Biochemical controls: how age is controlled (Introduction)

by David Turell , Monday, January 08, 2024, 17:35 (111 days ago) @ David Turell

By mitochondrial communications:

https://www.quantamagazine.org/cells-across-the-body-talk-to-each-other-about-aging-202...

"Recently, a set of papers documented a new biochemical pathway that regulates aging, one based on signals passed between mitochondria, the organelles best known as the powerhouse of the cell. Working with worms, the researchers found that damage to mitochondria in brain cells triggered a repair response that was then amplified, setting off similar reactions in mitochondria throughout the worm’s body. The effect of this repair activity was to extend the organism’s life span: The worms with repaired mitochondrial damage lived 50% longer.

"What’s more, cells in the germline — the cells that produce eggs and sperm — were central to this anti-aging communication system. It’s a finding that adds new dimensions to the fertility concerns implied when people talk about aging and their “biological clock.”

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"The research builds on a recent body of work that suggests that mitochondria are social organelles that can talk to one another even when they are in different tissues. In essence, the mitochondria function as cellular walkie-talkies, sending messages throughout the body that influence the survival and life span of the entire organism.

“'The important thing here is that in addition to genetic programs, there is also a very important factor to regulate aging, which is the communication between tissues,” said David Vilchez, who studies aging at the University of Cologne and was not involved in the new research.

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"Dillin had assumed that defective mitochondria would hasten death rather than prolong life — after all, mitochondria are central to cell functioning. Yet for some reason, gumming up the smooth functioning of the mitochondria compelled the worms to live longer.

"More intriguing was the fact that damaged mitochondria in the worms’ nervous system seemed to be driving the effect. “It really says that some mitochondria are more important than others,” said Dillin, who is now a professor at the University of California, Berkeley. “The neurons dictate this over the rest of the organism, and that was really surprising.”

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"When things go awry, such as when some components are missing or misfolded, mitochondria activate a stress response, known as the unfolded protein response, which delivers repair enzymes to help the complexes assemble properly and restore mitochondrial function. In this way, the unfolded protein response keeps cells healthy.

"Dillin expected this process to unfold only inside the neurons with damaged mitochondria. Yet he observed that cells in other tissues of the worm’s body also turned on repair responses even though their mitochondria were intact.

"It’s this repair activity that helped the worms live longer. Like taking a car to a mechanic regularly, the unfolded protein response seemed to keep cells in good running order and function as anti-aging detailing. What remained mysterious was how this unfolded protein response was communicated to the rest of the organism.

"After some investigation, Dillin’s team discovered that the mitochondria in stressed neurons were using vesicles — bubblelike containers that move materials around the cell or between cells — to carry a signal called Wnt beyond the nerve cells to other cells in the body. Biologists already knew that Wnt plays a role in setting up the body pattern during early embryonic development, during which it also triggers repair processes like the unfolded protein response. Still, how could Wnt signaling, when turned on in an adult, avoid activating the embryonic program?

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"That result suggested to him that germline cells play critical roles in relaying the Wnt signal between the nervous system and tissues throughout the rest of the body.

“'The germline is absolutely essential for this,” Dillin said. It isn’t clear, however, whether the germline mitochondria act as amplifiers, receiving the signal from the brain’s mitochondria and transmitting it to other tissues, or if the receiving tissues are “listening” for signals from both sources.

"Either way, the strength of the germline signal regulates the organism’s life span, Dillin said. As a worm ages, the quality of its eggs or sperm declines — what we refer to as the ticking of a biological clock. The decline is also reflected in the germ cells’ changing ability to transmit signals from the brain’s mitochondria, he suggested. As the worm grows older, its germline transmits the repair signal less effectively, and so its body declines, too."

Comment: ageing is a built-in process to make room for future individuals. Another evidence for design.