Identification of a functional AP1 element in the rat vasopressin gene promoter.
ABSTRACT Arginine vasopressin (AVP) is expressed in paraventricular, supraoptic, and suprachiasmatic nuclei of the hypothalamus, where transcription of the AVP gene is activated by various forms of stress, such as hyperosmolality, inflammation, and photic stimulation. In vasopressinergic neurons, the expression of the Fos/Jun family proteins is known to be rapidly induced after these stimuli as well. However, it is still unknown whether these proteins actually mediate AVP gene expression. In this study we examined in vitro the role of Fos/Jun protein in transcriptional regulation of the AVP gene using the BE(2)M17 neuroblastoma cell line. We found that 5'-promoter activity of the rat AVP gene (-803/+26) markedly increased when all combinations of the Fos/Jun family proteins were overexpressed. Coexpression of the cAMP-responsive element-binding protein-binding protein and steroid receptor coactivator-1a further enhanced the Fos/Jun-mediated transcription. Using site-directed mutagenesis and EMSA techniques, we identified an activation protein 1 (AP1)-like element (-134/-128; TGAATCA) in the AVP gene 5'-promoter region, which is the sole responsible site for the Fos/Jun-mediated transcription. We also found that 12-O-tetradecarbonyl phorbol 13-acetate stimulates AVP gene transcription partly via the AP1 site through the activation of ERK signaling. Together, these results suggest that a variety of Fos/Jun family member proteins stimulate transcription of the AVP gene through the AP1 site we identified. Furthermore, this effect may be activated by both protein kinase A and protein kinase C signaling pathways.
- SourceAvailable from: Daniel Lubelski[show abstract] [hide abstract]
ABSTRACT: The magnocellular neurons (MCNs) in the supraoptic nucleus (SON) of the hypothalamus selectively express either oxytocin (Oxt) or vasopressin (Avp) neuropeptide genes. In this paper we examine the cis-regulatory domains in the Avp gene promoter that are responsible for its cell-type specific expression. AAV vectors that contain various Avp gene promoter deletion constructs using EGFP as the reporter were stereotaxically injected into the rat SON. Two weeks following the injection immunohistochemical assays of EGFP expression from these constructs were done to determine whether the expressed EGFP reporter co-localizes with either the Oxt- or Avp-immunoreactivity in the MCNs. The results identify three major enhancer domains located at -2.0 to -1.5 kbp, -1.5 to -950 bp, and -950 to -543 bp in the Avp gene promoter that regulate the expression in Avp MCNs. The results also show that cell-type specific expression in Avp MCNs is maintained in constructs containing at least 288 bp of the promoter region upstream of the transcription start site, but this specificity is lost at 116 bp and below. Based on these data, we hypothesize that the -288 bp to -116 bp domain contains an Avp MCN specific activator and a possible repressor that inhibits expression in Oxt-MCNs, thereby leading to the cell-type specific expression of the Avp gene only in the Avp-MCNs.PLoS ONE 01/2012; 7(11):e48860. · 3.73 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: The formation of brain edema and subsequent intracranial hypertension are major predictors of unfavorable outcome following traumatic brain injury (TBI). Previously, we reported that arginine vasopressin (AVP) receptor antagonists reduce post-traumatic and post-ischemic brain edema in mice. The aim of the current study was to investigate further the contribution of arginine vasopressin V1a receptors to TBI-induced secondary brain damage in V1a receptor knock-out mice. V1a receptor knock-out (V1a-/-) and wild-type mice were subjected to controlled cortical impact (CCI), and edema (brain water content measured before and 24 h after CCI), primary and secondary contusion volume (15 min and 24 h after CCI), neurological function (1 day before and 7 days after CCI), body weight (before and 7 days after CCI) and mortality were measured. Twenty-four hours after CCI, V1a receptor knock-out mice had significantly less brain water content than wild-type mice (mean ± SEM: 79.8% ± 0.3 vs. 80.6% ± 0.2, respectively), and secondary contusion volume was significant smaller (38.2 ± 1.7 mm3 vs. 45.1 ± 1.5 mm3 in wild-type mice). Furthermore, the V1a receptor knock-out mice had less neurological dysfunction (3.2 ± 0.8 vs. 7.0 ± 1.4 in wild-type mice) and weight loss (1.0 ± 1.0% vs. 4.9 ± 1.8% in wild-type mice) 7 days after CCI. Our data show that mice lacking V1a receptors have less secondary brain damage following experimental traumatic brain injury. We therefore conclude that V1a receptors may represent a novel drug target for preventing post-traumatic brain edema.Journal of neurotrauma 02/2013; · 4.25 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: The oxytocin (Oxt) and vasopressin (Avp) magnocellular neurons (MCNs) in the hypothalamus are the only neuronal phenotypes that are present in the supraoptic nucleus (SON), and are characterized by their robust and selective expression of either the Oxt or Avp genes. In this paper, we take advantage of the differential expression of these neuropeptide genes to identify and isolate these two individual phenotypes from the rat SON by laser capture microdissection (LCM), and to analyze the differential expression of several of their transcription factor mRNAs by qRT-PCR. We identify these neuronal phenotypes by stereotaxically injecting recombinant Adeno-Associated Viral (rAAV) vectors which contain cell-type specific Oxt or Avp promoters that drive expression of EGFP selectively in either the Oxt or Avp MCNs into the SON. The fluorescent MCNs are then dissected by LCM using a novel Cap Road Map protocol described in this paper, and the purified MCNs are extracted for their RNAs. qRT-PCR of these RNAs show that some transcription factors (RORA and c-jun) are differentially expressed in the Oxt and Avp MCNs.PLoS ONE 01/2013; 8(7):e69407. · 3.73 Impact Factor