Analysis of human neuropeptide FF gene expression

Modulatory role of neuropeptide FF system in macrophages

Neuropeptide FF (NPFF) is an octapeptide that regulates various cellular processes, especially pain perception. Recently, there has been a growing interest in understanding the modulation of NPFF in neuroendocrine inflammation. This review aims to provide a thorough overview of the regulation of NPFF in macrophage-mediated biological processes. We delve into the impact of NPFF on macrophage polarization, self-renewal modulation, and the promotion of mitophagy, facilitating the transition from thermogenic fat to fat-storing adipose tissue. Additionally, we explore the NPFF-dependent regulation of the inflammatory response mediated by macrophages, its impact on the differentiation of macrophages, and its capacity to induce alterations in the transcriptome of macrophages. We also address the potential of NPFF as a therapeutic molecule in the field of neuroendocrine inflammation. Overall, our work offers an understanding of the influence of NPFF on macrophage, facilitating the exploration of its pharmacological significance in future studies.

The distribution of Neuropeptide FF and Neuropeptide VF in central and peripheral tissues and their role in energy homeostasis control

Neuropeptide FF (NPFF) and Neuropeptide VF (NPVF) are part of the extended RFamide peptide family characterized by their common arginine (R) and amidated phenylalanine (F)-motif at the carboxyl terminus. Both peptides signal through their respective high affinity G-protein coupled receptors, NPFFR2 and NPFFR1, but also show binding affinity for the other receptor due to their sequence similarity. NPFF and NPVF are highly conserved throughout evolution and can be found across the whole animal kingdom. Both have been implicated in a variety of biological mechanisms, including nociception, locomotion, reproduction, and response to pain and stress. However, more recently a new major functional role in the control of energy homeostasis has been discovered. In this article we will summarise the current knowledge on the distribution of NPFF, NPVF, and their receptors in central and peripheral tissues, as well as how this relates to the regulation of food intake and energy balance, which will help to better understand their role in these processes and thus might help finding treatments for impaired energy homeostasis disorders, such as obesity or anorexia.

Evidence for the Direct Effect of the NPFF Peptide on the Expression of Feeding-Related Factors in Spotted Sea Bass (Lateolabrax maculatus)

Neuropeptide FF (NPFF) is a family member of RF-amide peptides, which are suggested to be involved in the control of vertebrate feeding behavior. However, little is known about the effect of the NPFF peptide on feeding-related processes in basal vertebrates. In this study, four full-length cDNAs, npff, npffr1, npffr2-1, and npffr2-2, were cloned from spotted sea bass and characterized. The conserved NPFF peptide is biologically active because it functionally interacts with different receptors expressed in cultured eukaryotic cells to enhance CRE promoter activity. Tissue distribution analysis showed that the highest npff mRNA expression occurred in the telencephalon, hypothalamus, medulla, gonad and muscle, but the npffrs mRNAs were mainly distributed within the central nervous system (CNS). In situ hybridization (ISH) detected npff-expressing cells in several specific regions ranging across the telencephalon and midbrain to the hypothalamus. Incubation of the spotted sea bass conserved NPFF peptide significantly increased the expression of orexin (orx) and neuropeptide Y (npy) mRNA and decreased the expression of leptin (lep), somatostatin (ss), and cholecystokinin (cck) mRNA in brain cells. Similarly, the conserved NPFF peptide also heightened the expression of gastrin (gas), ghrelin (ghrl), and motilin (mtl) mRNA and significantly reduced the expression of cck mRNA in the intestine and stomach. Taken together, these data suggest that the NPFF peptide may play a stimulating role in regulating feeding-related processes in spotted sea bass.

RF-amide neuropeptides and their receptors in Mammals: Pharmacological properties, drug development and main physiological functions

RF-amide neuropeptides, with their typical Arg-Phe-NH2 signature at their carboxyl C-termini, belong to a lineage of peptides that spans almost the entire life tree. Throughout evolution, RF-amide peptides and their receptors preserved fundamental roles in reproduction and feeding, both in Vertebrates and Invertebrates. The scope of this review is to summarize the current knowledge on the RF-amide systems in Mammals from historical aspects to therapeutic opportunities. Taking advantage of the most recent findings in the field, special focus will be given on molecular and pharmacological properties of RF-amide peptides and their receptors as well as on their implication in the control of different physiological functions including feeding, reproduction and pain. Recent progress on the development of drugs that target RF-amide receptors will also be addressed.

Modulatory role of neuropeptide FF system in nociception and opiate analgesia

The tetra-peptide FMRF-NH(2) is a cardioexcitatory peptide in the clam. Using the antibody against this peptide, FMRF-NH(2)-like immunoreactive material was detected in mammalian CNS. Subsequently, mammalian FMRF-NH(2) immunoreactive peptides were isolated from bovine brain and characterized to be FLFQPQRF-NH(2) (NPFF) and AGEGLSSPFWSLAAPQRF-NH(2) (NPAF). The genes encoding NPFF precursor proteins and NPFF receptors 1 and 2 are expressed in all vertebrate species examined to date and are highly conserved. Among many biological roles suggested for the NPFF system, the possible modulatory role of NPFF in nocicetion and opiate analgesia has been most widely investigated. Pharmacologically, NPFF-related peptides were found to exhibit analgesia and also potentiate the analgesic activity of opiates when administered intrathecally but attenuate the opiate induced analgesia when administered intracerebroventricularly. RF-NH(2) peptides including NPFF-related peptides were found to delay the rate of acid sensing ion channels (ASIC) desensitization resulting in enhancing acid gated currents, raising the possibility that NPFF also may have a pain modulatory role through ASIC. The genes for NPFF as well as NPFF-R2, preferred receptor for NPFF, are highly unevenly expressed in the rat CNS with the highest levels localized to the superficial layers of the dorsal spinal cord. These two genes are also present in the dorsal root ganglia (DRG), though at low levels in normal rats. NPFF and NPFF-R2 mRNAs were found to be coordinately up-regulated in spinal cord and DRG of rats with peripheral inflammation. In addition, NPFF-R2 immunoreactivity in the primary afferents was increased by peripheral inflammation. The findings from the early studies on the analgesic and morphine modulating activities suggested a role for NPFF in pain modulation and this possibility is further supported by the distribution of NPFF and its receptor and the regulation of the NPFF system in vivo.

Identification of transcriptional regulators of neuropeptide FF gene expression

Neuropeptide FF (NPFF) is an RF-amide peptide with pleiotropic functions in the mammalian central nervous system, including pain modulation, opiate interactions, cardiovascular regulation and neuroendocrine effects. To gain insights into the transcriptional mechanisms that regulate NPFF gene expression, we cloned and sequenced 9.8 and 1.5 kb of the mouse and rat NPFF 5'-flanking region, respectively. Regions with high sequence homology between mouse, rat and human were expected to have high probability to interact with regulatory proteins and were studied further. Electromobility shift assays revealed one region that may interact with the homeobox proteins Oct-1, PDX1, Pit-1 and MEIS and two consensus DRE sites that bind a nuclear protein, which was identified as the downstream regulatory element antagonistic modulator DREAM by supershift assays. The distribution of NPFF gene expression was examined in the mouse using in situ hybridization and RT-PCR. NPFF expression was also evident during mouse embryogenesis. A fixed transcription initiation site for the mouse NPFF gene was found. A novel splice variant with a retained intron of the NPFF gene was characterized. Chimeric luciferase reporter gene constructs for the mouse NPFF gene revealed a minimal promoter region and a region with transcriptional suppressor features. An NGF responsive area was found using mouse NPFF reporter gene constructs. We postulate that Oct-1, PDX1, Pit-1, MEIS and DREAM are likely transcriptional regulators of NPFF gene expression.

Interleukin-1beta induces beta-calcitonin gene-related peptide secretion in human type II alveolar epithelial cells

Calcitonin gene-related peptide (CGRP) is a 37-amino acid neuropeptide mainly present in sensory nerve fibers, which is present in almost all organs, but it is also found in cultured rat type II alveolar epithelial cells (AEII). Our data have previously shown that CGRP may play an important role in inflammation as an immunomodulator. Proinflammatory factor IL-1beta induces CGRP release from neuron-derived sources. However, whether IL-1beta can induce CGRP secretion from a nonneural source, AEII cells, is not known. In the present study, we demonstrated that human AEII A549 cells expressed beta-CGRP, and IL-1beta (0.001-50 ng/ml) directly increased CGRP secretion from these cells in a time- and concentration-dependent manner. The mRNA level of beta-CGRP was also elevated by IL-1beta (1 ng/ml). In addition, we found that IL-1beta-induced CGRP production was mediated through the PKC-p38 mitogen-activated protein (MAP) kinase-NF-kappaB signaling pathway. Furthermore, IL-1beta-induced chemokines MCP-1 and IL-8 were partially inhibited by exogenous hCGRP (0.1-10 nM) and potentiated by hCGRP8-37 (0.1-10 nM), a CGRP1-receptor antagonist. In addition, the CGRP-inhibited chemokine effect was partially reduced by Rp-cAMP, a cAMP-PK inhibitor. These results suggest that AEII-derived CGRP may act in an autocrine/paracrine mode and play an important inhibitory role in the local area in lung inflammatory diseases.

Pain- and morphine-associated transcriptional regulation of neuropeptide FF and the G-protein-coupled NPFF2 receptor gene

Neuropeptide FF (NPFF) is involved in pain modulation, especially plasticity during inflammatory and neuropathic pain, and opiate interactions. Its nociceptive functions may be mediated by the NPFF2 receptor. To elucidate the role of the NPFF system in plasticity associated with pathologic pain, we studied the changes of NPFF mRNA and NPFF2 receptor mRNA in rat models of acute colonic inflammation, inflammatory pain, and neuropathic pain. Furthermore, we studied the mRNA levels of both NPFF and NPFF2 receptor in morphine-tolerant rats and after acute morphine injections. We found an activation of spinal NPFF and NPFF2 receptor during early inflammatory pain. Supraspinally, we found an up-regulation of NPFF2 receptor mRNA during acute colonic inflammation and neuropathic pain. Acute, but not chronic, morphine activated the genes supraspinally. The results give further evidence for the involvement of the NPFF system in pain modulation and may provide new therapeutic opportunities for pathologic pain.

Fluoride causes reversible dispersal of Golgi cisternae and matrix in neuroendocrine cells

A role for heterotrimeric G proteins in the regulation of Golgi function and formation of secretory granules is generally accepted. We set out to study the effect of activation of heterotrimeric G proteins by aluminum fluoride on secretory granule formation in AtT-20 corticotropic tumor cells and in melanotrophs from the rat pituitary. In AtT-20 cells, treatment with aluminum fluoride or fluoride alone for 60 min induced complete dispersal of Golgi, ER-Golgi intermediate compartment and Golgi matrix markers, while betaCOP immunoreactiviy retained a juxtanuclear position and TGN38 was unaffected. Electron microscopy showed compression of Golgi cisternae followed by conversion of the Golgi stacks into clusters of tubular and vesicular elements. In the melanotroph of the rat pituitary a similar compression of Golgi cisternae was observed, followed by a progressive loss of cisternae from the stacks. As shown in other cells, brefeldin A induced redistribution of the Golgi matrix protein GM130 to punctate structures in the cytoplasm in AtT-20 cells, while mannosidase II immunoreactivity was completely dispersed. Fluoride induced a complete dispersal of mannosidase II and GM130 immunoreactivity. The effect of fluoride was fully reversible with reestablishment of normal mannosidase II and GM130 immunoreactivity within 2 h. After 1 h of recovery, showing varying stages of reassembly, the patterns of mannosidase II and GM130 immunoreactivity were identical in individual cells, indicating that Golgi matrix and cisternae reassemble with similar kinetics during recovery from fluoride treatment. Instead of a specific aluminum fluoride effect on secretory granule formation in the trans-Golgi network, we thus observe a unique form of Golgi dispersal induced by fluoride alone, possibly via its action as a phosphatase inhibitor.

Neuropeptide ff, but not prolactin-releasing peptide, mRNA is differentially regulated in the hypothalamic and medullary neurons after salt loading

Hypothalamic paraventricular and supraoptic nuclei are involved in the body fluid homeostasis. Especially vasopressin peptide and mRNA levels are regulated by hypo- and hyperosmolar stimuli. Other neuropeptides such as dynorphin, galanin and neuropeptide FF are coregulated with vasopressin. In this study neuropeptide FF and another RF-amide peptide, the prolactin-releasing peptide mRNA levels were studied by quantitative in situ hybridization after chronic salt loading, a laboratory model of chronic dehydration. The neuropeptide FF mRNA expressing cells virtually disappeared from the hypothalamic supraoptic and paraventricular nuclei after salt loading, suggesting that hyperosmolar stress downregulated the NPFF gene transcription. The neuropeptide FF mRNA signal levels were returned to control levels after the rehydration period of 7 days. No changes were observed in those medullary nuclei that express neuropeptide FF mRNA. No significant changes were observed in the hypothalamic or medullary prolactin-releasing peptide mRNA levels. Neuropeptide FF mRNA is drastically downregulated in the hypothalamic magnocellular neurons after salt loading. Other neuropeptides studied in this model are concomitantly coregulated with vasopressin: i.e. their peptide levels are downregulated and mRNA levels are upregulated which is in contrast to neuropeptide FF regulation. It can thus be concluded that neuropeptide FF is not regulated through the vasopressin regulatory system but via an independent pathway. The detailed mechanisms underlying the downregulation of neuropeptide FF mRNA in neurons remain to be clarified.

Neuropeptide FF receptor 2 (NPFF2) is localized to pain-processing regions in the primate spinal cord and the lower level of the medulla oblongata

Studies have suggested that NPFF-like peptides and their receptors play important roles in physiological and pathological conditions. Here, we show, using multiple expression modalities, that the type 2 NPFF receptor (hNPFF2) is expressed in regions of the primate spinal cord and brainstem mediating pain sensation. In situ hybridization using an NPFF2 riboprobe, and immunohistochemistry using a novel NPFF2 antibody, demonstrated strong NPFF2 expression in the superficial layer of the dorsal horn, and in the spinal trigeminal nucleus of the brainstem of the African green monkey (AGM). In addition, autoradiography using a radiolabeled NPFF analog ([125I]1DMe) revealed dense binding signal in the superficial layer of the dorsal horn in the spinal cord. The distribution pattern of hNPFF2 in the AGM spinal cord and the lower level of the brainstem are consistent with a hypothesized potential role for NPFF peptides in modulation of sensory input, opioid analgesia and morphine tolerance through spinal and supraspinal mechanisms.

Expression of neuropeptide FF, prolactin-releasing peptide, and the receptor UHR1/GPR10 genes during embryogenesis in the rat

Recently, several RF-amide peptides have been identified in mammals. These peptides have a similar C-terminal RF-motif and share some G-protein coupled receptors. Neuropeptide FF (NPFF) and prolactin-releasing peptide (PrRP) are expressed in the same brain areas in the adult rat and act both in prolactin release and cardiovascular regulation. Here, we characterized the embryonal expression from embryonal day 14 to postnatal day 0 of both peptide mRNAs and the mRNA distribution of UHR1/GPR10-like receptor by using in situ hybridization (ISH) and quantitative reverse transcriptase-polymerase chain reaction. NPFF mRNA was found in the spinal cord, caudal solitary tract nucleus, and surprisingly, in the medullary reticular formation. The only peripheral organs displaying NPFF mRNA expression were the lungs and the spleen. PrRP gene expression was seen in the caudal solitary tract nucleus, medullary reticular formation, pontine isthmus and liver, kidney, and testis. The receptor UHR1/GPR10 gene was expressed consistently in the medullary reticular formation and the adrenal gland but also transiently in several locations. All three genes showed weak but even ISH signal in the pituitary. These findings suggest different roles for the peptides during development and indicate that UHR1/GPR10-like receptor could also bind other ligands in addition to PrRP.