There is growing evidence that implicates a role for Sonic hedgehog (SHH) in morphogenesis of the craniofacial complex. Mutations in human and murine SHH cause midline patterning defects that are manifested in the head as holoprosencephaly and cyclopia. In addition, teratogens such as jervine, which inhibit the response of tissues to SHH, also produce cyclopia. Thus, the loss of SHH signaling during early stages of neural plate patterning has a profound influence of craniofacial morphogenesis. However, the severity of these defects precludes analyses of SHH function during later stages of craniofacial development. We have used an embryonic chick system to study the role of SHH during these later stages of craniofacial development. Using a combination of surgical and molecular experiments, we show here that SHH is essential for morphogenesis of the frontonasal and maxillary processes (FNP and MXPs), which give rise to the mid- and upper face. Transient loss of SHH signaling in the embryonic face inhibits growth of the primordia and results in defects analogous to hypotelorism and cleft lip/palate, characteristics of the mild forms of holoprosencephaly. In contrast, excess SHH leads to a mediolateral widening of the FNP and a widening between the eyes, a condition known as hypertelorism. In severe cases, this widening is accompanied by facial duplications. Collectively, these experiments demonstrate that SHH has multiple and profound effects on the entire spectrum of craniofacial development, and perturbations in SHH signaling are likely to underlie a number of human craniofacial anomalies.

Reference

Barlow
A. J.
,
Francis-West
P. H.
(
1997
)
Ectopic application of recombinant BMP-2 and BMP-4 can change patterning of developing chick facial primordia.
Development
124
,
391
398
Belloni
E.
,
Muenke
M.
,
Roessler
E.
,
Traverso
G.
,
Siegel-Bartelt
J.
,
Frumkin
A.
,
Mitchell
H. F.
,
Donis-Keller
H.
,
Helms
C.
,
Hing
A. V.
,
Heng
H. H.
,
Koop
B.
,
Martindale
D.
,
Rommens
J. M.
,
Tsui
L. C.
,
Scherer
S. W.
(
1996
)
Identification of Sonic hedgehog as a candidate gene in holoprosencephaly.
Nature Genetics
14
,
353
356
Chiang
C.
,
Litingtung
Y.
,
Lee
E.
,
Young
K. E.
,
Corden
J. L.
,
Westphal
H.
,
Beachy
P. A.
(
1996
)
Cyclopia and defective axial patterning in mice lacking Sonic hedgehog gene function.
Nature
383
,
407
413
Cohen
M. M. J.
,
Sulik
K. K.
(
1992
)
Perspectives on holoprosencephaly: Part II. Central nervous system, craniofacial anatomy, syndrome commentary, diagnostic approach, and experimental studies.
J. Craniofac. Genetics Dev. Biol
12
,
196
244
Cole
R. K.
(
1942
)
The ‘talpid’ lethal in the domestic fowl.
J. Heredity
33
,
82
86
Cooper
M. K.
,
Porter
J. A.
,
Young
K. A.
,
Kelley
R. I.
,
Beachy
P. A.
(
1998
)
Plant-derived and synthetic teratogens inhibit the ability of target tissues to respond to Sonic hedgehog signaling.
Science
280
,
1603
1607
Couly
G.
,
Douarin
N. M. L.
(
1990
)
Head morphogenesis in embryonic avian chimeras: evidence for a segmental pattern in the ectoderm corresponding to the neuromeres.
Development
108
,
543
558
Couly
G. F.
,
Coltey
P. M.
,
Le Douarin
N. M.
(
1993
)
The triple origin of skull in higher vertebrates: a study in quail-chick chimeras.
Development
117
,
409
429
Cunniff
C.
,
Kratz
L. E.
,
Moser
A.
,
Natowicz
M. R.
,
Kelley
R. I.
(
1997
)
Clinical and biochemical spectrum of patients with RSH/Smith-Lemli-Opitz syndrome and abnormal cholesterol metabolism.
Am. J. Med. Genet
68
,
263
269
Ericson
J. M.
,
Kawakami
A.
,
Roelink
H.
,
Jessell
T. M.
(
1996
)
Two critical periods of Sonic Hedgehog signaling required for the specification of motor neuron identity.
Cell
87
,
661
673
Gaffield
W.
,
Keeler
R. F.
(
1996
)
Steroidal alkaloid teratogens: molecular proves for investigation of craniofacial malformations.
J. Toxicology Toxin Reviews
15
,
303
326
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
Hall
B. K.
,
Miyake
T.
(
1992
)
The membranous skeleton: the role of cell condensations in vertebrate skeletogenesis.
Anatomy and Embryology
186
,
107
124
Hamburger
V.
,
Hamilton
H. L.
(
1951
)
A series of normal stages in the development of the chick embryo.
J. Morph
88
,
49
92
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
Hammerschmidt
M.
,
Brook
A.
,
McMahon
A. P.
(
1997
)
The world according to hedgehog.
Trends Genet
13
,
14
21
Helms
J. A.
,
Kim
C. H.
,
Eichele
G.
,
Thaller
C.
(
1996
)
Retinoic acid signaling is required during early chick limb development.
Development
122
,
1385
1394
Helms
J. A.
,
Kim
C. H.
,
Hu
D.
,
Minkoff
R.
,
Thaller
C.
,
Eichele
G.
(
1997
)
Sonic hedgehog participates in craniofacial morphogenesis and is down-regulated by teratogenic doses of retinoic acid.
Dev. Biol
187
,
25
35
Hogan
B. L.
(
1996
)
Bone morphogenetic proteins in development.
Current Opin. Genet. Dev
6
,
432
438
Hui
C. C.
,
Joyner
A. L.
(
1993
)
A mouse model of greig cephalopolysyndactyly syndrome: the extra-toesJ mutation contains an intragenic deletion of the Gli3 gene.
Nat. Genet
3
,
241
246
Incardona
J. P.
,
Gaffield
W.
,
Kapur
R. P.
,
Roelink
H.
(
1998
)
The teratogenic Veratrum alkaloid cyclopamine inhibits sonic hedgehog signal transduction.
Development
125
,
3553
3562
Keeler
R. F.
(
1975
)
Teratogenic effects of cyclopamine and jervine in rats, mice and hamsters.
Proc. Soc. Exp. Biol. Med
149
,
302
306
Kelley
R. L.
,
Roessler
E.
,
Hennekam
R. C.
,
Feldman
G. L.
,
Kosaki
K.
,
Jones
M. C.
,
Palumbos
J. C.
,
Muenke
M.
(
1996
)
Holoprosencephaly in RSH/Smith-Lemli-Opitz syndrome: does abnormal cholesterol metabolism affect the function of Sonic Hedgehog.
Am. J. Med. Genet
66
,
478
484
Köntges
G.
,
Lumsden.
A.
(
1996
)
Rhombencephalic neural crest segmentation is preserved throughout craniofacial ontogeny.
Development
122
,
3229
3242
Lammer
E. J.
,
Chen
D. T.
,
Hoar
R. M.
,
Agnish
N. D.
,
Benke
P. J.
,
Braun
J. T.
,
Curry
C. J.
,
Fernhoff
P. M.
,
Grix
A. W. J.
,
Lott
I. T.
(
1985
)
Retinoic acid embryopathy.
New England J. Med
313
,
837
841
Lopez-Martínez
A.
,
Chang
D. T.
,
Chiang
C.
,
Porter
J. A.
,
Ros
M. A.
,
Simandl
B. K.
,
Beachy
P. A.
,
Fallon
J. F.
(
1995
)
Limb-patterning activity and restricted posterior localization of the amino-terminal product of Sonic hedgehog cleavage.
Current Biol
5
,
791
796
Marigo
V.
,
Davey
R. A.
,
Zuo
Y.
,
Cunningham
J. M.
,
C.J. T.
(
1996
)
Biochemical evidence that Patched is the Hedgehog receptor.
Nature
384
,
176
179
Martí
E.
,
Takada
R.
,
Bumcrot
D. A.
,
Sasaki
H.
,
McMahon
A. P.
(
1995
)
Distribution of Sonic hedgehog peptides in the developing chick and mouse embryo.
Development
121
,
2537
2547
McGonnell
I. M.
,
Clarke
J. D.
,
Tickle
C.
(
1998
)
Fate map of the developing chick face: analysis of expansion of facial primordia and establishment of the primary palate.
Dev. Dyn
212
,
102
118
Moury
J. D.
,
Schoenwolf
G. C.
(
1995
)
Cooperative model of epithelial shaping and bending during avian neurulation: autonomous movements of the neural plate, autonomous movements of the epidermis, and interactions in the neural plate/epidermis transition zone.
Dev. Dyn
204
,
323
337
Noden
D. M.
(
1988
)
Interactions and fates of avian craniofacial mesenchyme.
Development
103
,
121
140
Noden
D. M.
(
1991
)
Vertebrate craniofacial development: the relation between ontogenetic process and morphological outcome.
Brain, Behavior and Evolution
38
,
190
225
Osumi-Yamashita
N.
,
Ninomiya
Y.
,
Doi
H.
,
Eto
K.
(
1994
)
The contribution of both forebrain and midbrain crest cells to the mesenchyme in the frontonasal mass of mouse embryos.
Dev. Biol
164
,
409
19
Osumi-Yamashita
N.
,
Ninomiya
Y.
,
Eto
K.
(
1997
)
Mammalian craniofacial embryology in vitro.
Int. J. Dev. Biol
41
,
187
94
Pinto
C. B.
,
Hall
B. K.
(
1991
)
Toward an understanding of the epithelial requirement for osteogenesis in scleral mesenchyme of the embryonic chick.
J. Exp. Zool
259
,
92
108
Porter
J. A.
,
Ekker
S. C.
,
Park
W. J.
,
von Kessler
D. P.
,
Young
K. E.
,
Chen
C. H.
,
Ma
Y.
,
Woods
A. S.
,
Cotter
R. J.
,
Koonin
E. V.
,
Beachy
P. A.
(
1996
)
Hedgehog patterning activity: role of a lipophilic modification mediated by the carboxy-terminal autoprocessing domain.
Cell
86
,
21
34
Porter
J. A.
,
von Kessler
D. P.
,
Ekker
S. C.
,
Young
K. E.
,
Lee
J. J.
,
Moses
K.
,
Beachy
P. A.
(
1995
)
The product of hedgehog autoproteolytic cleavage active in local and long-range signalling.
Nature
374
,
363
6
Porter
J. A.
,
Young
K. E.
,
Beachy
P. A.
(
1996
)
Cholesterol modification of hedgehog signaling proteins in animal development.
Science
274
,
255
9
Psychoyos
D.
,
Stern
C. D.
(
1996
)
Restoration of the organizer after radical ablation of Hensen's node and the anterior primitive streak in the chick embryo.
Development
122
,
3263
73
Reddi
A. H.
(
1994
)
Bone and cartilage differentiation.
Current Opinion in Genetics and Development
4
,
737
744
Richman
J. M.
,
Tickle
C.
(
1989
)
Epithelia are interchangeable between facial primordia of chick embryos and morphogenesis is controlled by the mesenchyme.
Dev. Biol
136
,
201
210
Richman
J. M.
,
Tickle
C.
(
1992
)
Epithelial-mesenchymal interactions in the outgrowth of limb buds and facial primordia in chick embryos.
Dev. Biol
154
,
299
308
Riddle
R. D.
,
Johnson
R. L.
,
Laufer
E.
,
Tabin
C.
(
1993
)
Sonic hedgehog mediates the polarizing activity of the ZPA.
Cell
75
,
1401
1416
Roessler
E.
,
Belloni
E.
,
Gaudenz
K.
,
Jay
P.
,
Berta
P.
,
Scherer
S. W.
,
Tsui
L. C.
,
Muenke
M.
(
1996
)
Mutations in the human Sonic Hedgehog gene cause holoprosencephaly.
Nature Genetics
14
,
357
360
Rubenstein
J. L.
,
Beachy
P. A.
(
1998
)
Patterning of the embryonic forebrain.
Current Opinion in Neurobiology
8
,
18
26
Schneider
R.A.
,
Hu
D.
,
Helms
J.A.
(
1999
)
From head to toe: conservation of molecular signals regulating limb and craniofacial morphogenesis.
Cell and Tissue Research
296
,
103
109
Shimamura
K.
,
Hartigan
D. J.
,
Martinez
S.
,
Puelles
L.
,
Rubenstein
J. L.
(
1995
)
Longitudinal organization of the anterior neural plate and neural tube.
Development
121
,
3923
3933
Sim
F. R.
,
Matsumoto
N.
,
Goulding
E. H.
,
Denny
K. H.
,
Lamb
J.
,
Keeler
R. F.
,
Pratt
R. M.
(
1983
)
Specific craniofacial defects induced by jervine in the cultured rat embryo.
Teratogenesis, Carcinogenesis and Mutagenesis
3
,
111
121
Stone
D. M.
,
Hynes
M. e. a.
(
1996
)
The tumour-suppressor gene patched encodes a candidate receptor for Sonic hedgehog [see comments].
Nature
384
,
129
134
Tamarin
A.
,
Crawley
A.
,
Lee
J.
,
Tickle
C.
(
1984
)
Analysis of upperbeak defects in chicken embryos following with retinoic acid.
J. Embryol. Exp. Morph
84
,
105
123
Thorogood
P.
(
1988
)
The developmental specification of the vertebrate skull.
Development
103
,
141
153
Thorogood
P.
,
Bee
J.
,
Mark
K. v. d.
(
1986
)
Transient expression of collagen type II at epitheliomesenchymal interfaces during morphogenesis of the cartilaginous neurocranium.
Dev. Biol
116
,
497
509
Tyler
M. S.
,
Hall
B. K.
(
1977
)
Epithelial influences on skeletogenesis in the mandible of the embryonic chick.
Anat. Record
188
Wall
N. A.
,
Hogan
B. L.
(
1995
).
Expression of bone morphogenetic protein-4 (BMP-4), bone morphogenetic protein-7 (BMP-7), fibroblast growth factor-8 (FGF-8) and sonic hedgehog (SHH) during branchial arch development in the chick.
Mech. Dev
53
,
383
392
Wedden
S. E.
,
Ralphs
J. R.
,
Tickle
C.
(
1988
)
Pattern formation in the facial primordia.
Development
103
,
31
40
Weed
M.
,
Mundlos
S.
,
Olsen
B. R.
(
1997
)
The role of sonic hedgehog in vertebrate development.
Matrix Biology
16
,
53
58
Wolpert
L.
(
1988
)
Craniofacial development: a summing up.
Development
103
,
245
249
This content is only available via PDF.