Opposing Effects of Arkadia and Smurf on TGFβ1-induced IgA Isotype Expression

  • Choi, Seo-Hyun (Department of Molecular Bioscience, School of Bioscience and Biotechnology, Kangwon National University) ;
  • Seo, Goo-Young (Department of Molecular Bioscience, School of Bioscience and Biotechnology, Kangwon National University) ;
  • Nam, Eun-Hee (Department of Molecular Bioscience, School of Bioscience and Biotechnology, Kangwon National University) ;
  • Jeon, Seong-Hyun (Department of Molecular Bioscience, School of Bioscience and Biotechnology, Kangwon National University) ;
  • Kim, Hyun-A (Department of Molecular Bioscience, School of Bioscience and Biotechnology, Kangwon National University) ;
  • Park, Jae-Bong (Department of Biochemistry, College of Medicine, Hallym University) ;
  • Kim, Pyeung-Hyeun (Department of Molecular Bioscience, School of Bioscience and Biotechnology, Kangwon National University)
  • Received : 2007.05.11
  • Accepted : 2007.05.28
  • Published : 2007.10.31


$TGF-{\beta}1$ induces Ig germ-line ${\alpha}$ ($GL{\alpha}$) transcription and subsequent class switching recombination (CSR) to IgA. In the present study, we investigated the roles of two E3-ubiquitin ligases, Smurfs (HECT type) and Arkadia (RING finger type) on $TGF{\beta}1$-induced IgA CSR. We found that over-expression of Smurf1 and Smurf2 decreased $TGF{\beta}1$-induced $GL{\alpha}$ promoter activity and strengthened the inhibitory effect of Smad7 on the promoter activity. Further, over-expression of Smurf1 and Smurf2 decreased both Smad3/4-mediated and Runx3-mediated $GL{\alpha}$ promoter activities, suggesting that the Smurfs can down-regulate the major $TGF-{\beta}1$ signaling pathway and decrease $GL{\alpha}$ gene expression. In parallel, the over-expressed Smurf1 decreased the expression of endogenous IgA CSR-predictive transcripts ($GLT_{\alpha}$, $PST_{\alpha}$, and $CT_{\alpha}$) and also $TGF{\beta}1$-induced IgA secretion. Conversely over-expression of Arkadia abolished the inhibitory effect of Smad7 on $TGF{\beta}1$-induced $GLT_{\alpha}$ expression and IgA secretion. Similar results were obtained in the presence of over-expressed Smad7 and Smurf1. These results indicate that Arkadia can amplify $TGF{\beta}1$-induced IgA CSR by degrading Smad7, which interacts with Smurf1. We conclude that Smurf and Arkadia have opposite roles in the regulation of $TGF{\beta}1$-induced IgA isotype expression.


Supported by : Korea Research Foundation


  1. Afrakhte, M., Moren, A., Jossan, S., Itoh, S., Sampath, K., et al. (1998) Induction of inhibitory Smad6 and Smad7 mRNA by TGF-beta family members. Biochem. Biophys. Res. Commun. 249, 505−511
  2. Ebisawa, T., Fukuchi, M., Murakami, G., Chiba, T., Tanaka, K., et al. (2001) Smurf1 interacts with transforming growth factor- beta type I receptor through Smad7 and induces receptor degradation. J. Biol. Chem. 276, 12477−12480
  3. Hayashi, H., Abdollah, S., Qiu, Y., Cai, J., Xu, Y. Y., et al. (1997) The MAD-related protein Smad7 associates with the TGFbeta receptor and functions as an antagonist of TGFbeta signaling. Cell 89, 1165−1173
  4. Imamura, T., Takase, M., Nishihara, A., Oeda, E., Hanai, J., et al. (1997) Smad6 inhibits signalling by the TGF-beta superfamily. Nature 389, 622−626
  5. Kavsak, P., Rasmussen, R. K., Causing, C. G., Bonni, S., Zhu, H., et al. (2000) Smad7 binds to Smurf2 to form an E3 ubiquitin ligase that targets the TGF beta receptor for degradation. Mol. Cell 6, 1365−1375
  6. Shi, M. J. and Stavnezer, J. (1998) CBF alpha3 (AML2) is induced by TGF-beta1 to bind and activate the mouse germline Ig alpha promoter. J. Immunol. 161, 6751−6760
  7. Zhao, M., Qiao, M., Oyajobi, B. O., Mundy, G. R., and Chen, D. (2003) E3 ubiquitin ligase Smurf1 mediates core-binding factor alpha1/Runx2 degradation and plays a specific role in osteoblast differentiation. J. Biol. Chem. 278, 27939−27944
  8. Lagna, G., Hata, A., Hemmati-Brivanlou, A., and Massague, J. (1996) Partnership between DPC4 and SMAD proteins in TGF-beta signalling pathways. Nature 383, 832−836
  9. Park, S. R., Lee, E. K., Kim, B. C., and Kim, P. H. (2003) p300 cooperates with Smad3/4 and Runx3 in TGFbeta1-induced IgA isotype expression. Eur. J. Immunol. 33, 3386−3392
  10. Kim, K. I. and Baek, S. H. (2006) SUMOylation code in cancer development and metastasis. Mol. Cells 22, 247−253
  11. Meyers, S., Lenny, N., Sun, W., and Hiebert, S. W. (1996) AML-2 is a potential target for transcriptional regulation by the t(8;21) and t(12;21) fusion proteins in acute leukemia. Oncogene 13, 303−312
  12. Nakao, A., Afrakhte, M., Moren, A., Nakayama, T., Christian, J. L., et al. (1997a) Identification of Smad7, a TGFbeta-inducible antagonist of TGF-beta signalling. Nature 389, 631−635
  13. Zhang, Y., Chang, C., Gehling, D. J., Hemmati-Brivanlou, A., and Derynck, R. (2001) Regulation of Smad degradation and activity by Smurf2, an E3 ubiquitin ligase. Proc. Natl. Acad. Sci. USA 98, 974−979
  14. Kinoshita, K., Harigai, M., Fagarasan, S., Muramatsu, M., and Honjo, T. (2001) A hallmark of active class switch recombination: transcripts directed by I promoters on looped-out circular DNAs. Proc. Natl. Acad. Sci. USA 98, 12620−12623
  15. Jin, Y. H., Jeon, E. J., Li, Q. L., Lee, Y. H., Choi, J. K., et al. (2004) Transforming growth factor-beta stimulates p300- dependent RUNX3 acetylation, which inhibits ubiquitination- mediated degradation. J. Biol. Chem. 279, 29409−29417
  16. Li, S. C., Rothman, P. B., Zhang, J., Chan, C., Hirsh, D., et al. (1994) Expression of I mu-C gamma hybrid germline transcripts subsequent to immunoglobulin heavy chain class switching. Int. Immunol. 6, 491−497
  17. Nakao, A., Imamura, T., Souchelnytskyi, S., Kawabata, M., Ishisaki, A., et al. (1997b) TGF-beta receptor-mediated signalling through Smad2, Smad3 and Smad4. EMBO. J. 16, 5353− 5362
  18. Moren, A., Imamura, T., Miyazono, K., Heldin, C. H., and Moustakas, A. (2005) Degradation of the tumor suppressor Smad4 by WW and HECT domain ubiquitin ligases. J. Biol. Chem. 280, 22115−22123
  19. Zhu, H., Kavsak, P., Abdollah, S., Wrana, J. L., and Thomsen, G. H. (1999) A SMAD ubiquitin ligase targets the BMP pathway and affects embryonic pattern formation. Nature 400, 687−693 https://doi.org/10.1038/23301
  20. Zhang, Y., Musci, T., and Derynck, R. (1997) The tumor suppressor Smad4/DPC 4 as a central mediator of Smad function. Curr. Biol. 7, 270−276
  21. Koinuma, D., Shinozaki, M., Komuro, A., Goto, K., Saitoh, M., et al. (2003) Arkadia amplifies TGF-beta superfamily signalling through degradation of Smad7. EMBO. J. 22, 6458− 6470
  22. Hahn, S. A., Schutte, M., Hoque, A. T., Moskaluk, C. A., da Costa, L. T., et al. (1996) DPC4, a candidate tumor suppressor gene at human chromosome 18q21.1. Science 271, 350−353 https://doi.org/10.1126/science.271.5247.353
  23. Muramatsu, M., Kinoshita, K., Fagarasan, S., Yamada, S., Shinkai, Y., et al. (2000) Class switch recombination and hypermutation require activation-induced cytidine deaminase (AID), a potential RNA editing enzyme. Cell 102, 553−563
  24. Lin, X., Liang, M., and Feng, X. H. (2000) Smurf2 is a ubiquitin E3 ligase mediating proteasome-dependent degradation of Smad2 in transforming growth factor-beta signaling. J. Biol. Chem. 275, 36818−36822
  25. Park, S. R., Lee, J. H., and Kim, P. H. (2001) Smad3 and Smad4 mediate transforming growth factor-beta1-induced IgA expression in murine B lymphocytes. Eur. J. Immunol. 31, 1706−1715
  26. Wu, R. Y., Zhang, Y., Feng, X. H., and Derynck, R. (1997) Heteromeric and homomeric interactions correlate with signaling activity and functional cooperativity of Smad3 and Smad4/DPC4. Mol. Cell. Biol. 17, 2521−2528
  27. Zhang, Y., Feng, X., We, R., and Derynck, R. (1996) Receptorassociated Mad homologues synergize as effectors of the TGF- beta response. Nature 383, 168−172