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Updated: Oct 1, 2025
Measurements of Physiological Stress Responses in C. Elegans
Published on: May 21, 2020
The role of GRP78 in oxidative stress induced by tunicamycin in trabecular meshwork cells
Fang Chai1, Hong Yan2, Xiquan Zhao2
11Department of Ophthalmology, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, China; 2Department of Ophthalmology, Xi'an People's Hospital (Xi'an Fourth Hospital), Shaanxi Eye Hospital, Affiliated Guangren Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, 710004, China.
Objective:
To clarify the regulatory effect of GRP-78 induced by tunicamycin on endoplasmic reticulum (ER) stress.
Methods:
Tunicamycin was used to induce ER stress in trabecular meshwork cells (HTMC and GTM3). Cell apoptosis and ROS content were detected by flow cytometry to reveal the effect of tunicamycin on trabecular meshwork cells.
Results:
Tunicamycin could significantly increase the ROS content and the apoptosis rate in HTMC and GTM3 (p<0.01). The results showed that tunicamycin could increase the Ca2+ flow in cells. Tunicamycin can also increase expression levels of GRP78,VDAC1, ATF4, PERK, eIF2a, and CHOP (p<0.01). Overexpression of GRP78 protected cells from ER stress. Co-IP test showed that GRP78 directly bound to eIF2. These results suggest that GRP78 may play a regulatory role by regulating eIF2.
Conclusion:
Tunicamycin induces oxidative stress in trabecular meshwork cells, and the increase in GRP78 expression can protect the cells during ER stress by regulating eIF2.
Insights
Tunicamycin induces oxidative stress and cell apoptosis in trabecular meshwork cells. Increased GRP78 expression protects these cells from endoplasmic reticulum stress by regulating eIF2.
Area of Science:
- Cell Biology
- Molecular Biology
- Ocular Cell Research
Background:
- Endoplasmic reticulum (ER) stress is implicated in various cellular dysfunctions.
- Tunicamycin is a known inducer of ER stress.
- Trabecular meshwork cells play a crucial role in maintaining intraocular pressure.
Purpose of the Study:
- To investigate the role of GRP78 in tunicamycin-induced ER stress in trabecular meshwork cells.
- To elucidate the regulatory mechanism of GRP78 during ER stress.
Main Methods:
- Trabecular meshwork cells (HTMC and GTM3) were treated with tunicamycin to induce ER stress.
- Flow cytometry was used to assess cell apoptosis and reactive oxygen species (ROS) content.
- Expression levels of ER stress markers and GRP78 were analyzed.
- Co-immunoprecipitation (Co-IP) was performed to determine protein interactions.
Main Results:
- Tunicamycin significantly increased ROS content and apoptosis rates in trabecular meshwork cells (p<0.01).
- Tunicamycin elevated intracellular Ca2+ levels and upregulated key ER stress markers including GRP78, VDAC1, ATF4, PERK, eIF2a, and CHOP (p<0.01).
- Overexpression of GRP78 conferred protection against ER stress, and GRP78 was found to directly bind to eIF2.
Conclusions:
- Tunicamycin induces oxidative stress and apoptosis in trabecular meshwork cells.
- Elevated GRP78 expression plays a protective role during tunicamycin-induced ER stress.
- GRP78 may regulate ER stress response through interaction with eIF2.
