Conjoint action of phosphatidylinositol and adenylate cyclase systems in serotonin-induced facilitation at the crayfish neuromuscular junction

1989 ◽  
Vol 62 (6) ◽  
pp. 1251-1259 ◽  
Author(s):  
D. Dixon ◽  
H. L. Atwood
Keyword(s):  
Protein Kinase ◽  
Neuromuscular Junction ◽  
Adenylate Cyclase ◽  
Early Phase ◽  
Single Application ◽  
Dibutyryl Camp ◽  
Fluorescent Marker ◽  
Epsp Amplitude ◽  
Two Phases ◽  
Crayfish Neuromuscular Junction

1. Pulsatile application of serotonin (5-HT) leads to facilitation of excitatory postsynaptic potentials (EPSPs) in crayfish "opener" neuromuscular preparations. The facilitation resulting from a single application of serotonin shows two phases: an early, rapidly decaying phase, and a less intense, long-lasting phase of 1- to 2-h duration. A previous study implicated the phosphatidylinositol system as an essential component in serotonin-induced facilitation, especially the early phase. The present study was conducted to determine the roles of the adenylate cyclase and phosphatidylinositol systems in both phases of serotonin-induced facilitation. 2. Relatively brief applications of agents known to affect the intracellular concentration of cAMP (forskolin, 1 microM; and IBMX, 100 microM) cause an increase in EPSP amplitude, which persists for 1-2 h. 3. The duration of the less intense, long-lasting phase of serotonin-induced facilitation is prolonged in the presence of 1 microM IBMX. This concentration of IBMX does not affect EPSP amplitude by itself. A membrane-permeant analog of cAMP (applied in concentrations less than or equal to 1 mM) is also not effective in altering EPSP amplitude. However, when dibutyryl cAMP is applied in the presence of 1 microM IBMX, EPSP amplitude is increased (60-80%). 4. Localized presynaptic injection of the "Walsh Inhibitor" (PKI), which inhibits cAMP-activated protein kinase, blocks the less intense, long-lasting phase of serotonin-induced facilitation at synapses near the site of injection. Normal facilitation develops at synapses within the same preparation remote from the site of injection. Distribution of the injected inhibitor within the axon can be visualized by tagging PKI with a fluorescent marker.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Dual bradykinin B2 receptor signalling in A431 human epidermoid carcinoma cells: activation of protein kinase C is counteracted by a GS-mediated stimulation of the cyclic AMP pathway

1996 ◽  
Vol 313 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Claus LIEBMANN ◽  
Angela GRANESS ◽  
Beate LUDWIG ◽  
Antje ADOMEIT ◽  
Anette BOEHMER ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Dibutyryl Camp ◽  
A431 Cells ◽  
Kinase C ◽  
B2 Receptors ◽  
Rapid Activation ◽  
Stimulation Of

Cell membranes of the human epidermoid cell line A431 express classical bradykinin (BK) B2 receptors, as assessed by [3H]BK binding studies. Furthermore, stimulation by BK induced a time-dependent modulation of protein kinase C (PKC) activity in A431 cells: a rapid activation (t½ ≈1 min) is followed by a slow inhibition (t½ ≈20 min) of PKC translocation measured by [3H]phorbol 12,13-dibutyrate binding. In addition, BK stimulated both adenylate cyclase activity in A431 membranes and accumulation of intracellular cyclic AMP (cAMP) in intact cells in a retarded manner. A possible BK-induced activation of the cAMP pathway mediated via PKC, phospholipase D, prostaglandins or Ca2+/calmodulin was excluded. A 35 kDa protein was found in A431 membranes to be specifically phosphorylated in the presence of both BK and protein kinase A (PKA). An anti-αs-antibody, AS 348, abolished stimulation of adenylate cyclase activity in response to BK, cholera toxin and isoprenaline, strongly suggesting the involvement of Gs proteins in the BK action. The BK-activated cAMP signalling system might be important for the observed inactivation of PKC slowly evoked by BK: the BK-induced rapid activation of PKC is decreased by dibutyryl cAMP, and the slow inhibition of PKC is prevented by an inhibitor of PKA, adenosine 3ʹ:5ʹ-monophosphothioate (cyclic, Rp isomer). The inhibition of PKC translocation might be exerted directly at the level of PKC activation, since stimulation of phosphoinositide hydrolysis by BK was affected by neither dibutyryl cAMP nor forskolin. Thus our results provide the first evidence that A431 cells BK is able to activate two independent signal-transduction pathways via a single class of B2 receptors but two different G proteins. The lagging stimulation of the cAMP signalling pathway via Gs might serve to switch off PKC, which is rapidly activated via Gq-mediated stimulation of phosphoinositide hydrolysis.

Calmodulin Regulates Ciliary Beats in the Human Nasal Mucosa Through Adenylate/Guanylate Cyclases and Protein Kinases A/G

2021 ◽  
pp. 1-7
Author(s):  
Thi Nga Nguyen ◽  
Hideaki Suzuki ◽  
Jun-ichi Ohkubo ◽  
Tetsuro Wakasugi ◽  
Takuro Kitamura
Keyword(s):  
Protein Kinase ◽  
Adenylate Cyclase ◽  
Protein Kinases ◽  
Nasal Mucosa ◽  
Guanylate Cyclase ◽  
Regulatory Pathway ◽  
Calmodulin Antagonist ◽  
Human Nasal Mucosa ◽  
Cyclase Activator ◽  
Ciliary Beat

<b><i>Background:</i></b> The ciliary beat of the airway epithelium, including the sinonasal epithelium, has a significant role in frontline defense and is thought to be controlled by the level of intracellular Ca<sup>2+</sup>. Involvement of calmodulin and adenylate/guanylate cyclases in the regulation of ciliary beats has been reported, and here we investigated the interrelation between these components of the ciliary beat regulatory pathway. <b><i>Methods:</i></b> The inferior turbinates were collected from 29 patients with chronic hypertrophic rhinitis/rhinosinusitis during endoscopic sinonasal surgery. The turbinate mucosa was cut into thin strips, and mucociliary movement was observed under a phase-contrast light microscope equipped with a high-speed digital video camera. <b><i>Results:</i></b> The ciliary beat frequency (CBF) was significantly increased by stimulation with 100 μM CALP3 (calmodulin agonist), which was completely suppressed by adding 100 µM SQ22536 (adenylate cyclase inhibitor) and 10 µM ODQ (guanylate cyclase inhibitor) together and by adding 1 µM KT5720 (protein kinase A inhibitor) and 1 µM KT5823 (protein kinase G inhibitor) together. The CBF was significantly increased by stimulation with 10 µM forskolin (adenylate cyclase activator) and 10 µM BAY41-2272 (guanylate cyclase activator) and by stimulation with 100 µM 8-bromo-cAMP (cAMP analog) and 100 µM 8-bromo-cGMP (cGMP analog), which was not changed by adding 1 µM calmidazolium (calmodulin antagonist). <b><i>Conclusions:</i></b> These results confirmed that the regulatory pathway of ciliary beats in the human nasal mucosa involves calmodulin, adenylate/guanylate cyclases, and protein kinases A/G and indicate that adenylate/guanylate cyclases and protein kinases A/G act downstream of calmodulin, but not vice versa, and that these cyclases relay calmodulin signaling.

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