Sensitivity of myometrium to CGRP varies during mouse estrous cycle and in response to progesterone

Involvement of the calcitonin gene-related peptide system in the modulation of inflamed uterus contractile function in pigs

This study analyzed severe acute endometritis action on myometrial density and distribution of protein gene product (PGP)9.5- and calcitonin gene-related peptide (CGRP)-like immunoreactive nerve fibers and calcitonin receptor-like receptor (CLR) expression, and on CGRP receptor (CGRPR) participation in uterine contractility in pigs. E. coli suspension (E. coli group) or saline (SAL group) were injected into the uteri, or only laparotomy was performed (CON group). In the E. coli group myometrium, a lack of significant changes in PGP9.5 and CGRP innervation patterns and increased CLR protein level were revealed. In all groups, compared to the pretreatment period, human αCGRP increased amplitude in the myometrium, while reducing it in endometrium/myometrium. In the E. coli group endometrium/myometrium, human αCGRP lowered amplitude vs other groups. Human αCGRP reduced frequency in CON and SAL groups and enhanced it in the E. coli group endometrium/myometrium. The frequency in E. coli group increased vs other groups. CGRPR antagonist, human αCGRP8-37, reversed (CON, SAL groups) and eliminated (E. coli group) the rise in human αCGRP-induced myometrial amplitude. In endometrium/myometrium, human αCGRP8-37 abolished (CON group) and reversed (SAL group) a decrease in frequency, and reduced the rise in frequency (E. coli group) caused by human αCGRP. Collectively, in the myometrium, endometritis did not change PGP9.5 and CGRP innervation patterns and enhanced CLR protein level. CGRPR also mediated in CGRP action on inflamed uterus contractility.

Methylation of CALCA and CALCB in Pancreatic Ductal Adenocarcinoma

Calcitonin gene-related peptide (CGRP) plays a diverse and intricate role in chronic low-grade inflammation and is closely related to specific cancers. It includes two subtypes, CALCA (αCGRP) and CALCB (βCGRP), of which αCGRP expression accounts for more than 90%. Here, we show that methylation of CALCA and CALCB in pancreatic ductal adenocarcinoma was significantly higher than that in paracancer. Western blot and immunohistochemistry showed that CGRP, p-AKT, and p-CREB in the tumor tissues were lower than those in the paracarcinoma tissues. In vivo, the expressions of p-AKT and p-CREB in the pancreatic tissues of CALCA-KO rats were also lower than those of wild type. Methylation of CALCA and CALCB is increased in pancreatic adenocarcinoma, and under that condition, p-AKT and p-CREB levels were decreased.

Genomics and metabolomics of post-weaning return to estrus

The weaning-to-estrus interval is a multifaceted trait that has the potential to substantially improve production efficiency in today's global swine industry, if variation in this measure can be reduced. Systems-biology approaches should help close the knowledge gap and increase selection tools and management strategies-such as gilt development programs, farrowing, and lactation feeding programs-to decrease the weaning-to-estrus interval. Metabolomics, the study of small compounds within biofluids and tissues, provides links between genotype and phenotype. Given the complexity and influence of the environment on the weaning-to-estrus interval, incorporating metabolomics data will provide valuable insight and guidance for future physiological as well as genetic and genomic strategies to reduce this interval, thereby improving sow productivity.

Non-targeted Plasma Metabolome of Early and Late Lactation Gilts

Female pigs nursing their first litter (first-parity gilts) have increased energy requirements not only to support their piglets, but they themselves are still maturing. Non-targeted plasma metabolomics were used to investigate the differences between (1) post-farrowing and weaning (early or late lactation), (2) degree of body condition loss after lactation (extreme or minimal), and (3) interactions; to potentially identify compounds or pathways that could aide in alleviating energetic demands of lactation in gilts. Twenty first-parity gilts were selected with similar (P ≥ 0.4475) number of piglets born and nursed, and similar (P ≥ 0.3141) body condition traits (e.g., body weight and backfat thickness) post-farrowing, yet exhibited minimal or extreme loss (P ≤ 0.0094) in body weight (8.6 ± 1.48 kg and 26.1 ± 1.90 kg, respectively) and backfat thickness (1.3 ± 0.67 mm and 4.7 ± 0.86 mm, respectively) following lactation (weaning). Plasma samples from first-parity gilts at post-farrowing and weaning were investigated using UPLC-MS and GC-MS to generate a comprehensive metabolic profile. Each approach yielded approximately 700 detected features. An ANOVA was performed on each detected compound in R for time of collection, body condition change, and the interaction, followed by a false discovery correction. Two unknown features were different (P ≤ 0.05) for extreme vs. minimal body condition change. Several compound differences (P ≤ 0.05) were identified between post-farrowing and weaning. Thirty-two features detected by UPLC-MS had at least a log₂ fold-change of ±1.0 while only 18 features had a log₂ fold-change of ±0.6 or more for the significant GC-MS features. Annotation implicated various metabolic pathways. Creatinine was greater at weaning (P = 0.0224) and others have reported increased serum concentrations of creatinine in response to body weight loss. Hippurate and caprolactam, associated with protein catabolism, were also greater (P ≤ 0.0166) at weaning. Phospholipid features (P ≤ 0.0347) and inositol-related features (P ≤ 0.0236) were also greater at weaning. Inositol features may exert insulin-like effects. The energetic demands of lactation in gilts nursing their first litter indicated a greater difference exists between early and late lactation regardless of body condition loss.

Direct interactions between calcitonin-like receptor (CLR) and CGRP-receptor component protein (RCP) regulate CGRP receptor signaling

Calcitonin gene-related peptide (CGRP) is a neuropeptide with multiple neuroendocrine roles, including vasodilation, migraine, and pain. The receptor for CGRP is a G protein-coupled receptor (GPCR) that requires three proteins for function. CGRP binds to a heterodimer composed of the GPCR calcitonin-like receptor (CLR) and receptor activity-modifying protein (RAMP1), a single transmembrane protein required for pharmacological specificity and trafficking of the CLR/RAMP1 complex to the cell surface. In addition, the CLR/RAMP1 complex requires a third protein named CGRP-receptor component protein (RCP) for signaling. Previous studies have demonstrated that depletion of RCP from cells inhibits CLR signaling, and in vivo studies have demonstrated that expression of RCP correlates with CLR signaling and CGRP efficacy. It is not known whether RCP interacts directly with CLR to exert its effect. The current studies identified a direct interaction between RCP and an intracellular domain of CLR using yeast two-hybrid analysis and coimmunoprecipitation. When this interacting domain of CLR was expressed as a soluble fusion protein, it coimmunoprecipitated with RCP and inhibited signaling from endogenous CLR. Expression of this dominant-negative domain of CLR did not significantly inhibit trafficking of CLR to the cell surface, and thus RCP may not have a chaperone function for CLR. Instead, RCP may regulate CLR signaling in the cell membrane, and direct interaction between RCP and CLR is required for CLR activation. To date, RCP has been found to interact only with CLR and represents a novel neuroendocrine regulatory step in GPCR signaling.

Collection and preparation of rodent tissue samples for histopathological and molecular studies in carcinogenesis

Histology, as a mean of tissue visualization on a cellular level, is a fundamental tool in the study of cancer. The need for simultaneous delivery of quality histological material for pathological evaluation and subsequent genomic and proteomic studies, however, requires modification of traditional practices to include rapid isolation and stabilization of target tissue to preserve molecular integrity. Informative molecular analysis depends on the integrity of target molecules (RNA, DNA, and proteins) in the tissue during and after its collection. A reliable systematic approach to routine and genomic/proteomic sample collection and preparation presented is supported by detailed protocols.

Neuronal Control of Skin Function: The Skin as a Neuroimmunoendocrine Organ

This review focuses on the role of the peripheral nervous system in cutaneous biology and disease. During the last few years, a modern concept of an interactive network between cutaneous nerves, the neuroendocrine axis, and the immune system has been established. We learned that neurocutaneous interactions influence a variety of physiological and pathophysiological functions, including cell growth, immunity, inflammation, pruritus, and wound healing. This interaction is mediated by primary afferent as well as autonomic nerves, which release neuromediators and activate specific receptors on many target cells in the skin. A dense network of sensory nerves releases neuropeptides, thereby modulating inflammation, cell growth, and the immune responses in the skin. Neurotrophic factors, in addition to regulating nerve growth, participate in many properties of skin function. The skin expresses a variety of neurohormone receptors coupled to heterotrimeric G proteins that are tightly involved in skin homeostasis and inflammation. This neurohormone-receptor interaction is modulated by endopeptidases, which are able to terminate neuropeptide-induced inflammatory or immune responses. Neuronal proteinase-activated receptors or transient receptor potential ion channels are recently described receptors that may have been important in regulating neurogenic inflammation, pain, and pruritus. Together, a close multidirectional interaction between neuromediators, high-affinity receptors, and regulatory proteases is critically involved to maintain tissue integrity and regulate inflammatory responses in the skin. A deeper understanding of cutaneous neuroimmunoendocrinology may help to develop new strategies for the treatment of several skin diseases.

Overexpression and purification of human calcitonin gene-related peptide-receptor component protein in Escherichia coli

Calcitonin gene-related peptide (CGRP) is a neuropeptide secreted by the central and peripheral nervous system nerves that has important physiological functions such as vasodilation, cardiotonic actions, metabolic and pro-inflammatory effects. The CGRP receptor is unique among G-protein coupled receptors in that a functional CGRP receptor consists of at least three proteins: calcitonin like receptor (CLR), receptor activity modifying protein (RAMP1) and receptor component protein (RCP). RCP is a required factor in CGRP-mediated signal transduction and it couples the CGRP receptor to the signal transduction pathway. Here, we describe methods to overexpress and purify RCP for structure-function studies. Human RCP was cloned and overexpressed with a poly-histidine tag and as a maltose binding protein (MBP) fusion in Escherichia coli using commercially available expression vectors. While His tagged RCP is prone to aggregation, solubility is improved when RCP is expressed as a MBP fusion. Expression and purification procedures for these constructs are described. Results from these studies will facilitate structural analysis of human RCP, and allow further understanding of RCP function.

Pathophysiology and therapeutic possibilities of calcitonin gene-related peptide in hypertension

Calcitonin gene related peptide (CGRP), a 37 amino acid neuropeptide, is the most potent vasodilator known. Participation of CGRP in hypertension and related diseases, such as preeclampsia or vasospasm after subarachnoid haemorrage, is one of the most studied topics. In this review we summarize the published roles of CGRP in pathophysiology of hypertension in humans and in experimental models. We also discuss the effects of direct administration of CGRP in the treatment of hypertension and of anti-hypertensive drugs that enhance the release or response of endogenous calcitonin gene-related peptide: angiotensin converting enzyme inhibitors, selective antagonists for the angiotensin II receptor, beta-blockers, magnesium sulphate for preeclampsia and rutaecarpine, as well as the possibilities using CGRP in gene therapy for prevention of vasospasm after subarachnoid haemorrage.

Changes in renal haemodynamics induced by indomethacin in the rat involve cytochrome P450 arachidonic acid-dependent epoxygenases

A significant renal vasodilation was observed previously after an acute cyclo-oxygenase (COX) inhibition induced with indomethacin. Because this effect could be due to COX-dependent intrarenal metabolization of arachidonic acid through cytochrome P450 (CYP450) pathways, the aim of the present study was to investigate, in vivo, possible interactions between COX and CYP450 mono-oxygenases. Mean arterial pressure (MAP) and renal blood flow (RBF), using an electromagnetic flow transducer for RBF evaluation, were measured continuously in 71 anaesthetized euvolaemic rats. Appropriate solvents (vehicle), 3 mg/kg indomethacin, 17-octadecynoic acid (17-ODYA; 2 mmol/L), either miconazole (MI; 1.5 mmol/L) or N-methylsulphonyl-6-(2-propargyloxyphenyl)hexanamide (MS-PPOH; 5 mg/kg) and N'-hydroxyphenylformamidine (HET0016; 5 or 10 mg/kg) were administered to inhibit either COX, CYP450 mono-oxygenases, epoxygenases or hydroxylase, respectively. The CYP450 and COX inhibitors were also combined as follows: 17-ODYA/indomethacin, MI (or MS-PPOH)/indomethacin, HET0016/indomethacin and indomethacin/HET0016. Mean arterial pressure and RBF were not modified by vehicle, 17-ODYA or MI (or MS-PPOH). However, MAP decreased slightly (P < 0.05; paired t-test, 5 d.f.) and RBF increased transiently (P < 0.05; anova, 5 d.f.) after HET0016. In contrast, MAP decreased by 10 mmHg (P < 0.05) and RBF increased by 10% (P < 0.05) after indomethacin. This enhancement was prevented by 17-ODYA or MI (or MS-PPOH), but not by HET0016. Moreover, RBF increased step-wise to 21% in the indomethacin/HET0016 experiment (P < 0.05). Consequently, changes from baseline in renal vascular resistance differed among treatments, averaging -2 +/- 3 (vehicle), -13 +/- 3 (indomethacin; P < 0.05 vs vehicle), -4 +/- 3 (17-ODYA/indomethacin), -3 +/- 4 (MI or MS-PPOH/indomethacin), -15 +/- 3 (HET0016/indomethacin; P < 0.05) and -22 +/- 4% (indomethacin/HET0016; P < 0.05). In conclusion, these results demonstrate that the renal vasodilation induced by indomethacin can be prevented by prior inhibition of CYP450 mono-oxygenases and further suggest that the CYP450 epoxygenases pathway may prevail.

RAMP et récepteurs couplés aux protéines G

RAMPs (receptor activity-modifying proteins) were discovered in 1998 as accessory proteins needed to the functionnal activity of CGRP (calcitonin gene-related peptide) receptors. Three RAMPs generated by three different genes are known in human, rat and mice. The coding sequences of such genes are described, but as yet, regulation sequences are unknown. RAMPs interact with GPCR (G protein-coupled receptors) of class II. In the case of the calcitonin/CGRP peptide family, RAMPs determine the functionnal specificity of the receptor, glycosylate and translocate the receptor to the cell surface. CGRP receptors are observed in presence of the RAMP1/calcitonin receptor-like receptor (CRLR), but the association of RAMP2 or RAMP3 with CRLR generates an adrenomedullin receptor. The calcitonin receptor (CTR) is translocated alone to the cell surface, but interactions of RAMPs with CTR forms amylin receptors. If RAMPs can interact with glucagon, parathyroid hormone and VIP/PACAP (vasoactive intestinal peptide/pituitary adenylate cyclase activating polypeptide (VPACR1)) receptors, the functionnal specificity of these receptors remains unaltered. However, the complex VPACR1/RAMP2 enhances specifically the phosphoinoside signaling pathway.

Localization and modulation of calcitonin gene-related peptide-receptor component protein-immunoreactive cells in the rat central and peripheral nervous systems

Calcitonin gene-related peptide (CGRP) is widely distributed in the central and peripheral nervous system. Its highly diverse biological activities are mediated via the G protein-coupled receptor that uniquely requires two accessory proteins for optimal function. CGRP receptor component protein (RCP) is a coupling protein necessary for CGRP-receptor signaling. In this study, we established the anatomical distribution of RCP in the rat central and peripheral nervous system and its relationship to CGRP immunoreactivity. RCP-immunoreactive (IR) perikarya are widely and selectively distributed in the cerebral cortex, septal nuclei, hippocampus, various hypothalamic nuclei, amygdala, nucleus colliculus, periaqueductal gray, parabrachial nuclei, locus coeruleus, cochlear nuclei, dorsal raphe nuclei, the solitary tractus nucleus and gracile nucleus, cerebellar cortex, various brainstem motor nuclei, the spinal dorsal and ventral horns. A sub-population of neurons in the dorsal root ganglia (DRG) and trigeminal ganglia were strongly RCP-IR. Overall, the localization of RCP-IR closely matched with that of CGRP-IR. We also determined whether RCP in DRG and dorsal horn neurons can be modulated by CGRP receptor blockade and pain-related pathological stimuli. The intrathecal injection of the antagonist CGRP(8-37) markedly increased RCP expression in the lumbar DRG and spinal dorsal horn. Carrageenan-induced plantar inflammation produced a dramatic bilateral increase in RCP expression in the dorsal horn while a partial sciatic nerve ligation reduced RCP expression in the ipsilateral superficial dorsal horn. Our data suggest that the distribution of RCP immunoreactivity is closely matched with CGRP immunoreactivity in most of central and peripheral nervous systems. The co-localization of RCP and CGRP in motoneurons and primary sensory neurons suggests that CGRP has an autocrine or paracrine effect on these neurons. Moreover, our data also suggest that RCP expression in DRG and spinal cord can be modulated during CGRP receptor blockade, inflammation or neuropathic pain and this CGRP receptor-associated protein is dynamically regulated.

An Rpb4/Rpb7-like complex in yeast RNA polymerase III contains the orthologue of mammalian CGRP-RCP

The essential C17 subunit of yeast RNA polymerase (Pol) III interacts with Brf1, a component of TFIIIB, suggesting a role for C17 in the initiation step of transcription. The protein sequence of C17 (encoded by RPC17) is conserved from yeasts to humans. However, mammalian homologues of C17 (named CGRP-RCP) are known to be involved in a signal transduction pathway related to G protein-coupled receptors, not in transcription. In the present work, we first establish that human CGRP-RCP is the genuine orthologue of C17. CGRP-RCP was found to functionally replace C17 in Deltarpc17 yeast cells; the purified mutant Pol III contained CGRP-RCP and had a decreased specific activity but initiated faithfully. Furthermore, CGRP-RCP was identified by mass spectrometry in a highly purified human Pol III preparation. These results suggest that CGRP-RCP has a dual function in mammals. Next, we demonstrate by genetic and biochemical approaches that C17 forms with C25 (encoded by RPC25) a heterodimer akin to Rpb4/Rpb7 in Pol II. C17 and C25 were found to interact genetically in suppression screens and physically in coimmunopurification and two-hybrid experiments. Sequence analysis and molecular modeling indicated that the C17/C25 heterodimer likely adopts a structure similar to that of the archaeal RpoE/RpoF counterpart of the Rpb4/Rpb7 complex. These RNA polymerase subunits appear to have evolved to meet the distinct requirements of the multiple forms of RNA polymerases.

Calcitonin gene-related peptide-receptor component protein expression in the uterine cervix, lumbosacral spinal cord, and dorsal root ganglia

The neuropeptide calcitonin gene-related peptide (CGRP) may play a role in neurogenic inflammation, tissue remodeling of the uterine cervix, promoting vasodilation, parturition, and processing of sensory information in the spinal cord. CGRP-immunoreactive nerves of the cervix and spinal cord have been studied but cellular identification of the CGRP receptor has received little attention. CGRP-receptor component protein (CGRP-RCP) is a small protein associated with the CGRP receptor; thus, immunostaining for the CGRP-RCP can be used to identify sites of the CGRP receptor. We determined sites of CGRP-RCP immunoreactivity relative to the presence of CGRP-ir nerve fibers in the female rat uterine cervix, spinal cord, and dorsal root ganglia. CGRP-RCP immunoreactivity was expressed in the dorsal horn of the spinal cord, venules of the uterine cervix, and perikarya of sensory neurons in dorsal root ganglia. CGRP-immunoreactive fibers were adjacent to CGRP-RCP-immunoreactive vessels in the cervix and among CGRP-RCP-immunoreactive structures in the dorsal horn of the spinal cord. This suggests CGRP-RCP is associated with structures innervated by CGRP nerves and these interactions may be changed in tissues in response to an appropriate stimulus.

The role of the CGRP-receptor component protein (RCP) in adrenomedullin receptor signal transduction

G protein-coupled receptors are usually thought to act as monomer receptors that bind ligand and then interact with G proteins to initiate signal transduction. In this study we report an intracellular peripheral membrane protein named the calcitonin gene-related peptide (CGRP)-receptor component protein (RCP) required for signal transduction at the G protein-coupled receptor for adrenomedullin. Cell lines were made that expressed an antisense construct of the RCP cDNA, and in these cells diminished RCP expression correlated with loss of adrenomedullin signal transduction. In contrast, loss of RCP did not diminish receptor density or affinity, therefore RCP does not appear to act as a chaperone protein. Instead, RCP represents a novel class of protein required to couple the adrenomedullin receptor to the cellular signal transduction pathway. A candidate adrenomedullin receptor named the calcitonin receptor-like receptor (CRLR) has been described, which forms high affinity adrenomedullin receptors when co-expressed with the accessory protein receptor-activity modifying protein 2 (RAMP2). RCP co-immunoprecipitated with CRLR and RAMP2, indicating that a functional adrenomedullin receptor is composed of at least three proteins: the ligand binding protein (CRLR), an accessory protein (RAMP2), and a coupling protein for signal transduction (RCP).

Relaxation of myometrium by calcitonin gene-related peptide is independent of nitric oxide synthase activity in mouse uterus

Calcitonin gene-related peptide (CGRP) inhibits myometrial contractile activity. However, the responsiveness of the mouse myometrium to CGRP is dependent on the hormonal and gestational stage. The inhibitory effect of CGRP in the myometrium is prominent during gestation and declines at parturition. The present study was undertaken to examine if nitric oxide (NO) production by nitric oxide synthase (NOS) isoforms mediates the inhibitory action of CGRP on uterine contractions as has been suggested earlier. Transgenic mice deficient in either of the three major NOS isoforms: endothelial NOS (eNOS), inducible NOS (iNOS), and neuronal NOS (nNOS) were used. Isometric force measurements on myometrial strips obtained from NOS-deficient mice were carried out and the inhibitory capacity of CGRP was monitored. CGRP inhibited KCl-induced contractions of the myometrial strips obtained from eNOS(-/-), iNOS(-/-), and nNOS(-/-) mice with equal efficiency as in wild-type animals. Additionally, NOS protein expression in the mouse uterus during gestation and during the estrous cycle was examined by means of Western immunoblot analysis. No correlation between NOS expression and inhibitory activity of CGRP was evident. The results suggest that the inhibitory action of CGRP in the mouse uterus is independent of the activity of these NOS isoforms.

CGRP-RCP, a novel protein required for signal transduction at calcitonin gene-related peptide and adrenomedullin receptors

It is becoming clear that receptors that initiate signal transduction by interacting with G-proteins do not function as monomers, but often require accessory proteins for function. Some of these accessory proteins are chaperones, required for correct transport of the receptor to the cell surface, but the function of many accessory proteins remains unknown. We determined the role of an accessory protein for the receptor for calcitonin gene-related peptide (CGRP), a potent vasodilator neuropeptide. We have previously shown that this accessory protein, the CGRP-receptor component protein (RCP), is expressed in CGRP responsive tissues and that RCP protein expression correlates with the biological efficacy of CGRP in vivo. However, the function of RCP has remained elusive. In this study stable cell lines were made that express antisense RCP RNA, and CGRP- and adrenomedullin-mediated signal transduction were greatly reduced. However, the loss of RCP did not effect CGRP binding or receptor density, indicating that RCP did not behave as a chaperone but was instead coupling the CGRP receptor to downstream effectors. A candidate CGRP receptor named calcitonin receptor-like receptor (CRLR) has been identified, and in this study RCP co-immunoprecipitated with CRLR indicating that these two proteins interact directly. Since CGRP and adrenomedullin can both signal through CRLR, which has been previously shown to require a chaperone protein for function, we now propose that a functional CGRP or adrenomedullin receptor consists of at least three proteins: the receptor (CRLR), the chaperone protein (RAMP), and RCP that couples the receptor to the cellular signal transduction pathway.