(Verbatim from the Applicant): The most important risk factor for the development of osteoarthritis (OA) is age but the exact mechanism by which aging contributes to the development of OA is not known. The overall objectives of this proposal are to ascertain the role of IGF-I as a chondrocyte survival factor and establish a model for how an age-related decline in chondrocyte responsiveness to IGF-I contributes to the increased prevalence of OA with age. A decline in the number of chondrocytes in cartilage due to loss of cells from cell death has been noted with aging. Increased cell death has also been noted in OA cartilage. The factors normally responsible for keeping chondrocytes alive are not known. Based on new preliminary studies, the primary working hypothesis for this proposal is that IGF-I functions as a key autocrine survival factor for chondrocytes. A second hypothesis is that signals from the matrix mediated through the integrin family of cell-matrix receptors work in synergy with IGF-I to promote survival in cartilage. In the proposed studies, the link between aging, cell death and IGF-I action will be explored using human ankle cartilage from tissue donors of various ages. Since age-related development of OA in the ankle is uncommon, studies of this tissue can be used to separate effects of aging from effects of degeneration and OA, a problem in studies utilizing cartilage from hips or knees. In selected studies, results will be compared to those obtained using knee chondrocytes to determine if differences exist between cells from the two joints which may relate to the greater propensity for OA to develop in the knee.
The Specific Aims are to: 1) Determine if an aging-related reduction in the response to IGF-I results in an increased susceptibility of chondrocytes to cell death; 2) Determine if IGF-I acts in synergy with signals generated from the extracellular matrix via integrins to promote chondrocyte survival and 3) Determine if IGF-I cell survival signaling is impaired in chondrocytes from older adults. The results of these studies will provide important new information needed to better understand the link between aging and osteoarthritis, the most common cause of chronic disability in older adults.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
3R01AG016697-04S1
Application #
7058121
Study Section
Orthopedics and Musculoskeletal Study Section (ORTH)
Program Officer
Kohanski, Ronald A
Project Start
2001-02-01
Project End
2005-07-31
Budget Start
2005-05-01
Budget End
2005-07-31
Support Year
4
Fiscal Year
2005
Total Cost
$103,600
Indirect Cost
Name
Rush University Medical Center
Department
Type
Other Domestic Higher Education
DUNS #
068610245
City
Chicago
State
IL
Country
United States
Zip Code
60612
Willey, Jeffrey S; Long, David L; Vanderman, Kadie S et al. (2013) Ionizing radiation causes active degradation and reduces matrix synthesis in articular cartilage. Int J Radiat Biol 89:268-77
Loeser, Richard F; Goldring, Steven R; Scanzello, Carla R et al. (2012) Osteoarthritis: a disease of the joint as an organ. Arthritis Rheum 64:1697-707
Yammani, Raghunatha R; Loeser, Richard F (2012) Extracellular nicotinamide phosphoribosyltransferase (NAMPT/visfatin) inhibits insulin-like growth factor-1 signaling and proteoglycan synthesis in human articular chondrocytes. Arthritis Res Ther 14:R23
Loeser, Richard F; Olex, Amy L; McNulty, Margaret A et al. (2012) Microarray analysis reveals age-related differences in gene expression during the development of osteoarthritis in mice. Arthritis Rheum 64:705-17
Chubinskaya, Susan; Otten, Lori; Soeder, Stephan et al. (2011) Regulation of chondrocyte gene expression by osteogenic protein-1. Arthritis Res Ther 13:R55
Loeser, Richard F (2011) Aging and osteoarthritis. Curr Opin Rheumatol 23:492-6
Miranda, Keally J; Loeser, Richard F; Yammani, Raghunatha R (2010) Sumoylation and nuclear translocation of S100A4 regulate IL-1beta-mediated production of matrix metalloproteinase-13. J Biol Chem 285:31517-24
Long, D L; Loeser, R F (2010) p38gamma mitogen-activated protein kinase suppresses chondrocyte production of MMP-13 in response to catabolic stimulation. Osteoarthritis Cartilage 18:1203-10
Beier, Frank; Loeser, Richard F (2010) Biology and pathology of Rho GTPase, PI-3 kinase-Akt, and MAP kinase signaling pathways in chondrocytes. J Cell Biochem 110:573-80
Loeser, Richard F (2010) Age-related changes in the musculoskeletal system and the development of osteoarthritis. Clin Geriatr Med 26:371-86

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