Molecular mechanism of plasma sterilization in solution with the reduced pH method: importance of permeation of HOO radicals into the cell membrane

Adenylate cyclase toxin (ACT or CyaA) plays a crucial role in respiratory tract colonization and virulence of the whooping cough causative bacteriumBordetella pertussis. Secreted as soluble protein, it targets myeloid cells expressing the CD11b/CD18 integrin and on delivery of its N-terminal adenylate cyclase catalytic domain (AC domain) into the cytosol, generates uncontrolled toxic levels of cAMP that ablates bactericidal capacities of phagocytes. Our study deciphers the fundamentals of the heretofore poorly understood molecular mechanism by which the ACT enzyme domain directly crosses the host cell membrane. By combining molecular biology, biochemistry, and biophysics techniques, we discover that ACT has intrinsic phospholipase A (PLA) activity, and that such activity determines AC translocation. Moreover, we show that elimination of the ACT–PLA activity abrogates ACT toxicity in macrophages, particularly at toxin concentrations close to biological reality of bacterial infection. Our data support a molecular mechanism in which in situ generation of nonlamellar lysophospholipids by ACT–PLA activity into the cell membrane would form, likely in combination with membrane-interacting ACT segments, a proteolipidic toroidal pore through which AC domain transfer could directly take place. Regulation of ACT–PLA activity thus emerges as novel target for therapeutic control of the disease.

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Molecular mechanism of α-tocopheryl-phosphate transport across the cell membrane

Biochemical and Biophysical Research Communications ◽

10.1016/j.bbrc.2007.05.094 ◽

2007 ◽

Vol 359 (2) ◽

pp. 348-353 ◽

Cited By ~ 24

Author(s):

Yesim Negis ◽

Mohsen Meydani ◽

Jean-Marc Zingg ◽

Angelo Azzi

Keyword(s):

Cell Membrane ◽

Molecular Mechanism ◽

Phosphate Transport

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Molecular Mechanism of the Cell Membrane Pore Formation Induced by Bubble Stable Cavitation

The Journal of Physical Chemistry B ◽

10.1021/acs.jpcb.8b09391 ◽

2018 ◽

Vol 123 (1) ◽

pp. 71-78 ◽

Cited By ~ 8

Author(s):

Viet Hoang Man ◽

Phan Minh Truong ◽

Mai Suan Li ◽

Junmei Wang ◽

Nguyen-Thi Van-Oanh ◽

...

Keyword(s):

Cell Membrane ◽

Molecular Mechanism ◽

Pore Formation ◽

Membrane Pore

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Molecular mechanism of pyroptosis of mononuclear macrophages induced by pathogenic E. coli high pathogenicity island (HPI) in Yunnan Saba pigs

10.21203/rs.2.24631/v1 ◽

2020 ◽

Author(s):

Chunlan Shan ◽

Shushu Miao ◽

Chaoying Liu ◽

Weiwei Zhao ◽

Bo Zhang ◽

...

Keyword(s):

Cell Membrane ◽

Molecular Mechanism ◽

Pathogenicity Island ◽

Control Group ◽

Tunel Staining ◽

Membrane Pore ◽

Expression Levels ◽

E Coli ◽

Caspase 1 ◽

High Pathogenicity

Abstract Background In this study we evaluated the molecular mechanism by which pyroptosis is induced in mononuclear macrophages isolated from Saba pigs following infection with pathogenic E. coli high pathogenicity island (HPI). Mononuclear macrophages were divided into four treatment groups: control, Lipopolysaccharide (LPS) + adenosine triphosphate (ATP), HPI positive (+) strain and HPI negative (-) strain. The mononuclear macrophages and their culture supernatants were collected at 0.5, 3, 6, 9, 12 and 24 h after infection. DNA changes were detected by TUNEL staining and the integrity of the cell membrane was evaluated by propidium iodide (PI) staining. Changes in mRNA expression levels of NLRP3, caspase-1, IL-1β, and IL-18 gene in mononuclear macrophages were analyzed by quantitative real-time polymerase chain reaction (RT-PCR) and caspase-1 protein expression was detected by indirect immunofluorescence. IL-1β and IL-18 concentration in the mononuclear macrophage culture supernatant were measured by ELISA. Results Compared with the control group, TUNEL and PI staining of mononuclear macrophages was significantly increased following infection with the HPI + /HPI - strains ( P < 0.01 or P < 0.05), with significantly higher levels detected in the HPI + group compared with those in the HPI - group ( P < 0.01 and P < 0.05). Compared with the control group, the expression levels of NLRP3, caspase-1, IL-1β, and IL-18 in the HPI groups were upregulated after pathogenic E. coli infection, with significantly higher levels detected in the HPI + group compared with those in the HPI - group ( P < 0.01 or P < 0.05). Conclusions These findings showed that pathogenic E. coli HPI infection of Saba pigs results induced pyroptosis of mononuclear macrophages characterized by increased expression of NLRP3, caspase-1, IL-1β and IL-18 mRNA in mononuclear macrophages, the induction of cell membrane pore formation, nuclear DNA damage, and the secretion of IL-1β and IL-18 to enhance the inflammatory response.

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Sarcolemmal permeability changes during early myocardial anoxia

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100084089 ◽

1978 ◽

Vol 36 (2) ◽

pp. 642-643

Author(s):

M. Ashraf ◽

L. Landa ◽

L. Nimmo ◽

C. M. Bloor

Keyword(s):

Cell Membrane ◽

Membrane Permeability ◽

Coronary Artery Occlusion ◽

Artery Occlusion ◽

Cell Membrane Permeability ◽

Enzyme Release ◽

Sprague Dawley ◽

Sprague Dawley Rats ◽

Sarcolemmal Permeability ◽

Membrane Changes

Following coronary artery occlusion, the myocardial cells lose intracellular enzymes that appear in the serum 3 hrs later. By this time the cells in the ischemic zone have already undergone irreversible changes, and the cell membrane permeability is variably altered in the ischemic cells. At certain stages or intervals the cell membrane changes, allowing release of cytoplasmic enzymes. To correlate the changes in cell membrane permeability with the enzyme release, we used colloidal lanthanum (La+++) as a histological permeability marker in the isolated perfused hearts. The hearts removed from sprague-Dawley rats were perfused with standard Krebs-Henseleit medium gassed with 95% O2 + 5% CO2. The hypoxic medium contained mannitol instead of dextrose and was bubbled with 95% N2 + 5% CO2. The final osmolarity of the medium was 295 M osmol, pH 7. 4.

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Flagellar Attachment in Selected Trypanosomes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072927 ◽

1973 ◽

Vol 31 ◽

pp. 496-497

Author(s):

J. J. Paulin

Keyword(s):

Cell Membrane ◽

Lateral Surface ◽

The Body ◽

Flagellar Pocket ◽

Integral Component ◽

Free Flagellum ◽

Flagellar Axoneme

Movement in epimastigote and trypomastigote stages of trypanosomes is accomplished by planar sinusoidal beating of the anteriorly directed flagellum and associated undulating membrane. The flagellum emerges from a bottle-shaped depression, the flagellar pocket, opening on the lateral surface of the cell. The limiting cell membrane envelopes not only the body of the trypanosome but is continuous with and insheathes the flagellar axoneme forming the undulating membrane. In some species a paraxial rod parallels the axoneme from its point of emergence at the flagellar pocket and is an integral component of the undulating membrane. A portion of the flagellum may extend beyond the anterior apex of the cell as a free flagellum; the length is variable in different species of trypanosomes.

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Trophoblast Cell Membrane Interactions at Implantation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100068540 ◽

1970 ◽

Vol 28 ◽

pp. 310-311

Author(s):

A. C. Enders

Keyword(s):

Epithelial Cells ◽

Cell Membrane ◽

Membrane Fusion ◽

Trophoblast Cell ◽

Membrane Interactions ◽

Uterine Epithelial Cells ◽

Functional Complex ◽

Cytotrophoblast Cells ◽

Complex Relationships ◽

Syncytial Trophoblast

The alteration in membrane relationships seen at implantation include 1) interaction between cytotrophoblast cells to form syncytial trophoblast and addition to the syncytium by subsequent fusion of cytotrophoblast cells, 2) formation of a wide variety of functional complex relationships by trophoblast with uterine epithelial cells in the process of invasion of the endometrium, and 3) in the case of the rabbit, fusion of some uterine epithelial cells with the trophoblast.Formation of syncytium is apparently a membrane fusion phenomenon in which rapid confluence of cytoplasm often results in isolation of residual membrane within masses of syncytial trophoblast. Often the last areas of membrane to disappear are those including a desmosome where the cell membranes are apparently held apart from fusion.

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Some Conditions Necessary for Pinocytosis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100100457 ◽

1968 ◽

Vol 26 ◽

pp. 142-143

Author(s):

M. W. Brightman

Keyword(s):

Smooth Muscle ◽

Cell Membrane ◽

Toxic Effects ◽

Cytological Evidence ◽

Cell Processes

The cytological evidence for pinocytosis is the focal infolding of the cell membrane to form surface pits that eventually pinch off and move into the cytoplasm. This activity, which can be inhibited by oxidative and glycolytic poisons, is performed only by cell processes that are at least 300A wide. However, the interpretation of such toxic effects becomes equivocal if the membrane invaginations do not normally lead to the formation of migratory vesicles, as in some endothelia and in smooth muscle. The present study is an attempt to set forth some conditions under which pinocytosis, as distinct from the mere inclusion of material in surface invaginations, can take place.

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