The two-pore channel TPCN2 mediates NAADP-dependent Ca(2+)-release from lysosomal stores.
Second messenger-induced Ca(2+)-release from intracellular stores plays a key role in a multitude of physiological processes. In addition to 1,4,5-inositol trisphosphate (IP(3)), Ca(2+), and cyclic ADP ribose (cADPR) that trigger Ca(2+)-release from the endoplasmatic reticulum (ER), nicotinic acid adenine dinucleotide phosphate (NAADP) has been identified as a cellular metabolite that mediates Ca(2+)-release from lysosomal stores. While NAADP-induced Ca(2+)-release has been found in many tissues and cell types, the molecular identity of the channel(s) conferring this release remained elusive so far. Here, we show that TPCN2, a novel member of the two-pore cation channel family, displays the basic properties of native NAADP-dependent Ca(2+)-release channels. TPCN2 transcripts are widely expressed in the body and encode a lysosomal protein forming homomers. TPCN2 mediates intracellular Ca(2+)-release after activation with low-nanomolar concentrations of NAADP while it is desensitized by micromolar concentrations of this second messenger and is insensitive to the NAADP analog nicotinamide adenine dinucleotide phosphate (NADP). Furthermore, TPCN2-mediated Ca(2+)-release is almost completely abolished when the capacity of lysosomes for storing Ca(2+) is pharmacologically blocked. By contrast, TPCN2-specific Ca(2+)-release is unaffected by emptying ER-based Ca(2+) stores. In conclusion, these findings indicate that TPCN2 is a major component of the long-sought lysosomal NAADP-dependent Ca(2+)-release channel.
Zong
Xiangang
X
Center for Integrated Protein Science CIPS-M and Zentrum für Pharmaforschung, Department Pharmazie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, Munich, Germany.
Schieder
Michael
M
Cuny
Hartmut
H
Fenske
Stefanie
S
Gruner
Christian
C
Rötzer
Katrin
K
Griesbeck
Oliver
O
Harz
Hartmann
H
Biel
Martin
M
Wahl-Schott
Christian
C
D000595:Amino Acid Sequence; D000825:Animal Structures / Q000378:metabolism; D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006031:Glycosylation; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology; D052118:Lysosomal-Associated Membrane Protein 1 / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D009249:NADP / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D017386:Sequence Homology, Amino Acid; D019284:Thapsigargin / Q000494:pharmacology; D014162:Transfection; D025262:Vacuolar Proton-Translocating ATPases / Q000037:antagonists & inhibitors; D000097903:Two-Pore Channels
D002118:Calcium; D015220:Calcium Channels; D004791:Enzyme Inhibitors; D052118:Lysosomal-Associated Membrane Protein 1; D009249:NADP; D019284:Thapsigargin; D025262:Vacuolar Proton-Translocating ATPases; C546784:TPCN1 protein, mouse; D000097903:Two-Pore Channels; C546785:TPCN2 protein, mouse; C024376:NAADP