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Shh and Gli3 are dispensable for limb skeleton formation but regulate digit number and identity


Most current models propose Sonic hedgehog (Shh) as the primary determinant of anteroposterior development of amniote limbs1. Shh protein is said to be required to direct the formation of skeletal elements and to specify digit identity through dose-dependent activation of target gene expression. However, the identity of genes targeted by Shh, and the regulatory mechanisms controlling their expression, remain poorly understood. Gli3 (the gene implicated in human Greig cephalopolysyndactyly syndrome) is proposed to negatively regulate Shh by restricting its expression and influence to the posterior mesoderm2,3,4. Here we report genetic analyses in mice showing that Shh and Gli3 are dispensable for formation of limb skeletal elements: Shh-/- Gli3-/- limbs are distally complete and polydactylous, but completely lack wild-type digit identities. We show that the effects of Shh signalling on skeletal patterning and ridge maintenance are necessarily mediated through Gli3. We propose that the function of Shh and Gli3 in limb skeletal patterning is limited to refining autopodial morphology, imposing pentadactyl constraint on the limb's polydactyl potential, and organizing digit identity specification, by regulating the relative balance of Gli3 transcriptional activator and repressor activities.

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Figure 1: Gli3 regulates digit number and identity.
Figure 2: Shh signalling regulates Gli3 processing in the mouse limb.
Figure 3: Regulation of putative SHH target genes in the limb. E10.5 wild-type, Shh-/-, Gli3-/-, Shh-/- Gli3-/- and Shh-/- Gli3+/- forelimb buds were examined for expression of Gli1, Ptch1, Hoxd12, dHand and Bmp2.
Figure 4: Shh maintains ridge function by relieving an antagonistic regulatory cascade.

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  1. Ingham, P. W. & McMahon, A. P. Hedgehog signaling in animal development: paradigms and principles. Genes Dev. 15, 3059–3087 (2001)

    Article  CAS  PubMed  Google Scholar 

  2. Masuya, H., Sagai, T., Wakana, S., Moriwaki, K. & Shiroishi, T. A duplicated zone of polarizing activity in polydactylous mouse mutants. Genes Dev. 9, 1645–1653 (1995)

    Article  CAS  PubMed  Google Scholar 

  3. Büscher, D., Bosse, B., Heymer, J. & Rüther, U. Evidence for genetic control of Sonic hedgehog by Gli3 in mouse limb development. Mech. Dev. 62, 175–182 (1997)

    Article  PubMed  Google Scholar 

  4. Wang, B., Fallon, J. F. & Beachy, P. A. Hedgehog-regulated processing of Gli3 produces an anterior/posterior repressor gradient in the developing vertebrate limb. Cell 100, 423–434 (2000)

    Article  CAS  PubMed  Google Scholar 

  5. Méthot, N. & Basler, K. Hedgehog controls limb development by regulating the activities of distinct transcriptional activator and repressor forms of Cubitus interruptus. Cell 96, 819–831 (1999)

    Article  PubMed  Google Scholar 

  6. Méthot, N. & Basler, K. An absolute requirement for Cubitus interruptus in Hedgehog signaling. Development 128, 733–742 (2001)

    PubMed  Google Scholar 

  7. Aza-Blanc, P., Ramirez-Weber, F. A., Laget, M. P., Schwartz, C. & Kornberg, T. B. Proteolysis that is inhibited by Hedgehog targets Cubitus interruptus protein to the nucleus and converts it to a repressor. Cell 89, 1043–1053 (1997)

    Article  CAS  PubMed  Google Scholar 

  8. Pearse, R. V. & Tabin, C. J. The molecular ZPA. J. Exp. Zool. 282, 677–690 (1998)

    Article  CAS  PubMed  Google Scholar 

  9. Yang, Y. et al. Relationship between dose, distance and time in Sonic hedgehog-mediated regulation of anteroposterior polarity in the chick limb. Development 124, 4393–4404 (1997)

    CAS  PubMed  Google Scholar 

  10. Lewis, P. M. et al. Cholesterol modification of Sonic hedgehog is required for long-range signaling activity and effective modulation of signaling by Ptc1. Cell 105, 599–612 (2001)

    Article  CAS  PubMed  Google Scholar 

  11. Chiang, C. et al. Manifestation of the limb prepattern: Limb development in the absence of Sonic hedgehog function. Dev. Biol. 236, 421–435 (2001)

    Article  CAS  PubMed  Google Scholar 

  12. Kraus, P., Fraidenraich, D. & Loomis, C. A. Some distal limb structures develop in mice lacking Sonic hedgehog signaling. Mech. Dev. 100, 45–58 (2001)

    Article  CAS  PubMed  Google Scholar 

  13. Sanz-Ezquerro, J. J. & Tickle, C. “Fingering” the vertebrate limb. Differentiation 69, 91–99 (2001)

    Article  CAS  PubMed  Google Scholar 

  14. Dai, P. et al. Sonic hedgehog-induced activation of the Gli1 promoter is mediated by GLI3. J. Biol. Chem. 274, 8143–8152 (1999)

    Article  CAS  PubMed  Google Scholar 

  15. Brewster, R., Lee, J. & Ruiz i Altaba, A. Gli/Zic factors pattern the neural plate by defining domains of cell differentiation. Nature 393, 579–583 (1998)

    Article  ADS  CAS  PubMed  Google Scholar 

  16. Brewster, R., Mullor, J. L. & Ruiz i Altaba, A. Gli2 functions in FGF signaling during antero-posterior patterning. Development 127, 4395–4405 (2000)

    PubMed  Google Scholar 

  17. Shin, S. H., Kogerman, P., Lindstrom, E., Toftgard, R. & Biesecker, L. G. GLI3 mutations in human disorders mimic Drosophila Cubitus interruptus protein functions and localization. Proc. Natl Acad. Sci. USA 96, 2880–2884 (1999)

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  18. Sasaki, H., Nishizaki, Y., Hui, C.-c., Nakafuku, M. & Kondoh, H. Regulation of Gli2 and Gli3 activities by an amino-terminal repression domain: implication of Gli2 and Gli3 as primary mediators of Shh signaling. Development 126, 3915–3924 (1999)

    CAS  PubMed  Google Scholar 

  19. Hui, C. C. & Joyner, A. L. A mouse model of Greig cephalopolysyndactyly syndrome: the extra-toesJ mutation contains an intragenic deletion of the Gli3 gene. Nature Genet. 3, 241–246 (1993)

    Article  CAS  PubMed  Google Scholar 

  20. Zúñiga, A. & Zeller, R. Gli3 (Xt) and formin (ld) participate in the positioning of the polarising region and control of posterior limb-bud identity. Development 126, 13–21 (1999)

    PubMed  Google Scholar 

  21. te Welscher, P., Fernandez-Teran, M., Ros, M. A. & Zeller, R. Mutual genetic antagonism involving GLI3 and dHAND prepatterns the vertebrate limb bud mesenchyme prior to SHH signaling. Genes Dev. 16, 421–426 (2002)

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  22. Litingtung, Y. & Chiang, C. Specification of neuronal cell types in the ventral spinal cord is mediated by antagonistic interaction between Shh and Gli3. Nature Neurosci. 3, 979–985 (2000)

    Article  CAS  PubMed  Google Scholar 

  23. Caruccio, N. C. et al. Constitutive activation of Sonic hedgehog signaling in the chicken mutant talpid2: Shh-independent outgrowth and polarizing activity. Dev. Biol. 212, 137–149 (1999)

    Article  CAS  PubMed  Google Scholar 

  24. Martin, G. R. The roles of FGFs in the early development of vertebrate limbs. Genes Dev. 12, 1571–1586 (1998)

    Article  CAS  PubMed  Google Scholar 

  25. Zúñiga, A., Haramis, A.-P. G., McMahon, A. & Zeller, R. Signal relay by BMP antagonism controls the SHH/FGF4 feedback loop in vertebrate limb buds. Nature 401, 598–602 (1999)

    Article  ADS  PubMed  Google Scholar 

  26. Sun, X. et al. Conditional inactivation of Fgf4 reveals complexity of signalling during limb bud development. Nature Genet. 25, 83–86 (2000)

    Article  CAS  PubMed  Google Scholar 

  27. Fraidenraich, D., Lang, R. & Basilico, C. Distinct regulatory elements govern Fgf4 expression in the mouse blastocyst, myotomes, and developing limb. Dev. Biol. 204, 197–209 (1998)

    Article  CAS  PubMed  Google Scholar 

  28. Castilla, E. E. et al. Epidemiological analysis of rare polydactylies. Am. J. Med. Genet. 65, 295–303 (1996)

    Article  CAS  PubMed  Google Scholar 

  29. Qu, S. et al. Polydactyly and ectopic ZPA formation in Alx-4 mutant mice. Development 124, 3999–4008 (1997)

    CAS  PubMed  Google Scholar 

  30. Radhakrishna, U. et al. The phenotypic spectrum of Gli3 morphopathies includes autosomal dominant preaxial polydactyly type IV and postaxial polydactyly type A/B. Am. J. Hum. Genet. 65, 645–655 (1999)

    Article  CAS  PubMed  PubMed Central  Google Scholar 

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We thank Y.-F. Wang, R. Mernaugh and J. Lancman for technical assistance; R. Harland and B. Vogelstein for reagents; and S. Carroll and members of the Fallon laboratory for critical comments on the manuscript. This work was supported by grants from the National Institutes of Health to C.C. and J.F.F.

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Correspondence to John F. Fallon or Chin Chiang.

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Litingtung, Y., Dahn, R., Li, Y. et al. Shh and Gli3 are dispensable for limb skeleton formation but regulate digit number and identity. Nature 418, 979–983 (2002).

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