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Ghrelin and unacylated ghrelin stimulate human osteoblast growth via mitogen-activated protein kinase (MAPK)/phosphoinositide 3-kinase (PI3K) pathways in the absence of GHS-R1a.
J Endocrinol. 2006 Jan; 188(1):37-47.JE

Abstract

Recent studies demonstrate widespread expression of ghrelin among tissues and have uncovered its pleiotropic nature. We have examined gene expression of ghrelin and its two receptor splice variants, growth hormone secretagogue receptors (GHS-R) 1a and 1b, in human bone biopsies and in the human pre-osteoblastic SV-HFO cell line during differentiation. Additionally, we examined proliferative effects of ghrelin and unacylated ghrelin (UAG) in differentiating and non-differentiating cells. We detected GHS-R1b mRNA in human bone and osteoblasts but not ghrelin's cognate receptor GHS-R1a, using two different real-time PCR assays and both total RNA and mRNA. In osteoblasts GHS-R1b mRNA expression remained low during the first 14 days of culture, but increased 300% in differentiating cells by day 21. Both human bone biopsies and osteoblasts expressed ghrelin mRNA, and osteoblasts were found to secrete ghrelin. Overall, ghrelin gene expression was greater in differentiating than non-differentiating osteoblasts, but was not increased during culture in either group. Ghrelin and UAG induced thymidine uptake dose-dependently, peaking at 1 and 10 nM respectively, at day 6 of culture in both non-differentiating and differentiating osteoblasts. The proliferative response to ghrelin and UAG declined with culture time and state of differentiation. The proliferative effects of ghrelin and UAG were suppressed by inhibitors of extracellular-signal-regulated kinase (ERK) and phosphoinositide-3 kinase, and both peptides rapidly induced ERK phosphorylation. Overall, our data suggest new roles for ghrelin and UAG in modulating human osteoblast proliferation via a novel signal transduction pathway.

Authors+Show Affiliations

Department of Internal Medicine, Erasmus Medical Centre, Dr Molewaterplein 50, 3015 GD Rotterdam, The Netherlands.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16394173

Citation

Delhanty, P J D., et al. "Ghrelin and Unacylated Ghrelin Stimulate Human Osteoblast Growth Via Mitogen-activated Protein Kinase (MAPK)/phosphoinositide 3-kinase (PI3K) Pathways in the Absence of GHS-R1a." The Journal of Endocrinology, vol. 188, no. 1, 2006, pp. 37-47.
Delhanty PJ, van der Eerden BC, van der Velde M, et al. Ghrelin and unacylated ghrelin stimulate human osteoblast growth via mitogen-activated protein kinase (MAPK)/phosphoinositide 3-kinase (PI3K) pathways in the absence of GHS-R1a. J Endocrinol. 2006;188(1):37-47.
Delhanty, P. J., van der Eerden, B. C., van der Velde, M., Gauna, C., Pols, H. A., Jahr, H., Chiba, H., van der Lely, A. J., & van Leeuwen, J. P. (2006). Ghrelin and unacylated ghrelin stimulate human osteoblast growth via mitogen-activated protein kinase (MAPK)/phosphoinositide 3-kinase (PI3K) pathways in the absence of GHS-R1a. The Journal of Endocrinology, 188(1), 37-47.
Delhanty PJ, et al. Ghrelin and Unacylated Ghrelin Stimulate Human Osteoblast Growth Via Mitogen-activated Protein Kinase (MAPK)/phosphoinositide 3-kinase (PI3K) Pathways in the Absence of GHS-R1a. J Endocrinol. 2006;188(1):37-47. PubMed PMID: 16394173.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Ghrelin and unacylated ghrelin stimulate human osteoblast growth via mitogen-activated protein kinase (MAPK)/phosphoinositide 3-kinase (PI3K) pathways in the absence of GHS-R1a. AU - Delhanty,P J D, AU - van der Eerden,B C J, AU - van der Velde,M, AU - Gauna,C, AU - Pols,H A P, AU - Jahr,H, AU - Chiba,H, AU - van der Lely,A J, AU - van Leeuwen,J P T M, PY - 2006/1/6/pubmed PY - 2006/3/15/medline PY - 2006/1/6/entrez SP - 37 EP - 47 JF - The Journal of endocrinology JO - J Endocrinol VL - 188 IS - 1 N2 - Recent studies demonstrate widespread expression of ghrelin among tissues and have uncovered its pleiotropic nature. We have examined gene expression of ghrelin and its two receptor splice variants, growth hormone secretagogue receptors (GHS-R) 1a and 1b, in human bone biopsies and in the human pre-osteoblastic SV-HFO cell line during differentiation. Additionally, we examined proliferative effects of ghrelin and unacylated ghrelin (UAG) in differentiating and non-differentiating cells. We detected GHS-R1b mRNA in human bone and osteoblasts but not ghrelin's cognate receptor GHS-R1a, using two different real-time PCR assays and both total RNA and mRNA. In osteoblasts GHS-R1b mRNA expression remained low during the first 14 days of culture, but increased 300% in differentiating cells by day 21. Both human bone biopsies and osteoblasts expressed ghrelin mRNA, and osteoblasts were found to secrete ghrelin. Overall, ghrelin gene expression was greater in differentiating than non-differentiating osteoblasts, but was not increased during culture in either group. Ghrelin and UAG induced thymidine uptake dose-dependently, peaking at 1 and 10 nM respectively, at day 6 of culture in both non-differentiating and differentiating osteoblasts. The proliferative response to ghrelin and UAG declined with culture time and state of differentiation. The proliferative effects of ghrelin and UAG were suppressed by inhibitors of extracellular-signal-regulated kinase (ERK) and phosphoinositide-3 kinase, and both peptides rapidly induced ERK phosphorylation. Overall, our data suggest new roles for ghrelin and UAG in modulating human osteoblast proliferation via a novel signal transduction pathway. SN - 0022-0795 UR - https://www.unboundmedicine.com/medline/citation/16394173/Ghrelin_and_unacylated_ghrelin_stimulate_human_osteoblast_growth_via_mitogen_activated_protein_kinase__MAPK_/phosphoinositide_3_kinase__PI3K__pathways_in_the_absence_of_GHS_R1a_ L2 - https://joe.bioscientifica.com/doi/10.1677/joe.1.06404 DB - PRIME DP - Unbound Medicine ER -