Damage can be signalled by extracellular ATP (eATP) using plasma membrane (PM) receptors to effect cytosolic free calcium ion ([Ca2+]cyt) increase as a second messenger. The downstream PM Ca2+channels remain enigmatic. Here, the Extracellular ATP‐induced changes in single epidermal cell PM voltage and conductance were measured electrophysiologically, changes in root [Ca2+]cytwere measured with aequorin, and root transcriptional changes were determined by quantitative real‐time PCR. Two Extracellular ATP‐induced transient depolarization of Arabidopsis root elongation zone epidermal PM voltage was Ca2+dependent, requiring CNGC2 but not CNGC4 (its channel co‐subunit in immunity signalling). Activation of PM Ca2+influx currents also required CNGC2. The eATP‐induced [Ca2+]cytincrease and transcriptional response in CYCLIC NUCLEOTIDE‐GATED CHANNEL2 is required for eATP‐induced epidermal Ca2+influx, causing depolarization leading to [Ca2+]cytincrease and damage‐related transcriptional response.
Association of plasma membrane BKCachannels with BK‐β subunits shapes their biophysical properties and physiological roles; however, functional modulation of the mitochondrial BKCachannel (mitoBKCa) by BK‐β subunits is not established. MitoBKCa‐α and the regulatory BK‐β1 subunit associate in mouse cardiac mitochondria. A large fraction of mitoBKCadisplay properties similar to that of plasma membrane BKCawhen associated with BK‐β1 (left‐shifted voltage dependence of activation, In BK‐β1 knockout mice, cardiac mitoBKCadisplayed a low Co‐expression of BKCawith the BK‐β1 subunit in HeLa cells doubled the density of BKCain mitochondria. The present study supports the view that the cardiac mitoBKCachannel is functionally modulated by the BK‐β1 subunit; proper targeting and activation of mitoBKCashapes mitochondrial Ca2+handling.
Association of the plasma membrane BKCachannel with auxiliary BK‐β1–4 subunits profoundly affects the regulatory mechanisms and physiological processes in which this channel participates. However, functional association of mitochondrial BK (mitoBKCa) with regulatory subunits is unknown. We report that mitoBKCafunctionally associates with its regulatory subunit BK‐β1 in adult rodent cardiomyocytes. Cardiac mitoBKCais a calcium‐ and voltage‐activated channel that is sensitive to paxilline with a large conductance for K+of 300 pS. Additionally, mitoBKCadisplays a high open probability (
- NSF-PAR ID:
- 10456567
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- The Journal of Physiology
- Volume:
- 597
- Issue:
- 15
- ISSN:
- 0022-3751
- Page Range / eLocation ID:
- p. 3817-3832
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Summary Arabidopsis thaliana Ca2+channel subunit CYCLIC NUCLEOTIDE‐GATED CHANNEL2 (CNGC2) was identified as a critical component linking eATP receptors to downstream [Ca2+]cytsignalling in roots.cngc2 loss‐of‐function mutants were used:cngc2‐3 anddefence not death1 (which expresses cytosolic aequorin).cngc2 roots were significantly impaired. -
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Key points Accumulation of inorganic phosphate (P
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i promoted Ca2+ release at concentrations below 10 mm and decreased it at higher concentrations. This decrease correlated well with that of [Ca2+ ]SR .Pre‐treatment of permeabilized myofibres with 2 m
m Cl− channel blocker 9‐anthracenecarboxylic acid (9AC) inhibited both effects of Pi .The biphasic dependence of Ca
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Key points Vascular oxidative stress increases with advancing age.
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Vascular cells develop resilience to H2O2during ageing by preventing Ca2+overload and endothelial integrity promotes SMC survival.
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Time‐resolved stomatal conductance measurements using intact plants, and guard cell patch‐clamp experiments were performed.
We isolated
cpk quintuple mutants and analyzed stomatal movements in response to CO2, light and abscisic acid (ABA). Interestingly, we found thatcpk3/5/6/11/23 quintuple mutant plants, but not other analyzedcpk quadruple/quintuple mutants, were defective in high CO2‐induced stomatal closure and, unexpectedly, also in low CO2‐induced stomatal opening. Furthermore, K+‐uptake‐channel activities were reduced incpk3/5/6/11/23 quintuple mutants, in correlation with the stomatal opening phenotype. However, light‐mediated stomatal opening remained unaffected, and ABA responses showed slowing in some experiments. By contrast, CO2‐regulated stomatal movement kinetics were not clearly affected in plasma membrane‐targetedcbl1/4/5/8/9 quintuple mutant plants.Our findings describe combinatorial
cpk mutants that function in CO2control of stomatal movements and support the results of classical studies showing a role for Ca2+in this response.
