An Ancestral Deuterostome Family of Two-pore Channels Mediates Nicotinic Acid Adenine Dinucleotide Phosphate-dependent Calcium Release from Acidic Organelles

Eugen Brailoiu; Robert Hooper; Xinjiang Cai; G. Cristina Brailoiu; Michael V. Keebler; Nae J. Dun; Jonathan S. Marchant; Sandip Patel

doi:10.1074/jbc.C109.081943

An Ancestral Deuterostome Family of Two-pore Channels Mediates Nicotinic Acid Adenine Dinucleotide Phosphate-dependent Calcium Release from Acidic Organelles*

From the ^‡Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140,
the ^§Department of Cell and Developmental Biology, University College London, London WC1E 6BT, United Kingdom,
the ^¶Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, and
the ^‖Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota 55455

2 To whom correspondence should be addressed: E-mail: patel.s{at}ucl.ac.uk.

↵1 Present address: The Skirball Institute for Biomolecular Medicine, New York University Langone Medical Center, New York, NY 10016.

Abstract

Nicotinic acid adenine dinucleotide phosphate (NAADP) is a potent and widespread calcium-mobilizing messenger, the properties of which have been most extensively described in sea urchin eggs. The molecular basis for calcium release by NAADP, however, is not clear and subject to controversy. Recent studies have provided evidence that members of the two-pore channel (TPC) family in mammals are the long sought after target channels for NAADP. Here, we show that the TPC3 gene, which has yet to be functionally characterized, is present throughout the deuterostome lineage but is a pseudogene in humans and other primates. We report the molecular cloning of the complete ancestral TPC gene family from the sea urchin and demonstrate that all three isoforms localize to acidic organelles to mediate NAADP-dependent calcium release. Our data highlight the functional divergence of this novel gene family during deuterostome evolution and provide further evidence that NAADP mediates calcium release from acidic stores through activation of TPCs.

Footnotes

↵* This work was supported, in whole or in part, by National Institutes of Health Grants GM088790 (to J. S. M.), HL 090804 (to E. B.), and HL 090804-01A2S109 (to E. B.). This work was also supported by Biotechnology and Biological Sciences Research Council Grants BB/D018110/1 and BB/G013721/1 (to S. P.) and American Heart Association Fellowship Award 0625403U (to X. C.).
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EBI Data Bank with accession number(s) FN598566, FN598567, and FN598568.
↵ The on-line version of this article (available at http://www.jbc.org) contains supplemental Figs. S1 and S2.
↵3 The abbreviations used are:

IP₃

inositol trisphosphate

cADPR

cyclic ADP-ribose

NAADP

nicotinic acid adenine dinucleotide phosphate

TPC

two-pore channel

GFP

green fluorescent protein

HEK

human embryonic kidney

UTR

untranslated region

Sp

S. purpuratus.
- Received November 4, 2009.
- Revision received November 24, 2009.