The correct patterning of vertebrate skeletal elements is controlled by inductive interactions. Two vertebrate hedgehog proteins, Sonic hedgehog and Indian hedgehog, have been implicated in skeletal development. During somite differentiation and limb development, Sonic hedgehog functions as an inductive signal from the notochord, floor plate and zone of polarizing activity. Later in skeletogenesis, Indian hedgehog functions as a regulator of chondrogenesis during endochondral ossification. The vertebrate Gli zinc finger proteins are putative transcription factors that respond to Hedgehog signaling. In Drosophila, the Gli homolog cubitus interruptus is required for the activation of hedgehog targets and also functions as a repressor of hedgehog expression. We show here that Gli2 mutant mice exhibit severe skeletal abnormalities including cleft palate, tooth defects, absence of vertebral body and intervertebral discs, and shortened limbs and sternum. Interestingly, Gli2 and Gli3 (C.-c. Hui and A. L. Joyner (1993). Nature Genet. 3, 241–246) mutant mice exhibit different subsets of skeletal defects indicating that they implement specific functions in the development of the neural crest, somite and lateral plate mesoderm derivatives. Although Gli2 and Gli3 are not functionally equivalent, double mutant analysis indicates that, in addition to their specific roles, they also serve redundant functions during skeletal development. The role of Gli2 and Gli3 in Hedgehog signaling during skeletal development is discussed.

Bitgood
M. J.
,
McMahon
A. P.
(
1995
)
Hedgehog and Bmp genes are coexpressed at many diverse sites of cell-cell interaction in the mouse embryo.
Dev. Biol
172
,
126
138
Chang
D. T.
, et al. 
(
1994
)
Products, genetic linkage and limb patterning activity of a murine hedgehog gene.
Development
120
,
3339
3353
Christ
B.
,
Ordahl
C.
(
1995
)
Early stages of chick somite development.
Anat. Embryol
191
,
381
396
Cohn
M. J.
,
Tickle
C.
(
1996
)
Limbs: a model for pattern formation within the vertebrate body plan.
Trends Genet
12
,
253
257
Davis
A. P.
,
Capecchi
M. R.
(
1996
)
A mutational analysis of the 5 HoxD genes: dissection of genetic interactions during limb development in the mouse.
Development
122
,
1175
1185
Dietrich
S.
,
Schubert
F. R.
,
Gruss
P.
(
1993
)
Altered Pax gene expression in murine notochord mutants: The notochord is required to initiate and maintain ventral identity in the somite.
Mech. Dev
44
,
189
207
Dietrich
S.
,
Gruss
P.
(
1995
)
undulated phenotypes suggest a role of Pax-1 for the development of vertebral and extravertebral structures.
Dev. Biol
167
,
529
548
Dolle
P.
,
Izpisua-Belmonte
J.-C.
,
Falkenstein
H.
,
Renucci
A.
,
Duboule
D.
(
1989
)
Coordinate expression of the murine Hox-5 complex homeobox-containing genes during limb pattern formation.
Nature
342
,
767
772
Dominguez
M.
,
Brunner
M.
,
Hafen
E.
,
Basler
K.
(
1996
)
Sending and receiving the hedgehog signal: control by the Drosophila Gli protein cubitus interruptus.
Science
272
,
1621
1625
Echelard
Y.
,
Epstein
D. J.
,
St.-Jauques
B.
,
Shen
L.
,
Mohler
J. A.
,
McMahon
J. A.
,
McMahon
A. P.
(
1993
)
Sonic hedgehog, a member of a family of putative signaling molecules, is implicated in the regulation of CNS polarity.
Cell
75
,
1417
1430
Erlebacher
A.
,
Filvaroff
E.
,
Gitelman
S.
,
Derynck
R.
(
1995
)
Toward a molecular understanding of skeletal development.
Cell
80
,
371
378
Fan
C.-M.
,
Tessier-Lavigne
M.
(
1994
)
Patterning of mammalian somites by surface ectoderm and notochord: evidence for sclerotome induction by a hedgehog homolog.
Cell
79
,
1175
1186
Fan
C.-M.
,
Porter
J. A.
,
Chiang
C.
,
Chang
D. T.
,
Beachy
P.
,
Tessier-Lavigne
M.
(
1995
)
Long-range sclerotome induction by Sonic Hedgehog: direct role of the amino-terminal cleavage product and modulation by the cyclic AMP signaling pathway.
Cell
81
,
457
465
Franz
T.
(
1994
)
Extra-toes (Xt) homozygous mutant mice demonstrate a role for the Gli-3 gene in the development of the forebrain.
Acta Anat
150
,
38
44
Fromental-Ramain
C.
,
Warot
X.
,
Lakkaraju
S.
,
Favier
B.
,
Haack
H.
,
Birling
C.
,
Dierich
A.
,
Dolle
P.
,
Chambon
P.
(
1996
)
Specific and redundant functions of the paralogous Hoxa-9 and Hoxd-9 genes in forelimb and axial skeleton patterning.
Development
122
,
461
472
Gollop
T. R.
,
Fontes
L.R.
(
1985
)
The Greig cephalopolysyndactyly syndrome: Report of a family and review of the literature.
Am. J. Med. Genet
22
,
59
68
Goodrich
L. V.
,
Johnson
R. L.
,
Milenkovic
L.
,
McMahon
J. A.
,
Scott
M. P.
(
1996
)
Conservation of the hedgehog / patched signaling pathway from flies to mice: induction of a mouse patched gene by Hedgehog.
Genes Dev
10
,
301
312
Haack
H.
,
Gruss
P.
(
1993
)
The establishment of murine Hox-1 expression domains during patterning of the limb.
Dev. Biol
157
,
410
422
Hahn
H.
, et al. 
(
1996
)
Mutations of the human homolog of Drosophila patched in the nevoid basal cell carcinoma syndrome.
Cell
85
,
841
851
Hammerschmidt
M.
,
Bitgood
M. J.
,
McMahon
A. P.
(
1996
)
Protein kinase A is a common negative regulator of Hedgehog signaling in the vertebrate embryo.
Genes Dev
10
,
647
658
Hogan
B. L. M.
(
1996
)
Bone morphogenetic proteins: multifunctional regulators of vertebrate development.
Genes Dev
10
,
1580
1594
Hui
C.-c.
,
Joyner
A. L.
(
1993
)
A mouse model of Greigcephalopolysyndactyly syndrome: the extra-toesJ mutation contains an intragenic deletion of the Gli3 gene.
Nature Genet
3
,
241
246
Hui
C.-c.
,
Slusarski
D.
,
Platt
K.
,
Holmgren
R.
,
Joyner
A. L.
(
1994
)
Expression of three mouse homologs of the Drosophila segment polarity gene cubitus interruptus, Gli, Gli-2, and Gli-3, in ectoderm-and mesoderm-derived tissues suggests multiple roles during postimplantation development.
Dev. Biol
162
,
402
413
Hynes
M.
,
Porter
J. A.
,
Chiang
C.
,
Chang
D.
,
Tessier-Lavigne
,
Beachy
P. A.
,
Rosenthal
A.
(
1995
)
Induction of midbrain dopaminergic neurons by Sonic Hedgehog.
Neuron
15
,
35
44
Iseki
S.
,
Araga
A.
,
Ohuchi
H.
,
Nohno
T.
,
Yoshioka
H.
,
Hayashi
F.
,
Noji
S.
(
1996
)
Sonic hedgehog is expressed in epithelial cells during development of whsiker, hair, and tooth.
Biochem. Biophys. Res. Comm
218
,
688
693
Jegalian
B. G.
,
De Robertis
E. M.
(
1992
).
Homeotic transformations in the mouse induced by overexpression of a human Hox3.3 transgene.
Cell
71
,
901
910
Johnson
D. R.
(
1967
)
Extra-toes: a new mutant gene causing multiple abnormalities in the mouse.
J. Embryol. Exp. Morph
17
,
543
581
Johnson
R. L.
,
Laufer
E.
,
Riddle
R. D.
,
Tabin
C.
(
1994
)
Ectopic expression of Sonic hedgehog alters dorsal-ventral patterning of somites.
Cell
79
,
1165
1173
Johnson
R. L.
,
Grenier
J.
,
Scott
M. P.
(
1995
)
Patched overexpression alters wing disc size and pattern: transcriptional and post-transcriptional effects on hedgehog targets.
Development
121
,
4161
4170
Johnson
R. L.
, et al. 
(
1996
)
Human homolog of patched, a candidate gene for the basal cell nevus syndrome.
Science
272
,
1668
1671
Koseki
H.
,
Wallin
J.
,
Wilting
J.
,
Mizutani
Y.
,
Ebensperger
C.
,
Christ
B.
,
Balling
R.
(
1993
)
Pax1 as a mediator of notochordal signals in the dorsoventral specification of vertebrae.
Development
119
,
649
660
Koyama
E.
, et al. 
(
1996
)
Polarizing activity, Sonic hedgehog, and tooth development in embryonic and postnatal mouse.
Dev Dyn
206
,
59
72
Lanske
B.
, et al. 
(
1996
)
PTH/PTHrP receptor in early development and Indian Hedgehog-regulated bone growth.
Science
273
,
663
666
Laufer
E.
,
Nelson
C. E.
,
Johnson
R. L.
,
Morgan
B. A.
,
Tabin
C.
(
1994
)
Sonic hedgehog and FGF-4 act througha signaling cascade and feedback loop to integrate growth and patterning on the developing limb.
Cell
79
,
993
1003
Lufkin
T.
,
Mark
M.
,
Hart
C. P.
,
Dolle
P.
,
LeMeur
M.
,
Chambon
P.
(
1992
)
Homeotic transformation of the occipital bones of the skull by ectopic expression of a homeobox gene.
Nature
359
,
835
841
Margio
V.
,
Scott
M. P.
,
Johnson
R. L.
,
Goodrich
L. V.
,
Tabin
C. J.
(
1996
)
Conservation in hedgehog signaling: induction of a chicken patched homolog by Sonic hedgehog in the developing limb.
Development
122
,
1225
1233
Martin
J. F.
,
Bradley
A.
,
Olson
E. N.
(
1995
)
The paired -like homeo box gene MHox is required for early events of skeletogenesis in multiple lineages.
Genes Dev
9
,
1237
1249
Masuya
H.
,
Sagai
T.
,
Wakana
S.
,
Moriwaki
K.
,
Shiroishi
T.
(
1995
)
A duplicated zone of polarizing activity in polydactylous mouse mutants.
Genes Dev
9
,
1645
1653
Motzny
C.K.
,
Holmgren
R.
(
1995
)
The Drosophila cubitus interruptus protein and its role in the wingless and hedgehog signal transduction pathways.
Mech. Dev
52
,
137
150
Nagy
A.
,
Rossant
J.
,
Nagy
R.
,
Abramow-Newerly
W.
,
Roder
J.
(
1994
)
Derivation of completely cell culture-derived mice form early-passage.
Proc. Natl. Acad. Sci. USA
90
,
8424
8428
Neubuser
A.
,
Koseki
H.
,
Balling
R.
(
1995
)
Characterization anddevelopmental expression of Pax9, a paired-box-containing gene related to Pax1.
Dev. Biol
170
,
701
716
Niswander
L.
,
Jeffrey
S.
,
Martin
G. R.
,
Tickle
C.
(
1994
)
A positive feedback loop coordinates growth and patterning in the vertebrate limb.
Nature
371
,
609
612
Orenic
T. V.
,
Slusarski
D. C.
,
Kroll
K. L.
,
Holmgren
R. A.
(
1990
)
Cloning and characterization of the segment polarity gene cubitus interruptus Dominant of Drosophila.
Genes Dev
4
,
1053
1067
Pavletich
N. P.
,
Pabo
C. O.
(
1993
)
Crystal structure of a five-finger GLI-DNA complex: new perspectives on zinc fingers.
Science
261
,
1701
1707
Riddle
R. D.
,
Johnson
R. L.
,
Laufer
E.
,
Tabin
C.
(
1993
)
Sonic hedgehog mediates the polarizing activity of ZPA.
Cell
75
,
1401
1416
Roberts
D. J.
,
Johnson
R. L.
,
Burke
A. C.
,
Nelson
C. E.
,
Morgan
B. A.
,
Tabin
C.
(
1995
)
Sonic hedgehog is an endodermal signal inducing Bmp-4 and Hox genes during induction and regionalization of the chick hindgut.
Development
121
,
3163
3174
Satokata
I.
,
Maas
R.
(
1994
)
Msx1 deficient mice exhibit cleft palate and abnormalities of craniofacial and tooth development.
Nature Genet
6
,
348
355
Schimmang
T.
,
Lemaistre
M.
,
Vortkamp
A.
,
Ruther
U.
(
1992
)
Expression of the zinc finger gene Gli3 is affected in the morphogenetic mouse mutant extra-toes (Xt).
Development
116
,
799
804
Theiler
K.
(
1988
)
Vertebral malformations.
Adv. Anat. Embryol. Cell Biol
112
,
1
99
Tybulewicz
V. L. J.
,
Crawford
C. E.
,
KJackson
P. K.
,
Bronson
R. T.
,
Mulligan
R. C.
(
1991
)
Neonatal lethality and lymphopenia in mice with a homozygous disruption of the c-abl proto-oncogene.
Cell
65
,
1153
1163
Vaahtokari
A.
,
Aberg
T.
,
Jernvall
J.
,
Keranen
S.
,
Thesleff
I.
(
1996
)
The enamel knot as a signaling center in the developing mouse tooth.
Mech. Dev
54
,
39
43
Verbout
A. J.
(
1985
)
The development of the vertebral column.
Adv. Anat. Embryol. Cell Biol
90
,
1
122
Vortkamp
A.
,
Gessler
M.
,
and Grzeschik
K.-H.
(
1991
)
GLI3 zinc-finger gene interrupted by translocations in Greig syndrome families.
Nature
352
,
539
540
Vortkamp
A.
,
Franz
T.
,
Gessler
M.
,
Grzeschik
K.-H.
(
1992
)
Deletion of GLI3 supports the homology of the human Greig cephalopolysyndactyly syndrome (GCPS) and the mouse mutant extra toes (Xt).
Mammalian Genome
3
,
461
463
Vortkamp
A.
,
Lee
K.
,
Lanske
B.
,
Serge
G. V.
,
Kronenberg
H. M.
,
Tabin
C. J.
(
1996
)
Regulation of rate of cartilage differentiation by Indian Hedgehog and PTH-related protein.
Science
273
,
613
622
Wallin
J.
,
Wilting
J.
,
Koseki
H.
,
Fritsch
R.
,
Christ
B.
,
Balling
R.
(
1994
)
The role of Pax1 in axial skeleton development.
Development
120
,
1109
1121
Walterhouse
D.
,
Ahmed
M.
,
Slusarski
D.
,
Kalamaras
J.
,
Boucher
D.
,
Holmgren
R.
,
Iannaccone
P.
(
1993
)
gli, a putative zinc finger transcription factor, is expressed in a segmental pattern during normal mouse development.
Dev. Dyn
196
,
91
102
Zarkower
D.
,
Hodgkin
J.
(
1993
)
Zinc fingers in sex determination: only one of the two C. elegans Tra-1 proteins binds DNA in vivo.
Nucl.Acids Res
21
,
3691
3698
This content is only available via PDF.