STa and cGMP stimulate CFTR translocation to the surface of villus enterocytes in rat jejunum and is regulated by protein kinase G

2005 ◽  
Vol 289 (3) ◽  
pp. C708-C716 ◽  
Author(s):  
Franca Golin-Bisello ◽  
Neil Bradbury ◽  
Nadia Ameen
Keyword(s):  
Protein Kinase ◽  
Fluid Secretion ◽  
Secretory Diarrhea ◽  
Apical Plasma Membrane ◽  
Intracellular Camp ◽  
Rat Jejunum ◽  
Fourfold Increase ◽  
Anion Secretion ◽  
Cgmp Signaling ◽  
Camp And Cgmp

The cystic fibrosis transmembrane conductance regulator (CFTR) is critical to cAMP- and cGMP-activated intestinal anion secretion and the pathogenesis of secretory diarrhea. Enterotoxins released by Vibrio cholerae (cholera toxin) and Escherichia coli (heat stable enterotoxin, or STa) activate intracellular cAMP and cGMP and signal CFTR on the apical plasma membrane of small intestinal enterocytes to elicit chloride and fluid secretion. cAMP activates PKA, whereas cGMP signals a cGMP-dependent protein kinase (cGKII) to phosphorylate CFTR in the intestine. In the jejunum, cAMP also regulates CFTR and fluid secretion by insertion of CFTR from subapical vesicles to the surface of enterocytes. It is unknown whether cGMP signaling or phosphorylation regulates the insertion of CFTR associated vesicles from the cytoplasm to the surface of enterocytes. We used STa, cell-permeant cGMP, and cAMP agonists in conjunction with PKG and PKA inhibitors, respectively, in rat jejunum to examine whether 1) cGMP and cGK II regulate the translocation of CFTR to the apical membrane and its relevance to fluid secretion, and 2) PKA regulates cAMP-dependent translocation of CFTR because this intestinal segment is a primary target for toxigenic diarrhea. STa and cGMP induced a greater than fourfold increase in surface CFTR in enterocytes in association with fluid secretion that was inhibited by PKG inhibitors. cAMP agonists induced a translocation of CFTR to the cell surface of enterocytes that was prevented by PKA inhibitors. We conclude that cAMP and cGMP-dependent phosphorylation regulates fluid secretion and CFTR trafficking to the surface of enterocytes in rat jejunum.

scholarly journals Advances and Perspectives of Light-gated Phosphodiesterases for Optogenetic Applications

2020 ◽  
Author(s):  
Yuehui Tian ◽  
Shang Yang ◽  
Shiqiang Gao
Keyword(s):  
Intracellular Signaling ◽  
Second Messengers ◽  
Cell Physiology ◽  
Intracellular Camp ◽  
Animal Cells ◽  
Signaling Mechanism ◽  
Surface Receptors ◽  
Cgmp Signaling ◽  
Pros And Cons ◽  
Camp And Cgmp

Second messengers, cyclic adenosine 3'-5'-monophosphate (cAMP) and cyclic guanosine 3'-5'-monophosphate (cGMP) are playing important roles in many animal cells by regulating intracellular signaling pathways and modulating cell physiology. Environmental cues like temperature, light and chemical compounds can stimulate cell surface receptors and trigger the generation of second messengers and the following regulations. Spread of cAMP and cGMP is further shaped by cyclic nucleotide phosphodiesterases (PDEs) for orchestration of intracellular microdomain signaling. However, localized intracellular cAMP and cGMP signaling requires further investigation. Optogenetic manipulation of cAMP and cGMP offers new opportunities of spatio-temporally precise study of their signaling mechanism. Light-gated nucleotide cyclases are well developed and applied for cAMP/cGMP manipulation. Recently discovered rhodopsin phosphodiesterase gene from protists established new and direct biological connection between light and PDEs. Light-regulated PDEs are under development and of demand to complete the toolkit of cAMP/cGMP manipulation. In this review, we summarize the state of the art, pros and cons of artificial and natural light-regulated PDEs and discuss potential new strategies of developing light-gated PDEs for optogenetic manipulation.

CAP2b, a cardioacceleratory peptide, is present in Drosophila and stimulates tubule fluid secretion via cGMP

1995 ◽  
Vol 269 (6) ◽  
pp. R1321-R1326 ◽  
Author(s):  
S. A. Davies ◽  
G. R. Huesmann ◽  
S. H. Maddrell ◽  
M. J. O'Donnell ◽  
N. J. Skaer ◽  
...  
Keyword(s):  
High Performance Liquid Chromatography ◽  
Manduca Sexta ◽  
High Performance ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Cyclic Monophosphate ◽  
Cgmp Signaling ◽  
Camp And Cgmp ◽  
Tubule Fluid ◽  
Stimulation Of

A cardioacceleratory peptide, CAP2b, identified originally in the lepidopteran Manduca sexta, stimulates fluid secretion by Malpighian tubules of the dipteran Drosophila melanogaster. High-performance liquid chromatography analyses of adult D. melanogaster reveal the presence of a CAP2b-like peptide, that coelutes with M. sexta CAP2b and synthetic CAP2b and that has CAP2b-like effects on the M. sexta heart. CAP2b accelerates fluid secretion in tubules stimulated by adenosine 3',5'-cyclic monophosphate (cAMP) but has no effect on tubules stimulated by guanosine 3',5'-cyclic monophosphate (cGMP), implying that it acts through the latter pathway. By contrast, the action of leucokinin is additive to both cAMP and cGMP but not to thapsigargin, suggesting that leucokinin acts by the elevation of intracellular calcium. CAP2b stimulation elevates tubule cGMP levels but not those of cAMP. By contrast, leucokinin has no effect on levels of either cyclic nucleotide. Both CAP2b and cGMP increase transepithelial potential difference, suggesting that stimulation of vacuolar-adenosinetriphosphatase action underlies the corresponding increases in fluid secretion. Overall, the results show that a Drosophila CAP2b-related peptide acts to stimulate fluid secretion by Malpighian tubules through the cGMP-signaling pathway.

scholarly journals Advances, Perspectives and Potential Engineering Strategies of Light-Gated Phosphodiesterases for Optogenetic Applications

2020 ◽  
Vol 21 (20) ◽  
pp. 7544
Author(s):  
Yuehui Tian ◽  
Shang Yang ◽  
Shiqiang Gao
Keyword(s):  
Intracellular Signaling ◽  
Second Messengers ◽  
Cell Physiology ◽  
Intracellular Camp ◽  
Animal Cells ◽  
Signaling Mechanism ◽  
Surface Receptors ◽  
Cgmp Signaling ◽  
Pros And Cons ◽  
Camp And Cgmp

The second messengers, cyclic adenosine 3′-5′-monophosphate (cAMP) and cyclic guanosine 3′-5′-monophosphate (cGMP), play important roles in many animal cells by regulating intracellular signaling pathways and modulating cell physiology. Environmental cues like temperature, light, and chemical compounds can stimulate cell surface receptors and trigger the generation of second messengers and the following regulations. The spread of cAMP and cGMP is further shaped by cyclic nucleotide phosphodiesterases (PDEs) for orchestration of intracellular microdomain signaling. However, localized intracellular cAMP and cGMP signaling requires further investigation. Optogenetic manipulation of cAMP and cGMP offers new opportunities for spatio-temporally precise study of their signaling mechanism. Light-gated nucleotide cyclases are well developed and applied for cAMP/cGMP manipulation. Recently discovered rhodopsin phosphodiesterase genes from protists established a new and direct biological connection between light and PDEs. Light-regulated PDEs are under development, and of demand to complete the toolkit for cAMP/cGMP manipulation. In this review, we summarize the state of the art, pros and cons of artificial and natural light-regulated PDEs, and discuss potential new strategies of developing light-gated PDEs for optogenetic manipulation.

scholarly journals Selective inhibition of intestinal guanosine 3′,5′-cyclic monophosphate signaling by small-molecule protein kinase inhibitors

2018 ◽  
Vol 293 (21) ◽  
pp. 8173-8181 ◽  
Author(s):  
Marcel J. C. Bijvelds ◽  
Gary Tresadern ◽  
Ann Hellemans ◽  
Karine Smans ◽  
Natascha D. A. Nieuwenhuijze ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Small Molecule ◽  
Kinase Inhibitors ◽  
Selective Inhibition ◽  
Protein Kinase Inhibitors ◽  
Secretory Diarrhea ◽  
Dependent Protein Kinase ◽  
Anion Secretion ◽  
Cyclic Monophosphate ◽  
Dependent Protein

The guanosine 3′,5′-cyclic monophosphate (cGMP)-dependent protein kinase II (cGKII) serine/threonine kinase relays signaling through guanylyl cyclase C (GCC) to control intestinal fluid homeostasis. Here, we report the discovery of small-molecule inhibitors of cGKII. These inhibitors were imidazole-aminopyrimidines, which blocked recombinant human cGKII at submicromolar concentrations but exhibited comparatively little activity toward the phylogenetically related protein kinases cGKI and cAMP-dependent protein kinase (PKA). Whereas aminopyrimidyl motifs are common in protein kinase inhibitors, molecular modeling of these imidazole-aminopyrimidines in the ATP-binding pocket of cGKII indicated an unconventional binding mode that directs their amine substituent into a narrow pocket delineated by hydrophobic residues of the hinge and the αC-helix. Crucially, this set of residues included the Leu-530 gatekeeper, which is not conserved in cGKI and PKA. In intestinal organoids, these compounds blocked cGKII-dependent phosphorylation of the vasodilator-stimulated phosphoprotein (VASP). In mouse small intestinal tissue, cGKII inhibition significantly attenuated the anion secretory response provoked by the GCC-activating bacterial heat-stable toxin (STa), a frequent cause of infectious secretory diarrhea. In contrast, both PKA-dependent VASP phosphorylation and intestinal anion secretion were unaffected by treatment with these compounds, whereas experiments with T84 cells indicated that they weakly inhibit the activity of cAMP-hydrolyzing phosphodiesterases. As these protein kinase inhibitors are the first to display selective inhibition of cGKII, they may expedite research on cGMP signaling and may aid future development of therapeutics for managing diarrheal disease and other pathogenic syndromes that involve cGKII.

Adrenergic regulation of salt and fluid secretion in human medullary collecting duct cells

2004 ◽  
Vol 287 (4) ◽  
pp. F639-F648 ◽  
Author(s):  
Darren P. Wallace ◽  
Gail Reif ◽  
Anne-Marie Hedge ◽  
J. Brantley Thrasher ◽  
Paul Pietrow
Keyword(s):  
Collecting Duct ◽  
Short Circuit ◽  
Primary Cultures ◽  
Short Circuit Current ◽  
Fluid Secretion ◽  
Intracellular Camp ◽  
Anion Secretion ◽  
Cell Monolayers ◽  
Urine Composition ◽  
Camp Levels

Transepithelial salt and fluid secretion mediated by cAMP in initial inner medullary collecting ducts (IMCDi) may be important for making final adjustments to urine composition. We examined in primary cultures of human IMCDi cells the effects of adrenergic receptor (AR) agonists and antagonists on intracellular cAMP levels, short-circuit current ( ISC), and fluid secretion. Epinephrine (1 μM), norepinephrine (1 μM), and isoproterenol (10 nM) individually increased intracellular cAMP levels 57-, 2-, and 25-fold, respectively, and stimulated ISC 3.3-, 2.9-, and 3.4-fold, respectively. β-AR activation increased net fluid secretion by cultured human IMCDi cell monolayers from 0.09 ± 0.04 to 0.26 ± 0.05 μl·h−1·cm−2 and freshly isolated rat IMCDi from 0.02 ± 0.01 to 0.09 ± 0.02 nl·h−1·mm−1. In monolayers, these effects were eliminated by blocking β2-AR, but not β1-AR. Activation of α2-AR with guanabenz inhibited isoproterenol-induced ISC by 37% in human IMCDi monolayers and fluid secretion by 91% in rat IMCDi. Immunohistochemistry of human medullary tissue sections revealed greater expression of β2-AR than β1-AR; β2-AR was localized to the basolateral membranes of human IMCDi. Immunoblots identified α2A-AR and α2B-AR in cultured human IMCDi cell monolayers. We conclude that 1) catecholamines stimulate cAMP-dependent anion and fluid secretion by IMCDi cells primarily through β2-AR activation and 2) α2-AR activation attenuates cAMP-dependent anion secretion.

scholarly journals Syntaxin 3 is necessary for cAMP- and cGMP-regulated exocytosis of CFTR: implications for enterotoxigenic diarrhea

2010 ◽  
Vol 299 (6) ◽  
pp. C1450-C1460 ◽  
Author(s):  
Anne Collaco ◽  
Jai Marathe ◽  
Hannes Kohnke ◽  
Dmitri Kravstov ◽  
Nadia Ameen
Keyword(s):  
Plasma Membrane ◽  
Cyclic Nucleotide ◽  
Chloride Channels ◽  
Fluid Secretion ◽  
Apical Plasma Membrane ◽  
Rat Jejunum ◽  
Glutathione S Transferase ◽  
Binding Studies ◽  
Syntaxin 3

Enterotoxins elaborated by Vibrio cholerae and Escherichia coli cannot elicit fluid secretion in the absence of functional cystic fibrosis transmembrane conductance regulator (CFTR) chloride channels. After enterotoxin exposure, CFTR channels are rapidly recruited from endosomes and undergo exocytic insertion into the apical plasma membrane of enterocytes to increase the number of channels on the cell surface by at least fourfold. However, the molecular machinery that orchestrates exocytic insertion of CFTR into the plasma membrane is largely unknown. The present study used immunofluorescence, immunoblotting, surface biotinylation, glutathione S-transferase (GST) pulldown assays, and immunoprecipitation to identify components of the exocytic soluble N-ethylmaleimide (NEM)-sensitive factor attachment receptor (SNARE) vesicle fusion machinery in cyclic nucleotide-activated exocytosis of CFTR in rat jejunum and polarized intestinal Caco-2BBe cells. Syntaxin 3, an intestine-specific SNARE, colocalized with CFTR on the apical domain of enterocytes in rat jejunum and polarized Caco-2BBe cells. Coimmunoprecipitation and GST binding studies confirmed that syntaxin 3 interacts with CFTR in vivo. Moreover, heat-stable enterotoxin (STa) activated exocytosis of both CFTR and syntaxin 3 to the surface of rat jejunum. Silencing of syntaxin 3 by short hairpin RNA (shRNA) interference abrogated cyclic nucleotide-stimulated exocytosis of CFTR in cells. These observations reveal a new and important role for syntaxin 3 in the pathophysiology of enterotoxin-elicited diarrhea.

Involvement of αENaC and Nedd4-2 in the conversion from lung fluid secretion to fluid absorption at birth in the rat as assayed by RNA interference analysis

2007 ◽  
Vol 293 (4) ◽  
pp. L1069-L1078 ◽  
Author(s):  
Tianbo Li ◽  
Shyny Koshy ◽  
Hans G. Folkesson
Keyword(s):  
Extravascular Lung Water ◽  
Fluid Secretion ◽  
Alveolar Epithelial Cells ◽  
Na Channel ◽  
Fluid Absorption ◽  
Lung Water ◽  
Fourfold Increase ◽  
Lung Fluid ◽  
Near Term

To explore interactions between the epithelial Na channel (ENaC) and neural precursor expressed, developmentally downregulated protein 4-2 (Nedd4-2) at the conversion of the rat lung from fluid secretion to absorption at birth, we used small-interfering RNA (siRNA) against αENaC and Nedd4-2. siRNA-generating plasmid DNA (pDNA) was administered via trans-thoracic intrapulmonary (ttip) injection 24 h before ENaC and Nedd4-2 expression, extravascular lung water, and mortality were measured. αENaC mRNA and protein were specifically reduced by ∼65% after pSi-4 injection. Nedd4-2 mRNA and protein were reduced by ∼60% after pSi-N1 injection. Interestingly, αENaC and βENaC mRNA and protein expression were increased after Nedd4-2 silencing. Extravascular lung water was significantly increased after αENaC silencing and reduced after Nedd4-2 silencing. αENaC silencing resulted in a fourfold increase in newborn mortality, whereas silencing Nedd4-2 did not affect mortality. We also isolated distal lung epithelial (DLE) cells after in vivo αENaC or Nedd4-2 silencing and measured αENaC or Nedd4-2 expression in freshly isolated DLE cells. In these DLE cells, there were attenuated αENaC or Nedd4-2 mRNA and protein, thus demonstrating that αENaC and Nedd4-2 silencing occurred in alveolar epithelial cells after ttip injection. We also looked for pDNA by PCR to determine pDNA presence in the lungs and found strong evidence for pDNA presence in both lungs. Thus we provide evidence that ENaC and Nedd4-2 are involved in the transition from lung fluid secretion to fluid absorption near term and at birth.

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