C/EBPβ couples dopamine signalling to substance P precursor gene expression in striatal neurones

Abstract

Dopamine-induced changes in striatal gene expression are thought to play an important role in drug addiction and compulsive behaviour. In this study we report that dopamine induces the expression of the transcription factor CCAAT/ Enhancer Binding Protein b (C/EBP)-b in primary cultures of striatal neurones. We identifed the preprotachykinin-A (PPT-A) gene coding for substance P and neurokinin-A as a potential target gene of C/EBPb. We demonstrated that C/EBPb physically interacts with an element of the PPT-A promoter, thereby facilitating substance P precursor gene transcription. The regulation of PPT-A gene by C/EBPb could subserve many important physiological processes involving substance P, such as nociception, neurogenic inflammation and addiction. Given that substance P is known to increase dopamine signalling in the striatum and, in turn, dopamine increases substance P expression in medium spiny neurones, our results implicate C/EBPb in a positive feedback loop, changes of which might contribute to the development of drug addiction.

TORC1 is a calcium- and cAMP-sensitive coincidence detector involved in hippocampal long-term synaptic plasticity

“…Primary cultures of neurons were prepared from 17-day-old Swiss mice embryos and cultured as described (34,35). After 6 days in vitro, plasmid DNA was transfected by using Nupherin-neuron (Biomol, Plymouth Meeting, PA) and TransFectin (Bio-Rad, Hercules, CA) as described (35).…”

“…Four hours after stimulation, transfected cells were lysed and tested for luciferase and ␤-galactosidase activities as described (35).…”

“…Total RNA was extracted from primary neurons or brain samples, and analyzed by real-time RT-PCR as described (35). The oligonucleotide primers for TORC1, TORC2, and BDNF, as well as the methods of quantification are described in SI Materials and Methods.…”

CCAAT/Enhancer-binding Protein (C/EBP) β Is Acetylated at Multiple Lysines

“…GST-C/EBP␤ plasmids encode fusion proteins of GST with truncated forms of C/EBP␤ (residues 22-227, , and 22-103) as described previously (42). HIS-C/EBP␤ encodes C/EBP␤ tagged with six histidine residues at the N terminus (48). Recombinant HIS-C/ EBP␤ was expressed and purified on a nickel-nitrilotriacetic acid-agarose column (Qiagen).…”

Transcriptional Regulation of Acute Phase Protein Genes

“…This suggests that C/EBP isoform overexpression leads to chromatin changes compatible with RNA polymerase II recruitment and transcriptional activity. Whether recruitment of co-activators, such as p300 and CBP (Kovacs et al, 2003;Svotelis et al, 2005), and/or of remodeling SWI/SNF complexes (Kowenz-Leutz et al, 2010) are required, needs to be addressed. Thus, C/EBPs are a major regulator of APP inflammatory secondary responses in IECs.…”