The extracellular matrix (ECM) has classically been viewed as a static scaffold that provides support to cells and tissues. However, recent studies have shown that ECM molecules form highly dynamic structures that continually undergo movement and deformation in response to cell movement. Evidence is accumulating that ECM proteins may also be major regulators of growth factor activity. Fibronectin is one of the earliest ECM proteins to be assembled into the matrix and facilitates assembly of other ECM proteins. Using a fibronectin null cell model we have found that fibronectin is essential for assembly of multiple bone ECM proteins and is required for osteoblast mineralization but not differentiation. Fibronectin is also critical for assembly of latent TGF( binding protein-1 (LTBP1), an important regulator of TGF(, into the ECM. In addition, our recent dynamic imaging studies in living osteoblasts have suggested novel roles for cell movement in bone ECM assembly and reorganization. ? ? The proposed studies are centered around two main hypotheses. The first is that fibronectin is a multifunctional regulator of osteoblast function through its effects as an orchestrator of assembly of bone ECM proteins and through regulation of growth factor activity. The second is that dynamic cell movement is essential for the assembly and reorganization of bone ECM proteins. To test these hypotheses complimentary in vitro and in vivo approaches will be used.
In Aim 1 we will determine the role of fibronectin in osteoblast function through its role as a regulator of assembly of bone ECM proteins. Fibronectin-null osteoblast culture models will be used in conjunction with a conditional knockout approach to delete fibronectin in the osteoblast lineage.
In Aim 2 we will determine the role of fibronectin in regulating TGF( activity in bone via interactions with LTBP1. This will be done using fibronectin null osteoblasts as well as a novel TGF( reporter mouse line that can be used to measure in vivo TGF( activity.
In Aim 3 we will determine the dynamics of assembly and reorganization of bone ECM proteins and their interactions with fibronectin and determine the role of cell movement in ECM assembly and reorganization. This will be done using dynamic molecular imaging of bone ECM proteins together with quantification of cell and fibril dynamics by computational analysis. These studies will provide novel insights into the mechanisms of assembly of bone ECM proteins and provide new insights into the complex molecular pathways for ECM regulation of TGF( in bone. The data generated will have important implications for diseases associated with misregulation of TGF(, such as fibrotic diseases, osteoporosis, arthritis and cancer. ? ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR051517-05
Application #
7473252
Study Section
Skeletal Biology Development and Disease Study Section (SBDD)
Program Officer
Sharrock, William J
Project Start
2004-09-10
Project End
2009-08-31
Budget Start
2008-08-01
Budget End
2009-08-31
Support Year
5
Fiscal Year
2008
Total Cost
$234,642
Indirect Cost
Name
University of Missouri Kansas City
Department
Dentistry
Type
Schools of Dentistry
DUNS #
010989619
City
Kansas City
State
MO
Country
United States
Zip Code
64110
Morris, Josephine L; Cross, Stephen J; Lu, Yinhui et al. (2018) Live imaging of collagen deposition during skin development and repair in a collagen I - GFP fusion transgenic zebrafish line. Dev Biol 441:4-11
Jähn, Katharina; Kelkar, Shilpa; Zhao, Hong et al. (2017) Osteocytes Acidify Their Microenvironment in Response to PTHrP In Vitro and in Lactating Mice In Vivo. J Bone Miner Res 32:1761-1772
Prideaux, Matthew; Dallas, Sarah L; Zhao, Ning et al. (2015) Parathyroid Hormone Induces Bone Cell Motility and Loss of Mature Osteocyte Phenotype through L-Calcium Channel Dependent and Independent Mechanisms. PLoS One 10:e0125731
Kamel-ElSayed, Suzan A; Tiede-Lewis, LeAnn M; Lu, Yongbo et al. (2015) Novel approaches for two and three dimensional multiplexed imaging of osteocytes. Bone 76:129-40
Webster, Duncan J; Schneider, Philipp; Dallas, Sarah L et al. (2013) Studying osteocytes within their environment. Bone 54:285-95
Dallas, Sarah L; Prideaux, Matthew; Bonewald, Lynda F (2013) The Osteocyte: An Endocrine Cell and More. Endocr Rev :
Dallas, Sarah L; Veno, Patricia A (2012) Live imaging of bone cell and organ cultures. Methods Mol Biol 816:425-57
Lu, Yongbo; Yuan, Baozhi; Qin, Chunlin et al. (2011) The biological function of DMP-1 in osteocyte maturation is mediated by its 57-kDa C-terminal fragment. J Bone Miner Res 26:331-40
Dallas, Sarah L; Bonewald, Lynda F (2010) Dynamics of the transition from osteoblast to osteocyte. Ann N Y Acad Sci 1192:437-43
Dallas, Sarah L; Veno, Patricia A; Rosser, Jennifer L et al. (2009) Time lapse imaging techniques for comparison of mineralization dynamics in primary murine osteoblasts and the late osteoblast/early osteocyte-like cell line MLO-A5. Cells Tissues Organs 189:6-11

Showing the most recent 10 out of 12 publications