title: NPY revealed as a critical modulator of osteoblast function in vitro: new insights into the role of Y1 and Y2 receptors.
abstract: Neuropeptide Y (NPY) has recently emerged as a potential regulator of bone homeostasis. However, the relevance of NPY's role in osteoblast activity and the biological functions involving NPY receptors in bone homeostasis remain to be clarified. Here we report that chronically elevated NPY levels leaded to a modulation of the level of Y2 receptor expression marked with a transient down and upregulation according to the stage of osteoblast differentiation. We also show that NPY is a negative regulator of Y1 receptor expression. The pharmacological activation of Y2 receptor with its agonist resulted in similar effect. Functional analysis also revealed the osteogenic potential of NPY with osteoblast phenotype markers being significantly enhanced in osteoprogenitor cells stimulated by NPY, probably due to the down-regulation of Y1 receptor. In contrasts, these cells exhibit a reduction in calcium deposition in extracellular matrix most likely mediated via Y2 receptor signalling. Furthermore, we show that NPY modulates receptor activator of nuclear factor kB (NF-kB) (RANK) ligand and osteoprotegerin, two key factors regulating bone remodelling. Specifically, NPY inhibits the transcriptional activity of RANKL promoter in osteoprogenitor cells and enhances OPG expression in osteoblasts at early stages of differentiation. However, NPY effect on OPG seemed to be unrelated to Y2 receptor activation. Taken together the present data supported the contribution of NPY pathway in bone homeostasis via a direct action on osteoblasts cells.
authors.affiliation: Instituto de Engenharia Biomédica (INEB), Divisão de Biomateriais, NewTherapies Group, Universidade do Porto, Rua do Campo Alegre, 823, 4150-180 Porto, Portugal.
authors.forename: Liliana
authors.initials: L
authors.lastname: Teixeira
authors.forename: Daniela M
authors.initials: DM
authors.lastname: Sousa
authors.forename: Ana Filipa
authors.initials: AF
authors.lastname: Nunes
authors.forename: Mónica M
authors.initials: MM
authors.lastname: Sousa
authors.forename: Herbert
authors.initials: H
authors.lastname: Herzog
authors.forename: Meriem
authors.initials: M
authors.lastname: Lamghari
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000201:enzymology; D002454:Cell Differentiation; D002460:Cell Line; D005786:Gene Expression Regulation; D051379:Mice; D009478:Neuropeptide Y / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D053244:Osteoprotegerin / Q000235:genetics / Q000378:metabolism; D053245:RANK Ligand / Q000037:antagonists & inhibitors; D017476:Receptors, Neuropeptide Y / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017154:Stromal Cells / Q000166:cytology / Q000201:enzymology
chemical_list: D009478:Neuropeptide Y; D053244:Osteoprotegerin; D053245:RANK Ligand; D017476:Receptors, Neuropeptide Y; D000469:Alkaline Phosphatase