CMMB 403 Lecture Notes - Lecture 7: Sonic Hedgehog, Receptor Tyrosine Kinase, Surface Ectoderm
22 Sep 2018
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Cell to cell signalling pathways part 1. The four most prominent families of paracrine factors functioning during development. Function through the rtk (receptor tyrosine kinase) pathway. There are 3 types of these proteins present in vertebrates, one of them being sonic hedgehog (shh) Function upstream of transcription factors (smad 1 and 5) they activate. Function upstream of two other transcription factors (smad 2 and 3) they activate. Right after development of the neural tube. Notochord expresses shh very strongly, this expression is critical for the proper patterning of the nervous system. Shh protein is diffusible it diffuses up to the neural tube and at the tube, induces the creation of a floor plate. The floor plate also expresses shh, which leads to the production of another type of protein. Signal of shh is critical in creation of motor neurons (shh induces the creation of these neurons) Ectodermal competence and the ability to respond to the optic vesicle.
