scholarly journals Interruption of Multiple Cellular Processes in HT-29 Epithelial Cells by Pseudomonas aeruginosaExoenzyme S

1999 ◽  
Vol 67 (6) ◽  
pp. 2847-2854 ◽  
Author(s):  
Joan C. Olson ◽  
Jennifer E. Fraylick ◽  
Eileen M. McGuffie ◽  
Katherine M. Dolan ◽  
Timothy L. Yahr ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Dna Synthesis ◽  
Cell Function ◽  
Opportunistic Pathogen ◽  
Morphological Alteration ◽  
Long Term Effects ◽  
Cell Rounding ◽  
Inhibition Of Dna Synthesis ◽  
Ht 29

ABSTRACT Exoenzyme S (ExoS), an ADP-ribosylating enzyme produced by the opportunistic pathogen Pseudomonas aeruginosa, is directly translocated into eukaryotic cells by bacterial contact. Within the cell, ExoS ADP-ribosylates the cell signaling protein Ras and causes inhibition of DNA synthesis and alterations in cytoskeletal structure. To further understand the interrelationship of the different cellular effects of ExoS, functional analyses were performed on HT-29 epithelial cells after exposure to ExoS-producing P. aeruginosa 388 and the non-ExoS-producing strain 388ΔS. Two different mechanisms of morphological alteration were identified: (i) a more-transient and less-severe cell rounding caused by the non-ExoS-producing strain 388ΔS and (ii) a more-severe, long-term cell rounding caused by ExoS-producing strain 388. Long-term effects of ExoS on cell morphology occurred in conjunction with ExoS-mediated inhibition of DNA synthesis and the ADP-ribosylation of Ras. ExoS was also found to cause alterations in HT-29 cell function, leading to the loss of cell adhesion and microvillus effacement. Nonadherent ExoS-treated cells remained viable but had a high proportion of modified Ras. While microvillus effacement was detected in both 388- and 388ΔS-treated cells, effacement was more prevalent and rapid in cells exposed to strain 388. We conclude from these studies that ExoS can have multiple effects on epithelial cell function, with more severe cellular alterations associated with the enzymatic modification of Ras. The finding that ExoS had greater effects on cell growth and adherence than on cell viability suggests that ExoS may contribute to the P. aeruginosa infectious process by rendering cells nonfunctional.

scholarly journals Independent and Coordinate Effects of ADP-Ribosyltransferase and GTPase-Activating Activities of Exoenzyme S on HT-29 Epithelial Cell Function

2001 ◽  
Vol 69 (9) ◽  
pp. 5318-5328 ◽  
Author(s):  
Jennifer E. Fraylick ◽  
Jeannine R. La Rocque ◽  
Timothy S. Vincent ◽  
Joan C. Olson
Keyword(s):  
Dna Synthesis ◽  
Cell Function ◽  
Double Mutation ◽  
Exoenzyme S ◽  
Adp Ribosylation ◽  
Cell Rounding ◽  
Inhibition Of Dna Synthesis ◽  
Adp Ribosyltransferase ◽  
Ht 29

ABSTRACT Type III-mediated translocation of exoenzyme S (ExoS) into HT-29 epithelial cells by Pseudomonas aeruginosa causes complex alterations in cell function, including inhibition of DNA synthesis, altered cytoskeletal structure, loss of readherence, microvillus effacement, and interruption of signal transduction. ExoS is a bifunctional protein having both GTPase-activating (GAP) and ADP-ribosyltransferase (ADPRT) functional domains. Comparisons of alterations in HT-29 cell function caused by P. aeruginosastrains that translocate ExoS having GAP or ADPRT mutations allowed the independent and coordinate functions of the two activities to be assessed. An E381A ADPRT mutation revealed that ExoS ADPRT activity was required for effects of ExoS on DNA synthesis and long-term cell rounding. Conversely, the R146A GAP mutation appeared to have little impact on the cellular effects of ExoS. While transient cell rounding was detected following exposure to the E381A mutant, this rounding was eliminated by an E379A-E381A ADPRT double mutation, implying that residual ADPRT activity, rather than GAP activity, was effecting transient cell rounding by the E381A mutant. To explore this possibility, E381A and R146A-E381A mutants were examined for their ability to ADP-ribosylate Ras in vitro or in vivo. While no ADP-ribosylation of Ras was detected by either mutant in vitro, both mutants were able to modify Ras when translocated by the bacteria, with the R146A-E381A mutant causing more efficient modification than the E381A mutant, in association with increased inhibition of DNA synthesis. Comparisons of Ras ADP-ribosylation by wild-type and E381A mutant ExoS by two-dimensional electrophoresis found the former to ADP-ribosylate Ras at two sites, while the latter modified Ras only once. These studies draw attention to the key role of ExoS ADPRT activity in causing the effects of bacterially translocated ExoS on DNA synthesis and cell rounding. In addition, the studies provide insight into the enhancement of ExoS ADPRT activity within the eukaryotic cell microenvironment and into possible modulatory roles that the GAP and ADPRT domains might have on the function of each other.

scholarly journals Long-Term Exposure to Nanosized TiO2 Triggers Stress Responses and Cell Death Pathways in Pulmonary Epithelial Cells

2021 ◽  
Vol 22 (10) ◽  
pp. 5349
Author(s):  
Mayes Alswady-Hoff ◽  
Johanna Samulin Erdem ◽  
Santosh Phuyal ◽  
Oskar Knittelfelder ◽  
Animesh Sharma ◽  
...  
Keyword(s):  
Cell Death ◽  
Epithelial Cells ◽  
Health Effects ◽  
Stress Responses ◽  
Cell Stress ◽  
Lipid Classes ◽  
Long Term Effects ◽  
Cell Death Pathways ◽  
Pulmonary Epithelial Cells

There is little in vitro data available on long-term effects of TiO2 exposure. Such data are important for improving the understanding of underlying mechanisms of adverse health effects of TiO2. Here, we exposed pulmonary epithelial cells to two doses (0.96 and 1.92 µg/cm2) of TiO2 for 13 weeks and effects on cell cycle and cell death mechanisms, i.e., apoptosis and autophagy were determined after 4, 8 and 13 weeks of exposure. Changes in telomere length, cellular protein levels and lipid classes were also analyzed at 13 weeks of exposure. We observed that the TiO2 exposure increased the fraction of cells in G1-phase and reduced the fraction of cells in G2-phase, which was accompanied by an increase in the fraction of late apoptotic/necrotic cells. This corresponded with an induced expression of key apoptotic proteins i.e., BAD and BAX, and an accumulation of several lipid classes involved in cellular stress and apoptosis. These findings were further supported by quantitative proteome profiling data showing an increase in proteins involved in cell stress and genomic maintenance pathways following TiO2 exposure. Altogether, we suggest that cell stress response and cell death pathways may be important molecular events in long-term health effects of TiO2.

scholarly journals Long-Term Effects of Experimental Human Endotoxemia on Immune Cell Function

Shock ◽  
2019 ◽  
Vol 51 (6) ◽  
pp. 678-689 ◽  
Author(s):  
Yessica Alina Rodriguez-Rosales ◽  
Matthijs Kox ◽  
Esther van Rijssen ◽  
Bram van Cranenbroek ◽  
Marina van Welie ◽  
...  
Keyword(s):  
Cell Function ◽  
Immune Cell ◽  
Immune Cell Function ◽  
Long Term Effects ◽  
Human Endotoxemia

scholarly journals Long-term Effects of Local Irradiation of the Marrow on Erythron and Red Cell Function

Blood ◽  
1970 ◽  
Vol 36 (5) ◽  
pp. 617-622 ◽  
Author(s):  
WIL B. NELP ◽  
MAHENDRA N. GOHIL ◽  
STEVEN M. LARSON ◽  
RAE ELLEN BOWER
Keyword(s):  
Cell Function ◽  
Cell Activity ◽  
Maximum Level ◽  
Similar Degree ◽  
Partial Recovery ◽  
Long Term Effects ◽  
Sulfur Colloid ◽  
Secondary Recovery ◽  
99Mtc Sulfur Colloid

Abstract Changes in erythron and RE cell function were examined in the marrow of the rabbit after 250-5000 R of localized irradiation by comparing the amount of 59Fe and 99mTc sulfur colloid concentrated in the irradiated tibiofibula to that in the unirradiated control. At all levels of irradiation, there was immediate and severe loss of erythron function while RE cell activity remained nearly intact. Erythron function showed prompt partial recovery to a maximum level at approximately 8 days but with doses greater than 1000 R there was a secondary decline to 20 per cent of normal during the next 8 weeks. After 15 days, RE cell function had decreased to the same level as the erythron and subsequently fell in parallel with it. After 15 months, the marrow showed a secondary recovery of both RE cell and erythron function to 50 and 66 per cent of normal. The results of these experiments suggest that radiocolloid photoscans of the marrow showing decreased or absent RE cell activity will reflect a similar degree of erythropoietic damage if the studies are obtained weeks or months following radiation therapy.

scholarly journals Long-term effects of HIV-1 protease inhibitors on insulin secretion and insulin signaling in INS-1 beta cells

2004 ◽  
Vol 183 (3) ◽  
pp. 445-454 ◽  
Author(s):  
M Schütt ◽  
J Zhou ◽  
M Meier ◽  
H H Klein
Keyword(s):  
Insulin Secretion ◽  
Protease Inhibitors ◽  
Beta Cells ◽  
Insulin Signaling ◽  
Cell Function ◽  
Long Term Effects ◽  
Akt Phosphorylation ◽  
Glucose Stimulated Insulin Secretion ◽  
Hiv 1

The mechanism by which chronic treatment with HIV (human immunodeficiency virus)-1 protease inhibitors leads to a deterioration of glucose metabolism appears to involve insulin resistance, and may also involve impaired insulin secretion. Here we investigated the long-term effects of HIV-1 protease inhibitors on glucose-stimulated insulin secretion from beta cells and explored whether altered insulin secretion might be related to altered insulin signaling. INS-1 cells were incubated for 48 h with different concentrations of amprenavir, indinavir, nelfinavir, ritonavir or saquinavir, stimulated with 20 mM d-glucose, and insulin determined in the supernatant. To evaluate insulin signaling, cells were stimulated with 100 nM insulin for 2 min, and insulin-receptor substrate (IRS)-1, -2 and Akt phosphorylation determined. Incubation for 48 h with ritonavir, nelfinavir and saquinavir resulted in impaired glucose-induced insulin secretion at 2.5, 5 and 5 μM respectively, whereas amprenavir or indinavir had no effects even at 20 and 100 μM respectively. The impaired insulin secretion by ritonavir, nelfinavir and saquinavir was associated with decreased insulin-stimulated IRS-2 phosphorylation, and, for nelfinavir and saquinavir, with decreased insulin-stimulated IRS-1 and Thr308-Akt phosphorylation. No such effects on signaling were observed with amprenavir or indinavir. In conclusion, certain HIV-1 protease inhibitors, such as ritonavir, nelfinavir and saquinavir, not only induce peripheral insulin resistance, but also impair glucose-stimulated insulin secretion from beta cells. With respect to the long-term effect on beta-cell function there appear to be differences between the protease inhibitors that may be clinically relevant. Finally, these effects on insulin secretion after a 48 h incubation with protease inhibitor were associated with a reduction of the insulin-stimulated phosphorylation of insulin signaling parameters, particularly IRS-2, suggesting that protease inhibitor-induced alterations in the insulin signaling pathway may contribute to the impaired beta-cell function.

scholarly journals Erratum: Corrigendum: The differential short- and long-term effects of HIV-1 latency-reversing agents on T cell function

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
G. Clutton ◽  
Y. Xu ◽  
P. L. Baldoni ◽  
K. R. Mollan ◽  
J. Kirchherr ◽  
...  
Keyword(s):  
T Cell ◽  
Cell Function ◽  
Long Term Effects ◽  
T Cell Function ◽  
Short And Long Term ◽  
Hiv 1 ◽  
Reversing Agents

scholarly journals Steroids and TRP Channels: A Close Relationship

2020 ◽  
Vol 21 (11) ◽  
pp. 3819
Author(s):  
Karina Angélica Méndez-Reséndiz ◽  
Óscar Enciso-Pablo ◽  
Ricardo González-Ramírez ◽  
Rebeca Juárez-Contreras ◽  
Tamara Rosenbaum ◽  
...  
Keyword(s):  
Transient Receptor Potential ◽  
Cell Function ◽  
Trp Channels ◽  
Protein Complexes ◽  
Transmembrane Protein ◽  
Receptor Potential ◽  
Long Term Effects ◽  
Close Relationship ◽  
Transient Receptor

Transient receptor potential (TRP) channels are remarkable transmembrane protein complexes that are essential for the physiology of the tissues in which they are expressed. They function as non-selective cation channels allowing for the signal transduction of several chemical, physical and thermal stimuli and modifying cell function. These channels play pivotal roles in the nervous and reproductive systems, kidney, pancreas, lung, bone, intestine, among others. TRP channels are finely modulated by different mechanisms: regulation of their function and/or by control of their expression or cellular/subcellular localization. These mechanisms are subject to being affected by several endogenously-produced compounds, some of which are of a lipidic nature such as steroids. Fascinatingly, steroids and TRP channels closely interplay to modulate several physiological events. Certain TRP channels are affected by the typical genomic long-term effects of steroids but others are also targets for non-genomic actions of some steroids that act as direct ligands of these receptors, as will be reviewed here.

Sign in / Sign up

Export Citation Format

Share Document