Genome complexity: lysosome cell controls (Introduction)

by David Turell , Friday, April 28, 2017, 18:57 (2554 days ago) @ David Turell

The lysosome was thought to be a minor organelle as a garbage collector. its not. it exhibits major cellular controls:

https://www.quantamagazine.org/20170425-lysosomes-gene-regulation-signaling/?utm_source...

"Lysosomes first drew attention in the 1950s, when the Belgian biochemist Christian de Duve stumbled across the saclike intracellular structures while trying to purify a protein found in rat livers. He named the previously unknown sacs after the Greek for “digestive body” because their contents were highly acidic and filled with enzymes that break down virtually any biomolecule that’s set before them.

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"A critical clue came when the team tracked the protein’s movements within cells. When cells were bathed in amino acid-free media, mTOR seemed to spread evenly throughout the cytoplasm. But if the media contained amino acids, within minutes mTOR moved into distinct clusters at specific locations inside the cell, shepherded there by other proteins called Rag GTPases.

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"In a healthy, well-fed cell, lysosomes have a cornucopia of proteins to break down to their amino acid components, and those amino acids work with proteins on the lysosome surface to anchor mTORC1 and activate it. The mTORC1 in turn keeps cytoplasmic TFEB out of the nucleus. When a cell becomes starved or stressed, mTORC1 drops away from the lysosome and TFEB is freed to bind its targets on the nuclear DNA. Acting as a master sensor of lysosomal function, TFEB turns on genes for more lysosomal enzymes.

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"And the focus on deficiencies inside lysosomes had shifted to the lysosomal membrane and the ways in which it enlists TFEB, mTOR and roughly 200 other identified proteins in a conversation with the rest of the cell.

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"Lysosomes may once have seemed like garbage bins that were “boring on the outside,” Nixon says, but they are increasingly appreciated as regulated signal platforms crucial to cellular health. And as perspectives on the lysosome change, views of the associated biology shift, too. Perera notes that cancer researchers have long wanted to know more about the signals that let malignant cells grow and multiply nonstop, and about how the cells co-opt nutrients. The new view of lysosomes, she says, reveals that these are “all different aspects of the same problem.'”

Comment: this essay shows how a self-contained cell must work. We take out the garbage and the garbage can doesn't care. The can simply takes what we give it. But the organelle that handles cellular garbage can't do that. It has to carefully control when and how it receives garbage to handle it properly. Note how intricate this system is. It has to be designed. It cannot develop stepwise or cells would not survive. It must be in place all at once. Cells are highly active protein factories with byproducts and waste products that cannot be allowed to pile up. Logically, this system had to exist at the start of life or single-celled animals would not survive. Only a planning mind can do this: God.