Expression and association of TRPC subtypes with Orai1 and STIM1 in human parathyroid.
The mechanism behind Ca(2)(+) entry into the parathyroid cells has been widely debated, and the molecular identities of the responsible ion channels have not been established yet. In this study, we show that the parathyroid cells lack voltage-operated Ca(2)(+) channels. Passive store depletion by thapsigargin, on the other hand, induces a large non-voltage-activated non-selective cation current. The increase in intracellular Ca(2)(+) caused by thapsigargin is attenuated by 2-aminoethoxydiphenyl borate, a blocker of store-operated Ca(2)(+) entry (SOCE). Candidate molecules for non-voltage-operated Ca(2)(+) signaling were investigated. These included members of the transient receptor potential canonical (TRPC) ion channel family, as well as Ca(2)(+) release-activated Ca(2)(+) modulator 1 (Orai1) and stromal interaction molecule 1 (STIM1) that are key proteins in the SOCE pathway. Using RT-PCR screening, quantitative real-time PCR, and western blot, we showed expression of TRPC1, TRPC4, and TRPC6; Orai1; and STIM1 genes and proteins in normal and adenomatous human parathyroid tissues. Furthermore, co-immunoprecipitation experiments demonstrated a ternary complex of TRPC1-Orai1-STIM1, supporting a physical interaction between these molecules in human parathyroid.
Lu
Ming
M
Departments of Molecular Medicine and Surgery Oncology-Pathology, Karolinska Institutet, Karolinska University Hospital L1:03, 171 76 Stockholm, Sweden.
Bränström
Robert
R
Berglund
Erik
E
Höög
Anders
A
Björklund
Peyman
P
Westin
Gunnar
G
Larsson
Catharina
C
Farnebo
Lars-Ove
LO
Forsberg
Lars
L
D000236:Adenoma / Q000378:metabolism; D001896:Boron Compounds / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D000071740:ORAI1 Protein; D010280:Parathyroid Glands / Q000187:drug effects / Q000378:metabolism*; D010282:Parathyroid Neoplasms / Q000378:metabolism; D000071737:Stromal Interaction Molecule 1; D050052:TRPC Cation Channels / Q000235:genetics / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology
D001896:Boron Compounds; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D000071740:ORAI1 Protein; C510746:ORAI1 protein, human; C103530:STIM1 protein, human; D000071737:Stromal Interaction Molecule 1; D050052:TRPC Cation Channels; D019284:Thapsigargin; C109986:2-aminoethoxydiphenyl borate; D002118:Calcium