scholarly journals Dissection of autophagy in tobacco BY-2 cells under sucrose starvation conditions using the vacuolar H+-ATPase inhibitor concanamycin A and the autophagy-related protein Atg8

2015 ◽  
Vol 10 (11) ◽  
pp. e1082699 ◽  
Author(s):  
Kanako Yano ◽  
Takahiro Yanagisawa ◽  
Kyosuke Mukae ◽  
Yasuo Niwa ◽  
Yuko Inoue ◽  
...  
Keyword(s):  
Related Protein ◽  
Atpase Inhibitor ◽  
Sucrose Starvation ◽  
Concanamycin A ◽  
Starvation Conditions

Ethanol and carbon-source starvation enhance the accumulation of HSP80 in Neurospora crassa

1988 ◽  
Vol 34 (2) ◽  
pp. 162-168 ◽  
Author(s):  
H. S. Roychowdhury ◽  
M. Kapoor
Keyword(s):  
Heat Shock ◽  
Neurospora Crassa ◽  
Carbon Catabolite Repression ◽  
Normal Growth ◽  
Carbon Starvation ◽  
High Molecular Mass ◽  
Sucrose Starvation ◽  
Shock Response ◽  
Shock Proteins ◽  
Starvation Conditions

In Neurospora crassa, heat shock results in the induction of 9 to 11 heat shock proteins (HSP), of which HSP80 is the most abundant and the first to be synthesized. The induction of HSP80 was investigated during normal growth (2% sucrose) and under sucrose starvation. Transfer of mycelium to a medium supplemented with ethanol stimulated the synthesis of HSP80, even at the normal growth temperature of 28 °C. It was also synthesized under carbon starvation conditions, where the medium was supplemented with 0.02% sucrose, 0.3% acetate, 0.2% lactate, or ethanol. A 30–35 kilodalton polypeptide was induced by heat shock in carbon-sufficient media, but in 0.02% sucrose and 0.3% acetate containing media it was synthesized at normal temperatures. While the overall heat shock response remained unaltered in these cultures, the abundance of HSP90 and HSP70, relative to HSP80, was greater. HSP80 appears to be controlled by carbon-catabolite repression as well as heat shock. Another high molecular mass protein (tentatively designated alc'80') was observed to be induced by heat shock, provided carbon starvation conditions prevailed concurrently.

Arabidopsis RETINOBLASTOMA-RELATED PROTEIN 1 is involved in G1 phase cell cycle arrest caused by sucrose starvation

2007 ◽  
Vol 66 (3) ◽  
pp. 259-275 ◽  
Author(s):  
Hiroto Hirano ◽  
Hirofumi Harashima ◽  
Atsuhiko Shinmyo ◽  
Masami Sekine
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Phase Cell ◽  
G1 Phase ◽  
Related Protein ◽  
Sucrose Starvation ◽  
Cycle Arrest

Glucose activates H+-ATPase in kidney epithelial cells

2004 ◽  
Vol 287 (1) ◽  
pp. C97-C105 ◽  
Author(s):  
Suguru Nakamura
Keyword(s):  
Epithelial Cells ◽  
Atpase Activity ◽  
Physiological Effect ◽  
Bicarbonate Transport ◽  
Epithelial Cell Line ◽  
Atpase Inhibitor ◽  
Concanamycin A ◽  
Vacuolar Acidification ◽  
Kidney Epithelial Cells ◽  
Effect Of Glucose

The vacuolar H+-ATPase (V-ATPase) acidifies compartments of the vacuolar system of eukaryotic cells. In renal epithelial cells, it resides on the plasma membrane and is essential for bicarbonate transport and acid-base homeostasis. The factors that regulate the H+-ATPase remain largely unknown. The present study examines the effect of glucose on H+-ATPase activity in the pig kidney epithelial cell line LLC-PK1. Cellular pH was measured by performing ratiometric fluorescence microscopy using the pH-sensitive indicator BCECF-AM. Intracellular acidification was induced with NH3/NH4+ prepulse, and rates of intracellular pH (pHi) recovery (after in situ calibration) were determined by the slopes of linear regression lines during the first 3 min of recovery. The solutions contained 1 μM ethylisopropylamiloride and were K+ free to eliminate Na+/H+ exchange and H+-K+-ATPase activity. After NH3/NH4+-induced acidification, LLC-PK1 cells had a significant pHi recovery rate that was inhibited entirely by 100 nM of the V-ATPase inhibitor concanamycin A. Acute removal of glucose from medium markedly reduced V-ATPase-dependent pHi recovery activity. Readdition of glucose induced concentration-dependent reactivation of V-ATPase pHi recovery activity within 2 min. Glucose replacement produced no significant change in cell ATP or ADP content. H+-ATPase activity was completely inhibited by the glycolytic inhibitor 2-deoxy-d-glucose (20 mM) but only partially inhibited by the mitochondrial electron transport inhibitor antimycin A (20 μM). The phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin (500 nM) abolished glucose activation of V-ATPase, and activity was restored after wortmannin removal. Glucose activates V-ATPase activity in kidney epithelial cells through the glycolytic pathway by a signaling pathway that requires PI3K activity. These findings represent an entirely new physiological effect of glucose, linking it to cellular proton secretion and vacuolar acidification.

ANG II-dependent HCO3- reabsorption in surviving rat distal tubules: expression/activation of H(+)-ATPase

1997 ◽  
Vol 272 (6) ◽  
pp. F799-F808 ◽  
Author(s):  
D. Z. Levine ◽  
M. Iacovitti ◽  
S. Buckman ◽  
M. T. Hincke ◽  
B. Luck ◽  
...  
Keyword(s):  
Important Determinant ◽  
Ang Ii ◽  
Atpase Inhibitor ◽  
Cellular Hypertrophy ◽  
Concanamycin A ◽  
Luminal Perfusion ◽  
Enhanced Expression ◽  
Distal Tubules ◽  
Dimethyl Amiloride

Distal tubules (DT) from sham or five-sixths nephrectomized (Nx) rats were perfused in vivo to evaluate the hypothesis that, after Nx, endogenous angiotensin II (ANG II) modulates DT in vivo bicarbonate reabsorption (JtCO2) via H(+)-adenosinetriphosphatase (H(+)-ATPase) and Na+/H+ exchange. In Nx rats JtCO2 was increased (65 +/- 7 vs. -24 +/- 21 pmol.min-1.mm-1, P < 0.01). Both luminal and intravenous AT1-receptor blockade by losartan reduced Nx DT JtCO2 (41 +/- 6 and 34 +/- 4 pmol.min-1.min-1, respectively, P < 0.05), whereas neither 10(-9) M nor 10(-11) M ANG II luminal perfusion increased JtCO2, suggesting preexisting high endogenous ANG II levels. The Na+/H+ antiporter inhibitors 5-(N-ethyl-N-isopropyl)-amiloride and 5-(N,N-dimethyl)-amiloride were without effect. Luminal perfusion of 5 nM concanamycin A, a V-type H(+)-ATPase inhibitor, reduced Nx DT JtCO2 (45 +/- 8 pmol.min-1.mm-1, P < 0.05). In Nx A-type intercalated cells, we demonstrated cellular hypertrophy, elaboration of apical microplicae, and enhanced expression/apical polarization of H(+)-ATPase. Thus ANG II is an important determinant in sustaining brisk DT JtCO2 following Nx and is associated with enhanced expression and A-type intercalated cell apical polarization of H(+)-ATPase.

scholarly journals A polyphenol, pyrogallol changes the acidic pH of the digestive vacuole of Plasmodium falciparum

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Nur Saidatul Aqilah Ja’afar ◽  
Nik Nor Imam Nik Mat Zin ◽  
Fatin Sofia Mohamad ◽  
Nurhidanatasha Abu-Bakar
Keyword(s):  
Plasmodium Falciparum ◽  
Proton Pump ◽  
Antimalarial Activity ◽  
Fluorescein Isothiocyanate ◽  
Drug Candidate ◽  
Digestive Vacuole ◽  
Atpase Inhibitor ◽  
Trophozoite Stage ◽  
Concanamycin A ◽  
Ic50 Value

Pyrogallol has a capability of generating free radicals like other antimalarial drugs such as artemisinin, which is thought to inhibit the proton pump located in the membrane of the Plasmodium falciparum digestive vacuole, thus alkalinising this acidic organelle. This study aimed to determine pH changes of the malaria parasite’s digestive vacuole following treatment with pyrogallol. The antimalarial activity of this compound was evaluated by a malarial SYBR Green 1 fluorescence-based assay to determine the 50% inhibitory concentration (IC50). Based on the IC50 value, different concentrations of pyrogallol were selected to ensure changes of the digestive vacuole pH were not due to parasite death. This was measured by flow cytometry after 4-hour pyrogallol treatment on the fluorescein isothiocyanate-dextran-accumulated digestive vacuole of the mid-trophozoite stage parasites. Pyrogallol showed a moderate antimalarial activity with the IC50 of 2.84 ± 9.40 µM. The treatment of 1.42, 2.84 and 5.67 µM pyrogallol increased 2.9, 3.0 and 3.1 units of the digestive vacuole pH, respectively as compared with the untreated parasite (pH 5.6 ± 0.78). The proton pump, V-type H+-ATPase might be inhibited by pyrogallol, hence causing the digestive vacuole pH alteration, which is similar with the result shown by a standard V-type H+-ATPase inhibitor, concanamycin A. This study provides a fundamental understanding on the antimalarial activity and mechanism of action of pyrogallol that has a potential to be the antimalarial drug candidate.

scholarly journals The Early Phagosomal Stage of Francisella tularensis Determines Optimal Phagosomal Escape and Francisella Pathogenicity Island Protein Expression

2008 ◽  
Vol 76 (12) ◽  
pp. 5488-5499 ◽  
Author(s):  
Audrey Chong ◽  
Tara D. Wehrly ◽  
Vinod Nair ◽  
Elizabeth R. Fischer ◽  
Jeffrey R. Barker ◽  
...  
Keyword(s):  
Protein Expression ◽  
Francisella Tularensis ◽  
Pathogenicity Island ◽  
Endocytic Pathway ◽  
Atpase Inhibitor ◽  
Murine Bone Marrow ◽  
Concanamycin A ◽  
Late Endosomes ◽  
Endosomal Acidification ◽  
Schu S4

ABSTRACT Francisella tularensis is an intracellular pathogen that can survive and replicate within macrophages. Following phagocytosis and transient interactions with the endocytic pathway, F. tularensis rapidly escapes from its original phagosome into the macrophage cytoplasm, where it eventually replicates. To examine the importance of the nascent phagosome for the Francisella intracellular cycle, we have characterized early trafficking events of the F. tularensis subsp. tularensis strain Schu S4 in a murine bone marrow-derived macrophage model. Here we show that early phagosomes containing Schu S4 transiently interact with early and late endosomes and become acidified before the onset of phagosomal disruption. Inhibition of endosomal acidification with the vacuolar ATPase inhibitor bafilomycin A1 or concanamycin A prior to infection significantly delayed but did not block phagosomal escape and cytosolic replication, indicating that maturation of the early Francisella-containing phagosome (FCP) is important for optimal phagosomal escape and subsequent intracellular growth. Further, Francisella pathogenicity island (FPI) protein expression was induced during early intracellular trafficking events. Although inhibition of endosomal acidification mimicked the early phagosomal escape defects caused by mutation of the FPI-encoded IglCD proteins, it did not inhibit the intracellular induction of FPI proteins, demonstrating that this response is independent of phagosomal pH. Altogether, these results demonstrate that early phagosomal maturation is required for optimal phagosomal escape and that the early FCP provides cues other than intravacuolar pH that determine intracellular induction of FPI proteins.

pH-independent retrograde targeting of glycolipids to the Golgi complex

1998 ◽  
Vol 274 (2) ◽  
pp. C319-C332 ◽  
Author(s):  
Florencia B. Schapiro ◽  
Clifford Lingwood ◽  
Wendy Furuya ◽  
Sergio Grinstein
Keyword(s):  
Golgi Complex ◽  
Retrograde Transport ◽  
Vero Cells ◽  
Atpase Inhibitor ◽  
B Subunit ◽  
Concanamycin A ◽  
Ratio Imaging ◽  
Toxin Receptor ◽  
Luminal Ph ◽  
Secretory System

A small fraction of the molecules internalized by endocytosis reaches the Golgi complex through a retrograde pathway that is poorly understood. In the present work, we used bacterial toxins to study the retrograde pathway in Vero cells. The recombinant B subunit of verotoxin 1B (VT1B) was labeled with fluorescein to monitor its progress within the cell by confocal microscopy. This toxin, which binds specifically to the glycolipid globotriaosyl ceramide, entered endosomes by both clathrin-dependent and -independent pathways, reaching the Golgi complex. Once internalized, the toxin-receptor complex did not recycle back to the plasma membrane. The kinetics of internalization and the subcellular distribution of VT1B were virtually identical to those of another glycolipid-binding toxin, the B subunit of cholera toxin (CTB). Retrograde transport of VT1B and CTB was unaffected by addition of weak bases in combination with concanamycin, a vacuolar-type ATPase inhibitor. Ratio imaging confirmed that these agents neutralized the luminal pH of the compartments where the toxin was located. Therefore, the retrograde transport of glycolipids differs from that of proteins like furin and TGN38, which require an acidic luminal pH. Additional experiments indicated that the glycolipid receptors of VT1B and CTB are internalized independently and not as part of lipid “rafts” and that internalization is cytochalasin insensitive. We conclude that glycolipids utilize a unique, pH-independent retrograde pathway to reach compartments of the secretory system and that assembly of F-actin is not required for this process.

scholarly journals Reversible Association between the V1and V0 Domains of Yeast Vacuolar H+-ATPase Is an Unconventional Glucose-Induced Effect

1998 ◽  
Vol 18 (12) ◽  
pp. 7064-7074 ◽  
Author(s):  
Karlett J. Parra ◽  
Patricia M. Kane
Keyword(s):  
Glucose Metabolism ◽  
Glucose Deprivation ◽  
Proton Pumping ◽  
Atpase Inhibitor ◽  
General Stress Response ◽  
Concanamycin A ◽  
Extracellular Glucose ◽  
Domain V ◽  
Glucose Effects

ABSTRACT The yeast vacuolar H+-ATPase (V-ATPase) is a multisubunit complex responsible for organelle acidification. The enzyme is structurally organized into two major domains: a peripheral domain (V1), containing the ATP binding sites, and an integral membrane domain (V0), forming the proton pore. Dissociation of the V1 and V0 domains inhibits ATP-driven proton pumping, and extracellular glucose concentrations regulate V-ATPase activity in vivo by regulating the extent of association between the V1 and V0 domains. To examine the mechanism of this response, we quantitated the extent of V-ATPase assembly in a variety of mutants with known effects on other glucose-responsive processes. Glucose effects on V-ATPase assembly did not involve the Ras-cyclic AMP pathway, Snf1p, protein kinase C, or the general stress response protein Rts1p. Accumulation of glucose 6-phosphate was insufficient to maintain or induce assembly of the V-ATPase, suggesting that further glucose metabolism is required. A transient decrease in ATP concentration with glucose deprivation occurs quickly enough to help trigger disassembly of the V-ATPase, but increases in cellular ATP concentrations with glucose readdition cannot account for reassembly. Disassembly was inhibited in two mutant enzymes lacking ATPase and proton pumping activities or in the presence of the specific V-ATPase inhibitor, concanamycin A. We propose that glucose effects on V-ATPase assembly occur by a novel mechanism that requires glucose metabolism beyond formation of glucose 6-phosphate and generates a signal that can be sensed efficiently only by a catalytically competent V-ATPase.

Sign in / Sign up

Export Citation Format

Share Document