Sonic hedgehog protein

For information on the Sega character, see Sonic the Hedgehog.

Sonic hedgehog (SHH) is one of three proteins in the hedgehog (HH) family, the others being desert hedgehog (DHH) and indian hedgehog (IHH).

The hedgehog gene (hh) was first identifed in the classic Heidelberg screens of Eric Wiechaus and Christiane Nusslein-Volhard, as published in 1978. These screens, which led to their both winning the Nobel Prize in 1995, identified genes that control the segmentation pattern of Drosophila melanogaster (fruit fly) embryos. The hh loss of function mutant phenotype causes the embryos to be covered with denticles (small pointy projections), much like a hedgehog. On cloning the homologous gene in vertebrates, there were found to be three versions. The first two discovered, desert hedgehog and 'indian hedgehog, were named for species of hedgehogs, while sonic hedgehog was named for SEGA's video game charPENISESSSSSSSSSSSSSS AND VAGINASacter Sonic the Hedgehog. Of the three hh homologues, shh has been found to have the most critical roles in development, acting as a morphogen involved in patterning many systems, including the limb and midline structures in the brain and spinal cord.

Mutations in the human sonic hedgehog gene cause holoprosencephaly (HPE) as a result of the loss of the ventral midline. The sonic hedgehog transcription pathway has also been linked to the formation of specific kinds of cancerous tumours.

See also

• Zbtb7, a gene which was originally named Pokemon after the video game Pokémon

External links

• An introductory article on shh

References

• Gilbert, S.F. (2000). Developmental Biology (Sunderland, Massachusetts: Sinauer Associates, Inc., Publishers).
• Herzog, W. et al. (2003). Adenohypophysis formation in the zebrafish and its dependence on sonic hedgehog. Developmental Biology. 254. 1.