Contributions of Cell Signalling Pathways In The Context of Early Eye Development

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The developmental stages of an organism are vital, as the outcome will influence the organism from the moment it’s born to the moment it dies. Stem cells are the first cells that make up an organism; they are pluripotent giving them the ability to differentiate into any type of cell. Paratore and Sommer suggest that during organogenesis, the ectoderm, mesoderm and endoderm develop into internal organs, and early in this stage the notochord is developed inducing the formation of the neural plate and the neural tube, both important during early eye development. [1] As is suggested by Del Bene and Wittbrodt, a deepening groove in the neural plate gives rise to the optic vesicle, this later contacts the overlying ectoderm inducing a lens …show more content…
Some of these signalling pathways would be Hedgehog, Wnt and BMP’s, all playing a crucial part in the early “stages” of the developing eye.

Hedgehog
The hedgehog signalling pathway is composed of different signalling proteins belonging to the “Hedgehog” family, one of the most common ones being Sonic Hedgehog (Shh). These proteins are secreted morphogens (substance that controls pattern development) that are crucial to early patterning, cell migration and organ and cell differentiation. [4] Shh is secreted at high levels by the notochord, the concentrations of it being at its highest in the floor plate of the neural tube and lowest in the roof plate, where memebers of the TGF-ß family are found. [2] Shh binds to a primary patched (PTCH) receptor that in the absence of Shh inhibits and activates a smoothened (SMO) transmembrane domain G protein-linked protein leading to the transcription of downstream target genes into the nucleus (Fig. 1 [1]). [1,4] Nevertheless, in the presence of Shh, the patched receptor is blocked resulting in the nuclear translocation of Gli and transcriptional activation of target genes (Fig. 1 [2]). [1,4] Some of the many activities of Shh in vertebrate development are the roles that it plays in the patterning of the ventral neural tube and its role in early eye development. As suggested by Kobayashi et. Al. Shh signalling plays a crucial role in the

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