hi there i have a neuroscience question: in the figure below, please explain wha

Question

hi there

i have a neuroscience question:

in the figure below, please explain what is happening. how the neurons and glial are being formed.

also the role of the following:

BMPs

noggin and chordin

TGF betas

sonic hedgehog

proneurs and bHLHs

Formation of neurons and alia 1 Neural induction 2Organizer centers 3 Neural patterning Neuroectoderm Neural tube Ectoderm Noggin/ chordin Ventricle TGF-Bs-O- -Sonic Epidermis hedgehog Dorsal centers Ventral centers Astrog!ogenesis 5 oligodendrogenesis 4 Neurogenesis It's about proportion Proneural Olig1/2 Nkx2.1 Notch -Oroducts bHLH gene Notch/ Proneural Astrocyte precursors Oligodendrocyte precursors Neuronal precursors Astrocytes Oligodendrocytes Neurons NEUROSCIENCE 5e, Figure 22.10 2012 Sinauer Associates, Inc.

Explanation / Answer

Ans. This diagram is a schematic overview of formation of different nervous system cells like neurons, astrocytes and oligodendrocytes from same origin i.e., ectoderm as a result of action of different factors at different levels. It is a case of differentiation of ectoderm into various functional cells of nervous system.

In this diagram it is given there are mainly three steps of differentiation that lead to the formation of particular type of cells.

a. Neural induction: In this case the secretion of BMPs (Bone Morphogenetic Proteins) from ectoderm takes place that may cause differentiation f epidermis. But the inhibition of BMP due to binding of antagonist noggin cause the conversion of neuroectoderm from ectoderm. This is neural induction.

b. Organizing center: Noggin protein also facilitate the formation of organizing center in the forebrain. TGF- beta regulators are the members of BMP family, so they inhibit the formation of ventral centers but facilitate the dorsal center formation.

c. neural patterning: Due to sonic hedgehog there is formation of patterns in the neural tube formed at organizing centre formation. This step is a crucial step as it will allow the formation of various type of precursur cells for formation of various cells.

bHLH gene leads to the induction of neurogenesis, while the notch protein inhibits this process. Similarly presence of olig 1/2 helps in the oligodendrogenesis, while presence of proneural bHLH inhibits this process. On the other hand the presence of Notch nrg leads to the astriogliogenesis, and bHLH inhibits it. In this way we can see it is totally coordinated process and the presence ofg one type of protein cause one process to occur.

Function of :

BMPs : They are moprp[hogens required for the development of the nervous system. changes in BMP signaling governs the formation of central as well as peripheral nervous systems.

noggin and chordin: They are ntagonists of the bone morphogenetic proteins (BMPs).

TGF betas:  It is a protein secreted by T lymphocytes. tinvolve in  control of cell growth, cell proliferation, cell differentiation and apoptosis.

sonic hedgehog: It is a morphogen protein that perform patterning of many systems It is involved in patterning of nervous system also.It induce floor plate and diverse ventral cell types within the neural tube.

proneural bHLHs: Proneural genes have basic-helix-loop-helix transcription factors. They are required for providing neural identity to naïve ectodermal cells (delamination and subsequent neuronal differentiation)

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