Expression and characterization of human transient receptor potential melastatin 3 (hTRPM3).
Transient receptor potential (TRP) cation-selective channels are an emerging class of proteins that are involved in a variety of important biological functions including pain transduction, thermosensation, mechanoregulation, and vasorelaxation. Utilizing a bioinformatics approach, we have identified the full-length human TRPM3 (hTRPM3) as a member of the TRP family. The hTRPM3 gene is comprised of 24 exons and maps to human chromosome 9q-21.12. hTRPM3 is composed of 1555 amino acids and possesses the characteristic six-transmembrane domain of the TRP family. hTRPM3 is expressed primarily in kidney and, at lesser levels, in brain, testis, and spinal cord as demonstrated by quantitative RT-PCR and Northern blotting. In situ hybridization in human kidney demonstrated that hTRPM3 mRNA expression is predominantly found in the collecting tubular epithelium. Heterologous expression of hTRPM3 in human embryonic kidney cells (HEK 293) showed that hTRPM3 is localized to the cell membrane. hTRPM3-expressing cells exhibited Ca2+ concentration-dependent Ca2+ entry. Depletion of intracellular Ca2+ stores by lowering extracellular Ca2+ concentration and treatment with the Ca2+-ATPase inhibitor thapsigargin or the muscarinic receptor agonist carbachol further augmented hTRPM3-mediated Ca2+ entry. The nonselective Ca2+ channel blocker, lanthanide gadolinium (Gd3+), partially inhibited hTRPM3-mediated Ca2+ entry. These results are consistent with the hypothesis that hTRPM3 mediates a Ca2+ entry pathway that apparently is distinct from the endogenous Ca2+ entry pathways present in HEK 293 cells.
Lee
Ning
N
Metabolic and Cardiovascular Diseases Drug Discovery, Pharmaceutical Research Institute, Bristol-Myers Squibb Company, Princeton, New Jersey 08543, USA. ning.lee@bms.com
Chen
Jian
J
Sun
Lucy
L
Wu
Shujian
S
Gray
Kevin R
KR
Rich
Adam
A
Huang
Minxue
M
Lin
Jun-Hsiang
JH
Feder
John N
JN
Janovitz
Evan B
EB
Levesque
Paul C
PC
Blanar
Michael A
MA
D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002490:Central Nervous System / Q000502:physiology; D002899:Chromosomes, Human, Pair 9; D005682:Gadolinium / Q000494:pharmacology; D015870:Gene Expression; D006801:Humans; D007473:Ion Channels / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000502:physiology*; D028581:Lanthanoid Series Elements / Q000494:pharmacology; D008297:Male; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000032:analysis; D050053:TRPM Cation Channels; D013737:Testis / Q000502:physiology
D002121:Calcium Channel Blockers; D007473:Ion Channels; D028581:Lanthanoid Series Elements; D012333:RNA, Messenger; D050053:TRPM Cation Channels; C475667:TRPM3 protein, human; D005682:Gadolinium; D002118:Calcium