic activity.

NF-kappa B is a potent transcriptional activator that resides in latent form in the cytoplasm complexed to its inhibitor I kappa B. Phosphorylation of I kappa B by protein kinase C (PKC) releases NF-kappa B, enabling its translocation to the nucleus. Since PKC can activate NF-kappa B and PKC is activated by long-term potentiation (LTP), we investigated NF-kappa B expression after hippocampal LTP induced in vivo. We first described the expression of the NF-kappa B subunits, p50 and p65, and I kappa B alpha mRNAs, in each cell field of the hippocampus. In other brain locations I kappa B alpha mRNA exhibited a more selective expression than p50 and p65. We then demonstrated specific NF-kappa B-like DNA-binding activity in hippocampal whole-cell extracts and in synaptosomes using electrophoretic mobility shift assays by the following criteria: (1) latent binding was revealed after deoxycholate treatment; (2) binding was competed off by unlabeled kappa B oligonucleotides; and (3) antibodies to either p50 or p65 blocked binding. Since p50 gene expression is auto-regulated by NF-kappa B, we used its expression as a reporter for NF-kappa B activity using quantitative in situ hybridization. Both p50 and p65 increased their expression in response to either LTP-inducing or low-frequency control stimulation, although the increase in p65 mRNA levels was greater after LTP than control stimulation. In contrast to p50 and p65, I kappa B alpha hybridization levels were not increased, but were inversely correlated with the magnitude of LTP. Since NF-kappa B subunit gene expression in the hippocampus is increased by augmented synaptic activity, NF-kappa B activation may contribute to alterations in target gene expression that accompany activity-dependent synaptic plasticity, but only in a combinatorial fashion with other transcription factors.

Animals↗
PubMed1996

Prolonged alteration in E-box binding after a single systemic kainate injection: potential relation to F1/GAP-43 gene expression.

The presence in hippocampus of a basic helix-loop-helix (bHLH) family of transcription factors (TFs) specifically binding in an electrophoretic mobility shift assay (EMSA) to the E-box recognition element was established by selective blockade of binding both by cold competition and by an antibody to MyoD1, an E-box TF. Protein source was from a micro-dissected preparation enriched in hippocampal granule cells. Specific E-box binding of hippocampal transcription factors was significantly reduced in kainate acid (KA) treated animals. This was observed at 24 and 72 h, but not before (3, 6 h) or after (96 h). This is the first report to our knowledge to study functional regulation of E-box binding protein in adult hippocampus. To determine the generality of this E-box regulatory event, we studied four other situations, in addition to kainate treatment, where axonal growth is known or has been suggested to increase: NGF treatment of PC12 cells, unilateral hilar lesions, long-term potentiation after 1 h, and postnatal rat hippocampal development. In all four cases, decreased E-box binding was observed. The recent link of F1/GAP-43 mRNA induction in hippocampal granule cells by KA to growth of their axons, the mossy fibers in the adult rat, suggests a potential role for the F1/GAP-43 5' flanking promoter region in regulating neurite outgrowth. Since in all cases decreased E-box binding preceded increased F1/GAP-43 mRNA expression, it is suggested that E-box binding to the F1/GAP-43 promoter in hippocampal granule cells could negatively regulate F1/GAP-43 gene expression. Indeed, analysis of recognition elements on the F1/GAP-43 gene revealed an arrangement, previously described in other genes, of multiple adjacent E-box elements. E-box binding of bHLH transcription factors is likely to occur on several different genes in addition to F1/GAP-43. It is, therefore, attractive to think that E-box binding is regulated by in vivo activation of the adult brain and that this gene regulatory event participates in the orchestration of molecular and cellular responses underlying axonal growth.

Amino Acid Sequence↗