BIO380H5 Lecture Notes - Lecture 11: Prenatal Development, Inner Cell Mass, Cdx2
Notes
1st Hour
SS9 (slide 21)
Mechanisms of ICM Pluripotency
1. Cells in the Inner cell mass
a. Cells that are inside the embryo and are going to form most of the cells of the body
2. How do cells in ICM maintain pluripotency?
a. Trophectoderm cells are polar
i. Directionality to their properties
ii. Apicobasal axis
1. Localized expression of certain proteins
a. These proteins are found on the apical side
i. PAR & aPKC
2. These proteins are compatible to and bind to Amot
a. Inhibit amot
b. Amot is an essential factor for the Hippo kinase pathway
3. Inhibition of Amot
a. Results in Yap/Taz-TEAD transcription factors to allow
transcription to occur
b. This results in expression of Cdx2
i. Important
ii. Cdx2 is responsible for trophectoderm differentiation
4. Hippo Kinase pathway
a. Purpose is to intern the process
iii. E-cadherin
1. Cell-to-cell adhesion
2. Is located on the basolateral area
3. E-cadherin homophilic adherens junctions
iv. Amot is not inhibited when bound to the E-cadherin
1. The hippo kinase pathway is not inhibited
2. The Yap/Taz TEAD is inhibited
a. No longer expression of Cdx2
i. The factors of trophectoderm cells will no longer be
found in the ICM
3. The Oct4 Tx factor is now essential for the expression of Pluripotency
GRN
a. 2 options
i. Retain Oct 4
1. Primordial germ cells
ii. Lose Oct 4
1. Epiblast (embryo)
b. If the cell was divided in vertical (parallel to apicobasal axis)
i. Both daughter cells will have symmetrical factors
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