title: Inhibition of the human epithelial calcium channel TRPV6 by 2-aminoethoxydiphenyl borate (2-APB).
abstract: TRPV6, a highly calcium-selective member of the transient receptor potential (TRP) channel superfamily, is a major pathway for calcium absorption in the fetal and adult body. It is expressed abundantly in the duodenum, the placenta and exocrine tissues. TRVP6 was postulated to contribute to store-operated calcium channel (SOC) activity in certain cell types such as exocrine cells. In this study, we tested 2-APB, a widely used SOC inhibitor on human TRPV6 (hTRPV6) activity using fluorescence imaging, patch clamp and radioactive tracer techniques in transiently and stably transfected HEK293 cells. We found that the basal calcium and cadmium influx was higher in HEK293 cells transfected with hTRPV6 than in non-transfected cells. 2-APB inhibited hTRPV6 activity in both transient and stably transfected cells. This effect was slightly sensitive toward extracellular calcium. The extracellular sodium concentration did not affect the inhibition of hTRPV6 by 2-APB. However, N-methyl-d-glucamine significantly diminished the inhibitory effect of 2-APB presumably through direct interaction with this compound. Furthermore, 2-APB inhibited the activity of TRPV6 orthologs but not human TRPV5. 2-APB may serve as a parental compound for the development of therapeutic strategies specifically targeting the hTRPV6 calcium channel.
authors.affiliation: Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland. gergely.kovacs@ibmm.unibe.ch
authors.forename: Gergely
authors.initials: G
authors.lastname: Kovacs
authors.forename: Nicolas
authors.initials: N
authors.lastname: Montalbetti
authors.forename: Alexandre
authors.initials: A
authors.lastname: Simonin
authors.forename: Tamas
authors.initials: T
authors.lastname: Danko
authors.forename: Bernadett
authors.initials: B
authors.lastname: Balazs
authors.forename: Akos
authors.initials: A
authors.lastname: Zsembery
authors.forename: Matthias A
authors.initials: MA
authors.lastname: Hediger
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001896:Boron Compounds / Q000494:pharmacology*; D002104:Cadmium / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects*; D004847:Epithelial Cells / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D051381:Rats; D016415:Sequence Alignment; D050916:TRPV Cation Channels / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014162:Transfection
chemical_list: D001896:Boron Compounds; D050916:TRPV Cation Channels; C120776:TRPV6 channel; D002104:Cadmium; C109986:2-aminoethoxydiphenyl borate; D002118:Calcium