Wacker SJ, Aponte-Santamaría C, Kjellbom P, Nielsen S, de Groot BL, Rützler M. The identification of novel, high affinity AQP9 inhibitors in an intracellular binding site.
Mol Membr Biol 2013;
30:246-60. [PMID:
23448163 DOI:
10.3109/09687688.2013.773095]
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Abstract
BACKGROUND
The involvement of aquaporin (AQP) water and small solute channels in the etiology of several diseases, including cancer, neuromyelitis optica and body fluid imbalance disorders, has been suggested previously. Furthermore, results obtained in a mouse model suggested that AQP9 function contributes to hyperglycemia in type-2 diabetes. In addition, the physiological role of several AQP family members remains poorly understood. Small molecule inhibitors of AQPs are therefore desirable to further study AQP physiological and pathophysiological functions.
METHODS
The binding of recently established AQP9 inhibitors to a homology model of AQP9 was investigated by molecular dynamics simulations and molecular docking. Putative inhibitor binding sites identified with this procedure were modified by site-directed mutagenesis. Active compounds were measured in a mammalian cell water permeability assay of mutated AQP9 isoforms and tested for changes in inhibitory effects.
CONTROLS
Three independent cell lines were established for each mutated AQP9 isoform and functionality of mutant isoforms was established.
PRINCIPAL FINDINGS
We have identified putative binding sites of recently established AQP9 inhibitors. This information facilitated successful identification of novel AQP9 inhibitors with low micromolar IC50 values in a cell based assay by in silico screening of a compound library targeting specifically this binding site.
SIGNIFICANCE
We have established a successful strategy for AQP small molecule inhibitor identification. AQP inhibitors may be relevant as experimental tools, to enhance our understanding of AQP function, and in the treatment of various diseases.
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