Corticotropin‐releasing hormone‐binding protein is up‐regulated by brain‐derived neurotrophic factor and is secreted in an activity‐dependent manner in rat cerebral cortical neurons

Abstract

A recent study revealed that corticotropin-releasing hormone (CRH) in the cerebral cortex (CTX) plays a regulatory role in emotional behaviors in rodents. Given the functional interaction between brain-derived neurotrophic factor (BDNF) and the CRH-signaling pathway in the hypothalamic-pituitary-adrenal axis, we hypothesized that BDNF may regulate gene expression of CRH and its related molecules in the CTX. Findings of real-time quantitative PCR (RT-qPCR) indicated that stimulation of cultured rat cortical neurons with BDNF led to marked elevations in the mRNA levels of CRH and CRH-binding protein (CRH-BP). The BDNF-induced up-regulation of CRH-BP mRNA was attenuated by inhibitors of tropomyosin related kinase (Trk) and MEK, but not by an inhibitor for PI3K and Phospholipase C gamma (PLCγ). The up-regulation was partially blocked by an inhibitor of lysine-specific demethylase (KDM) 6B. Fluorescent imaging identified the vesicular pattern of pH-sensitive green fluorescent protein-fused CRH-BP (CRH-BP-pHluorin), which co-localized with mCherry-tagged BDNF in cortical neurons. In addition, live-cell imaging detected drastic increases of pHluorin fluorescence in neurites upon membrane depolarization. Finally, we confirmed that tetrodotoxin partially attenuated the BDNF-induced up-regulation of CRH-BP mRNA, but not that of the protein. These observations indicate the following: In cortical neurons, BDNF led to gene expression of CRH-BP and CRH. TrkB, MEK, presumably ERK, and KDM6B are involved in the BDNF-induced gene expression of CRH-BP, and BDNF is able to induce the up-regulation in a neuronal activity-independent manner. It is suggested that CRH-BP is stored into BDNF-containing secretory granules in cortical neurons, and is secreted in response to membrane depolarization.

Moderate Prenatal Ethanol Exposure Stimulates CXCL12/CXCR4 Chemokine System in Radial Glia Progenitor Cells in Hypothalamic Neuroepithelium and Peptide Neurons in Lateral Hypothalamus of the Embryo and Postnatal Offspring

“…The rats were sacrificed at P10, and the LH was dissected as described (Chang et al, ). Total RNA was then extracted from each microdissected sample, cDNA was synthesized, and qRT‐PCR was performed, as previously described in our publications (Barson et al, ; Chang et al, , ) and others (Adachi et al, ; West et al, ). The primers for CXCL12, CXCR4, and the neuropeptides were designed with ABI Primer Express version 3.0 software from published sequences, and their sequences and concentrations are presented in Table .…”

CCL2/CCR2 system in neuroepithelial radial glia progenitor cells: involvement in stimulatory, sexually dimorphic effects of maternal ethanol on embryonic development of hypothalamic peptide neurons

“…Total RNA was then extracted from each microdissected sample, cDNA was synthesized, and qRT-PCR was performed, as previously described in our publications [ 9 , 11 , 44 ] and others [ 45 , 46 ]. The primers for BLBP, CCL2, CCR2, and MCH, designed with ABI Primer Express Version 3.0 software from published sequences, and their concentrations are presented in Table 1 .…”

Vexin is upregulated in cerebral cortical neurons by brain‐derived neurotrophic factor

“…Imaging or cell fixation was carried out 24 hours after gene transfection. Astrocyte pure cultures were prepared as previously described 6 . Briefly, primary cultures of astrocytes were prepared from the cerebral cortex of neonatal Wistar rats.…”