Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Pac1”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed1998

Expression of PACAP, and PACAP type 1 (PAC1) receptor mRNA during development of the mouse embryo.

Pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP) have been reported to have a number of neurotrophic effects. We have examined the expression of mRNA for PACAP and PACAP type 1 (PAC1) receptor in the mouse embryo by in situ hybridization and the effects of PACAP and VIP on the growth of mouse embryos in vitro. Although we were unable to detect gross effects of either peptide on the growth rates of embryos maintained in culture, mRNAs for both PAC1 receptor and PACAP peptide were present in the nervous system from day 9.5 of embryonic development. PAC1 receptor mRNA was most abundant in the neural tube and the rhombencephalon and was present also in the dorsal root and trigeminal ganglia and the sympathetic chain. The distribution of mRNA for the PACAP peptide overlapped in part with that of the receptor, but was more extensively distributed in the rhombencephalon and in the developing hypothalamus. Within the neural tube, PAC1 receptor mRNA was located in the roof and floor plates, while the distribution of PACAP peptide mRNA was more complex, being located in two columns of cells in the ventromedial neural tube (consistent with the position of developing autonomic motor neurons) and in cells in the dorsolateral neural tube. These data are concordant with a role for PACAP or a related peptide in neural development.

Animals↗
PubMed2003

Expression of the receptor for pituitary adenylate cyclase-activating polypeptide (PAC1-R) in reactive astrocytes.

We generated transgenic mice that express an enhanced green fluorescent protein (EGFP) under the control of the mouse glial fibrillary acidic protein (GFAP) promoter. In one of the transgenic lines, the green fluorescence of EGFP was undetectable in almost all of the brain regions, including the neocortex, in untreated animals. However, when reactive astrogliosis was induced by cortical stab wounding, the strong fluorescence of EGFP was observed around the needle track but was not found in the corresponding area of the contralateral hemisphere. The EGFP-expressing cells had the morphological features of reactive astrocytes such as thick processes. The EGFP-expressing cells were found to overlap with the astroglial marker GFAP, but not with the microglial marker CD11b or the neuronal marker NeuN. Furthermore, there were some EGFP-expressing cells that expressed vimentin-like immunoreactivity, the specific marker for reactive astrocytes. These results strongly suggest that the EGFP-expressing cells are reactive astrocytes, but not resting astrocytes. Using these transgenic mice, immunostaining for the PAC1 receptor (PAC1-R) was performed. PAC1-R, which is a pituitary adenylate cyclase-activating polypeptide (PACAP)-specific receptor, binds PACAP, which is known to have a wide variety of functions. An immunohistochemical study revealed the localization of PAC1-R in reactive astrocytes visualized with EGFP around the needle track at 5 days postsurgery.

Animals↗
PubMed1999

Identification and functional properties of the pituitary adenylate cyclase activating peptide (PAC1) receptor in human benign hyperplastic prostate.

Pituitary adenylate cyclase activating peptide (PACAP) is a novel neuropeptide with regulatory and trophic functions that is related to vasoactive intestinal peptide (VIP). Here we investigate the expression of specific PACAP receptors (PAC1) and common VIP/PACAP receptors (VPAC1 and VPAC2) in the human hyperplastic prostate by immunological methods. The PAC1 receptor corresponded to a 60-KDa protein whereas the already known VPAC1 and VPAC2 receptors possessed molecular masses of 58 and 68 KDa, respectively. The heterogeneity of VIP/PACAP receptors in this tissue was confirmed by radioligand binding studies using [125I]PACAP-27 by means of stoichiometric and pharmacological experiments. At least two classes of PACAP binding sites showing different affinities could be resolved, with Kd values of 0.81 and 51.4 nM, respectively. The order of potency in displacing [125I]PACAP-27 binding was PACAP-27 approximately equal to PACAP-38 > VIP. PACAP-27 and VIP stimulated similarly adenylate cyclase activity, presumably through common VIP/PACAP receptors. The PAC1 receptor was not coupled to activation of either adenylate cyclase, nitric oxide synthase, or phospholipase C. It appears to be a novel subtype of PAC1 receptor because PACAP-27 (but not PACAP-38 or VIP) led to increased phosphoinositide synthesis, an interesting feature because phosphoinositides are involved via receptor mechanisms in the regulation of cell proliferation.

Aged↗
PubMed2004

VPAC receptor modulation of neuroexcitability in intracardiac neurons: dependence on intracellular calcium mobilization and synergistic enhancement by PAC1 receptor activation.

Pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP) have been found within mammalian intracardiac ganglia, but the cellular effects of these neuropeptides remain poorly understood. Fluorometric calcium imaging and whole cell patch clamp recordings were used to examine the effects of PACAP and VIP on [Ca2+]i and neuroexcitability, respectively, in intracardiac neurons of neonatal rats. PACAP and VIP evoked rapid increases in [Ca2+]i that exhibited both transient and sustained components. Pharmacological experiments using PAC1 and VPAC receptor-selective antagonists demonstrated that the elevations in [Ca2+]i result from the activation of VPAC receptors. The transient increases in [Ca2+]i were shown to be the product of Ca2+ mobilization from caffeine/ryanodine-sensitive intracellular stores and were not due to inositol 1,4,5-trisphosphate-mediated calcium release. In contrast, the sustained [Ca2+]i elevations were dependent on extracellular Ca2+ and were blocked by the transient receptor channel antagonist, 2-aminoethoxydiphenyl borate, which suggests that they are due to Ca2+ entry via store-operated channels. In addition to elevating [Ca2+]i, both PACAP and VIP depolarized intracardiac neurons, and PACAP was further shown to augment action potential firing in these cells. Depolarization of intracardiac neurons by the neuropeptides was dependent on activation of VPAC receptors and the concomitant increases in [Ca2+]i. Although activation of PAC1 receptors alone had no direct effects on neuroexcitability, PAC1 receptor stimulation potentiated the VPAC receptor-induced depolarizations. Furthermore, enhanced action potential firing was only observed upon concurrent stimulation of PAC1 and VPAC receptors, which indicates that these receptors act synergistically to enhance neuroexcitability in intracardiac neurons.

Animals↗
PubMed2006

Functional analysis of recombinant mutants of maxadilan with a PAC1 receptor-expressing melanophore cell line.

Maxadilan, a 61-amino-acid vasodilatory peptide, was initially isolated from the salivary glands of the sand fly Lutzomyia longipalpis. Although its primary sequence has no homology to that of pituitary adenylate cyclase-activating peptide, maxadilan is an agonist for the PAC1 receptor. A total of 58 substitution and deletion mutants was engineered in an effort to determine which residues were important for receptor activation. The mutants were characterized functionally using an assay based on pigment granule translocation in PAC1-expressing Xenopus laevis melanophores. Substitution of charged residues and proline 43 could alter (but not eliminate) the agonist activity of the mutants. In contrast, we found that several multiple substitution mutants of the predicted beta-strand threonine residues became antagonists at the PAC1 receptor. The results suggest that these threonine residues are cooperatively involved in PAC1 activation.

Amino Acid Sequence↗
PubMed2000

Differential activation of phospholipase D by VPAC and PAC1 receptors.

To investigate the phospholipase D (PLD) responses of the VIP/PACAP receptors, VPAC1 and VPAC2, and the PACAP-specific PAC1 receptors (short and "hop" intracellular loop 3 (i3) splice variants), stable CHO cell lines expressing similar levels of each wildtype receptor were generated (except for the VPAC1 receptor clone which showed considerably lower expression and lesser responses in signalling assays). All clones caused activation of PLD in response to agonists, as monitored by [3H]phosphatidylbutanol production. The PLD responses of the PAC1 "hop", but not the "null" receptor, were sensitive to the ARF inhibitor, brefeldin A (BFA) (as were VPAC1 and VPAC2 responses). Chimeric constructs of VPAC2 receptors containing i3 of either PAC1 hop or PAC1 null receptors were transiently expressed in COS 7 cells and PLD responses were measured. Only the PLD response of the hop construct was sensitive to BFA. This suggests that i3 motifs in certain Group II GPCRs may play a key role in determining their linkage to ARF-dependent PLD activation.

Amino Acid Sequence↗
PubMed2000

Nerve growth factor upregulates the PAC1 promoter by activating the MAP kinase pathway in rat PC12 cells.

We report that: (1) An increase in the transcription activity is a mechanism by which trophic peptides may regulate the expression of PAC1. (2) An activation of the PAC1 promoter does not necessarily correlate with the neurotrophin-promoted neuritogenesis. (3) Activation of the PAC1 promoter is probably an early event since the EGF response is rather weak and transient in PC12 cells. (4) MAP kinase pathway activation is necessary for the NGF effect. The mechanism of the antagonism between PACAP and NGF observed on the PAC1 promoter activity and already described in regulating chromaffin cell proliferation, remains to be explained.

Alternative Splicing↗
PubMed2006

PAC1 receptor: emerging target for septic shock therapy.

Septic shock is a systemic response to severe bacterial infections, generally caused by Gram-negative bacterial endotoxins, with multiple manifestations such as hypotension, tissue injury, disseminated intravascular coagulation, and multi-organ failure. All these effects, are induced by the generation of pro-inflammatory and vasodilator mediators, cell adhesion molecules, coagulation factors, and acute-phase proteins. Vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) are two immunopeptides with anti-inflammatory properties exerted through type 1 and 2 VIP receptors (VPAC1 and VPAC2, respectively), and PACAP receptor (PAC1). The present results recapitulate the protective role of PAC1 in an experimental model of lethal endotoxemia using a knockout for the PAC1 receptor. Our results demonstrate that VIP and PACAP decrease lipopolysaccharide (LPS)-induced interleukin-6 (IL-6) production, neutrophil infiltration and intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and fibrinogen expression through PAC1 receptor, providing an advantage to design more specific drugs complementing standard intensive care therapy in septic shock.

Animals↗
PubMed2006

PACAP receptor (PAC1-R) expression in rat and rhesus monkey thymus.

The expression of PACAP receptor (PAC1-R) was investigated in the thymus of rats and rhesus monkeys. In the rat thymus, PAC1-R positive cells were found in the intermediate type of thymic epithelial cells of the medulla. PAC1-R-positive cells were also seen in the thymic medulla of the rhesus monkey. The thymus showed unusual structures in some rhesus monkey dams (F0) and offspring (F1) exposed to 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD). Additionally, in these rhesus monkeys, PAC1-R expression was different from that in the control thymus.

Animals↗
PubMed2005

Altered calmodulin response to light in the suprachiasmatic nucleus of PAC1 receptor knockout mice revealed by proteomic analysis.

In mammals circadian rhythms are generated by a light-entrainable oscillator located in the hypothalamic suprachiasmatic nucleus (SCN). Light signals reach the SCN via a monosynaptic neuronal pathway, the retinohypothalamic tract, originating in a subset of retinal ganglion cells. The nerve terminals of these cells contain the classical neurotransmitter glutamate and the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP), and there is evidence that these two transmitters interact to mediate photoentrainment of the oscillator in the SCN. To elucidate light-provoked PACAP receptor signaling we used proteomic analysis. Wild-type mice and mice lacking the PAC1 receptor (PAC1-/-) were light stimulated at early night, and the SCN was examined for proteins that were differentially expressed using two-dimensional gel electrophoresis and identification by tandem mass spectrometry. The most striking finding, which was subsequently confirmed by Western blotting, was a significant reduction of calmodulin (CaM) in wild-type mice as compared with PAC1-/- mice. Analysis at the mRNA level by quantitative in situ hybridization histochemistry was inconclusive, indicating that a translational mechanism might be involved. The findings indicate that PAC1 receptor signaling in the SCN in response to light stimulation induces a down-regulation of CaM expression and that CaM is involved in the photic-entrainment mechanism.

Animals↗
PubMed1997

Differential regulation of the dual-specificity protein-tyrosine phosphatases CL100, B23, and PAC1 in mesangial cells.

The extracellular-signal-regulated kinase (ERK), the best described MAP kinase cascade, is a major signaling system by which cells transduce extracellular cues into intracellular responses. ERK is activated by phosphorylation both on tyrosine and threonine residues. Therefore, a new clas of protein-tyrosine phosphatases (PTPases) that exhibit dual catalytic activity toward both regulatory sites on ERK is of special interest in the control of intracellular signaling. This study examined the expression and regulation of the dual-specificity PTPases CL100, B23, and PAC1. Findings included differential expression of these phosphatases in diverse cell lines and an expression of all three dual-specificity PTPases in human mesangial cells (HMC), thereby allowing investigation of their regulation in a single cell line. The MEK antagonist PD 098059 and selective extracellular agonists of ERK were used to demonstrate the induction of CL100, PAC1, and B23 in response to activation of the ERK cascade. In contrast, anisomycin, an agonist of the recently described MAP kinases stress-activated protein kinase (SAPK) and p38 MAP kinase, stimulated CL100 gene expression but had little effect on PAC1 and B23. This effect of anisomycin was partly inhibited in the presence of the p38 MAP kinase antagonist SB 203580. This study suggests a potential mechanism to regulate ERK activity through feedback inhibition by demonstrating the ERK cascade's induction of the dual-specificity PTPases CL100, PAC1, and B23. Moreover, this study suggests an ERK-independent induction of CL100 following stimulation of SAPK and p38 MAP kinase. This mode of induction of a phosphatase capable of inactivating ERK may play an important role in the cellular stress response.

Animals↗
PubMed2006

Lack of the PAC1 receptor alters the circadian expression of VIP mRNA in the suprachiasmatic nucleus of mice.

PACAP in the retinohypothalamic tract mediates photic information to the suprachiasmatic nucleus via the PAC1 receptor. The diurnal and circadian VIP mRNA expressions in the suprachiasmatic nucleus of PAC1-/- and wild type mice were quantified. During light/dark cycles identical VIP mRNA rhythms were found while the oscillation pattern differed between the two types of animals during constant darkness. The results show that the circadian VIP mRNA expression is influenced by the absence of PAC1 signalling.

Animals↗
PubMed1999

Structural motifs of pituitary adenylate cyclase-activating polypeptide (PACAP) defining PAC1-receptor selectivity.

Pituitary adenylate cyclase-activating polypeptide (PACAP) interacts with three types of PACAP/VIP-receptors. The PAC1-receptor accepts PACAP as a high affinity ligand but not vasoactive intestinal peptide (VIP) similarly binding to VPAC1- and VPAC2-receptors. To identify those amino acids not present in VIP defining PAC1-receptor selectivity of PACAP, radio receptor binding assays on AR4-2J cells were performed. It could be shown that PACAP(1-27) exhibited a distinct and much higher susceptibility to VIP-amino acid substitutions, compared to PACAP(1-38). Positions 4 and 5 seem to be most important for receptor binding of PACAP(1-27), whereas position 13 was identified to be crucial for maximal affinity of PACAP(1-38). PACAP(29-38) extension analogues of VIP revealed a stabilizing effect of the C-terminus of PACAP(1-38) on the optimal peptide conformation. The substitution analogues were also checked for their capacity to stimulate IP3 and cAMP formation in AR4-2J cells. Compared to PACAP(1-27) and PACAP(1-38), most analogues revealed potencies reduced congruously to their lower binding affinities. However, one of the analogues, PACAP(1-27) substituted in position 5, may represent a weak antagonist since this peptide was less potent in inducing second messengers than in label displacement. Our findings indicate that PACAP(1-27) and PACAP(1-38) differ in terms of their requirement of the amino acids in positions 4, 5, 9, 11 and 13 for maximal interaction with the PAC1-receptor.

Alternative Splicing↗
PubMed2002

Expression of VPAC2 receptor and PAC1 receptor splice variants in the trigeminal ganglion of the adult rat.

PACAP and VIP are members of the VIP/secretin/glucagon family of peptides with neurotransmitter, neuroprotective, and neurotrophic functions. PACAP and VIP are known to be upregulated in primary sensory neurons following nerve injury, implying that these neuropeptides could be mediators of sensory transmission in neuropathic pain states. Nerve injury at the level of the trigeminal root is thought to be the prime cause of trigeminal neuralgia. Since cross-excitation (a chemically-mediated form of nonsynaptic transmission) within the TG is postulated to play a central role in trigeminal neuralgia, we studied the expression of PACAP and VIP receptors in the TG by RT PCR and immunocytochemistry. Of the three known receptors (PAC1, VPAC1 and VPAC2), RT PCR revealed the presence of mRNA for VPAC2 and several splice variants of the PAC1 receptor. Immunocytochemistry showed PAC1 and VPAC2 to be present in small-diameter TG neurons. Thus, PACAP and VIP are potential mediators of cross-excitation in the TG.

Afferent Pathways↗
PubMed2004

Ageing and the diurnal expression of mRNAs for vasoactive intestinal peptide and for the VPAC2 and PAC1 receptors in the suprachiasmatic nucleus of male rats.

Ageing alters fundamental aspects of circadian rhythmicity in mammals; the effects include reduced rhythm amplitude and alterations in period length and in entrainment to the light/dark cycle. Such changes may reflect disruptions in cellular function within the suprachiasmatic nucleus (SCN), the site of the predominant circadian pacemaker. In the SCN, vasoactive intestinal peptide (VIP)-synthesizing neurones receive various inputs, including retinohypothalamic projections containing pituitary adenylate cyclase activating peptide (PACAP). SCN VIP cells establish connections with local neurones and send efferents beyond the nucleus. Considerable evidence implicates VIP and PACAP in circadian rhythm maintenance and/or entrainment to photic Zeitgebers. These actions involve members of a distinct family of receptors; mRNAs for two such receptors, VPAC2 and PAC1, are present in the SCN. This study used isotopic in situ hybridization to examine the effects of ageing on expression of mRNAs for VIP, VPAC2 and PAC1 in the SCN of male rats under a 12 : 12 h light/dark cycle. Analysis of film autoradiographs from young adult (2-3 months) or aged (19-20 months) rats, at eight time points across the light/dark cycle, showed loss of diurnal rhythmicity and reduced levels for VIP mRNA in the aged group. A diurnal rhythm of VPAC2 receptor mRNA was present in both groups, but its levels were reduced in the aged rats. There were no differences between the two groups for PAC1 receptor mRNA expression. The present results indicate that ageing reduces VIP and VPAC2 receptor mRNA and eliminates diurnal expression of VIP mRNA within the SCN of aged male rats.

Aging↗
PubMed2000

PAC1 null females display decreased fertility.

We report here that PAC1 KO females display decreased fertility, whereas male fertility was normal. ICC on pituitary section showed that FSH, LH, and prolactin synthesis were not affected in KO mice. Moreover, the pituitary-gonadal axis responded properly to an acute fasting test in KO mice. Hence, the phenotype of PAC1 null mice provides clear evidence for the role of PAC1 receptor in reproduction process.

Animals↗
PubMed1998

Sequences within the herpesvirus-conserved pac1 and pac2 motifs are required for cleavage and packaging of the murine cytomegalovirus genome.

The DNA sequence motifs pac1 [an A-rich region flanked by poly(C) runs] and pac2 (CGCGGCG near an A-rich region) are conserved near herpesvirus genomic termini and are believed to mediate cleavage of genomes from replicative concatemers. To determine their importance in the cleavage process, we constructed a number of recombinant murine cytomegaloviruses with a second cleavage site inserted at an ectopic location within the viral genome. Cleavage at a wild-type ectopic site occurred as frequently as at the natural cleavage site, whereas mutation of this ectopic site revealed that some of the conserved motifs of pac1 and pac2 were essential for cleavage whereas others were not. Within pac1, the left poly(C) region was very important for cleavage and packaging but the A-rich region was not. Within pac2, the A-rich region and adjacent sequences were essential for cleavage and packaging and the CGCGGCG region contributed to, but was not strictly essential for, efficient cleavage and packaging. A second A-rich region was not important at all. Furthermore, mutations that prevented cleavage also blocked duplication and deletion of the murine cytomegalovirus 30-bp terminal repeat at the ectopic site, suggesting that repeat duplication and deletion are consequences of cleavage. Given that the processes of genome cleavage and packaging appear to be highly conserved among herpesviruses, these findings should be relevant to other members of this family.

3T3 Cells↗
PubMed2006

Expression of the human PAC1 receptor leads to dose-dependent hydrocephalus-related abnormalities in mice.

Hydrocephalus is a common and potentially devastating birth defect affecting the CNS, and its relationship with G protein-coupled receptors (GPCRs) is unknown. We have expressed 2, 4, or 6 copies of a GPCR--the human PAC1 receptor with a 130-kb transgene in the mouse nervous system in a pattern closely resembling that of the endogenous gene. Consistent with PAC1 actions, PKA and PKC activity were elevated in the brains of Tg mice. Remarkably, Tg mice developed dose-dependent hydrocephalus-like characteristics, including enlarged third and lateral ventricles and reduced cerebral cortex, corpus callosum, and subcommissural organ (SCO). Neuronal proliferation and apoptosis were implicated in hydrocephalus, and we observed significantly reduced neuronal proliferation and massively increased neuronal apoptosis in the developing cortex and SCO of Tg embryos, while neurite outgrowth and neuronal migration in vitro remain uncompromised. Ventricular ependymal cilia are crucial for directing cerebrospinal fluid flow, and ependyma of Tg mice exhibited disrupted cilia with increased phospho-CREB immunoreactivity. These data demonstrate that altered neuronal proliferation/apoptosis and disrupted ependymal cilia are the main factors contributing to hydrocephalus in PAC1-overexpressing mice. This is the first report to our knowledge demonstrating that misregulation of GPCRs can be involved in hydrocephalus-related neurodevelopmental disorders.

Animals↗