Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

An aspartic acid repeat polymorphism in asporin inhibits chondrogenesis and increases susceptibility to osteoarthritis


Osteoarthritis is the most common form of human arthritis. We investigated the potential role of asporin, an extracellular matrix component expressed abundantly in the articular cartilage of individuals with osteoarthritis, in the pathogenesis of osteoarthritis. Here we report a significant association between a polymorphism in the aspartic acid (D) repeat of the gene encoding asporin (ASPN) and osteoarthritis. In two independent populations of individuals with knee osteoarthritis, the D14 allele of ASPN is over-represented relative to the common D13 allele, and its frequency increases with disease severity. The D14 allele is also over-represented in individuals with hip osteoarthritis. Asporin suppresses TGF-β–mediated expression of the genes aggrecan (AGC1) and type II collagen (COL2A1) and reduced proteoglycan accumulation in an in vitro model of chondrogenesis. The effect on TGF-β activity is allele-specific, with the D14 allele resulting in greater inhibition than other alleles. In vitro binding assays showed a direct interaction between asporin and TGF-β. Taken together, these findings provide another functional link between extracellular matrix proteins, TGF-β activity and disease, suggesting new therapeutic strategies for osteoarthritis.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Genomic structure and LD of the ASPN region.
Figure 2: The frequency of individuals with the D14 variant of ASPN correlates with radiographic severity of knee osteoarthritis.
Figure 3: Effect of stable overexpression of asporin D13 and asporin D14 on the expression of cartilage marker genes during chondrogenic differentiation of ATDC5 cells.
Figure 4: Asporin inhibits TGF-β1–induced and noninduced expression of cartilage matrix genes in ATDC5 cells.
Figure 5: Asporin D14 inhibits TGF-β1–induced expression of cartilage marker genes more strongly than asporin D13.
Figure 6: Enhanced inhibition of TGF-β signaling is unique to the D14 variant.
Figure 7: Asporin binds to TGF-β1 in vitro.

Accession codes




  1. Felson, D.T. et al. The prevalence of knee osteoarthritis in the elderly: the Framingham Osteoarthritis Study. Arthritis Rheum. 30, 914–918 (1987).

    CAS  Article  Google Scholar 

  2. Kellgren, J.H. & Lawrence, J.S. Radiological assessment of osteoarthrosis. Ann. Rheum. Dis. 16, 494–502 (1957).

    CAS  Article  Google Scholar 

  3. Kellgren, J.H., Lawrence, J.S. & Bier, F. Genetic factors in generalized osteoarthrosis. Ann. Rheum. Dis. 22, 237–255 (1963).

    CAS  Article  Google Scholar 

  4. Spector, T.D., Cicuttini, F., Baker, J., Loughlin, J. & Hart, D. Genetic influences on osteoarthritis in women: A twin study. BMJ 312, 940–943 (1996).

    CAS  Article  Google Scholar 

  5. Spector, T.D. & MacGregor, A.J. Risk factors for osteoarthritis: genetics. Osteoarthritis Cartilage 12, S39–S44 (2004).

    Article  Google Scholar 

  6. Loughlin, J. Genetic epidemiology of primary osteoarthritis. Curr. Opin. Rheumatol. 13, 111–116 (2001).

    CAS  Article  Google Scholar 

  7. Loughlin, J., Dowling, B., Mustafa, Z. & Chapman, K. Association of the interleukin-1 gene cluster on chromosome 2q13 with knee osteoarthritis. Arthritis Rheum. 46, 1519–1527 (2002).

    CAS  Article  Google Scholar 

  8. Smith, A.J.P. et al. Extended haplotypes and linkage disequilibrium in the IL1R1-IL1A-IL1B-IL1RN gene cluster: association with knee osteoarthritis. Genes Immun. 5, 451–460 (2004).

    Article  Google Scholar 

  9. Grimaud, E., Heymann, D. & Redini, F. Recent advances in TGF-β effects on chondrocyte metabolism Potential therapeutic roles of TGF-β in cartilage disorders. Cytokine Growth Factor Rev. 13, 241–257 (2002).

    CAS  Article  Google Scholar 

  10. Lorenzo, P. et al. Identification and characterization of asporin. a novel member of the leucine-rich repeat protein family closely related to decorin and biglycan. J. Biol. Chem. 276, 12201–12211 (2001).

    CAS  Article  Google Scholar 

  11. Henry, S.P. et al. Expression pattern and gene characterization of asporin. a newly discovered member of the leucine-rich repeat protein family. J. Biol. Chem. 276, 12212–12221 (2001).

    CAS  Article  Google Scholar 

  12. Ameye, L. & Young, M.F. Mice deficient in small leucine-rich proteoglycans: novel in vivo models for osteoporosis, osteoarthritis, Ehlers-Danlos syndrome, muscular dystrophy, and corneal diseases. Glycobiology 12, 107R–116R (2002).

    CAS  Article  Google Scholar 

  13. Gill, M.R., Oldberg, A. & Reinholt, F.P. Fibromodulin-null murine knee joints display increased incidences of osteoarthritis and alterations in tissue biochemistry. Osteoarthritis Cartilage 10, 751–757 (2002).

    CAS  Article  Google Scholar 

  14. Ameye, L. et al. Abnormal collagen fibrils in tendons of biglycan/fibromodulin-deficient mice lead to gait impairment, ectopic ossification, and osteoarthritis. FASEB J. 16, 673–680 (2002).

    CAS  Article  Google Scholar 

  15. Haga, H., Yamada, R., Ohnishi, Y., Nakamura, Y. & Tanaka, T. Gene-based SNP discovery as part of the Japanese Millennium Genome Project: identification of 190,562 genetic variations in the human genome. J. Hum. Genet. 47, 605–610 (2002).

    CAS  Article  Google Scholar 

  16. Ikeda, T. et al. Identification of sequence polymorphisms in two sulfation-related genes, PAPSS2 and SLC26A2, and an association analysis with knee osteoarthritis. J. Hum. Genet. 46, 538–543 (2001).

    CAS  Article  Google Scholar 

  17. Shukunami, C. et al. Chondrogenic differentiation of clonal mouse embryonic cell line ATDC5 in vitro:differentiation-dependent gene expression of parathyroid hormone (PTH)/PTH-related peptide receptor. J. Cell Biol. 133, 457–468 (1996).

    CAS  Article  Google Scholar 

  18. Shukunami, C. et al. Cellular hypertrophy and calcification of embryonal carcinoma-derived chondrogenic cell line ATDC5 in vitro. J. Bone Miner. Res. 12, 1174–1188 (1997).

    CAS  Article  Google Scholar 

  19. Watanabe, H., de Caestecker, M.P. & Yamada, Y. Transcriptional cross-talk between Smad, ERK1/2, and p38 mitogen-activated protein kinase pathways regulates transforming growth factor-β-induced aggrecan gene expression in chondrogenic ATDC5 cells. J. Biol. Chem. 276, 14466–14473 (2001).

    CAS  Article  Google Scholar 

  20. Shukunami, C., Ohta, Y., Sakuda, M. & Hiraki, Y. Sequential progression of the differentiation program by bone morphogenetic protein-2 in chondrogenic cell line ATDC5. Exp. Cell Res. 241, 1–11 (1998).

    CAS  Article  Google Scholar 

  21. Hildebrand, A. et al. Interaction of the small interstitial proteoglycans biglycan, decorin, and fibromodulin with transforming growth factor β. Biochem. J. 302, 527–534 (1994).

    CAS  Article  Google Scholar 

  22. van Beuningen, H.M., van der Kraan, P.M., Aruntz, O.J. & van den Berg, W.B. Transforming growth factor-β1 stimulates articular chondrocyte proteoglycan synthesis and induces osteophyte formation in the murine knee joint. Lab. Invest. 71, 279–290 (1994).

    CAS  PubMed  Google Scholar 

  23. Scharstuhl, A. et al. Inhibition of endogenous TGF-β during experimental osteoarthritis prevents osteophyte formation and impairs cartilage repair. J. Immunol. 169, 507–514 (2002).

    CAS  Article  Google Scholar 

  24. Serra, R. et al. Expression of a truncated, kinase-defective TGF-β type II receptor in mouse skeletal tissue promotes terminal chondrocyte differentiation and osteoarthritis. J. Cell Biol. 139, 541–552 (1997).

    CAS  Article  Google Scholar 

  25. Yang, X. et al. TGF-β/Smad3 signals repress chondrocyte hypertrophic differentiation and are required for maintaining articular cartilage. J. Cell Biol. 153, 35–46 (2001).

    CAS  Article  Google Scholar 

  26. Neptune, E.R. et al. Dysregulation of TGF-β activation contributes to pathogenesis in Marfan syndrome. Nat. Genet. 33, 407–411 (2003).

    CAS  Article  Google Scholar 

  27. Border, W.A. et al. Natural inhibitor of transforming growth factor-β protects against scarring in experimental kidney disease. Nature 360, 361–364 (1992).

    CAS  Article  Google Scholar 

  28. Isaka, Y. et al. Gene therapy by skeletal muscle expression of decorin prevents fibrotic disease in rat kidney. Nat. Med. 2, 418–423 (1996).

    CAS  Article  Google Scholar 

  29. Yang, V.W., LaBrenz, S.R., Rosenberg, L.C., McQuillan, D.J. & Hook, M. Decorin is a Zn2+ metalloprotein. J. Biol. Chem. 274, 12454–12460 (1999).

    CAS  Article  Google Scholar 

  30. Dugan, T.A., Yang, V.W., McQuillan, D.J. & Hook, M. Decorin binds fibrinogen in a Zn2+-dependent interaction. J. Biol. Chem. 278, 13655–13662 (2003).

    CAS  Article  Google Scholar 

  31. Singh, K. et al. Calcium-binding properties of osteopontin derived from non-osteogenic sources. J. Biochem. (Tokyo) 114, 702–707 (1993).

    CAS  Article  Google Scholar 

  32. Meulenbelt, I. et al. Investigation of the association of the CRTM and CRTL1 genes with radiographically evident osteoarthritis in subjects from the Rotterdam study. Arthritis Rheum. 40, 1760–1765 (1997).

    CAS  Article  Google Scholar 

  33. Uitterlinden, A.G. et al. Adjacent genes, for COL2A1 and the vitamin D receptor, are associated with separate features of radiographic osteoarthritis of the knee. Arthritis Rheum. 43, 1456–1464 (2000).

    CAS  Article  Google Scholar 

  34. Mabuchi, A. et al. Identification of sequence polymorphisms of the COMP (cartilage oligomeric matrix protein) gene and association study in osteoarthrosis of the knee and hip joints. J. Hum. Genet. 46, 456–462 (2001).

    CAS  Article  Google Scholar 

  35. Suzuki, A. et al. Functional haplotypes of PADI4, encoding citrullinating enzyme peptidylarginine deaminase 4, are associated with rheumatoid arthritis. Nat. Genet. 34, 395–402 (2003).

    CAS  Article  Google Scholar 

  36. Yamada, R. et al. Association between a single-nucleotide polymorphism in the promoter of the human interleukin-3 gene and rheumatoid arthritis in Japanese patients, and maximum-likelihood estimation of combinatorial effect that two genetic loci have on susceptibility to the disease. Am. J. Hum. Genet. 68, 674–685 (2001).

    CAS  Article  Google Scholar 

  37. Excoffier, L. & Slatkin, M. Maximum-likelihood estimation of molecular haplotype frequencies in a diploid population. Mol. Biol. Evol. 12, 921–927 (1995).

    CAS  PubMed  Google Scholar 

Download references


We thank the affected individuals for participating in the study; Y. Ishii, K. Tamai, H. Ishibashi, S. Okinaga, H. Hiraoka, H. Kawaguchi, S. Saitoh, T. Kubo, Y. Takatori, H. Mototani, M. Mori, K. Yoshimura, M. Oka, M. Nakajima and K. Toyoshima for help; and A. Narita for technical assistance. This work was supported by the Japanese Millennium Project.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Shiro Ikegawa.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Fig. 1

Expression of the asporin gene (ASPN) in articular cartilage from OA patients and normal (non-OA) subjects. (PDF 51 kb)

Supplementary Fig. 2

Stable overexpression of human asporin inhibits cartilage matrix accumulation in ATDC5 cells. (PDF 47 kb)

Supplementary Fig. 3

Relative inhibition of the chondrocyte differentiation marker genes AGC1 and COL2A1 by asporin D13 and D14. (PDF 39 kb)

Supplementary Table 1

Allelic frequency of the aspartic acid (D)-repeat polymorphism of asporin in Japanese patients with knee and hip osteoarthritis. (PDF 51 kb)

Supplementary Table 2

Association between seven polymorphisms in ASPN and knee osteoarthritis. (XLS 29 kb)

Supplementary Table 3

Clinical parameters. (XLS 29 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Kizawa, H., Kou, I., Iida, A. et al. An aspartic acid repeat polymorphism in asporin inhibits chondrogenesis and increases susceptibility to osteoarthritis. Nat Genet 37, 138–144 (2005).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing