title: TRPV4 partially participates in proliferation of human brain capillary endothelial cells.
abstract: OBJECTIVE
  The vanilloid type 4 transient receptor potential channel (TRPV4) is a potential environmental sensor to multiple stimuli in many types of cells. In this study, we show that TRPV4 activated by 4α-phorbol 12,13-didecanoate (4αPDD) and hypo-osmotic stimulation (HOS) is a regulator of intracellular calcium ([Ca(2+)](i)) in human brain capillary endothelial cells (HBCEs), and its activation can partially regulate cell proliferation of HBCEs.
  
  
  METHODS
  The expression of TRPV4 in HBCEs was analyzed at the mRNA and protein levels. The function of TRPV4 in HBCEs was evaluated using a TRPV4 agonist, 4αPDD, and HOS while measuring [Ca(2+)](i) and membrane currents.
  
  
  RESULTS
  Analysis of the mRNA transcripts of the TRPV subfamily revealed that TRPV2 and TRPV4 were expressed in HBCEs. Immunoreactivity to the TRPV4 protein was also detected in HBCEs, which were positively stained by von Willebrand factor and CD31. When 4αPDD was applied, [Ca(2+)](i) in HBCEs was elevated in a concentration-dependent manner. In addition, exposure of HBCEs to HOS at 228mOsm induced an elevation of [Ca(2+)](i). Application of 4αPDD also activated non-selective cation currents (NSCCs). Pretreatment of HBCEs with short interference RNA targeting TRPV4 (siRNA) significantly reduced the 4αPDD-induced elevation of [Ca(2+)](i). When HBCEs were treated for 24h with concentrations of 4αPDD between 0.3 and 3 μM, the cell proliferation was potentiated in a concentration-dependent manner. The potentiation was partially inhibited in HBCEs treated with siRNA.
  
  
  CONCLUSIONS
  These data suggest that endogenous TRPV4, which functions as a regulator of [Ca(2+)](i) in HBCEs, partially controls cell proliferation.
authors: Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, 1-100 Kusumoto, Chikusa, Nagoya 464-8650, Japan.
authors: Noriyuki
authors: N
authors: Hatano
authors: Hiroka
authors: H
authors: Suzuki
authors: Yuka
authors: Y
authors: Itoh
authors: Katsuhiko
authors: K
authors: Muraki
mesh_terms: D001921:Brain / Q000098:blood supply* / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D002118:Calcium / Q000378:metabolism*; D002196:Capillaries / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D018929:Cell Culture Techniques; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008564:Membrane Potentials / Q000187:drug effects; D009994:Osmolar Concentration; D010704:Phorbols / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012430:Ruthenium Red / Q000494:pharmacology; D050916:TRPV Cation Channels / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: C517592:4alpha-phorbol 12,13-didecanone; D010704:Phorbols; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D050916:TRPV Cation Channels; C416986:TRPV4 protein, human; D012430:Ruthenium Red; D002118:Calcium