… and repressive? I noticed the contraption is named “EZH2O.” Of course, Elkay meant ‘easy H2O,’ but I just took an epigenetics seminar where we learned about EZH2, a key enzyme in the Polycomb Repressive Complex 2 (PRC2). EZH2 is key in catalyzing and maintaining the [tri-methylation if lysine 27 in the tail of histone 3 (written “H3K27me3”)] during mitosis (Hansen et al. 2008). At least I think that’s how it works (if anyone knows better, please correct me if I’m wrong!).

So, real quick, your chromosomes are made up of DNA wrapped around histone proteins. This is essential because with some 3 billion base pairs of DNA, if it weren’t packaged up nicely by histones it would be a HUGE MESS inside your cells. Anyway, these histones have ‘tails’ sticking out that can be modified in ways that basically allow genes to be turned on or off. This is significant because all of your DNA full of the Commands for Life is in every single one of your cells – yet not all genes are expressed. The addition of methyl-groups (methylation) to histone tails (as well as to DNA itself) is associated with gene silencing.

So when your DNA replicates during mitosis, EZH2 binds to H3K27, and slaps that tri-methyl mark to it, effectively telling the gene(s) in the region to ‘shut up’ so they don’t get transcribed (Hansen et al. 2008). This way, your liver cells stay hepatic, your kidney cells renal, and your soul cells funky. It’s apparently also critical in silencing HOXD and other during early development (Tsai et al. 2010). (Again, I’m not a molecular biologist so please someone correct me if I’m wrong!)

Hopefully these new water fountains aren’t part of a bigger epigenetic experiment in which someone’s subtly altering people’s gene expression through malevolent manipulation of methyltransferase…