Sonic hedgehog gene

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 (London), 383,407-413. 

Roiissicr, E., Belloni, E., Gaudenz, K., Jay, P, Berta, R, Scherer, S., Tsui, L., and Muenke, M. (1996). Mutations in the human Sonic hedgehog gene cause holoprosencephaly. Naltuv Getret. 14, 357-360. 

Sonic hedgehog is not only sufficient, but also is required for the correct differentiation of ventral cell types in the neural tube. Targeted disruption or deletion of the Sonic hedgehog gene in mice [73] and humans [74] leads to defects in the maintenance of the notochord and establishment of the floor plate, with subsequent development of severe malformations of forebrain and cranium characteristic of human holoprosencephaly. Thus, failure of the induction of the optic stalk and other cells in the forebrain of Sonic hedgehog null mouse embryos produces holoprosencephaly and cyclopia [73]. 

Chiang C et al. (1996) Cyclopia and defective axial patterning in mice lacking Sonic hedgehog gene function. Nature, 383 407-413. 

Sato N, Leopold PL, Crystal RG (2001) Effect of adenovirus-mediated expression of Sonic hedgehog gene on hair regrowth in mice with chemotherapy-induced alopecia. J Natl Cancer Inst 93(24) 1858-1864... 

Asai, J., Takenaka, H., Kusano, K. E, II, M., Luedemann, C., Curry, C., Eaton, E., Iwakura, A., Tsutsumi, Y., Hamada, H., Kishimoto, S., Thorne, T., BCishore, R., and Losordo, D. W. 2006. Topical sonic hedgehog gene therapy accelerates wound healing in diabetes by enhancing endothelial progenitor cell-mediated microvascular remodeling. Circulation, 113,2413-2424. 

The best examples of pleiotropy have been provided by developmental biologists. Two examples illustrate the pleiotropic action of developmental genes. Sonic hedgehog participates in the formation of the different cell types that form the neural tube, in limb development and in somitogenesis, a process by which mesodermic cells aggregate to form bones and muscles. 

Expression of another set of genes establishes the right-left axis and characteristic asymmetries of the body.333-336 In the chick activin 2(3, also a member of the TGF-P family, as well as Nodal and Sonic hedgehog (Shh) participate in control. The gene Pitx2 is a downstream transcription target for this signaling cascade in vertebrates. 

H, Don Is-Keller, II., I lelms, C., Hing, A., Heng, H., Koop,B., Mart indale, D Kommens, J., Tsui, L., and Scherer, S. (1996). Identification of Sonic hedgehog as a candidate gene responsible for holoprosencephaly. iVafitn GmeS. 14,353-356. 

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