Naslov
Osteocytes can Modulate Osteoblastic Activity via NPY Signaling

Autori
Igwe, JC ; San Miguel, SM ; Paic, Frane ; Li, HT ; Kalajzic, Ivo

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Journal of Bone and Mineral Research / - , 2009, 144-144

Skup
30th Annual Meeting of American Society for Bone and Mineral Research

Mjesto i datum
Montréal, Kanada, 12.09.2008. - 16.09.2008

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
osteocytes; gene expression analysis

Sažetak
Osteocytes are characterized by long neuronal-like cell processes, which may actively participate in the release of molecules that modulate the function of other surrounding bone cells. The location of osteocytes and their inherent inability to divide represents a major obstacle for studying osteocyte biology. We have previously shown that dentin matrix protein 1 (DMP1) is preferentially expressed in cells embedded within the bone matrix (osteocytes) or in partially embedded cells (preosteocytes). This was the key observation leading to generation of an osteocyte-specific GFP transgenic mouse (DMP-1GFP). To investigate the expression of regulatory molecules produced by osteocytes, we utilized dual transgenic mouse in which osteocytes are idenitified by DMP-1-GFP(green), while osteoblasts are labeled by Col2.3GFP(blue). An in vivo gene expression analysis was generated by fluorescence activated sorting of neonatal calvarial cells derived from these dual transgenic mice. It was an intriguing observation that the osteocytes expressed neuropeptide Y (NPY), a gene whose role in the central control of bone mass has been well established. We confirmed this result by immunohistochemical detection of NPY in osteocytes. Furthermore, NPY mRNA expression was observed in DMP1GFP+ cells (osteocytes) and Col2.3GFP+ cells (osteoblasts/osteocytes) derived from fluorescent sorting of primary calvarial osteogenic cultures. RNA analysis of the isolated osteocytes demonstrated increased levels of NPY mRNA transcripts in both DMP1GFP+ and Col2.3GFP+ populations. In addition, we investigate the expression of NPY receptors in cultured osteoblast lineage cells. qPCR analysis of cultured calvarial osteoblasts demonstrated that mRNA of the NPY receptor subtypes Y1 and Y6 increased significantly between day 7 and day 14 of culture. We further investigated the effect of NPY at this stage of culture by in vitro treatment with NPY protein. Northern blot analysis of RNA from 1 nM NPY treated calvarial osteoblasts, showed a significant reduction of osteocalcin and bone sialoprotein expression at day 14 of culture. These results demonstrate the effect of NPY on mature osteoblasts, suggesting a novel, local regulation of osteoblast function by osteocytes via NPY signaling.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti

POVEZANOST RADA