The molecular basis for calcium release by NAADP
Lead Research Organisation:
UNIVERSITY COLLEGE LONDON
Department Name: Neuroscience Physiology and Pharmacology
Abstract
All cells of the body are physically separated from their surrounding environment by a membrane. In order for cells to respond to factors in the blood (such as hormones) which normally can not pass through the membrane, special 'messenger' molecules are used that are generated inside the cell upon contact of the stimulus with the cell. One of these molecules, NAADP controls cell function by mediating changes in the concentration of calcium. These calcium changes are important for many processes including, for example, fertilisation. Understanding how NAADP increases calcium levels is important to understand how cells work but at present we do not know the identity of the protein or 'channel' that opens in response to NAADP to allow calcium levels to change. In this proposal, we will study a family of proteins that we know very little about but which our initial experiments suggest are the channels for NAADP. We will define their location within the cell, determine exactly how they respond to NAADP and whether they are needed for hormones which make NAADP to mediate changes in calcium. The results of our experiments will provide urgently needed information on how NAADP functions and experimental tools to further study the effects of NAADP.
Technical Summary
Cytosolic calcium ions form the basis of a ubiquitous signal transduction pathway that controls a huge number of physiological processes. Understanding how changes in cytosolic calcium occur in response to extracellular cues is crucial for understanding how calcium dependent events are regulated, and has major implications for the many diseases in which calcium signals are perturbed. Recent studies have established a new calcium signalling pathway regulated by the potent calcium mobilizing messenger NAADP. Unlike the 'traditional' messenger molecules, IP3 and cyclic ADP-ribose, NAADP mobilizes acidic stores of calcium. Moreover, NAADP has the unique ability to coordinate the activity of other intracellular calcium channels. However, despite the critical importance of NAADP in triggering agonist-evoked calcium signals, the molecular identity of the target channel has yet to be unequivocally defined. This paucity in information is substantially hampering efforts to characterize the physiological roles of NAADP. In this application, we will test whether the target channels for NAADP are a family of proteins that bear homology to voltage-sensitive calcium channels and which in animals are almost completely uncharacterised. Using a combination of molecular and cell biology approaches, and based on substantial preliminary data, we expect to localize the candidate channels to the endo-lysosomal system, demonstrate their sensitivity to NAADP and establish their contribution to physiologically relevant agonist-evoked calcium signals. Determining the molecular basis for NAADP action will represent a major breakthrough in the signal transduction field that will not only substantially further our understanding of how calcium signals are generated but also provide truly novel opportunities for future study of this ubiquitous signalling pathway.
Organisations
People |
ORCID iD |
| Sandip Patel (Principal Investigator) |
Publications
Hooper R
(2012)
Calcium Signaling
Patel S
(2010)
Acidic calcium stores open for business: expanding the potential for intracellular Ca2+ signaling.
in Trends in cell biology
Brailoiu E
(2009)
Essential requirement for two-pore channel 1 in NAADP-mediated calcium signaling.
in The Journal of cell biology
Churamani D
(2012)
The signaling protein CD38 is essential for early embryonic development.
in The Journal of biological chemistry
Ramakrishnan L
(2010)
A single residue in a novel ADP-ribosyl cyclase controls production of the calcium-mobilizing messengers cyclic ADP-ribose and nicotinic acid adenine dinucleotide phosphate.
in The Journal of biological chemistry
Hooper R
(2011)
Membrane topology of NAADP-sensitive two-pore channels and their regulation by N-linked glycosylation.
in The Journal of biological chemistry
Dickinson GD
(2010)
Deviant nicotinic acid adenine dinucleotide phosphate (NAADP)-mediated Ca2+ signaling upon lysosome proliferation.
in The Journal of biological chemistry
Pereira GJ
(2011)
Nicotinic acid adenine dinucleotide phosphate (NAADP) regulates autophagy in cultured astrocytes.
in The Journal of biological chemistry
Rybalchenko V
(2012)
Membrane potential regulates nicotinic acid adenine dinucleotide phosphate (NAADP) dependence of the pH- and Ca2+-sensitive organellar two-pore channel TPC1.
in The Journal of biological chemistry
Lin-Moshier Y
(2012)
Photoaffinity labeling of nicotinic acid adenine dinucleotide phosphate (NAADP) targets in mammalian cells.
in The Journal of biological chemistry
Brailoiu E
(2010)
An NAADP-gated two-pore channel targeted to the plasma membrane uncouples triggering from amplifying Ca2+ signals.
in The Journal of biological chemistry
Brailoiu GC
(2010)
Acidic NAADP-sensitive calcium stores in the endothelium: agonist-specific recruitment and role in regulating blood pressure.
in The Journal of biological chemistry
Yamaguchi S
(2011)
Transient receptor potential mucolipin 1 (TRPML1) and two-pore channels are functionally independent organellar ion channels.
in The Journal of biological chemistry
Brailoiu E
(2010)
An ancestral deuterostome family of two-pore channels mediates nicotinic acid adenine dinucleotide phosphate-dependent calcium release from acidic organelles.
in The Journal of biological chemistry
Jha A
(2014)
Convergent regulation of the lysosomal two-pore channel-2 by Mg²?, NAADP, PI(3,5)P2 and multiple protein kinases.
in The EMBO journal
Churamani D
(2013)
The N-terminal region of two-pore channel 1 regulates trafficking and activation by NAADP.
in The Biochemical journal
Churamani D
(2012)
Domain assembly of NAADP-gated two-pore channels.
in The Biochemical journal
Penny CJ
(2016)
Isolated pores dissected from human two-pore channel 2 are functional.
in Scientific reports
Patel S
(2009)
In with the TRP channels: intracellular functions for TRPM1 and TRPM2.
in Science signaling
Patel S
(2015)
Function and dysfunction of two-pore channels
in Science Signaling
Rahman T
(2014)
Two-pore channels provide insight into the evolution of voltage-gated Ca2+ and Na+ channels.
in Science signaling
Patel S
(2018)
Thinking through acidic Ca2+ stores.
in Science signaling
Love NR
(2015)
NAD kinase controls animal NADP biosynthesis and is modulated via evolutionarily divergent calmodulin-dependent mechanisms.
in Proceedings of the National Academy of Sciences of the United States of America
Lin-Moshier Y
(2014)
The Two-pore channel (TPC) interactome unmasks isoform-specific roles for TPCs in endolysosomal morphology and cell pigmentation.
in Proceedings of the National Academy of Sciences of the United States of America
Patel S
(2018)
Two-pore channels open up.
in Nature
| Description | We have identified and characterized a new class of ion channels known as the two-pore channels (TPCs). Our findings indicate that these proteins are responsible for releasing calcium from acidic organelles such as lysosomes in response to the second messenger NAADP. This is a major breakthrough as a definitive molecular correlate for NAADP action was not known. TPCs are now being studied by many groups worldwide. |
| Exploitation Route | TPCs now present themselves as novel therapeutic targets. See outcomes from independent work funded by Parkinson's UK. |
| Sectors | Healthcare Pharmaceuticals and Medical Biotechnology |
| URL | http://jcb.rupress.org/content/186/2/164.2.full.pdf+html |
| Description | A role for a novel animal endo-lysosomal Ca2+/H+ exchanger in Ca2+ signalling and chemotaxis |
| Amount | £428,461 (GBP) |
| Funding ID | BB/K000942/1 |
| Organisation | Biotechnology and Biological Sciences Research Council (BBSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 01/2013 |
| End | 01/2016 |
| Description | Abnormal lysosomal calcium signalling in Parkinson's: Clues from lysosomal storage disorders |
| Amount | £34,798 (GBP) |
| Funding ID | K-1107 |
| Organisation | Parkinson's UK |
| Sector | Charity/Non Profit |
| Country | United Kingdom |
| Start | 05/2012 |
| End | 03/2014 |
| Description | Membrane contact sites between endolysosomes and the ER as novel hubs in Ca2+ signalling |
| Amount | £430,122 (GBP) |
| Funding ID | BB/N01524X/1 |
| Organisation | Biotechnology and Biological Sciences Research Council (BBSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 06/2016 |
| End | 06/2019 |
| Description | Mis-coordinated Ca2+ signalling in Parkinson's |
| Amount | £92,276 (GBP) |
| Organisation | Parkinson's UK |
| Sector | Charity/Non Profit |
| Country | United Kingdom |
| Start | 08/2013 |
| End | 09/2016 |
| Description | Targeting two-pore channel 2 in LRRK2-dependent Parkinson's disease |
| Amount | £34,798 (GBP) |
| Funding ID | K-1412 |
| Organisation | Parkinson's UK |
| Sector | Charity/Non Profit |
| Country | United Kingdom |
| Start | 01/2015 |
| End | 09/2015 |