Developmental Signals - Sonic hedgehog

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Introduction

(SHH) A secreted growth factor that binds patched (ptc) receptor on cell membrane. This protein has many different functions in different tissues of the developing embryo, the main role would be of establishing "pattern". SHH name derives from homology to the original fruitfly (drosophila) "hedgehog" mutation, where these flies have hairs located in regions (ventral) which are normally hair-free, and therefore have a disrupted body pattern.


Sonic Hedgehog (SHH) was isolated by homology to the Hh gene. SHH is a true signaling switch used in differentiating subpopulations of cells throughout the embryo. Depending on where the signal is being secreted, how far away the responsive cell population is and how SHH is proteolytically cleaved, will determine SHH function. SHH binds to the membrane receptors Patched (ptc) and BOC/CDON.

Nomenclature note lower case shh for other species, upper case SHH in humans.

Functions

Developmental patterning signal.

Neural

SHH is secreted by the notochord, ventralizes the neural tube, inducing the floor plate and motor neurons.

  • neural crest cell survival in the foregut endoderm of jaw development PNAS


Limb

SHH is secreted by the zone of polarizing activity (ZPA) organizing limb axis formation.

Other

SHH has still others roles in organ development in lung, pancreas.

Signaling pathway

The secreted protein binds to the cell surface membrane protein the patched receptor (ptc).

Links


Cite this page: Hill, M.A. (2019, August 21) Embryology Developmental Signals - Sonic hedgehog. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Developmental_Signals_-_Sonic_hedgehog

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© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G