Investigations conducted in our laboratory revealed that skeletal cells synthesize growth factors that modify the replication, differentiation and function of the osteoblast. Locally produced factors are regulated by changes in synthesis, receptor binding and binding proteins. Osteoblasts synthesize bone morphogenetic proteins (BMPs). However, information about the regulation of BMPs in bone is limited. We found that BMPs stimulate osteoblasts to produce noggin and gremlin, proteins that bind and impair the actions of BMPs in vitro, although activities of noggin and gremlin independent of BMP binding have not been excluded. The objective of this project is to understand the function of noggin and gremlin in bone in vivo and to study their mechanisms of action in vitro. We created transgenic mice that overexpress noggin under the control of the osteocalcin promoter. These mice develop osteopenia and fractures, despite a normal number of osteoblasts, indicating that either BMPs are required for the maintenance of bone integrity, or that noggin has direct actions on bone cell function. In the course of the proposed studies, we plan to investigate the roles of noggin and gremlin in vivo and in vitro.
Our Specific Aims are: (1) to determine the function of noggin and gremlin in vivo by transgenic overexpression of the two glycoproteins under the control of the osteocalcin promoter so that expression occurs in osteoblasts and in the bone microenvironment. The skeletal phenotype of transgenic mice will be compared to that of wild-type mice and determined by histomorphometry, contact radiography, densitometry and micro-CT scanning; (2) to determine the function of noggin and gremlin in vivo by targeted gene inactivation in osteoblasts, achieved by intercrosses between transgenic mice expressing the Cre recombinase under the control of the osteocalcin promoter and mice in which the noggin and gremlin gene are flanked by loxP sequences. The skeletal phenotype will be assessed with histomorphometric and radiological techniques; and (3) to determine the mechanism of action of noggin and gremlin in vitro, utilizing retroviral vectors to overexpress noggin and gremlin in stromal and osteoblastic cell lines. The impact of noggin and gremlin on the differentiation and function of cells of the osteoblastic lineage will be determined and also compared to that of noggin and gremlin mutants that fail to bind BMPs. These investigations should clarify the role of noggin and gremlin, as well as the role of BMPs, in bone cell function.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR021707-25
Application #
6881248
Study Section
Orthopedics and Musculoskeletal Study Section (ORTH)
Program Officer
Sharrock, William J
Project Start
1981-04-01
Project End
2007-03-31
Budget Start
2005-04-01
Budget End
2006-03-31
Support Year
25
Fiscal Year
2005
Total Cost
$229,866
Indirect Cost
Name
St. Francis Hospital and Medical Center
Department
Type
DUNS #
077314656
City
Hartford
State
CT
Country
United States
Zip Code
06105
Zanotti, Stefano; Kalajzic, Ivo; Aguila, Hector Leonardo et al. (2014) Sex and genetic factors determine osteoblastic differentiation potential of murine bone marrow stromal cells. PLoS One 9:e86757
He, Qing; Yang, Xuehui; Gong, Yan et al. (2014) Deficiency of Sef is associated with increased postnatal cortical bone mass by regulating Runx2 activity. J Bone Miner Res 29:1217-31
Canalis, Ernesto; Zanotti, Stefano; Smerdel-Ramoya, Anna (2014) Connective tissue growth factor is a target of notch signaling in cells of the osteoblastic lineage. Bone 64:273-80
Yang, Jibing; Velikoff, Miranda; Canalis, Ernesto et al. (2014) Activated alveolar epithelial cells initiate fibrosis through autocrine and paracrine secretion of connective tissue growth factor. Am J Physiol Lung Cell Mol Physiol 306:L786-96
Canalis, Ernesto (2013) Wnt signalling in osteoporosis: mechanisms and novel therapeutic approaches. Nat Rev Endocrinol 9:575-83
Zanotti, Stefano; Canalis, Ernesto (2012) Nemo-like kinase inhibits osteoblastogenesis by suppressing bone morphogenetic protein and WNT canonical signaling. J Cell Biochem 113:449-56
Zanotti, Stefano; Canalis, Ernesto (2012) Notch regulation of bone development and remodeling and related skeletal disorders. Calcif Tissue Int 90:69-75
Canalis, Ernesto; Brunet, Lisa J; Parker, Kristen et al. (2012) Conditional inactivation of noggin in the postnatal skeleton causes osteopenia. Endocrinology 153:1616-26
Canalis, Ernesto; Parker, Kristen; Zanotti, Stefano (2012) Gremlin1 is required for skeletal development and postnatal skeletal homeostasis. J Cell Physiol 227:269-77
Beamer, Wesley G; Shultz, Kathryn L; Coombs 3rd, Harold F et al. (2011) BMD regulation on mouse distal chromosome 1, candidate genes, and response to ovariectomy or dietary fat. J Bone Miner Res 26:88-99

Showing the most recent 10 out of 114 publications