Discovery of lipophilic two-pore channel agonists.

Gerndt, Susanne; Krogsaeter, Einar; Patel, Sandip; Bracher, Franz; Grimm, Christian

Two pore channels (TPCs) have been a hot topic in recent literature. Their involvement in various diseases like viral infections and cancer is of great interest for drug research. Due to their localization in the endo-lysosomal system and the lack of cell permeable activators, complex techniques were required for studying channel functions. Here we review the first published lipophilic small molecule activators of TPCs. In independent high-throughput screens, several new agonists were discovered, which now allow simple and fast investigation of TPCs in more detail in intact cells and in vivo. Zhang et al. identified tricyclic and phenothiazine anti-depressants as TPC1 and 2 activators by screening a library of approved drugs. In contrast, Gerndt et al. screened an extensive compound library with mostly new chemotypes and drug structures. The latter resulted in two structurally distinct high affinity agonists, which are able to selectively activate TPC2 in either an NAADP- or PI(3,5)P2 -like manner. Here, we discuss the advantages and drawbacks of the identified molecules and their structural features. The versatility by which TPCs can be activated indicates many opportunities for future studies.