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Sex and the single cell

Sex chromosomes in every cell of the body exert widespread and sometimes unexpected effects.

It was the mouse equivalent of the midnight munchies. Instead of sleeping normally, Karen Reue’s lab mice were waking early and nibbling on extra snacks, which was making them obese. On investigation, she was surprised to find that the probable reason for this out-of-hours feeding was the genetic sex of their cells — the number and kind of sex chromosomes they contain. “It wasn’t at all what we expected,” says Reue, a geneticist at the University of California, Los Angeles (UCLA).

“There is a huge consequence to having two X chromosomes versus an X and a Y.

The idea that our body cells have a ‘sex’, and that this property has consequences for our health, has taken biologists by surprise. Experiments performed in the mid-twentieth century had implied that the hormones produced by the ovaries or testes were the source of physiological differences between males and females. But Reue’s findings are part of a growing body of evidence showing that hormones are only part of the story. It now seems that the genetic sex of cells is crucial too. Cellular sex may also help to explain why women and men have different susceptibilities to conditions such as obesity, heart disease, neurodegeneration, autoimmunity and cancer, and why such conditions can behave differently in the two sexes. Certainly, when it comes to metabolism, “there is a huge consequence to having two X chromosomes versus an X and a Y throughout your whole body,” says Reue…

To read more, click here: Nature Outlook article on cellular sex (5th October 2017)