Thread

The UV index is not the warm sensation of sunlight on bare skin

99 points · 79 comments · evakhoury

Terr_ · 1790113424 · focus · HN ↗
> Sunburn is triggered when your DNA is damaged from light absorption [...] This interferes with protein synthesis and wreaks havoc in your body over time
Not a skin-scientist, but this seems misleading: Sunburn is not caused by some bad DNA floating around, nor damaged cells making making mistakes or pumping out wrong proteins to inflame their neighbors.
Instead, your cells have techniques to measure a variety of risk factors and signals (which does include DNA-molecule weirdness [0]) and when things get too risky the well-behaved ones will self-destruct, to avoid the chance of turning into a cancer.
So the sunburn you see and feel is instead due to cells signalling "something damaged me and I can't be trusted, I'm shutting down, recycle me" to your immune-system, plus the attendant bustle of hazmat-cleanup and increased security-sweeps for cancer-leftovers and other potential causes of the damage.
[0] <a href="https://www.nature.com/articles/newbio241074a0" rel="nofollow">https://www.nature.com/articles/newbio241074a0
1. EA-3167 · 1790120029 · focus · HN ↗
  DNA is the instruction set for protein synthesis. If your DNA is damaged beyond repair that's an issue, and sure apoptosis is the usual result and not cancer. At the same time however when cells die either from the direct impact of DNA damage or apoptosis they both stop working and spill their contents into the area... including signalling molecules that promote inflammation.
  The sunburn you feel isn't a distress signal from cells warning that they can't be trusted, it's tissue death and an inflammatory reaction triggered by a cytokine response.
  1. Terr_ · 1790214665 · focus · HN ↗
    > > [The sunburn you feel is] cells signalling "something damaged me and I can't be trusted, I'm shutting down, recycle me" to your immune-system, plus the attendant bustle of hazmat-cleanup and increased security-sweeps for cancer-leftovers and other potential causes of the damage.cells signalling "something damaged me and I can't be trusted, I'm shutting down, recycle me" to your immune-system, plus the attendant bustle of hazmat-cleanup and increased security-sweeps
    > The sunburn you feel isn't a distress signal from cells warning that they can't be trusted, it's tissue death and an inflammatory reaction triggered by a cytokine response.
    I feel that's more of a restatement than a contradiction.
    The cell shutdown is (eventually) violent and messy, signalling involves cytokines, and the "hazmat and security" metaphor is an inflammation response.

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