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Dev Neurobiol 2017 Dec 01;7712:1385-1400. doi: 10.1002/dneu.22544.
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Sonic hedgehog antagonists reduce size and alter patterning of the frog inner ear.

Zarei S , Zarei K , Fritzsch B , Elliott KL .

Sonic hedgehog (Shh) signaling plays a major role in vertebrate development, from regulation of proliferation to the patterning of various organs. In amniotes, Shh affects dorsoventral patterning in the inner ear but affects anteroposterior patterning in teleost ears. It remains unknown how altered function of Shh relates to morphogenetic changes that coincide with the evolution of limbs and novel auditory organs in the ear. In this study, we used the tetrapod, Xenopus laevis, to test how increasing concentrations of the Shh signal pathway antagonist, Vismodegib, affects ear development. Vismodegib treatment dose dependently alters the development of the ear, hypaxial muscle, and indirectly the Mauthner cell through its interaction with the inner ear afferents. Together, these phenotypes have an effect on escape response. The altered Mauthner cell likely contributes to the increased time to respond to a stimulus. In addition, the increased hypaxial muscle in the trunk likely contributes to the subtle change in animal C-start flexion angle. In the ear, Vismodegib treatment results in decreasing segregation between the gravistatic sensory epithelia as the concentration of Vismodegib increases. Furthermore, at higher doses, there is a loss of the horizontal canal but no enantiomorphic transformation, as in bony fish lacking Shh. Like in amniotes, Shh signaling in frogs affects dorsoventral patterning in the ear, suggesting that auditory sensory evolution in sarcopterygians/tetrapods evolved with a shift of Shh function in axis specification. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1385-1400, 2017.

PubMed ID: 29030893
PMC ID: PMC5693645
Article link: Dev Neurobiol
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: gli1 gli2 gli3 myo6 ptch1 shh smo
GO keywords: Hedgehog signaling complex [+]
Antibodies: Myo6 Ab1 Neuronal Ab4 Tuba4a Ab25

Phenotypes: Xla Wt + Vismodegib (Figure 1 A') [+]

Article Images: [+] show captions
References [+] :
Amato, Hedgehog signaling in vertebrate eye development: a growing puzzle. 2004, Pubmed