ACTIVATION AND PHYSIOLOGICAL ROLE OF Na+/H+ EXCHANGE IN LAMPREY (LAMPETRA FLUVIATILIS) ERYTHROCYTES

1994 ◽  
Vol 191 (1) ◽  
pp. 89-105 ◽  
Author(s):  
L Virkki ◽  
M Nikinmaa
Keyword(s):  
Sodium Transport ◽  
Physiological Role ◽  
Cell Swelling ◽  
Intracellular Acidification ◽  
Adrenergic Stimulation ◽  
Sodium Influx ◽  
Lampetra Fluviatilis ◽  
Physiological Conditions ◽  
Red Cell Ph

The effects of intracellular acidification, osmotic shrinkage and ss-adrenergic stimulation on sodium transport across the membrane of lamprey (Lampetra fluviatilis) erythrocytes were investigated. Unidirectional ouabain-insensitive sodium flux, measured using radioactive 22Na, was increased markedly by intracellular acidification, to a lesser extent by osmotic shrinkage and only modestly by ss-adrenergic stimulation. Na+/H+ exchange was activated in all of these cases. However, net sodium influx (and cell swelling caused by the influx of osmotically obliged water) was seen only in cells subjected to intracellular acidification. In contrast, practically no changes in red cell pH or in water or ion (Na+, K+ and Cl-) contents were seen after osmotic shrinkage or ss-adrenergic stimulation. Calculations of the [Na+]o/[Na+]i and [H+]o/[H+]i ratios across the erythrocyte membrane suggest that the virtual lack of net sodium movements in osmotically shrunken erythrocytes is due to the absence of a driving force for net transport of these ions via the Na+/H+ exchange pathway. It also appears that, in physiological conditions, the increase in the activity of the Na+/H+ exchanger by ss-adrenergic stimulation is too small to mediate detectable net sodium transport.

Metabolism at the pyruvate branch point in the radula retractor muscle of the whelk, Busycon contrarium

1982 ◽  
Vol 60 (11) ◽  
pp. 2973-2977 ◽  
Author(s):  
W. Ross Ellington
Keyword(s):  
Branch Point ◽  
Physiological Role ◽  
Redox Balance ◽  
Retractor Muscle ◽  
Physiological Conditions ◽  
Wet Weight ◽  
Octopine Dehydrogenase

The radula retractor muscle of the whelk Busycon contrarium contains high activities of both octopine dehydrogenase (~500 μmol∙min−1∙g wet weight−1) and strombine dehydrogenase (~150 μmol∙min−1∙g wet weight−1). Experiments were conducted with in vitro radula muscle preparations to assess under what physiological conditions these dehydrogenases function. Alanopine–strombine accumulated during anoxia, postanoxic recovery, and potassium-induced contractures in radula retractor muscles. No significant accumulation of octopine was observed. Although the accumulation of alanopine–strombine was significant, it was quantitatively small when compared with the production of succinate. Thus, it appears that alanopine–strombine formation has only an accessory role in cytoplasmic redox balance in B. contrarium radula retractor muscle. The physiological role of octopine dehydrogenase in this system remains unclear.

scholarly journals Elaborating the Physiological Role of YAP as a Glucose Metabolism Regulator: A Systematic Review

2021 ◽  
Vol 55 (2) ◽  
pp. 193-205
Keyword(s):  
Systematic Review ◽  
Glucose Metabolism ◽  
Glucose Transporter ◽  
Physiological Role ◽  
Size Control ◽  
Metabolic Disturbances ◽  
Oncogenic Potential ◽  
Physiological Conditions ◽  
Control Research

Yes-associated protein (YAP) is one of the Hippo pathway's two effectors, a pathway associated with organ size control. Research on YAP has focused on its oncogenic potential. However, in cancer cells, aside from inducing growth, YAP was also found to regulate glucose metabolism. Therefore, we aimed to explore YAP's control of glucose metabolism and whether these findings are translatable to physiological conditions. We conducted a systematic review of the MEDLINE database through PubMed in April 2020 and repeated the search in September 2020. We found that YAP induced the transcriptional activity of most genes associated with glucose metabolism from enzymes to transport proteins. In glycolysis and gluconeogenesis, YAP upregulated all enzymes except for enolase and pyruvate kinase. Multiple research has also shown YAP's ability to regulate the expression of glucose transporter of the GLUT family. Additionally, glucose concentration, hypoxia, and hormones such as insulin and glucagon regulate YAP activity and depend on YAP to exert their biological activity. In this review, we have shown that YAP is a central regulator of glucose metabolism, controlling both enzymes and proteins involved in glucose transport. YAP is also situated strategically in several pathways controlling glucose and was found to mediate their effects. If these results were consistent in physiological conditions and across glucose-associated metabolic disturbances, then YAP may become a prospective therapeutic target.

scholarly journals N-terminal sumoylation of centromeric histone H3 variant Cse4 regulates its proteolysis to prevent mislocalization to non-centromeric chromatin

2017 ◽  
Author(s):  
Kentaro Ohkuni ◽  
Reuben Levy-Myers ◽  
Jack Warren ◽  
Wei-Chun Au ◽  
Yoshimitsu Takahashi ◽  
...  
Keyword(s):  
Genome Stability ◽  
Histone H3 ◽  
Physiological Role ◽  
Centromeric Chromatin ◽  
E3 Ligases ◽  
Physiological Conditions ◽  
Evolutionarily Conserved ◽  
Histone H3 Variant

AbstractStringent regulation of cellular levels of evolutionarily conserved centromeric histone H3 variant (CENP-A in humans, CID in flies, Cse4 in yeast) prevents its mislocalization to non-centromeric chromatin. Overexpression and mislocalization of CENP-A has been observed in cancers and leads to aneuploidy in yeast, flies, and human cells. Ubiquitin-mediated proteolysis of Cse4 by E3 ligases such as Psh1 and Sumo-Targeted Ubiquitin Ligase (STUbL) Slx5 prevent mislocalization of Cse4. Previously, we identified Siz1 and Siz2 as the major E3 ligases for sumoylation of Cse4. In this study, we identify lysine 65 (K65) in Cse4 as a SUMO site and show that sumoylation of Cse4 K65 regulates its ubiquitin-mediated proteolysis by Slx5. Strains expressing cse4 K65R exhibit reduced levels of sumoylated and ubiquitinated Cse4 in vivo. Furthermore, co-immunoprecipitation experiments reveal reduced interaction of cse4 K65R with Slx5. Defects in sumoylation of cse4 K65R contribute to increased stability and mislocalization of cse4 K65R under normal physiological conditions. Based on the increased stability of cse4 K65R in psh1∆ strains but not in slx5∆ strains, we conclude that Slx5 targets sumoylated Cse4 K65 for ubiquitination-mediated proteolysis independent of Psh1. In summary, we have identified and characterized the physiological role of Cse4 sumoylation and determined that sumoylation of Cse4 K65 regulates ubiquitin-mediated proteolysis and prevents mislocalization of Cse4 which is required for genome stability.

cAMP and calcium-dependent mechanisms of phospholamban phosphorylation in intact hearts

1990 ◽  
Vol 258 (2) ◽  
pp. H318-H325 ◽  
Author(s):  
L. Vittone ◽  
C. Mundina ◽  
G. Chiappe de Cingolani ◽  
A. Mattiazzi
Keyword(s):  
Physiological Role ◽  
Intracellular Camp ◽  
Adrenergic Stimulation ◽  
Sr Protein ◽  
Myocardial Relaxation ◽  
Calcium Dependent ◽  
High Beta ◽  
Camp Levels ◽  
Phospholamban Phosphorylation

The present work was undertaken with two main goals: 1) to further elucidate the physiological role of the adenosine 3',5'-cyclic monophosphate (cAMP) and Ca2(+)-calmodulin (Ca2(+)-Cm)-dependent mechanisms of phospholamban phosphorylation (32PiPHL), and 2) to study the possible interaction between these two systems in the intact heart. Interventions that increased twitch or tetanic tension without modifying cAMP levels [high extracellular Ca2+ concentration [( Ca2+]o) or BAY K 8644 in catecholamine-depleted hearts] failed to alter 32PiPHL. Moderate and high beta-adrenergic stimulation (3 x 10(-9) and 3 x 10(-8) M isoproterenol, respectively) increased cAMP from 0.345 +/- 0.032 to 0.636 +/- 0.069 and 0.772 +/- 0.060 pmol/mg wet wt, and 32PiPHL from 26.8 +/- 4.1 to 58.6 +/- 13.1 and 174.7 +/- 13.8 pmol 32Pi/mg sarcoplasmic reticular [SR] protein, respectively. Both doses of isoproterenol produced an enhanced myocardial relaxation. Reversal of the positive inotropic effect of isoproterenol by interventions that decrease intracellular Ca2+ supply failed to reduce the enhancement in 32PiPHL and myocardial relaxation elicited by 3 x 10(-9) M isoproterenol but diminished the increase in 32PiPHL induced by 3 x 10(-8) M isoproterenol to 116.3 +/- 10.9 without significant changes in cAMP. Changes in myocardial relaxation closely paralleled the changes in 32PiPHL. These results suggest that 1) 32PiPHL may be enhanced by the cAMP-dependent mechanism independently of the Ca2(+)-Cm system, and 2) 32PiPHL and myocardial relaxation may be modified by intracellular Ca2+ changes only at high-intracellular cAMP levels.

Cell volume regulation in rabbit proximal straight tubule perfused in vitro

1987 ◽  
Vol 252 (5) ◽  
pp. F922-F932 ◽  
Author(s):  
K. L. Kirk ◽  
J. A. Schafer ◽  
D. R. DiBona
Keyword(s):  
Cell Volume ◽  
Volume Regulation ◽  
Time Course ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Physiological Role ◽  
Cell Swelling ◽  
Computer Based

Volume regulation in the perfused proximal nephron of the rabbit was examined quantitatively with a computer-based method for estimating cell volume from differential interference-contrast microscopic images of isolated nephron segments. Following a hyperosmotic challenge (290-390 mosmol), the cells shrank as simple osmometers without a subsequent regulatory volume increase. Conversely, cell swelling induced by a hyposmotic challenge (290-190 mosmol) was completely reversed with a triphasic time course in which a rapid (less than 2 min) initial volume decline was followed by secondary swelling and shrinking phases. A similar regulatory volume decrease was observed following isosmotic cell swelling that was induced by exposure to 290 mosmol, urea-containing solutions. In addition, the cells partially reversed isosmotic swelling that was induced by the luminal replacement of a relatively impermeant cation (i.e., choline) with Na+ and a concomitant increase in luminal solute entry. Our results support two conclusions. First, there exist quantitative differences between the volume regulatory behaviors of perfused and nonperfused proximal tubules, the latter of which exhibit an incomplete and monotonic reversal of hyposmotic cell swelling (M. Dellasega and J. Grantham, Am. J. Physiol. 224: 1288-1294, 1973). Second, the primary physiological role of cell volume regulation in the proximal nephron may be to minimize isosmotic cell swelling associated with acute imbalances in the rates of cell solute entry and exit.

scholarly journals Vanin 1: Its Physiological Function and Role in Diseases

2019 ◽  
Vol 20 (16) ◽  
pp. 3891 ◽  
Author(s):  
Roberta Bartucci ◽  
Anna Salvati ◽  
Peter Olinga ◽  
Ykelien L. Boersma
Keyword(s):  
Energy Production ◽  
Coenzyme A ◽  
Physiological Function ◽  
Complex Function ◽  
Pantothenic Acid ◽  
Physiological Role ◽  
Complete Understanding ◽  
Major Function ◽  
Physiological Conditions

The enzyme vascular non-inflammatory molecule-1 (vanin 1) is highly expressed at gene and protein level in many organs, such as the liver, intestine, and kidney. Its major function is related to its pantetheinase activity; vanin 1 breaks down pantetheine in cysteamine and pantothenic acid, a precursor of coenzyme A. Indeed, its physiological role seems strictly related to coenzyme A metabolism, lipid metabolism, and energy production. In recent years, many studies have elucidated the role of vanin 1 under physiological conditions in relation to oxidative stress and inflammation. Vanin’s enzymatic activity was found to be of key importance in certain diseases, either for its protective effect or as a sensitizer, depending on the diseased organ. In this review, we discuss the role of vanin 1 in the liver, kidney, intestine, and lung under physiological as well as pathophysiological conditions. Thus, we provide a more complete understanding and overview of its complex function and contribution to some specific pathologies.

scholarly journals CRABP1 protects the heart from isoproterenol-induced acute and chronic remodeling

2018 ◽  
Vol 236 (3) ◽  
pp. 151-165 ◽  
Author(s):  
Sung Wook Park ◽  
Shawna D Persaud ◽  
Stanislas Ogokeh ◽  
Tatyana A Meyers ◽  
DeWayne Townsend ◽  
...  
Keyword(s):  
Cardiac Function ◽  
Cardiac Injury ◽  
Physiological Role ◽  
Left Ventricular ◽  
Adrenergic Stimulation ◽  
Reduced Ejection Fraction ◽  
Left Ventricular Dilation ◽  
Chronic Remodeling ◽  
Apoptosis And Necrosis

Excessive and/or persistent activation of calcium-calmodulin protein kinase II (CaMKII) is detrimental in acute and chronic cardiac injury. However, intrinsic regulators of CaMKII activity are poorly understood. We find that cellular retinoic acid-binding protein 1 (CRABP1) directly interacts with CaMKII and uncover a functional role for CRABP1 in regulating CaMKII activation. We generated Crabp1-null mice (CKO) in C57BL/6J background for pathophysiological studies. CKO mice develop hypertrophy as adults, exhibiting significant left ventricular dilation with reduced ejection fraction at the baseline cardiac function. Interestingly, CKO mice have elevated basal CaMKII phosphorylation at T287, and phosphorylation on its substrate phospholamban (PLN) at T17. Acute isoproterenol (ISO) challenge (80 mg/kg two doses in 1 day) causes more severe apoptosis and necrosis in CKO hearts, and treatment with a CaMKII inhibitor KN-93 protects CKO mice from this injury. Chronic (30 mg/kg/day) ISO challenge also significantly increases hypertrophy and fibrosis in CKO mice as compared to WT. In wild-type mice, CRABP1 expression is increased in early stages of ISO challenge and eventually reduces to the basal level. Mechanistically, CRABP1 directly inhibits CaMKII by competing with calmodulin (CaM) for CaMKII interaction. This study demonstrates increased susceptibility of CKO mice to ISO-induced acute and chronic cardiac injury due to, at least in part, elevated CaMKII activity. Deleting Crabp1 results in reduced baseline cardiac function and aggravated damage challenged with acute and persistent β-adrenergic stimulation. This is the first report of a physiological role of CRABP1 as an endogenous regulator of CaMKII, which protects the heart from ISO-induced damage.

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