Joel Kontinen
There’s a whole lotta shakin' goin' on in our cells every single nanosecond, although we might not notice it. Old cells die off, some are killed, and new ones step in to take their place.
In other words, we learnt to recycle aeons ago.
In 2017, the Nobel Prize in Physiology or Medicine was awarded to Yoshinori Ohsumi, a professor at the Tokyo Institute of Technology, for his work on the mechanisms of autophagy (αὐτόφαγος, autóphagos), a term that means self-eating.
We also have other ways of getting rid of old cells: apoptosis or programmed cell death, and phagocytosis.
A new paper takes a look at the mechanics of phagocytosis or the process of eating cells. Cells called macrophages or ‘big eaters’ (μακρος, makros ‘large’ and φαγειν. phagein ‘eat’) devour damaged cells.
An article in Science Daily gives the gist of what happens:
“Phagocytosis is a biological mechanism whereby specialized cells ingest and degrade old, dead, or damaged cells to prevent tissue damage due to their accumulation. But phagocytosis appears to also have an educational role. Scientists at the Centro Nacional de Investigadores Cardiovasculares Carlos III (CNIC) report in the Journal of Experimental Medicine that phagocytosis not only eliminates useless cells, but also 'educates' macrophages, the immune cells that carry it out.”
It all sounds like intelligent design. The Darwinian blind watchmaker could hardly have envisioned such a move.
The article goes on to say:
“Macrophages are immune cells that normally are distributed throughout all body tissues and work to rid the organism of any type of biological material that needs to be eliminated, from injurious material such as glass particles and viruses to proteins or larger complexes that appear, for example, during embryonic development. Macrophages are also important for eliminating dangerous cells, for example, cancer cells or lymphocytes that recognize self molecules and that could cause an autoimmune immune disorder, such as those found in patients with lupus of rheumatoid arthritis.”
The researchers noticed that there are different kinds of “phagocytosing macrophages” in different tissues.
And there’s more:
“The act of ingesting expired cells educates the immune system in how to maintain tissues in a clean and healthy state, and that macrophages play a very important role in this process. The study identifies in detail the molecules that carry out important tasks in the phagocytic process in each tissue, from the gut to the liver and bone marrow. Surprisingly, the researchers found that each tissue has its own specific molecular toolkit for eliminating unwanted cells.”
There’s no shortage of wonders in our cells: they not only demolish but also build. For instance, they make 100,000 ribosomes every single hour.
Ribosomes are “ingeniously designed” nanomachines.
Complexity does not just happen; it has to be designed.
Source:
Centro Nacional de Investigaciones Cardiovasculares. 2017. Cell 'canibalism' [sic] educates our defenses. Science Daily (3 May).
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