The integrity of the cartilage surface and its surrounding synovium affects the homeostasis and long-term function of an articulating joint. The loss of superficial zone chondrocytes and fibrillation of the cartilage surface are early signs of osteoarthritis. Intimal cell hyperplasia and sub-intimal fibrosis is striking in rheumatoid arthritis where joint destruction is, in part, mediated by aggressive and invasive synovial overgrowth. This application proposes to explore the role of the secreted protein lubricin (also known as megakaryocyte stimulating factor precursor, superficial zone protein, camptodactyly-arthropathy-coxa vara-pericarditis syndrome protein, and proteoglycan 4) in the maintenance of articulating joints. This protein has several important roles in joint homeostasis, including the protection and boundary lubrication of articulating surfaces, and the regulation of intimal cell growth. Genetic deficiency of this protein causes the autosomal recessive CACP syndrome, which is associated with precocious joint failure, and acquired deficiency of this protein likely contributes to joint failure in osteoarthritis and rheumatoid arthritis. Since lubricin is a protein that is synthesized by surface chondrocytes and synviocytes and is secreted into the synovial fluid, we speculate that it may be a useful agent, or target, in the treatment of common joint disease. This application has four major aims:
Aim 1) Characterize the lubricin knockout mouse with respect to cell biological properties of synoviocytes, and the biophysical and structural properties of the articular surface (lamina splendens).
Aim 2) Delineate which domains in lubricin are important for its post-translational modification and biologic properties, such as protein-protein interactions, lubrication, and cell growth regulation.
Aim 3) Create a transgenic mouse in which lubricin expression can be exogenously regulated. This will allow us to explore the temporal role of lubricin in joint development and homeostasis.
Aim 4) Identify hereditary and acquired alterations of lubricin function within synovial fluid from patients with CACP syndrome and common diseases of joints including osteoarthritis, rheumatoid arthritis, and traumatic joint injury.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR050180-04
Application #
7119282
Study Section
Orthopedics and Musculoskeletal Study Section (ORTH)
Program Officer
Tyree, Bernadette
Project Start
2003-07-01
Project End
2008-06-30
Budget Start
2006-07-01
Budget End
2007-06-30
Support Year
4
Fiscal Year
2006
Total Cost
$408,525
Indirect Cost
Name
Case Western Reserve University
Department
Genetics
Type
Schools of Medicine
DUNS #
077758407
City
Cleveland
State
OH
Country
United States
Zip Code
44106
Waller, Kimberly A; Zhang, Ling X; Jay, Gregory D (2017) Friction-Induced Mitochondrial Dysregulation Contributes to Joint Deterioration in Prg4 Knockout Mice. Int J Mol Sci 18:
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Larson, K M; Zhang, L; Badger, G J et al. (2017) Early genetic restoration of lubricin expression in transgenic mice mitigates chondrocyte peroxynitrite release and caspase-3 activation. Osteoarthritis Cartilage 25:1488-1495
He, Y; Zhang, M; Huang, A Y et al. (2017) Confocal imaging of mouse mandibular condyle cartilage. Sci Rep 7:43848
Teeple, Erin; Karamchedu, Naga Padmini; Larson, Katherine M et al. (2016) Arthroscopic irrigation of the bovine stifle joint increases cartilage surface friction and decreases superficial zone lubricin. J Biomech 49:3106-3110
Zhang, Minjie; Mani, Sriniwasan B; He, Yao et al. (2016) Induced superficial chondrocyte death reduces catabolic cartilage damage in murine posttraumatic osteoarthritis. J Clin Invest 126:2893-902
Karamchedu, Naga Padmini; Tofte, Josef N; Waller, Kimberly A et al. (2016) Superficial zone cellularity is deficient in mice lacking lubricin: a stereoscopic analysis. Arthritis Res Ther 18:64
Alquraini, Ali; Garguilo, Steven; D'Souza, Gerard et al. (2015) The interaction of lubricin/proteoglycan 4 (PRG4) with toll-like receptors 2 and 4: an anti-inflammatory role of PRG4 in synovial fluid. Arthritis Res Ther 17:353
Hill, Adele; Waller, Kimberly A; Cui, Yajun et al. (2015) Lubricin restoration in a mouse model of congenital deficiency. Arthritis Rheumatol 67:3070-81
Ai, Minrong; Cui, Yajun; Sy, Man-Sun et al. (2015) Anti-lubricin monoclonal antibodies created using lubricin-knockout mice immunodetect lubricin in several species and in patients with healthy and diseased joints. PLoS One 10:e0116237

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