title: A small molecule restores function to TRPML1 mutant isoforms responsible for mucolipidosis type IV.
abstract: Mucolipidosis type IV (MLIV) is an autosomal recessive lysosomal storage disorder often characterized by severe neurodevelopmental abnormalities and neuro-retinal degeneration. Mutations in the TRPML1 gene are causative for MLIV. We used lead optimization strategies to identify--and MLIV patient fibroblasts to test--small-molecule activators for their potential to restore TRPML1 mutant channel function. Using the whole-lysosome planar patch-clamp technique, we found that activation of MLIV mutant isoforms by the endogenous ligand PI(3,5)P2 is strongly reduced, while activity can be increased using synthetic ligands. We also found that the F465L mutation renders TRPML1 pH insensitive, while F408Δ impacts synthetic ligand binding. Trafficking defects and accumulation of zinc in lysosomes of MLIV mutant fibroblasts can be rescued by the small molecule treatment. Collectively, our data demonstrate that small molecules can be used to restore channel function and rescue disease associated abnormalities in patient cells expressing specific MLIV point mutations.
authors.affiliation: 1] Department of Pharmacy-Center for Drug Research and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität München, Munchen 81377, Germany [2].
authors.forename: Cheng-Chang
authors.initials: CC
authors.lastname: Chen
authors.affiliation: 1] Department of Pharmacy, Ludwig-Maximilians-Universität München, Munchen 81377, Germany [2].
authors.forename: Marco
authors.initials: M
authors.lastname: Keller
authors.affiliation: Department of Biology, Ludwig-Maximilians-Universität München, Munchen 82152, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Hess
authors.affiliation: Institute of Metabolic Disease, Baylor Research Institute, Dallas, Texas, USA.
authors.forename: Raphael
authors.initials: R
authors.lastname: Schiffmann
authors.affiliation: Rudolf-Boehm-Institute for Pharmacology and Toxicolgy, Universität Leipzig, Leipzig 04107, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Urban
authors.affiliation: Department of Pharmacy, Ludwig-Maximilians-Universität München, Munchen 81377, Germany.
authors.forename: Annette
authors.initials: A
authors.lastname: Wolfgardt
authors.affiliation: Rudolf-Boehm-Institute for Pharmacology and Toxicolgy, Universität Leipzig, Leipzig 04107, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schaefer
authors.affiliation: Department of Pharmacy, Ludwig-Maximilians-Universität München, Munchen 81377, Germany.
authors.forename: Franz
authors.initials: F
authors.lastname: Bracher
authors.affiliation: Department of Pharmacy-Center for Drug Research and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität München, Munchen 81377, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Biel
authors.affiliation: Department of Pharmacy-Center for Drug Research and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität München, Munchen 81377, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Wahl-Schott
authors.affiliation: 1] Department of Pharmacy-Center for Drug Research and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität München, Munchen 81377, Germany [2].
authors.forename: Christian
authors.initials: C
authors.lastname: Grimm
mesh_terms: D002478:Cells, Cultured; D055724:Electrophysiological Phenomena; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D008247:Lysosomes / Q000378:metabolism; D009081:Mucolipidoses / Q000235:genetics* / Q000503:physiopathology / Q000517:prevention & control*; D009154:Mutation / Q000235:genetics*; D018408:Patch-Clamp Techniques; D018129:Phosphatidylinositol Phosphates / Q000494:pharmacology*; D020033:Protein Isoforms; D050051:Transient Receptor Potential Channels / Q000187:drug effects* / Q000235:genetics* / Q000502:physiology; D015032:Zinc / Q000378:metabolism
chemical_list: D008024:Ligands; C416674:MCOLN1 protein, human; D018129:Phosphatidylinositol Phosphates; D020033:Protein Isoforms; D050051:Transient Receptor Potential Channels; C106336:phosphatidylinositol 3,5-diphosphate; D015032:Zinc