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"exec" writes:

Arthur T Knackerbracket has found the following story:

Scientists at the University of Virginia School of Medicine have discovered a strange new organelle inside our cells that helps to prevent cancer by ensuring that genetic material is sorted correctly as cells divide.

The researchers have connected problems with the organelle (a subcellular structure) to a subset of breast cancer tumors that make lots of mistakes when segregating chromosomes. Excitingly, they found their analysis offered a new way for doctors to sort patient tumors as they choose therapies. They hope these insights will allow doctors to better personalize treatments to best benefit patients—sparing up to 40% of breast cancer patients, for example, a taxing treatment that won't be effective.

"Some percentage of women get chemotherapy drugs for breast cancer that are not very effective. They are poisoned, in pain and their hair falls out, so if it isn't curing their disease, then that's tragic," said researcher P. Todd Stukenberg of UVA's Department of Biochemistry and Molecular Genetics and the UVA Cancer Center. "One of our goals is to develop new tests to determine whether a patient will respond to a chemotherapeutic treatment, so they can find an effective treatment right away."

The organelle Stukenberg and his team have discovered is essential, but ephemeral. It forms only when needed to ensure chromosomes are sorted correctly and disappears when its work is done. That's one reason scientists haven't discovered it before now.

Another reason is its mind-bending nature: Stukenberg likens it to a droplet of liquid that condenses within other liquid. "That was the big 'wow' moment, when I saw that on the microscope," he said.

These droplets act as mixing bowls, concentrating certain cellular ingredients to allow biochemical reactions to occur in a specific location. "What's exciting is that cells have this new organelle and certain things will be recruited into it and other things will be excluded," Stukenberg said. "The cells enrich things inside the droplet and, all of a sudden, new biochemical reactions appear only in that location. It's amazing."

It's tempting to think of the droplet like oil in water, but it's really the opposite of that. Oil is hydrophobic—it repels water. This new organelle, however, is more sophisticated.

"It's more of a gel, where cellular components can still go in and out, but it contains binding sites that concentrate a small set of the cell's contents," Stukenberg explained. "Our data suggests this concentration of proteins is really important. I can get complex biochemical reactions to occur inside a droplet that I've been failing to reconstitute in a test tube for years. This is the secret sauce I've been missing."

Stukenberg and his colleagues described their latest findings in the scientific journal Nature Cell Biology.

Prasad Trivedi et al. The inner centromere is a biomolecular condensate scaffolded by the chromosomal passenger complex, Nature Cell Biology (2019). DOI: 10.1038/s41556-019-0376-4

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