Neuropeptide AF (human)

Neuropeptide AF and FF modulation of adipocyte metabolism. Primary insights from functional genomics and effects on beta-adrenergic responsiveness.[Pubmed:12149260]

J Biol Chem. 2002 Oct 18;277(42):39169-78.

The presence of a neuropeptide AF and FF receptor (NPFF-R2) mRNA in human adipose tissue (Elshourbagy, N. A., Ames, R. S., Fitzgerald, L. R., Foley, J. J., Chambers, J. K., Szekeres, P. G., Evans, N. A., Schmidt, D. B., Buckley, P. T., Dytko, G. M., Murdock, P. R., Tan, K. B., Shabon, U., Nuthulaganti, P., Wang, D. Y., Wilson, S., Bergsma, D. J., and Sarau, H. M. (2000) J. Biol. Chem. 275, 25965-25971) suggested these peptides, principally recognized for their pain modulating effects, may also impact on adipocyte metabolism, an aspect that has not been explored previously. Our aim was thus to obtain more insights into the actions of these peptides on adipocytes, an approach initially undertaken with a functional genomic assay. First we showed that 3T3-L1 adipocytes express both NPFF-R1 and NPFF-R2 transcripts, and that NPAF binds adipocyte membranes with a nanomolar affinity as assessed by surface plasmon resonance technology. Then, and following a 24-h treatment with NPFF or NPAF (1 microm), we have measured using real-time quantitative reverse transcriptase-PCR the mRNA steady state levels of already well characterized genes involved in key pathways of adipose metabolism. Among the 45 genes tested, few were modulated by NPFF ( approximately 10%) and a larger number by NPAF ( approximately 27%). Interestingly, NPAF increased the mRNA levels of beta2- and beta3-adrenergic receptors (AR), and to a lesser extent those of beta1-ARs. These variations in catecholamine receptor mRNAs correlated with a clear induction in the density of beta2- and beta3-AR proteins, and in the potency of beta-AR subtype-selective agonists to stimulate adenylyl cyclase activity. Altogether, these data show that NPFF-R1 and NPFF-R2 are functionally present in adipocytes and suggest that besides their well described pain modulation effects, NPAF and to a lesser extent NPFF, may have a global impact on body energy storage and utilization.

Receptor for the pain modulatory neuropeptides FF and AF is an orphan G protein-coupled receptor.[Pubmed:10851242]

J Biol Chem. 2000 Aug 25;275(34):25965-71.

Opiate tolerance and dependence are major clinical and social problems. The anti-opiate neuropeptides FF and AF (NPFF and NPAF) have been implicated in pain modulation as well as in opioid tolerance and may play a critical role in this process, although their mechanism of action has remained unknown. Here we describe a cDNA encoding a novel neuropeptide Y-like human orphan G protein-coupled receptor (GPCR), referred to as HLWAR77 for which NPAF and NPFF have high affinity. Cells transiently or stably expressing HLWAR77 bind and respond in a concentration-dependent manner to NPAF and NPFF and are also weakly activated by FMRF-amide (Phe-Met-Arg-Phe-amide) and a variety of related peptides. The high affinity and potency of human NPFF and human NPAF for HLWAR77 strongly suggest that these are the cognate ligands for this receptor. Expression of HLWAR77 was demonstrated in brain regions associated with opiate activity, consistent with the pain-modulating activity of these peptides, whereas the expression in adipose tissue suggests other physiological and pathophysiological activities for FMRF-amide neuropeptides. The discovery that the anti-opiate neuropeptides are the endogenous ligands for HLWAR77 will aid in defining the physiological role(s) of these ligands and facilitate the identification of receptor agonists and antagonists.

Gene for pain modulatory neuropeptide NPFF: induction in spinal cord by noxious stimuli.[Pubmed:10220558]

Mol Pharmacol. 1999 May;55(5):804-11.

Neuropeptides FF (NPFF), AF (NPAF), and SF (NPSF) are homologous amidated peptides that were originally identified on the basis of similarity to the molluscan neuropeptide FMRF-amide. They have been hypothesized to have wide-ranging functions in the mammalian central nervous system, including pain modulation, opiate function, cardiovascular regulation, and neuroendocrine function. We have cloned the NPFF gene from human, bovine, rat, and mouse, and show that the precursor mRNA encodes for all three of the biochemically identified peptides (NPFF, NPAF, and NPSF). We demonstrate that NPFF precursor mRNA expression by Northern analysis and map sites of expression by in situ hybridization. We confirm the validity of the in situ hybridization by showing that its distribution in the brain and spinal cord matches the distribution of NPFF and NPSF immunoreactivity. We go on to show that the mRNA levels (as measured by in situ hybridization) in the spinal cord can be up-regulated by a model for inflammatory pain (carrageenan injection), but not by a model for neuropathic pain (lumbar nerve ligation). Our results confirm the evolutionary conservation of NPFF, NPAF, and NPSF neuropeptide expression in mammalian brain. They also provide a context for the interpretation of the pain-sensitizing effects of injections of these peptides that have been previously reported. Our results support a model for the role of these peptides in pain regulation at the level of the spinal cord.