Tissue-specific and neural activity-regulated expression of human BDNF gene in BAC transgenic mice

Abstract

BackgroundBrain-derived neurotrophic factor (BDNF) is a small secreted protein that has important roles in the developing and adult nervous system. Altered expression or changes in the regulation of the BDNF gene have been implicated in a variety of human nervous system disorders. Although regulation of the rodent BDNF gene has been extensively investigated, in vivo studies regarding the human BDNF gene are largely limited to postmortem analysis. Bacterial artificial chromosome (BAC) transgenic mice harboring the human BDNF gene and its regulatory flanking sequences constitute a useful tool for studying human BDNF gene regulation and for identification of therapeutic compounds modulating BDNF expression.ResultsIn this study we have generated and analyzed BAC transgenic mice carrying 168 kb of the human BDNF locus modified such that BDNF coding sequence was replaced with the sequence of a fusion protein consisting of N-terminal BDNF and the enhanced green fluorescent protein (EGFP). The human BDNF-BAC construct containing all BDNF 5' exons preceded by different promoters recapitulated the expression of endogenous BDNF mRNA in the brain and several non-neural tissues of transgenic mice. All different 5' exon-specific BDNF-EGFP alternative transcripts were expressed from the transgenic human BDNF-BAC construct, resembling the expression of endogenous BDNF. Furthermore, BDNF-EGFP mRNA was induced upon treatment with kainic acid in a promotor-specific manner, similarly to that of the endogenous mouse BDNF mRNA.ConclusionGenomic region covering 67 kb of human BDNF gene, 84 kb of upstream and 17 kb of downstream sequences is sufficient to drive tissue-specific and kainic acid-induced expression of the reporter gene in transgenic mice. The pattern of expression of the transgene is highly similar to BDNF gene expression in mouse and human. This is the first study to show that human BDNF gene is regulated by neural activity.

A Polymorphism Associated with Depressive Disorders Differentially Regulates Brain Derived Neurotrophic Factor Promoter IV Activity

“…These results confirm previous studies using transgenic mice carrying a bacterial artificial chromosome containing the human BDNF locus that also showed BDNF expression in these regions (45). However, these bacterial artificial chromosome-based studies could not attribute the expression patterns produced directly to BP4.…”

Growth Arrest and DNA-Damage-Inducible, Beta (GADD45b)-Mediated DNA Demethylation in Major Psychosis

“…Although there are regulatory differences between human BDNF IXabcd and mouse BDNF IXa (Pruunsild et al, 2011), there also exist several similarities. In vivo and in vitro human BDNF IXabcd and mouse BDNF IXa are similarly induced by neuronal activity (Pruunsild et al, 2011;Koppel et al, 2009). In addition, both human and mouse transcripts are wellexpressed widely throughout the body and the brain Pruunsild et al, 2007).…”

A meta-analysis of circulating BDNF concentrations in anorexia nervosa

“…Up to nine promoters (Liu et al 2006;Pruunsild et al 2007) have been identifi ed in the rat. Each of the promoters controls alternative transcripts which are characterized by differential expression patterns that are specifi c to brain regions and tissues (Timmusk et al 1993) and which are regulated by neural activity (Koppel et al 2009). All transcripts are translated into proBDNF , which subsequently is cleaved by proteolysis into the mature BDNF protein (Seidah et al 1996).…”