An NAADP-gated two-pore channel targeted to the plasma membrane uncouples triggering from amplifying Ca2+ signals.
Nicotinic acid adenine dinucleotide phosphate (NAADP) is a ubiquitous messenger proposed to stimulate Ca(2+) release from acidic organelles via two-pore channels (TPCs). It has been difficult to resolve this trigger event from its amplification via endoplasmic reticulum Ca(2+) stores, fuelling speculation that archetypal intracellular Ca(2+) channels are the primary targets of NAADP. Here, we redirect TPC2 from lysosomes to the plasma membrane and show that NAADP evokes Ca(2+) influx independent of ryanodine receptors and that it activates a Ca(2+)-permeable channel whose conductance is reduced by mutation of a residue within a putative pore. We therefore uncouple TPC2 from amplification pathways and prove that it is a pore-forming subunit of an NAADP-gated Ca(2+) channel.
Brailoiu
Eugen
E
Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA.
Rahman
Taufiq
T
Churamani
Dev
D
Prole
David L
DL
Brailoiu
G Cristina
GC
Hooper
Robert
R
Taylor
Colin W
CW
Patel
Sandip
S
D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology*; D008247:Lysosomes / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009249:NADP / Q000031:analogs & derivatives* / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics / Q000378:metabolism; D000097903:Two-Pore Channels
D002118:Calcium; D015220:Calcium Channels; D009249:NADP; D019837:Ryanodine Receptor Calcium Release Channel; C407357:TPCN1 protein, human; D000097903:Two-Pore Channels; C530224:TPCN2 protein, human; C024376:NAADP