Travis
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- Joined
- Jul 14, 2016
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- 3,189
Interesting. When read an article on the prostaglandin D synthase enzyme, I noticed that it's strongest ligands were all-trans-retinoid acid, cis-retinaldehyde, and bilirubin—a metabolite of heme. This made me imagine that prostaglandin D was in some how responsible for maintaining heme levels, and also shows how all-trans-retinoid acid occupies a central role in eicosanoid signalling. You would think that all-trans-retinoid acid would be a good inhibitor of prostaglandin D synthase, but it does so many other things that it could be a bad idea to use it for this purpose—too nonspecific, as well as too highly-active elsewhere."Recently, Schug et al. showed that when the cellular retinoic acid binding protein-II (CRABP-II) expression levels were higher than FABP5 in the cells, retinoic acid (RA) bound to CRABP- II. Subsequently, CRABP-II relocated to the nucleus and delivered RA to RAR, resulting in inhibition of cell proliferation and induction of apoptosis. On the contrary, when the FABP5 to CRABP-II ratio is high, RA serves as a physiological ligand for PPARδ, which induces cell survival and proliferation. Therefore, it is important to identify the cytosolic ligand binding proteins and the expression levels of the proteins for defining the physiological effects of ligands.
The Role of PPARs in Cancer
If retinoid acid fits well in the prostaglandin D synthase enzyme, and is a ligand for PPARδ, then it would be easy to imagine that prostaglandin D₂ is a ligand for PPARδ.
Where does prostaglandin D₂ bind? Nobody seems to know.. . .