Relationship of Calcium and Membrane Guanylate Cyclase in Adrenocorticotropin-Induced Steroidogenesis*

Nambi, Ponnal; Aiyar, Nambi; Roberts, Audrey N.; Sharma, Rameshwar K.

doi:10.1210/endo-111-1-196

Cited by 40 publications

(18 citation statements)

References 16 publications

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“…The mechanisms by which hyperammonemia affects steroidogenesis are not clear, but altered function of the glutamate‐nitric oxide cGMP pathway (Hermenegildo et al,1998; Rodrigo et al,2007; Hilgier et al,2009) could contribute to this effect. Steroidogenesis is modulated by nitric oxide (Del Punta et al,1996; Hanke et al,1998; Cymeryng et al,1999) and cGMP (Nambi et al,1982). The HPA axis is also modulated by nitric oxide and cGMP (Kafka et al,1986; Gadek‐Michalska and Bugajski,2008).…”

Section: Discussionmentioning

confidence: 99%

Chronic hyperammonemia alters the circadian rhythms of corticosteroid hormone levels and of motor activity in rats

Ahabrach

Piedrafita

Ayad

et al. 2009

J of Neuroscience Research

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Patients with liver cirrhosis may present hepatic encephalopathy with a wide range of neurological disturbances and alterations in sleep quality and in the sleep-wake circadian rhythm. Hyperammonemia is a main contributor to the neurological alterations in hepatic encephalopathy. We have assessed, in an animal model of chronic hyperammonemia without liver failure, the effects of hyperammonemia per se on the circadian rhythms of motor activity, temperature, and plasma levels of adrenal corticosteroid hormones. Chronic hyperammonemia alters the circadian rhythms of locomotor activity and of cortisol and corticosterone levels in blood. Different types of motor activity are affected differentially. Hyperammonemia significantly alters the rhythm of spontaneous ambulatory activity, reducing strongly ambulatory counts and slightly average velocity during the night (the active phase) but not during the day, resulting in altered circadian rhythms. In contrast, hyperammonemia did not affect wheel running at all, indicating that it affects spontaneous but not voluntary activity. Vertical activity was affected only very slightly, indicating that hyperammonemia does not induce anxiety. Hyperammonemia abolished completely the circadian rhythm of corticosteroid hormones in plasma, completely eliminating the peaks of cortisol and corticosterone present in control rats at the start of the dark period. The data reported show that chronic hyperammonemia, similar to that present in patients with liver cirrhosis, alters the circadian rhythms of corticosteroid hormones and of motor activity. This suggests that hyperammonemia would be a relevant contributor to the alterations in corticosteroid hormones and in circadian rhythms in patients with liver cirrhosis.

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Section: Discussionmentioning

confidence: 99%

Chronic hyperammonemia alters the circadian rhythms of corticosteroid hormone levels and of motor activity in rats

Ahabrach

Piedrafita

Ayad

et al. 2009

J of Neuroscience Research

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“…Ca2+-binding proteins, such as calmodulin, play an important role in the secretion mechanism of the adrenal gland (Nambi et al 1982;Widmaier & Hall, 1987;Papadopoulos et al 1990). Kopelman et al (1983) and Gibbons et al (1984) noted the interrela¬ tion of the renin-angiotensin-aldosterone system and the sympathetic nervous system in compensatory response to haemorrhage.…”

Section: Discussionmentioning

confidence: 99%

Distinct regional localization of neurocalcin, a Ca2+-binding protein, in the bovine adrenal gland

Nakano

Terasawa²,

Watanabe³

et al. 1993

Journal of Endocrinology

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Neurocalcin (molecular weight 23,000 and 24,000) is a Ca(2+)-binding protein with three putative Ca(2+)-binding domains and is present in large amounts in nervous tissues. Neurocalcin isoproteins separated by C18 reverse-phase column chromatography are insoluble in buffer solution and it is impossible to determine the dissociation constant of neurocalcin with Ca2+. To overcome this difficulty, recombinant neurocalcin was synthesized, based on one of the cDNAs of the neurocalcin isoproteins. Stoichiometric titration experiments, using recombinant neurocalcin, indicated that this protein bound 2 mol Ca2+/mol protein and that the apparent dissociation constant for Ca2+ was 2.2 mumol/l, suggesting that neurocalcin plays a physiological role in cellular function. Immunoblotting showed that neurocalcin is present in the bovine adrenal gland in addition to the nervous tissues. Neurocalcin, identified by immunoblotting, was purified from the bovine adrenal gland. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of neurocalcin from the bovine brain showed 23 kDa and 24 kDa double bands, while SDS-PAGE of neurocalcin from the adrenal gland showed a single band of apparently 24 kDa, suggesting that the expression of neurocalcin isoproteins differs from tissue to tissue. The content of neurocalcin in the adrenal gland was 10 micrograms protein/100 g wet tissue. Immunohistochemical analysis showed the occurrence of neurocalcin in zona glomerulosa and adrenal medulla but not in zona fasciculata or zona reticularis. The restricted localization of neurocalcin in the adrenal gland suggests that a similar Ca2+signal pathway may be present in zona glomerulosa a nd the adrenal medulla.

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“…The reaction was terminated by the addition of 225 μl of 50 mM sodium acetate buffer, pH 6.2, followed by heating on a boiling water bath for 3 min. The amount of cyclic GMP formed was determined by radioimmunoassay (Nambi et al, 1982). All assays were done in triplicate and except where stated otherwise, were performed three times.…”

Section: Methodsmentioning

confidence: 99%

Membrane Guanylate Cyclase catalytic Subdomain: Structure and Linkage with Calcium Sensors and Bicarbonate

Ravichandran

Duda

Pertzev

et al. 2017

Front. Mol. Neurosci.

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Membrane guanylate cyclase (MGC) is a ubiquitous multi-switching cyclic GMP generating signaling machine linked with countless physiological processes. In mammals it is encoded by seven distinct homologous genes. It is a single transmembrane spanning multi-modular protein; composed of integrated blocks and existing in homo-dimeric form. Its core catalytic domain (CCD) module is a common transduction center where all incoming signals are translated into the production of cyclic GMP, a cellular signal second messenger. Crystal structure of the MGC’s CCD does not exist and its precise identity is ill-defined. Here, we define it at a sub-molecular level for the phototransduction-linked MGC, the rod outer segment guanylate cyclase type 1, ROS-GC1. (1) The CCD is a conserved 145-residue structural unit, represented by the segment V820-P964. (2) It exists as a homo-dimer and contains seven conserved catalytic elements (CEs) wedged into seven conserved motifs. (3) It also contains a conserved 21-residue neurocalcin δ-modulated structural domain, V836-L857. (4) Site-directed mutagenesis documents that each of the seven CEs governs the cyclase’s catalytic activity. (5) In contrast to the soluble and the bacterium MGC which use Mn2+-GTP substrate for catalysis, MGC CCD uses the natural Mg2+-GTP substrate. (6) Strikingly, the MGC CCD requires anchoring by the Transmembrane Domain (TMD) to exhibit its major (∼92%) catalytic activity; in isolated form the activity is only marginal. This feature is not linked with any unique sequence of the TMD; there is minimal conservation in TMD. Finally, (7) the seven CEs control each of four phototransduction pathways- -two Ca2+-sensor GCAPs-, one Ca2+-sensor, S100B-, and one bicarbonate-modulated. The findings disclose that the CCD of ROS-GC1 has built-in regulatory elements that control its signal translational activity. Due to conservation of these regulatory elements, it is proposed that these elements also control the physiological activity of other members of MGC family.

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Relationship of Calcium and Membrane Guanylate Cyclase in Adrenocorticotropin-Induced Steroidogenesis*

Cited by 40 publications

References 16 publications

Chronic hyperammonemia alters the circadian rhythms of corticosteroid hormone levels and of motor activity in rats

Chronic hyperammonemia alters the circadian rhythms of corticosteroid hormone levels and of motor activity in rats

Distinct regional localization of neurocalcin, a Ca2+-binding protein, in the bovine adrenal gland

Membrane Guanylate Cyclase catalytic Subdomain: Structure and Linkage with Calcium Sensors and Bicarbonate

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