Transcriptional Regulation of Brain-derived Neurotrophic Factor Coding Exon IX

Abstract

Brain-derived neurotrophic factor (BDNF) is an active neurotrophin abundantly expressed throughout the nervous system. It plays an important role in synaptic transmission, plasticity, neuronal proliferation, differentiation, survival, and death. The Bdnf gene in rodents has eight non-coding exons and only a single coding exon (IX). Despite its recognized regulation by neuronal activity, relatively little is known about its transcriptional regulation, and even less about the transcription factor candidates that may play such a role. The goal of the present study was to probe for such a candidate that may regulate exon IX in the rat Bdnf gene. Our in silico analysis revealed tandem binding sites for nuclear respiratory factor 2 (NRF-2) on the promoter of exon IX. NRF-2 is of special significance because it co-regulates the expressions of mediators of energy metabolism (cytochrome c oxidase) and mediators of neuronal activity (glutamatergic receptors). To test our hypothesis that NRF-2 also regulates the Bdnf gene, we performed electrophoretic mobility shift assay (EMSA), chromatin immunoprecipitation (ChIP), promoter cloning, and site-directed mutagenesis, real-time quantitative PCR (RT-qPCR), and Western blotting analysis. Results indicate that NRF-2 functionally regulates exon IX of the rat Bdnf gene. The binding sites of NRF-2 are conserved between rats and mice. Overexpressing NRF-2 up-regulated the expression of Bdnf exon IX, whereas knocking down NRF-2 down-regulated such expression. These findings are consistent with our hypothesis that NRF-2, in addition to regulating the coupling between neuronal activity and energy metabolism, also regulates the expression of BDNF, which is intimately associated with energy-demanding neuronal activity.

The Bdnf and Npas4 genes are targets of HDAC3-mediated transcriptional repression

“…Table lists the primers used for ChIP and qPCR analysis. The exon specific Bdnf primers described in Nair et al [83] were used for the analysis…”

Methylene Blue Preserves Cytochrome Oxidase Activity and Prevents Neurodegeneration and Memory Impairment in Rats With Chronic Cerebral Hypoperfusion

“…Moreover, at the transcriptional molecular level, there is a coupling of genes for CO enzymatic activity with genes for neuronal synaptic excitation (Wong-Riley, 2012). Specifically, the transcriptional regulation of CO genes is coupled with the transcription of nuclear respiratory factor genes, such as NRF-1 and NRF-2, which in turn are coupled with transcription of excitatory neurotransmitter receptors, such as NMDA receptor subunit genes for glutamatergic excitatory synaptic activity (GluN1 and GluN2) (Dhar and Wong-Riley, 2009;Wong-Riley, 2012;Nair and Wong-Riley, 2016). Therefore, all ten nuclear CO genes and the three mitochondrial CO transcription factors are transcribed in the same "transcription factory" that is neuronal activity-dependent (Wong-Riley, 2012).…”

Cytochrome c Oxidase on the Crossroads of Transcriptional Regulation and Bioenergetics

“…Besides the COX subunits, NRF-2 affects the mRNAs of other nuclear-encoded mitochondrial proteins, like TFAM, TOM20, SURF1, and VDAC1 and provides the link between the activity of gene expression and the energy demands of the cells (Ongwijitwat et al, 2006). As in case of NRF-1, NRF-2 has the additional regulation targets among the genes encoding the crucial neuronal proteins, like NMDA receptor (Priya et al, 2013a) and brain-derived neurotrophic factor (BDNF) in rat visual cortex (Nair and Wong-Riley, 2016). Curiously, both NRF-1 and NRF-2 regulate the expression of the same subunits 1 and 2b of NMDA receptor.…”

“…BDNF is regarded as the most widely expressed, active, and well characterized neurotrophin in developing and adult mammalian central nervous system. The gene is differentially expressed in different brain regions as well as in peripheral tissues (Nair and Wong-Riley, 2016).…”