Constitutive activity of the human TRPML2 channel induces cell degeneration

Shaya Lev, David A. Zeevi, Ayala Frumkin, Vered Offen-Glasner, Gideon Bach, Baruch Minke*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

The mucolipin (TRPML) ion channel proteins represent a distinct subfamily of channel proteins within the transient receptor potential (TRP) superfamily of cation channels. Mucolipin 1, 2, and 3 (TRPML1, -2, and -3, respectively) are channel proteins that share high sequence homology with each other and homology in the transmembrane domain with other TRPs. Mutations in the TRPML1 protein are implicated in mucolipidosis type IV, whereas mutations in TRPML3 are found in the varitint-waddler mouse. The properties of the wild type TRPML2 channel are not well known. Here we show functional expression of the wild type human TRPML2 channel (h-TRPML2). The channel is functional at the plasma membrane and characterized by a significant inward rectification similar to other constitutively active TRPML mutant isoforms. The h-TRPML2 channel displays nonselective cation permeability, which is Ca2+-permeable and inhibited by low extracytosolic pH but not Ca2+ regulated. In addition, constitutively active h-TRPML2 leads to cell death by causing Ca 2+ overload. Furthermore, we demonstrate by functional mutation analysis that h-TRPML2 shares similar characteristics and structural similarities with other TRPML channels that regulate the channel in a similar manner. Hence, in addition to overall structure, all three TRPML channels also share common modes of regulation.

Original languageEnglish
Pages (from-to)2771-2782
Number of pages12
JournalJournal of Biological Chemistry
Volume285
Issue number4
DOIs
StatePublished - 22 Jan 2010

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