Early embryology; controls over stem cells (Introduction)

by David Turell , Thursday, July 23, 2020, 19:56 (1584 days ago) @ David Turell

Complex controlling molecules and genes are described:

https://phys.org/news/2020-07-self-eating-stem-cells-key-regenerative.html

"The new preclinical study, for the first time, shows how the stem cells keeps CMA at low levels to promote that self-renewal, and when the stem cell is ready, it switches that suppression off to enhance CMA, among other activities, and differentiate into specialized cells.

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"Autophagy is a cell-eating mechanism necessary for survival and function of most living organisms. When cells self-eat, the intracellular materials are delivered to lysosomes, which are organelles that help break down these materials. There are a few forms of autophagy. However, unlike the other forms, which are present in all eukaryotic cells, CMA is unique to mammals. To date, the physiological role of CMA remains unclear.

"Using metabolomic and genetic laboratory techniques on the embryonic stem cells of mice, the researchers sought to better understand significant changes that took place during their pluripotent state and subsequent differentiation.

"They found that CMA activity is kept at a minimum due to two cellular factors critical for pluripotency—Oct4 and Sox2—that suppresses a gene known as LAMP2A, which provides instructions for making a protein called lysosomal associated membrane protein-2 necessary in CMA. The minimal CMA activity allows stem cells to maintain high levels of alpha-ketoglutarate, a metabolite that is crucial to reinforce a cell's pluripotent state, the researchers found.

"When it's time for differentiation, the cells begin to upregulate CMA due to the reduction in Oct4 and Sox2. Augmented CMA activity leads to the degradation of key enzymes responsible for the production of alpha-ketoglutarate. This leads to a reduction in alpha-ketoglutarate levels as well as an increases in other cellular activities to promote differentiation. These findings reveal that CMA and alpha-ketoglutarate dictate the fate of embryonic stem cells.

"Embryonic stem cells are often called pluripotent due to their remarkable ability to give rise to every cell type in the body, except the placenta and umbilical cord. Embryonic stem cells not only provide a superb system to study early mammalian development, but also hold great promise for regenerative therapies to treat various human disorders."

Comment: as usual a complex, highly controlled system, obviously designed. The better we understand it, the better we can correct errors.