α-Lipoic Acid Inhibits Apoptosis by Suppressing the Loss of Ku Proteins in Helicobacter pylori-Infected Human Gastric Epithelial Cells

Helicobacter pylori (H. pylori) is a Gram-negative bacterium that colonizes the gastric mucosa and triggers various stomach diseases. H. pylori induces reactive oxygen species (ROS) production and DNA damage. The heterodimeric Ku70/Ku80 protein plays an essential role in the repair of DNA double-str...

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Autores principales: Park, Dayong, Lim, Joo Weon, Kim, Hyeyoung
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9370604/
https://www.ncbi.nlm.nih.gov/pubmed/35956382
http://dx.doi.org/10.3390/nu14153206
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author Park, Dayong
Lim, Joo Weon
Kim, Hyeyoung
author_facet Park, Dayong
Lim, Joo Weon
Kim, Hyeyoung
author_sort Park, Dayong
collection PubMed
description Helicobacter pylori (H. pylori) is a Gram-negative bacterium that colonizes the gastric mucosa and triggers various stomach diseases. H. pylori induces reactive oxygen species (ROS) production and DNA damage. The heterodimeric Ku70/Ku80 protein plays an essential role in the repair of DNA double-strand breaks (DSB). Oxidative stress stimulate apoptosis and DNA damage that can be repaired by Ku70/80. However, excessive reactive oxygen species (ROS) can cause Ku protein degradation, resulting in DNA fragmentation and apoptosis. α-lipoic acid (α-LA), which is found in organ meats such as liver and heart, spinach, broccoli, and potatoes, quenches free radicals, chelates metal ions, and reduces intracellular DNA damage induced by oxidative stress. Here, we investigated whether H. pylori decreases Ku70/80 and induces apoptosis, and whether α-LA inhibits changes induced by H. pylori. We analyzed ROS, DNA damage markers (γ-H2AX, DNA fragmentation), levels of Ku70/80, Ku–DNA binding activity, Ku80 ubiquitination, apoptosis indices (Bcl-2, Bax, apoptosis-inducing factor (AIF), and caspase-3), and viability in a human gastric epithelial adenocarcinoma cell line (AGS). H. pylori increased ROS, DNA damage markers, Ku80 ubiquitination, and consequently induced apoptosis. It also decreased nuclear Ku70/80 levels and Ku–DNA-binding activity; increased Bax expression, caspase-3 cleavage, and truncated AIF; but decreased Bcl-2 expression. These H. pylori-induced alterations were inhibited by α-LA. The antioxidant N-acetylcysteine and proteasome inhibitor MG-132 suppressed H. pylori-induced cell death and decreased nuclear Ku70/80 levels. The results show that oxidative stress induced Ku70/80 degradation via the ubiquitin–proteasome system, leading to its nuclear loss and apoptosis in H. pylori-infected cells. In conclusion, α-LA inhibited apoptosis induced by H. pylori by reducing ROS levels and suppressing the loss of Ku70/80 proteins in AGS cells.
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spelling pubmed-93706042022-08-12 α-Lipoic Acid Inhibits Apoptosis by Suppressing the Loss of Ku Proteins in Helicobacter pylori-Infected Human Gastric Epithelial Cells Park, Dayong Lim, Joo Weon Kim, Hyeyoung Nutrients Article Helicobacter pylori (H. pylori) is a Gram-negative bacterium that colonizes the gastric mucosa and triggers various stomach diseases. H. pylori induces reactive oxygen species (ROS) production and DNA damage. The heterodimeric Ku70/Ku80 protein plays an essential role in the repair of DNA double-strand breaks (DSB). Oxidative stress stimulate apoptosis and DNA damage that can be repaired by Ku70/80. However, excessive reactive oxygen species (ROS) can cause Ku protein degradation, resulting in DNA fragmentation and apoptosis. α-lipoic acid (α-LA), which is found in organ meats such as liver and heart, spinach, broccoli, and potatoes, quenches free radicals, chelates metal ions, and reduces intracellular DNA damage induced by oxidative stress. Here, we investigated whether H. pylori decreases Ku70/80 and induces apoptosis, and whether α-LA inhibits changes induced by H. pylori. We analyzed ROS, DNA damage markers (γ-H2AX, DNA fragmentation), levels of Ku70/80, Ku–DNA binding activity, Ku80 ubiquitination, apoptosis indices (Bcl-2, Bax, apoptosis-inducing factor (AIF), and caspase-3), and viability in a human gastric epithelial adenocarcinoma cell line (AGS). H. pylori increased ROS, DNA damage markers, Ku80 ubiquitination, and consequently induced apoptosis. It also decreased nuclear Ku70/80 levels and Ku–DNA-binding activity; increased Bax expression, caspase-3 cleavage, and truncated AIF; but decreased Bcl-2 expression. These H. pylori-induced alterations were inhibited by α-LA. The antioxidant N-acetylcysteine and proteasome inhibitor MG-132 suppressed H. pylori-induced cell death and decreased nuclear Ku70/80 levels. The results show that oxidative stress induced Ku70/80 degradation via the ubiquitin–proteasome system, leading to its nuclear loss and apoptosis in H. pylori-infected cells. In conclusion, α-LA inhibited apoptosis induced by H. pylori by reducing ROS levels and suppressing the loss of Ku70/80 proteins in AGS cells. MDPI 2022-08-05 /pmc/articles/PMC9370604/ /pubmed/35956382 http://dx.doi.org/10.3390/nu14153206 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Park, Dayong
Lim, Joo Weon
Kim, Hyeyoung
α-Lipoic Acid Inhibits Apoptosis by Suppressing the Loss of Ku Proteins in Helicobacter pylori-Infected Human Gastric Epithelial Cells
title α-Lipoic Acid Inhibits Apoptosis by Suppressing the Loss of Ku Proteins in Helicobacter pylori-Infected Human Gastric Epithelial Cells
title_full α-Lipoic Acid Inhibits Apoptosis by Suppressing the Loss of Ku Proteins in Helicobacter pylori-Infected Human Gastric Epithelial Cells
title_fullStr α-Lipoic Acid Inhibits Apoptosis by Suppressing the Loss of Ku Proteins in Helicobacter pylori-Infected Human Gastric Epithelial Cells
title_full_unstemmed α-Lipoic Acid Inhibits Apoptosis by Suppressing the Loss of Ku Proteins in Helicobacter pylori-Infected Human Gastric Epithelial Cells
title_short α-Lipoic Acid Inhibits Apoptosis by Suppressing the Loss of Ku Proteins in Helicobacter pylori-Infected Human Gastric Epithelial Cells
title_sort α-lipoic acid inhibits apoptosis by suppressing the loss of ku proteins in helicobacter pylori-infected human gastric epithelial cells
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9370604/
https://www.ncbi.nlm.nih.gov/pubmed/35956382
http://dx.doi.org/10.3390/nu14153206
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