Transcriptional regulation of the human prepronociceptin gene

Regulation of the Genes Encoding the ppN/OFQ and NOP Receptor

Over the years, the ability of N/OFQ-NOP receptor system in modulating several physiological functions, including the release of neurotransmitters, anxiety-like behavior responses, modulation of the reward circuitry, inflammatory signaling, nociception, and motor function, has been examined in several brain regions and at spinal level. This chapter collects information related to the genes encoding the ppN/OFQ and NOP receptor, their regulation, and relative transcriptional control mechanisms. Furthermore, genetic manipulations, polymorphisms, and epigenetic alterations associated with different pathological conditions are discussed. The evidence here collected indicates that the study of ppN/OFQ and NOP receptor gene expression may offer novel opportunities in the field of personalized therapies and highlights this system as a good "druggable target" for different pathological conditions.

Regulation of the prepronociceptin gene and its effect on neuronal differentiation

Nociceptin/orphanin FQ (NOP/OFQ) is the endogenous ligand for the NOP receptor and is processed from a precursor protein in the family of opioid peptides. Prepronociceptin (ppN/OFQ) mRNA has been shown to be upregulated by an increase in cAMP, a treatment that leads to differentiation of NS20Y neuroblastoma cells. Although a large increase in endogenous ppN/OFQ mRNA upon cAMP stimulation can be shown in cellular systems, a similar increase cannot be expressed in pGL3 luciferase vector containing 1.3 kb proximal promoter, suggesting that a larger portion of the sequence or a different chromatin structure is necessary for a fully functional promoter. The induction of ppN/OFQ mRNA by cAMP appears to be mediated by a cAMP-response element. Chromatin immunoprecipitation (ChIP) assays show that CREB is recruited to the promoter region upon treatment of NS20Y cells with dibutyryl cAMP. In addition, the production of ppN/OFQ mRNA is regulated by histone acetylation, also through CREB, as the histone deacetylase (HDAC) inhibitor trichostatin A increases both CREB binding to the promoter and ppN/OFQ mRNA expression. In rat progenitor and mouse neuroblastoma cell lines, agents that increase ppN/OFQ mRNA expression also induce neurite outgrowth, suggesting a close relationship between ppN/OFQ and cellular differentiation.

Transcriptional regulation of the mouse fatty acid amide hydrolase gene

Fatty acid amide hydrolase (FAAH) is a membrane-bound enzyme that inactivates a family of fatty acid amide molecules which are implicated in physiological processes such as pain and sleep. We cloned a 1.9 kb fragment of the 5'-untranslated region of the mouse FAAH gene into the pGL3 basic luciferase reporter vector and showed that this sequence has promoter activity in vitro. By primer extension analysis, we have determined the transcription start site to be 200 bases upstream of the ATG initiation codon and found that a TATA motif was absent. A number of putative response elements, including those for estrogen and glucocorticoids, were identified in this sequence. We have demonstrated that the estrogen and glucocorticoid receptors down-regulate transcriptional activity independent of their ligand. These data should help in understanding the mechanisms of FAAH gene transcription.

Regulation of transcription of the human prepronociceptin gene by Sp1

Nociceptin/orphanin FQ is a recently discovered neuropeptide and the endogenous ligand for opioid receptor-like-1. The promoter region of the precursor protein prepronociceptin (ppN/OFQ) has been cloned and sequenced. We have previously shown that a stretch of 110 bases immediately 5' to the first intron 23 bp upstream of the ATG start codon is responsible for significant enhancement of transcription of the human ppN/OFQ gene. We performed electromobility shift assays (EMSAs) using oligonucleotides spanning portions of the promoter region close to the intron to determine which DNA elements were important for transcriptional regulation. EMSAs using Sp1 antibody revealed a cis-acting regulatory element from bases 35-67 that appeared to bind Sp1 transcription factor and cause a shift to higher molecular weight. Deletion of this 30-bp region of DNA from the 1.2 kb promoter caused a significant loss of transcription as measured by luciferase reporter assays. Mutation of four bases at the Sp1 binding site also induced a significant loss of transcription compared to wildtype constructs. Finally, an Sp1- but not Etf-binding consensus oligonucleotide was able to compete with the interaction of the oligo with the NS20Y nuclear extract. Combined with the data from the supershift EMSAs, it appears that Sp1 is the transcription factor binding to the GC region close to the intron to regulate transcription of the human ppN/OFQ gene.