NO upregulation of a cyclic nucleotide-gated channel contributes to calcium elevation in endothelial cells

We investigated whether nitric oxide (NO) upregulates a cyclic nucleotide-gated (CNG) channel and whether this contributes to sustained elevation of intracellular calcium levels ([Ca2+]i) in porcine pulmonary artery endothelial cells (PAEC). Exposure of PAEC to an NO donor, NOC-18 (1 mM), for 18 h increased the protein and mRNA levels of CNGA2 40 and 50%, respectively ( P < 0.05). [Ca2+]iin NO-treated cells was increased 50%, and this increase was maintained for up to 12 h after removal of NOC-18 from medium. Extracellular calcium is required for the increase in [Ca2+]iin NO-treated cells. Thapsigargin induced a rapid cytosolic calcium rise, whereas both a CNG and a nonselective cation channel blocker caused a faster decline in [Ca2+]i, suggesting that capacitive calcium entry contributes to the elevated calcium levels. Antisense inhibition of CNGA2 expression attenuated the NO-induced increases in CNGA2 expression and [Ca2+]iand in capacitive calcium entry. Our results demonstrate that exogenous NO upregulates CNGA2 expression and that this is associated with elevated [Ca2+]iand capacitive calcium entry in porcine PAEC.

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A mis‐regulated cyclic nucleotide‐gated channel mediates cytosolic calcium elevation and activates immunity in Arabidopsis

New Phytologist ◽

10.1111/nph.17218 ◽

2021 ◽

Author(s):

Chunhui Zhao ◽

Yinhua Tang ◽

Junli Wang ◽

Yanhong Zeng ◽

Hequan Sun ◽

...

Keyword(s):

Cyclic Nucleotide ◽

Cytosolic Calcium ◽

Gated Channel ◽

Calcium Elevation

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Hypoxia-induced pulmonary endothelin-1 expression is unaltered by nitric oxide

Journal of Applied Physiology ◽

10.1152/japplphysiol.00829.2001 ◽

2002 ◽

Vol 92 (3) ◽

pp. 1152-1158 ◽

Cited By ~ 15

Author(s):

Scott Earley ◽

Leif D. Nelin ◽

Louis G. Chicoine ◽

Benjimen R. Walker

Keyword(s):

Nitric Oxide ◽

Endothelial Cells ◽

Promoter Activity ◽

Umbilical Vein ◽

Hypoxia Inducible Factor ◽

Hypoxic Exposure ◽

Mrna Levels ◽

Protective Effects ◽

No Donor ◽

Umbilical Vein Endothelial Cells

Nitric oxide (NO) attenuates hypoxia-induced endothelin (ET)-1 expression in cultured umbilical vein endothelial cells. We hypothesized that NO similarly attenuates hypoxia-induced increases in ET-1 expression in the lungs of intact animals and reasoned that potentially reduced ET-1 levels may contribute to the protective effects of NO against the development of pulmonary hypertension during chronic hypoxia. As expected, hypoxic exposure (24 h, 10% O2) increased rat lung ET-1 peptide and prepro-ET-1 mRNA levels. Contrary to our hypothesis, inhaled NO (iNO) did not attenuate hypoxia-induced increases in pulmonary ET-1 peptide or prepro-ET-1 mRNA levels. Because of this surprising finding, we also examined the effects of NO on hypoxia-induced increases in ET peptide levels in cultured cell experiments. Consistent with the results of iNO experiments, administration of the NO donor S-nitroso- N-acetyl-penicillamine to cultured bovine pulmonary endothelial cells did not attenuate increases in ET peptide levels resulting from hypoxic (24 h, 3% O2) exposure. In additional experiments, we examined the effects of NO on the activity of a cloned ET-1 promoter fragment containing a functional hypoxia inducible factor-1 binding site in reporter gene experiments. Whereas moderate hypoxia (24 h, 3% O2) had no effect on ET-1 promoter activity, activity was increased by severe hypoxic (24 h, 0.5% O2) exposure. ET-1 promoter activity after S-nitroso- N-acetyl-penicillamine administration during severe hypoxia was greater than that in normoxic controls, although activity was reduced compared with that in hypoxic controls. These findings suggest that hypoxia-induced pulmonary ET-1 expression is unaffected by NO.

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Control of cAMP in lung endothelial cell phenotypes. Implications for control of barrier function

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1999.277.1.l119 ◽

1999 ◽

Vol 277 (1) ◽

pp. L119-L126 ◽

Cited By ~ 44

Author(s):

Troy Stevens ◽

Judy Creighton ◽

W. Joseph Thompson

Keyword(s):

Endothelial Cells ◽

Adenylyl Cyclase ◽

Barrier Function ◽

Enzyme Regulation ◽

Calcium Sensitivity ◽

Cytosolic Calcium ◽

Calcium Entry ◽

Camp Accumulation ◽

Camp Phosphodiesterase ◽

Conversion Rates

Pulmonary microvascular endothelial cells (PMVECs) form a more restrictive barrier to macromolecular flux than pulmonary arterial endothelial cells (PAECs); however, the mechanisms responsible for this intrinsic feature of PMVECs are unknown. Because cAMP improves endothelial barrier function, we hypothesized that differences in enzyme regulation of cAMP synthesis and/or degradation uniquely establish an elevated content in PMVECs. PMVECs possessed 20% higher basal cAMP concentrations than did PAECs; however, increased content was accompanied by 93% lower ATP-to-cAMP conversion rates. In PMVECs, responsiveness to β-adrenergic agonist (isoproterenol) or direct adenylyl cyclase (forskolin) activation was attenuated and responsiveness to phosphodiesterase inhibition (rolipram) was increased compared with those in PAECs. Although both types of endothelial cells express calcium-inhibited adenylyl cyclase, constitutive PMVEC cAMP accumulation was not inhibited by physiological rises in cytosolic calcium, whereas PAEC cAMP accumulation was inhibited 30% by calcium. Increasing either PMVEC calcium entry by maximal activation of store-operated calcium entry or ATP-to-cAMP conversion with rolipram unmasked calcium inhibition of adenylyl cyclase. These data indicate that suppressed calcium entry and low ATP-to-cAMP conversion intrinsically influence calcium sensitivity. Adenylyl cyclase-to-cAMP phosphodiesterase ratios regulate cAMP at elevated levels compared with PAECs, which likely contribute to enhanced microvascular barrier function.

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Odorant Inhibition of the Olfactory Cyclic Nucleotide-gated Channel with a Native Molecular Assembly

The Journal of General Physiology ◽

10.1085/jgp.200609577 ◽

2006 ◽

Vol 128 (3) ◽

pp. 365-371 ◽

Cited By ~ 20

Author(s):

Tsung-Yu Chen ◽

Hiroko Takeuchi ◽

Takashi Kurahashi

Keyword(s):

Cyclic Nucleotide ◽

Inhibitory Effect ◽

Molecular Assembly ◽

Definitive Evidence ◽

Wide Range ◽

Cng Channel ◽

Gated Channel ◽

Receptor Neurons ◽

G Protein Coupled ◽

Fine Tune

Human olfaction comprises the opposing actions of excitation and inhibition triggered by odorant molecules. In olfactory receptor neurons, odorant molecules not only trigger a G-protein–coupled signaling cascade but also generate various mechanisms to fine tune the odorant-induced current, including a low-selective odorant inhibition of the olfactory signal. This wide-range olfactory inhibition has been suggested to be at the level of ion channels, but definitive evidence is not available. Here, we report that the cyclic nucleotide-gated (CNG) cation channel, which is a key element that converts odorant stimuli into electrical signals, is inhibited by structurally unrelated odorants, consistent with the expression of wide-range olfactory inhibition. Interestingly, the inhibitory effect was small in the homo-oligomeric CNG channel composed only of the principal channel subunit, CNGA2, but became larger in channels consisting of multiple types of subunits. However, even in the channel containing all native subunits, the potency of the suppression on the cloned CNG channel appeared to be smaller than that previously shown in native olfactory neurons. Nonetheless, our results further showed that odorant suppressions are small in native neurons if the subsequent molecular steps mediated by Ca2+ are removed. Thus, the present work also suggests that CNG channels switch on and off the olfactory signaling pathway, and that the on and off signals may both be amplified by the subsequent olfactory signaling steps.

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Ryanodine Receptors Control Cytosolic Calcium Elevation Following Activation of Store-Operated Calcium Entry in Activated but not Resting Human T Lymphocytes

Biophysical Journal ◽

10.1016/j.bpj.2009.12.2927 ◽

2010 ◽

Vol 98 (3) ◽

pp. 539a

Author(s):

Pratima Thakur ◽

Sepehr Dadsetan ◽

Alla F. Fomina

Keyword(s):

T Lymphocytes ◽

Ryanodine Receptors ◽

Cytosolic Calcium ◽

Calcium Entry ◽

Human T Lymphocytes ◽

Store Operated Calcium Entry ◽

Calcium Elevation

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cGMP/Protein Kinase G Signaling Suppresses Inositol 1,4,5-Trisphosphate Receptor Phosphorylation and Promotes Endoplasmic Reticulum Stress in Photoreceptors of Cyclic Nucleotide-gated Channel-deficient Mice

Journal of Biological Chemistry ◽

10.1074/jbc.m115.641159 ◽

2015 ◽

Vol 290 (34) ◽

pp. 20880-20892 ◽

Cited By ~ 22

Author(s):

Hongwei Ma ◽

Michael R. Butler ◽

Arjun Thapa ◽

Josh Belcher ◽

Fan Yang ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Protein Kinase ◽

Er Stress ◽

Cyclic Nucleotide ◽

Protein Kinase G ◽

Cng Channel ◽

Inositol 1,4,5 Trisphosphate ◽

Gated Channel ◽

Trisphosphate Receptor ◽

Deficient Mice

Photoreceptor cyclic nucleotide-gated (CNG) channels play a pivotal role in phototransduction. Mutations in the cone CNG channel subunits CNGA3 and CNGB3 are associated with achromatopsia and cone dystrophies. We have shown endoplasmic reticulum (ER) stress-associated apoptotic cone death and increased phosphorylation of the ER Ca2+ channel inositol 1,4,5-trisphosphate receptor 1 (IP3R1) in CNG channel-deficient mice. We also presented a remarkable elevation of cGMP and an increased activity of the cGMP-dependent protein kinase (protein kinase G, PKG) in CNG channel deficiency. This work investigated whether cGMP/PKG signaling regulates ER stress and IP3R1 phosphorylation in CNG channel-deficient cones. Treatment with PKG inhibitor and deletion of guanylate cyclase-1 (GC1), the enzyme producing cGMP in cones, were used to suppress cGMP/PKG signaling in cone-dominant Cnga3−/−/Nrl−/− mice. We found that treatment with PKG inhibitor or deletion of GC1 effectively reduced apoptotic cone death, increased expression levels of cone proteins, and decreased activation of Müller glial cells. Furthermore, we observed significantly increased phosphorylation of IP3R1 and reduced ER stress. Our findings demonstrate a role of cGMP/PKG signaling in ER stress and ER Ca2+ channel regulation and provide insights into the mechanism of cone degeneration in CNG channel deficiency.

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