Smad2 role in mesoderm formation, left–right patterning and craniofacial development


Signalling by the transforming growth factor-β (TGF-β) superfamily of proteins depends on the phosphorylation and activation of SMAD proteins by heteromeric complexes of ligand-specific type I and type II receptors with serine/threonine-kinase activity1. The vertebrate SMAD family includes at least nine members, of which Smad2 has been shown to mediate signalling by activin and TGF-β2,3,4,5. In Xenopus, Smad2 can induce dorsal mesoderm, mimicking Vg-1, activin and nodal2,4. Here we investigate the function of Smad2 in mammalian development by generating two independent Smad2 mutant alleles in mice by gene targeting. We show that homozygous mutant embryos fail to form an organized egg cylinder and lack mesoderm, like mutant mice lacking nodal6,7 or ActRIB, the gene encoding the activin type-I receptor8. About 20 per cent of Smad2 heterozygous embryos have severe gastrulation defects and lack mandibles or eyes, indicating that the gene dosage of Smad2 is critical for signalling. Mice trans-heterozygous for both Smad2 and nodal mutations display a range of phenotypes, including gastrulation defects, complex craniofacial abnormalities such as cyclopia, and defects in left–right patterning, indicating that Smad2 may mediate nodal signalling in these developmental processes. Our results show that Smad2 function is essential for early development and for several patterning processes in mice.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: The Smad2mh1 mutation results in early embryonic lethality and other defects.
Figure 2: The early developmental defects in Smad2mh2-lacZ mutant embryos.
Figure 3: Defects in egg-cylinder organization and primitive streak formation in Smad2mh1 mutant embryos.
Figure 4: Gastrulation, craniofacial and laterality defects in Smad2mh1/+, nodallacZ/+ trans-heterozygotes.


  1. 1

    Heldin, C. H., Miyazono, K. & ten Dijke, P. TGF-β signalling from cell membrane to nucleus through SMAD proteins. Nature 390, 465–471 (1997).

    ADS  CAS  Article  Google Scholar 

  2. 2

    Graff, J. M., Bansal, A. & Melton, D. Xenopus Mad proteins transduce distinct subsets of signals for the TGFβ superfamily. Cell 85, 479–487 (1996).

    CAS  Article  Google Scholar 

  3. 3

    Macias-Silva, M. et al. MADR2 is a substrate of the TGFβ receptor and its phosphorylation is required for nuclear accumulation and signaling. Cell 87, 1215–1224 (1996).

    CAS  Article  Google Scholar 

  4. 4

    Baker, J. C. & Harland, R. M. Anovel mesoderm inducer, Madr2, functions in the activin signal transduction pathway. Genes Dev. 10, 1880–1889 (1996).

    CAS  Article  Google Scholar 

  5. 5

    Zhang, Y., Feng,, We, R. & Derynck, R. Receptor-associated Mad homologues synergize as effectors of the TGF-β response. Nature 383, 168–172 (1996).

    ADS  CAS  Article  Google Scholar 

  6. 6

    Conlon, F. L. et al. Aprimary requirement for nodal in the formation and maintenance of the primitive streak in the mouse. Development 120, 1919–1928 (1994).

    CAS  PubMed  Google Scholar 

  7. 7

    Iannaccone, P. M., Zhou, X., Khokha, M., Boucher, D. & Kuehn, M. R. Insertional mutation of a gene involved in growth regulation of the early mouse embryo. Dev. Dyn. 194, 198–208 (1992).

    CAS  Article  Google Scholar 

  8. 8

    Gu, Z. et al. The type I activin receptor ActRIB is required for egg cylinder organization and gastrulation in the mouse. Genes Dev. 12, 844–857 (1998).

    CAS  Article  Google Scholar 

  9. 9

    Mountford, P. et al. Dicistronic targeting constructs: reporters and modifiers of mammalian gene expression. Proc. Natl Acad. Sci. USA 91, 4303–4307 (1994).

    ADS  CAS  Article  Google Scholar 

  10. 10

    Hogan, B., Beddington, R., Costantini, F. & Lacy, E. in Manipulating the Mouse Embryo 51–73 (Cold Spring Harbor Laboratory Press, New York, 1994).

    Google Scholar 

  11. 11

    Tam, P. L. P. & Behrignger, R. R. Mouse gastrulation: the formation of a mammalian body plan. Mech. Dev. 68, 3–25 (1997).

    CAS  Article  Google Scholar 

  12. 12

    Wilkinson, D. G., Bhatt, S. & Herrmann, B. G. Expression pattern of the mouse T gene and its role in mesoderm formation. Nature 343, 657–659 (1990).

    ADS  CAS  Article  Google Scholar 

  13. 13

    Waldrip, W. R., Bikoff, E. K., Hoodless, P. A., Wrana, J. L. & Robertson, E. J. Smad2 signaling in extraembryonic tissues determines anterior-posterior polarity of the early mouse embryo. Cell 92, 797–808 (1998).

    CAS  Article  Google Scholar 

  14. 14

    Zhou, X., Sasaki, H., Lowe, L., Hogan, B. L. & Kuehn, M. R. Nodal is a novel TGF-β-like gene expressed in the mouse node during gastrulation. Nature 361, 543–547 (1993).

    ADS  CAS  Article  Google Scholar 

  15. 15

    Varlet, I., Collignon, J. & Robertson, E. J. nodal expression in the primitive endoderm is required for specification of the anterior axis during mouse gastrulation. Development 124, 1033–1044 (1997).

    CAS  Google Scholar 

  16. 16

    Collignon, J., Varlet, I. & Robertson, E. J. Relationship between asymmetric nodal expression and the direction of embryonic turning. Nature 381, 155–158 (1996).

    ADS  CAS  Article  Google Scholar 

  17. 17

    Lowe, L. A. et al. Conserved left–right asymmetry of nodal expression and alterations in murine situs inversus. Nature 381, 158–161 (1996).

    ADS  CAS  Article  Google Scholar 

  18. 18

    Oh, S. P. & Li, E. The signaling pathway mediated by the type IIB activin receptor controls axial patterning and lateral asymmetry in the mouse. Genes Dev. 11, 1812–1826 (1997).

    CAS  Article  Google Scholar 

  19. 19

    Hoodless, P. A. et al. MADR1, a MAD-related protein that functions in BMP2 signaling pathways. Cell 85, 489–500 (1996).

    CAS  Article  Google Scholar 

  20. 20

    Green, J. B., New, H. V. & Smith, J. C. Responses of embryonic Xenopus cells to activin and FGF are separated by multiple dose thresholds and correspond to distinct axes of the mesoderm. Cell 71, 731–739 (1992).

    CAS  Article  Google Scholar 

  21. 21

    Jones, C. M., Kuehn, M. R., Hogan, B. L., Smith, J. C. & Wright, C. V. Nodal-related signals induce axial mesoderm and dorsalize mesoderm during gastrulation. Development 121, 3651–3662 (1995).

    CAS  PubMed  Google Scholar 

  22. 22

    Lagna, G., Hata, A., Hemmati-Brivanlou, A. & Massagué, J. Partnership between DPC4 and SMAD proteins in TGF-β signalling pathways. Nature 383, 832–836 (1996).

    ADS  CAS  Article  Google Scholar 

  23. 23

    Chen, X. et al. Smad4 and FAST-1 in the assembly of activin-responsive factor. Nature 389, 85–89 (1997).

    ADS  CAS  Article  Google Scholar 

  24. 24

    Sirard, C. et al. The tumor suppressor gene Smad4/Dpc4 is required for gastrulation and later for anterior development of the mouse embryo. Genes Dev. 12, 107–119 (1998).

    CAS  Article  Google Scholar 

  25. 25

    Li, E., Bestor, T. H. & Jaenisch, R. Targeted mutation of the DNA methyltransferase gene results in embryonic lethality. Cell 69, 915–926 (1992).

    CAS  Article  Google Scholar 

  26. 26

    Laird, P. W. et al. Simplified mammalian DNA isolation procedure. Nucleic Acids Res. 19, 4293 (1991).

    CAS  Article  Google Scholar 

  27. 27

    Nakao, A. et al. Identification of Smad2, a human Mad-related protein in the transforming growth factor β signaling pathway. J. Biol. Chem. 272, 2896–2900 (1997).

    CAS  Article  Google Scholar 

  28. 28

    Kaufman, M. H. The Atlas of Mouse Development(Academic, San Diego, 1992).

    Google Scholar 

  29. 29

    Wilkinson, D. G. In Situ Hybridixation: A Practical Approach(Oxford University Press, London, 1992).

Download references


We thank E. Robertson for nodallacZ mice; P. Ten Dijke for Smad2 antibody; A. Smith for pGT1.8Iresβgeo; P. Oh for help with whole-mount in situ hybridization; H. Lei, M. Okano and L. Yu for technical assistance; and Z. Gu and T. Gridley for comments on the manuscript. This work was funded by Bristol Myers-Squibb (E.L.) and a postdoctoral fellowship from the Japan Society for the Promotion of Science (M.N.).

Author information



Corresponding author

Correspondence to En Li.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Nomura, M., Li, E. Smad2 role in mesoderm formation, left–right patterning and craniofacial development. Nature 393, 786–790 (1998).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.