title: Endogenous expression of TRPV5 and TRPV6 calcium channels in human leukemia K562 cells.
abstract: In blood cells, changes in intracellular Ca(2+) concentration ([Ca(2+)](i)) are associated with multiple cellular events, including activation of cellular kinases and phosphatases, degranulation, regulation of cytoskeleton binding proteins, transcriptional control, and modulation of surface receptors. Although there is no doubt as to the significance of Ca(2+) signaling in blood cells, there is sparse knowledge about the molecular identities of the plasmalemmal Ca(2+) permeable channels that control Ca(2+) fluxes across the plasma membrane and mediate changes in [Ca(2+)](i) in blood cells. Using RNA expression analysis, we have shown that human leukemia K562 cells endogenously coexpress transient receptor potential vanilloid channels type 5 (TRPV5) and type 6 (TRPV6) mRNAs. Moreover, we demonstrated that TRPV5 and TRPV6 channel proteins are present in both the total lysates and the crude membrane preparations from leukemia cells. Immunoprecipitation revealed that a physical interaction between TRPV5 and TRPV6 may take place. Single-channel patch-clamp experiments demonstrated the presence of inwardly rectifying monovalent currents that displayed kinetic characteristics of unitary TRPV5 and/or TRPV6 currents and were blocked by extracellular Ca(2+) and ruthenium red. Taken together, our data strongly indicate that human myeloid leukemia cells coexpress functional TRPV5 and TRPV6 calcium channels that may interact with each other and contribute into intracellular Ca(2+) signaling.
authors.affiliation: Institute of Cytology RAS, St. Petersburg 194064, Russia.
authors.forename: Svetlana B
authors.initials: SB
authors.lastname: Semenova
authors.forename: Irina O
authors.initials: IO
authors.lastname: Vassilieva
authors.forename: Alla F
authors.initials: AF
authors.lastname: Fomina
authors.forename: Andrey L
authors.initials: AL
authors.lastname: Runov
authors.forename: Yuri A
authors.initials: YA
authors.lastname: Negulyaev
mesh_terms: D002118:Calcium / Q000493:pharmacokinetics; D015220:Calcium Channels / Q000235:genetics* / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D007202:Indicators and Reagents / Q000493:pharmacokinetics; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology*; D008564:Membrane Potentials / Q000502:physiology; D018408:Patch-Clamp Techniques; D012333:RNA, Messenger / Q000378:metabolism; D012430:Ruthenium Red / Q000493:pharmacokinetics; D050916:TRPV Cation Channels / Q000235:genetics* / Q000378:metabolism
chemical_list: D015220:Calcium Channels; D007202:Indicators and Reagents; D012333:RNA, Messenger; D050916:TRPV Cation Channels; C492239:TRPV5 protein, human; C422827:TRPV6 protein, human; D012430:Ruthenium Red; D002118:Calcium