Inhibition by ammonia of intracellular cAMP accumulation in dictyostelium discoideum: Its significance for the regulation of morphogenesis

1979 ◽  
Vol 1 (1) ◽  
pp. 13-20 ◽  
Author(s):  
J. Schindler ◽  
M. Sussman
Keyword(s):  
Dictyostelium Discoideum ◽  
Intracellular Camp ◽  
Camp Accumulation ◽  
Intracellular Camp Accumulation

Ca2+ signaling in human fetoplacental vasculature: effect of CGRP on umbilical vein smooth muscle cytosolic Ca2+ concentration

2005 ◽  
Vol 289 (2) ◽  
pp. H960-H967 ◽  
Author(s):  
Yuan-Lin Dong ◽  
Sujatha Vegiraju ◽  
Chandrasekhar Yallampalli
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Umbilical Vein ◽  
Scatchard Analysis ◽  
Intracellular Camp ◽  
Camp Accumulation ◽  
Atpase Inhibitor ◽  
Intracellular Ca ◽  
Intracellular Camp Accumulation

CGRP is a potent vasodilator with increased levels in fetoplacental circulation during late pregnancy. We have recently demonstrated that acute CGRP exposure to fetoplacental vessels in vitro induced vascular relaxation, but the signaling pathway of CGRP in fetoplacental vasculature remains unclear. We hypothesized that CGRP relaxes fetoplacental vasculature via regulating smooth muscle cytosolic Ca2+ concentrations. In the present study, by using human umbilical vein smooth muscle (HUVS) cells (HUVS-112D), we examined CGRP receptors, cAMP generation, and changes in cellular Ca2+ concentrations on CGRP treatment. These cells express mRNA for CGRP receptor components, calcitonin receptor-like receptor, and receptor activity-modifying protein-1. Direct saturation binding for 125I-labeled CGRP to HUVS cells and Scatchard analysis indicate specificity of the receptors for CGRP [dissociation constant ( KD) = 67 nM, maximum binding capcity (Bmax) = 2.7 pmol/million cells]. Exposure of HUVS cells to CGRP leads to a dose-dependent increase in intracellular cAMP accumulation, and this increase is prevented by CGRP antagonist CGRP8–37. Using fura-2-loaded HUVS cells, we monitored the effects of CGRP on intracellular Ca2+ concentration ([Ca2+]i). In the presence of extracellular Ca2+, bradykinin (10−6 M), a fetoplacental vasoconstrictor, increases HUVS cells [Ca2+]i concentration. CGRP (10−8 M) abolishes bradykinin-induced [Ca2+]i elevation. When the cells were pretreated with glibenclamide, an ATP-sensitive potassium channel blocker, the CGRP actions on bradykinin-induced Ca2+ influx were profoundly inhibited. In the absence of extracellular Ca2+, CGRP (10−8 M) attenuated the increase of [Ca2+]i induced by a sarcoplasmic reticulum Ca2+ pump ATPase inhibitor thapsigargin (10−5 M). Furthermore, Rp-cAMPS, a cAMP-dependent protein kinase A inhibitor, blocks CGRP actions on thapsigargin-induced Ca2+ release from sarcoplasmic reticulum. Our results suggested that CGRP relaxes human fetoplacental vessels by not only inhibiting the influx of extracellular Ca2+ but also attenuating the release of intracellular Ca2+ from the sarcoplasmic reticulum, and these actions might be attributed to CGRP-induced intracellular cAMP accumulation.

scholarly journals EppA, a Putative Substrate of DdERK2, Regulates Cyclic AMP Relay and Chemotaxis in Dictyostelium discoideum

2006 ◽  
Vol 5 (7) ◽  
pp. 1136-1146 ◽  
Author(s):  
Songyang Chen ◽  
Jeffrey E. Segall
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Mitogen Activated Protein Kinase ◽  
Intracellular Camp ◽  
Mitogen Activated Protein ◽  
Delayed Development ◽  
Induced Signal ◽  
Extracellular Camp ◽  
Intracellular Camp Accumulation ◽  
Dimensional Electrophoresis

ABSTRACT The mitogen-activated protein kinase DdERK2 is critical for cyclic AMP (cAMP) relay and chemotaxis to cAMP and folate, but the details downstream of DdERK2 are unclear. To search for targets of DdERK2 in Dictyostelium discoideum,32PO4 3−-labeled protein samples from wild-type and Dderk2 − cells were resolved by 2-dimensional electrophoresis. Mass spectrometry was used to identify a novel 45-kDa protein, named EppA (ERK2-dependent phosphoprotein A), as a substrate of DdERK2 in Dictyostelium. Mutation of potential DdERK2 phosphorylation sites demonstrated that phosphorylation on serine 250 of EppA is DdERK2 dependent. Changing serine 250 to alanine delayed development of Dictyostelium and reduced Dictyostelium chemotaxis to cAMP. Although overexpression of EppA had no significant effect on the development or chemotaxis of Dictyostelium, disruption of the eppA gene led to delayed development and reduced chemotactic responses to both cAMP and folate. Both eppA gene disruption and overexpression of EppA carrying the serine 250-to-alanine mutation led to inhibition of intracellular cAMP accumulation in response to chemoattractant cAMP, a pivotal process in Dictyostelium chemotaxis and development. Our studies indicate that EppA regulates extracellular cAMP-induced signal relay and chemotaxis of Dictyostelium.

scholarly journals Effect of Soluble Adenylyl Cyclase (ADCY10) Inhibitors on the LH-Stimulated cAMP Synthesis in Mltc-1 Leydig Cell Line

2021 ◽  
Vol 22 (9) ◽  
pp. 4641
Author(s):  
Thi Mong Diep Nguyen ◽  
Laura Filliatreau ◽  
Danièle Klett ◽  
Nong Van Hai ◽  
Nguyen Thuy Duong ◽  
...  
Keyword(s):  
Adenylyl Cyclase ◽  
Leydig Cells ◽  
Intracellular Camp ◽  
Camp Accumulation ◽  
Adenylyl Cyclases ◽  
High Concentration ◽  
Soluble Adenylyl Cyclase ◽  
Bicarbonate Ions ◽  
Intracellular Camp Accumulation

In contrast to all transmembrane adenylyl cyclases except ADCY9, the cytosolic soluble adenylyl cyclase (ADCY10) is insensitive to forskolin stimulation and is uniquely modulated by calcium and bicarbonate ions. In the present paper, we focus on ADCY10 localization and a kinetic analysis of intracellular cAMP accumulation in response to human LH in the absence or presence of four different ADCY10 inhibitors (KH7, LRE1, 2-CE and 4-CE) in MTLC-1 cells. ADCY10 was immuno-detected in the cytoplasm of MLTC-1 cells and all four inhibitors were found to inhibit LH-stimulated cAMP accumulation and progesterone level in MLTC-1 and testosterone level primary Leydig cells. Interestingly, similar inhibitions were also evidenced in mouse testicular Leydig cells. In contrast, the tmAC-specific inhibitors ddAdo3′ and ddAdo5′, even at high concentration, exerted weak or no inhibition on cAMP accumulation, suggesting an important role of ADCY10 relative to tmACs in the MLTC-1 response to LH. The strong synergistic effect of HCO3− under LH stimulation further supports the involvement of ADCY10 in the response to LH.

Stimulation of pituitary cAMP accumulation by human pancreatic GH-releasing factor-(1-44)

1984 ◽  
Vol 247 (5) ◽  
pp. E609-E615 ◽  
Author(s):  
M. D. Culler ◽  
T. Kenjo ◽  
N. Obara ◽  
A. Arimura
Keyword(s):  
Cell Cultures ◽  
Intracellular Camp ◽  
Camp Accumulation ◽  
Gh Secretion ◽  
Pituitary Growth Hormone ◽  
Order Of Magnitude ◽  
Novel Method ◽  
Intracellular Camp Accumulation ◽  
Stimulation Of ◽  
Related Increase

This study seeks to determine whether hpGRF-(1-44) stimulates pituitary growth hormone (GH) secretion and cAMP accumulation in a manner that is consistent with the concept of cAMP as an intracellular mediator of GH release. Addition of 10 nM hpGRF-(1-44) to rat anterior pituitary cell cultures stimulated a rapid elevation of intracellular cAMP that preceded or coincided with increases in GH and cAMP secretion. A dose-related increase in GH and cAMP release and in intracellular cAMP accumulation was observed in response to increasing concentrations of hpGRF-(1-44). Stimulation of cAMP accumulation and release, however, occurred over a hpGRF-(1-44) concentration range that was approximately one order of magnitude higher than required for dose-related GH release. Simultaneous addition of 0.05 nM hpGRF-(1-44) and 0.2, 0.5, or 1.0 mM 3-isobutyl-1-methylxanthine (MIX) to the cultures resulted in a significant potentiation of intracellular cAMP accumulation and release. Potentiation of GH release was not observed, however, probably due to attainment of maximal or near maximal GH release by MIX alone. The addition of increasing doses of exogenous N6-O2'-dibutyryladenosine 3',5'-cyclic monophosphate (DBcAMP) to cell cultures resulted in a dose-related increase in GH secretion. The results of this study are consistent with the concept of cAMP as a second messenger for hpGRF-(1-44) in stimulating GH release. Additionally, a novel method for cAMP extraction that utilizes trifluoroacetic acid is described.

γ-MSH increases intracellular cAMP accumulation and GnRH release in vitro and LH release in vivo

FEBS Letters ◽  
2003 ◽  
Vol 543 (1-3) ◽  
pp. 66-70 ◽  
Author(s):  
S.A. Stanley ◽  
S. Davies ◽  
C.J. Small ◽  
J.V. Gardiner ◽  
M.A. Ghatei ◽  
...  
Keyword(s):  
Intracellular Camp ◽  
Camp Accumulation ◽  
Gnrh Release ◽  
Lh Release ◽  
Release In Vitro ◽  
Intracellular Camp Accumulation

Gonadotrophin release by gonadotrophs incubated with gonadotrophin-releasing hormone is independent of intracellular cAMP accumulation

1981 ◽  
Vol 97 (3) ◽  
pp. 329-337 ◽  
Author(s):  
L. Benoist ◽  
M. Le Dafniet ◽  
W. H. Rotsztejn ◽  
J. Besson ◽  
j. Duval
Keyword(s):  
Secondary Process ◽  
Intracellular Camp ◽  
Pituitary Cells ◽  
Camp Accumulation ◽  
Camp Content ◽  
Releasing Hormone ◽  
Rat Pituitary ◽  
Gonadotrophin Releasing Hormone ◽  
Rat Pituitary Cells ◽  
Intracellular Camp Accumulation

Abstract. Rat pituitary cells were dispersed with trypsin and separated by sedimentation at unit gravity. The distributions of prolactin (Prl), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were determined, and two enriched cell populations (mammotrophs and gonadotrophs) were subsequently cultured. During a 4 h incubation, gonadotrophin-releasing hormone (GnRH) stimulated the release of LH and of FSH by both the unfractionated population and the enriched gonadotrophs; the magnitude of this stimulation increased with the length of the pre-culture periods, and the amount of LH released into the medium correlated strongly with the amount of FSH, whatever the length of the pre-culture period. The cellular cAMP content was also enhanced during the 4 h incubation, but no correlation was found between the hormone release and the cAMP accumulation. Furthermore, during the first 30 min of incubation with GnRH there was no increase of cellular cAMP, whatever cell population used. We conclude that the gonadotrophin release was independent of the cAMP accumulation observed in pituitary cells several hours after stimulation by GnRH; consequently, the late increase in the nucleotide is suggested to be a non-specific secondary process.

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