Amazing stuff!
"Scientists have uncovered a surprising new healing mechanism in injured cells called cathartocytosis, in which cells "vomit" out their internal machinery to revert more quickly to a stem cell-like state. While this messy shortcut helps tissues regenerate faster, it also leaves behind debris that can fuel inflammation and even cancer. ..."
"When injured, cells have well-regulated responses to promote healing. These include a long-studied self-destruction process that cleans up dead and damaged cells as well as a more recently identified phenomenon that helps older cells revert to what appears to be a younger state to help grow back healthy tissue.
Now, a new study in mice ... reveals a previously unknown cellular purging process that may help injured cells revert to a stem cell-like state more rapidly. The investigators dubbed this newly discovered response cathartocytosis, taking from Greek root words that mean cellular cleansing. ...
As with many shortcuts, this one has potential downsides: According to the investigators, cathartocytosis is fast but messy, which may help shed light on how injury responses can go wrong, especially in the setting of chronic injury. For example, ongoing cathartocytosis in response to an infection is a sign of chronic inflammation and recurring cell damage that is a breeding ground for cancer. In fact, the festering mess of ejected cellular waste that results from all that cathartocytosis may also be a way to identify or track cancer, according to the researchers. ..."
From the highlights and abstract:
"Highlights
• Defining cathartocytosis, an injury-induced process cells use to downscale cellular machinery
• Three-dimensional reconstruction detailing how cells reorganize organelles during paligenosis
• Cathartocytosis and autophagy occur together in paligenosis but are mechanistically distinct
• EPG5 prevents fusion of autophagic compartments with the apical membrane after injury
Summary
Injury causes differentiated cells to undergo massive reprogramming to become proliferative and repair tissue via paligenosis.
Gastric chief cells use paligenosis to reprogram into progenitor-like spasmolytic-polypeptide-expressing metaplasia (SPEM) cells. Stage 1 of paligenosis is the downscaling of mature cell architecture via a process involving lysosomes.
Here, we notice that sulfated glycoproteins are not only digested during paligenosis but also excreted into the gland. Various genetic and pharmacological approaches show that endoplasmic reticulum membranes and secretory granule cargo are also excreted and that the process proceeds in parallel with but is mechanistically independent of autophagy.
Three-dimensional light and electron microscopy demonstrated that excretion occurs via unique, complex, multi-chambered invaginations of the apical plasma membrane. As this lysosome-independent cell cleansing process does not seem to have been priorly described, we termed it “cathartocytosis.” Cathartocytosis allows a cell to rapidly eject excess material without waiting for autophagic and lysosomal digestion, providing for efficient cellular downscaling."
Cells ‘vomit’ waste to promote healing, mouse study reveals (original news release) "Newly discovered purging process in gastric cells hints at how injury recovery can go wrong"
Cathartocytosis: Jettisoning of cellular material during reprogramming of differentiated cells (open access)
Graphical abstract
Figure 2 Focused ion beam scanning electron microscopy demonstrates apical membrane deformation and secreted vesicular material 24 h after injury
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