TY - JOUR
T1 - Constitutive activity of the human TRPML2 channel induces cell degeneration
AU - Lev, Shaya
AU - Zeevi, David A.
AU - Frumkin, Ayala
AU - Offen-Glasner, Vered
AU - Bach, Gideon
AU - Minke, Baruch
PY - 2010/1/22
Y1 - 2010/1/22
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=77449137885&partnerID=8YFLogxK
U2 - 10.1074/jbc.M109.046508
DO - 10.1074/jbc.M109.046508
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C2 - 19940139
AN - SCOPUS:77449137885
SN - 0021-9258
VL - 285
SP - 2771
EP - 2782
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 4
ER -