Osteoarthritis is a severe debilitating disease manifested by degeneration of articular cartilage-lining joint cavities. The maintenance of healthy cartilage depends on balancing the synthetic and degradative processes involved in turnover of cartilage extracellular matrix. Cartilage extracellular matrices are composed predominately of collagen and proteoglycans tethered to single filaments of another matrix macromolecule, hyaluronan (HA). This HA, in turn, is bound or anchored directly to the chondrocyte membrane via interaction with an HA receptor protein, recently identified as CD44. Most studies of cartilage catabolism have centered on the extracellular processing of matrix components via proteases and protease inhibitors. However, enzymes(s) involved in the extracellular degradation of cartilage HA have never been documented, nor have other cellular mechanisms for HA catabolism. This knowledge is lacking despite the fact that HA plays a central role in the organization of cartilage extracellular matrix. Preliminary studies have shown that CD44 receptors mediate the endocytosis of HA for intracellular degradation. The binding and internalization of HA is blocked by HA hexasaccharides (competitive inhibitors of HA binding), as well as anti-CD44 antibodies. Small degradation fragments of HA are also detected intracellularly and the generation of these fragments is inhibited by the lysosomotropic agent, chloroquine. Catabolic cell mediators up-regulate CD44 expression, resulting in increased capacity of chondrocytes to accumulate intracellular HA. Thus for the first time, a mechanism for the catabolism of HA by the chondrocyte is evolving.
The Specific Aims of this proposal are to: (i) determine the exact rates of HA endocytosis, including HA of various sizes and HA """"""""decorated"""""""" with proteoglycan fragments and link protein; (ii) determine how the level of expression of CD44 affects the rate of HA endocytosis.
This second aim will involve the use of antisense inhibition of CD44 in both chondrocyte cultures, and cultures of intact cartilage tissue slices; and (iii) characterize changes in CD44 and isoform expression in human cartilage that occur during aging and disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR043384-04
Application #
6055606
Study Section
Orthopedics and Musculoskeletal Study Section (ORTH)
Program Officer
Tyree, Bernadette
Project Start
1996-09-30
Project End
2000-08-31
Budget Start
1999-09-01
Budget End
2000-08-31
Support Year
4
Fiscal Year
1999
Total Cost
Indirect Cost
Name
Rush University Medical Center
Department
Type
DUNS #
City
Chicago
State
IL
Country
United States
Zip Code
60612
Knudson, Warren; Ishizuka, Shinya; Terabe, Kenya et al. (2018) The pericellular hyaluronan of articular chondrocytes. Matrix Biol :
Danielson, Ben T; Knudson, Cheryl B; Knudson, Warren (2015) Extracellular processing of the cartilage proteoglycan aggregate and its effect on CD44-mediated internalization of hyaluronan. J Biol Chem 290:9555-70
Hida, Daisuke; Danielson, Ben T; Knudson, Cheryl B et al. (2015) CD44 knock-down in bovine and human chondrocytes results in release of bound HYAL2. Matrix Biol 48:42-54
Luo, Na; Knudson, Warren; Askew, Emily B et al. (2014) CD44 and hyaluronan promote the bone morphogenetic protein 7 signaling response in murine chondrocytes. Arthritis Rheumatol 66:1547-58
Ariyoshi, W; Okinaga, T; Knudson, C B et al. (2014) High molecular weight hyaluronic acid regulates osteoclast formation by inhibiting receptor activator of NF-*B ligand through Rho kinase. Osteoarthritis Cartilage 22:111-20
Ono, Yohei; Sakai, Tadahiro; Hiraiwa, Hideki et al. (2013) Chondrogenic capacity and alterations in hyaluronan synthesis of cultured human osteoarthritic chondrocytes. Biochem Biophys Res Commun 435:733-9
Mellor, Liliana; Knudson, Cheryl B; Hida, Daisuke et al. (2013) Intracellular domain fragment of CD44 alters CD44 function in chondrocytes. J Biol Chem 288:25838-50
Ariyoshi, Wataru; Takahashi, Nobunori; Hida, Daisuke et al. (2012) Mechanisms involved in enhancement of the expression and function of aggrecanases by hyaluronan oligosaccharides. Arthritis Rheum 64:187-97
Patchigolla, R Krishna R; Knudson, Warren; Schmid, Thomas M (2012) Matrix metalloproteinase-9 in a unique proteoglycan form in avian embryonic growth plate cartilage. Arch Biochem Biophys 520:42-50
Takahashi, Nobunori; Knudson, Cheryl B; Thankamony, Sai et al. (2010) Induction of CD44 cleavage in articular chondrocytes. Arthritis Rheum 62:1338-48

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