Monday, March 5, 2012

Chemistry of our skin: Aquaglyceroporins

Aquaglyceroporins are "membrane proteins that form water channels over cell membranes. They faciliate transport of water and solutes like glycerol or urea." (This document, p. 78) In other words, aquaporins regulate the water flux in our skin (specifically in our epidermis, or outer layer of our skin). They are embedded in our cell membranes to help with the transport of water. The one that interests us is listed as aquaglyceroporin-3, or AQP3 for short.

We don't find AQP3 in our stratum corneum or first layer of our skin - it's found in the basal layer (lowest level in the picture) to just below the stratum corneum. "In the viable epidermis, AQP3 provides a short circuit for water between the base of the epidermis and the SC in order to maintain constant water content in viable epidermis. In addition to its water permeability function, AQP3 is also permeable to solutes such as urea and glycerol, and studies have suggested its role in the transport of these solutes within the epidermis." (Page 78, this document).

Why do we care about AQP3? Because it's interesting, and because it could be the reason you're suffering from dry skin that doesn't seem to get better no matter how much lotion you apply.  "AQP3 is expressed in the basal layer of mammalian skin and is responsible for the epidermal water/glycerol transport. The hydration of SC [stratum corneum], evaluated by high-frequency skin surface conductometry and the estimation of radioactive  3H2O, was reduced in AQP3-deficient mice." (Page 25, this document). What can you do about this dry skin? "Although AQP3 acts as a water channel in the basal keratinocytes, the reduced SC hydration could not be corrected by skin occlusion or exposure to a highly humid environment." (page 25, same document).

So what does this all mean? It means that if you have dry skin thanks to some kind of deficiency in your AQP3 levels, then there's not much you can do. You can apply lotion to soothe the symptoms, but you aren't going to achieve anything more than a superficial reduction in your dry skin.

Join me tomorrow for more fun with skin chemistry!

1 comment:

Lise M Andersen said...

Great post Susan (love the graphics too)