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Intracellular Zinc Dyshomeostasis Caused by a Disrupted TRPML1‐TMEM163 Protein Interaction
Author(s) -
Silva Joshua,
Cuajungco Math
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.566.5
Subject(s) - intracellular , hek 293 cells , microbiology and biotechnology , subcellular localization , mutant , biology , extracellular , internalization , transport protein , chemistry , biotinylation , biochemistry , cell , receptor , cytoplasm , gene
Dysfunctional Mucolipin‐1 (TRPML1) ion channel protein causes the human lysosomal storage disorder Mucolipidosis type IV (MLIV). Cells affected by MLIV display higher intracellular zinc levels compared to normal cells; however, the mechanism behind this zinc accumulation is unknown. We recently identified a putative zinc transporter called transmembrane‐163 protein (TMEM163) as an interacting partner for TRPML1. We hypothesize that TMEM163′s interaction with TRPML1 influences its subcellular localization. We also propose that the interaction between the two proteins regulates intracellular zinc homeostasis. To examine their functional relationship, we created N‐terminus deletion mutants of TMEM163. Co‐immunoprecipitation shows disruption of TRPML1 binding to the deletion mutants compared against wild‐type (WT) TMEM163. Cell surface biotinylation reveals that plasma membrane (PM) localization of TMEM163 mutants increased upon co‐expression with TRPML1 in human embryonic kidney (HEK)‐293 cells, while WT TMEM163 PM localization decreases with co‐expressed TRPML1, suggesting that TRPML1 influences TMEM163′s internalization. Spectrofluorometric analysis of HEK‐293 cells co‐expressing TMEM163 mutants and TRPML1 shows an increase in intracellular zinc levels relative to control when the cells are transiently exposed to zinc. Overall, these data suggest that the loss of TMEM163 protein interaction with TRPML1 results in its abnormal subcellular localization, which consequently affects intracellular zinc homeostasis. Future studies characterizing the role of TMEM163 on MLIV pathology could further explain the contribution of zinc in progressive cell death and open new research avenues to develop potential therapies for the disease.