Identification of compounds enhancing Aqp4 stop codon readthrough

An unusual stop codon readthrough event generates a conserved C-terminally elongated variant of the water channel protein Aquaporin 4 (AQP4). In the brain, AQP4 is astrocyte-specific, required for normal functioning of the glymphatic system, and involved in the clearance of the Alzheimers associated protein Amyloid beta. Further, the readthrough variant is localized exclusively perivascularly, and the perivascular pool of AQP4 is reduced in Alzheimers and several other neurological diseases. However, there are currently no means of increasing or restoring the perivascular pool AQP4. Here we identify a compound that can enhance Aqp4 stop codon readthrough. We screened 2600 compounds, mostly approved drugs and pharmacologically active natural compounds, using a luciferase reporter system. 28 candidate lead compounds were then subjected to a variety of secondary screening steps using orthogonal reporter systems and characterizing dose-response activities. Finally, we tested the top compounds abilities to generate readthrough of the endogenous Aqp4 transcript, identifying Apigenin as an enhancer of this biological phenomenon. This compound can allow modulation of readthrough in experimental systems, mechanistic studies of programmed readthrough, and suggests the potential for modulating Alzheimers disease through pharmacological enhancement of perivascular AQP4.