Mode of growth hormone action in osteoblasts

Douglas J. DiGirolamo, Aditi Mukherjee, Keertik Fulzele, Yujun Gan, Xuemei Cao, Stuart J. Frank, Thomas L. Clemens

Research output: Contribution to journalArticle

71 Citations (Scopus)

Abstract

Growth hormone (GH) affects bone size and mass in part through stimulating insulin-like growth factor type 1 (IGF-1) production in liver and bone. Whether GH acts independent of IGF-1 in bone remains unclear. To define the mode of GH action in bone, we have used a Cre/loxP system in which the type 1 IGF-1 receptor (Igf1r) has been disrupted specifically in osteoblasts in vitro and in vivo. Calvarial osteoblasts from mice homozygous for the floxed IGF-1R allele (IGF-1Rflox/flox) were infected with adenoviral vectors expressing Cre. Disruption of IGF-1R mRNA(>90%) was accompanied by near elimination of IGF-1R protein but retention of GHR protein. GH-induced STAT5 activation was consistently greater in osteoblasts with an intact IGF-1R. Osteoblasts lacking IGF-1R retained GH-induced ERK and Akt phosphorylation and GH-stimulated IGF-1 and IGFBP-3 mRNA expression. GH-induced osteoblast proliferation was abolished by Cre-mediated disruption of the IGF-1R or co-incubation of cells with an IGF-1-neutralizing antibody. By contrast, GH inhibited apoptosis in osteoblasts lacking the IGF-1R. To examine the effects of GH on osteoblasts in vivo, mice wild type for the IGF-1R treated with GH subcutaneously for 7 days showed a doubling in the number of osteoblasts lining trabecular bone, whereas osteoblast numbers in similarly treated mice lacking the IGF-1R in osteoblasts were not significantly affected. These results indicate that although direct IGF-1R-independent actions of GH on osteoblast apoptosis can be demonstrated in vitro, IGF-1R is required for anabolic effects of GH in osteoblasts in vivo.

Original languageEnglish (US)
Pages (from-to)31666-31674
Number of pages9
JournalJournal of Biological Chemistry
Volume282
Issue number43
DOIs
StatePublished - Oct 26 2007
Externally publishedYes

Fingerprint

Osteoblasts
Growth Hormone
Somatomedins
Bone
Bone and Bones
Apoptosis
Anabolic Agents
IGF Type 1 Receptor
Messenger RNA
Insulin-Like Growth Factor Binding Protein 3
Phosphorylation
Neutralizing Antibodies
Linings
Liver
Proteins
Chemical activation
Alleles
Cells

ASJC Scopus subject areas

  • Biochemistry

Cite this

DiGirolamo, D. J., Mukherjee, A., Fulzele, K., Gan, Y., Cao, X., Frank, S. J., & Clemens, T. L. (2007). Mode of growth hormone action in osteoblasts. Journal of Biological Chemistry, 282(43), 31666-31674. https://doi.org/10.1074/jbc.M705219200

Mode of growth hormone action in osteoblasts. / DiGirolamo, Douglas J.; Mukherjee, Aditi; Fulzele, Keertik; Gan, Yujun; Cao, Xuemei; Frank, Stuart J.; Clemens, Thomas L.

In: Journal of Biological Chemistry, Vol. 282, No. 43, 26.10.2007, p. 31666-31674.

Research output: Contribution to journalArticle

DiGirolamo, DJ, Mukherjee, A, Fulzele, K, Gan, Y, Cao, X, Frank, SJ & Clemens, TL 2007, 'Mode of growth hormone action in osteoblasts', Journal of Biological Chemistry, vol. 282, no. 43, pp. 31666-31674. https://doi.org/10.1074/jbc.M705219200
DiGirolamo DJ, Mukherjee A, Fulzele K, Gan Y, Cao X, Frank SJ et al. Mode of growth hormone action in osteoblasts. Journal of Biological Chemistry. 2007 Oct 26;282(43):31666-31674. https://doi.org/10.1074/jbc.M705219200
DiGirolamo, Douglas J. ; Mukherjee, Aditi ; Fulzele, Keertik ; Gan, Yujun ; Cao, Xuemei ; Frank, Stuart J. ; Clemens, Thomas L. / Mode of growth hormone action in osteoblasts. In: Journal of Biological Chemistry. 2007 ; Vol. 282, No. 43. pp. 31666-31674.
@article{b85c0acc468c441dad3b593847e9fd2c,
title = "Mode of growth hormone action in osteoblasts",
abstract = "Growth hormone (GH) affects bone size and mass in part through stimulating insulin-like growth factor type 1 (IGF-1) production in liver and bone. Whether GH acts independent of IGF-1 in bone remains unclear. To define the mode of GH action in bone, we have used a Cre/loxP system in which the type 1 IGF-1 receptor (Igf1r) has been disrupted specifically in osteoblasts in vitro and in vivo. Calvarial osteoblasts from mice homozygous for the floxed IGF-1R allele (IGF-1Rflox/flox) were infected with adenoviral vectors expressing Cre. Disruption of IGF-1R mRNA(>90{\%}) was accompanied by near elimination of IGF-1R protein but retention of GHR protein. GH-induced STAT5 activation was consistently greater in osteoblasts with an intact IGF-1R. Osteoblasts lacking IGF-1R retained GH-induced ERK and Akt phosphorylation and GH-stimulated IGF-1 and IGFBP-3 mRNA expression. GH-induced osteoblast proliferation was abolished by Cre-mediated disruption of the IGF-1R or co-incubation of cells with an IGF-1-neutralizing antibody. By contrast, GH inhibited apoptosis in osteoblasts lacking the IGF-1R. To examine the effects of GH on osteoblasts in vivo, mice wild type for the IGF-1R treated with GH subcutaneously for 7 days showed a doubling in the number of osteoblasts lining trabecular bone, whereas osteoblast numbers in similarly treated mice lacking the IGF-1R in osteoblasts were not significantly affected. These results indicate that although direct IGF-1R-independent actions of GH on osteoblast apoptosis can be demonstrated in vitro, IGF-1R is required for anabolic effects of GH in osteoblasts in vivo.",
author = "DiGirolamo, {Douglas J.} and Aditi Mukherjee and Keertik Fulzele and Yujun Gan and Xuemei Cao and Frank, {Stuart J.} and Clemens, {Thomas L.}",
year = "2007",
month = "10",
day = "26",
doi = "10.1074/jbc.M705219200",
language = "English (US)",
volume = "282",
pages = "31666--31674",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "43",

}

TY - JOUR

T1 - Mode of growth hormone action in osteoblasts

AU - DiGirolamo, Douglas J.

AU - Mukherjee, Aditi

AU - Fulzele, Keertik

AU - Gan, Yujun

AU - Cao, Xuemei

AU - Frank, Stuart J.

AU - Clemens, Thomas L.

PY - 2007/10/26

Y1 - 2007/10/26

N2 - Growth hormone (GH) affects bone size and mass in part through stimulating insulin-like growth factor type 1 (IGF-1) production in liver and bone. Whether GH acts independent of IGF-1 in bone remains unclear. To define the mode of GH action in bone, we have used a Cre/loxP system in which the type 1 IGF-1 receptor (Igf1r) has been disrupted specifically in osteoblasts in vitro and in vivo. Calvarial osteoblasts from mice homozygous for the floxed IGF-1R allele (IGF-1Rflox/flox) were infected with adenoviral vectors expressing Cre. Disruption of IGF-1R mRNA(>90%) was accompanied by near elimination of IGF-1R protein but retention of GHR protein. GH-induced STAT5 activation was consistently greater in osteoblasts with an intact IGF-1R. Osteoblasts lacking IGF-1R retained GH-induced ERK and Akt phosphorylation and GH-stimulated IGF-1 and IGFBP-3 mRNA expression. GH-induced osteoblast proliferation was abolished by Cre-mediated disruption of the IGF-1R or co-incubation of cells with an IGF-1-neutralizing antibody. By contrast, GH inhibited apoptosis in osteoblasts lacking the IGF-1R. To examine the effects of GH on osteoblasts in vivo, mice wild type for the IGF-1R treated with GH subcutaneously for 7 days showed a doubling in the number of osteoblasts lining trabecular bone, whereas osteoblast numbers in similarly treated mice lacking the IGF-1R in osteoblasts were not significantly affected. These results indicate that although direct IGF-1R-independent actions of GH on osteoblast apoptosis can be demonstrated in vitro, IGF-1R is required for anabolic effects of GH in osteoblasts in vivo.

AB - Growth hormone (GH) affects bone size and mass in part through stimulating insulin-like growth factor type 1 (IGF-1) production in liver and bone. Whether GH acts independent of IGF-1 in bone remains unclear. To define the mode of GH action in bone, we have used a Cre/loxP system in which the type 1 IGF-1 receptor (Igf1r) has been disrupted specifically in osteoblasts in vitro and in vivo. Calvarial osteoblasts from mice homozygous for the floxed IGF-1R allele (IGF-1Rflox/flox) were infected with adenoviral vectors expressing Cre. Disruption of IGF-1R mRNA(>90%) was accompanied by near elimination of IGF-1R protein but retention of GHR protein. GH-induced STAT5 activation was consistently greater in osteoblasts with an intact IGF-1R. Osteoblasts lacking IGF-1R retained GH-induced ERK and Akt phosphorylation and GH-stimulated IGF-1 and IGFBP-3 mRNA expression. GH-induced osteoblast proliferation was abolished by Cre-mediated disruption of the IGF-1R or co-incubation of cells with an IGF-1-neutralizing antibody. By contrast, GH inhibited apoptosis in osteoblasts lacking the IGF-1R. To examine the effects of GH on osteoblasts in vivo, mice wild type for the IGF-1R treated with GH subcutaneously for 7 days showed a doubling in the number of osteoblasts lining trabecular bone, whereas osteoblast numbers in similarly treated mice lacking the IGF-1R in osteoblasts were not significantly affected. These results indicate that although direct IGF-1R-independent actions of GH on osteoblast apoptosis can be demonstrated in vitro, IGF-1R is required for anabolic effects of GH in osteoblasts in vivo.

UR - http://www.scopus.com/inward/record.url?scp=35748958108&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=35748958108&partnerID=8YFLogxK

U2 - 10.1074/jbc.M705219200

DO - 10.1074/jbc.M705219200

M3 - Article

VL - 282

SP - 31666

EP - 31674

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 43

ER -