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Use of a Caspase Multiplexing Assay to Determine Apoptosis in a Hypothalamic Cell Model
Published on: April 16, 2014
MicroRNA-21 abrogates palmitate-induced cardiomyocyte apoptosis through caspase-3/NF-κB signal pathways
Xiaodi Zhou, Bo Chang, Yuzhong Gu1
1Department of Cardiology, The Sixth People's Hospital of Nantong; Nantong-China. guyuzhongnt@163.com.
Objective:
The aim of the study was to investigate the role of microRNA-21 (miR-21) in cardiomyocyte apoptosis and to determine a possible mechanism.
Methods:
H9c2 embryonic rat heart-derived cells were used in the study. Cell viability was determined using the 3-(4.5-dimethyl-2-thiazolyl)-2,5- diphenyl-2-H-tetrazolium bromide (MTT) assay, and flow cytometry was used to evaluate cell apoptosis. Reverse transcription-polymerase chain reaction and western blot assays were used to detect mRNA and protein expression of the apoptosis-related proteins and miR-21. ELISA was used to detect reactive oxygen species (ROS).
Results:
Palmitate exposure greatly reduced miR-21 expression in cardiomyocytes. Apoptosis increased when miR-21 was inhibited with or without palmitate exposure. Consistently, reduced apoptosis was observed when miR-21 was overexpressed in cardiomyocytes. Caspase-3 activity was reduced after palmitate exposure. Bcl-2 protein expression was increased in H9c2 cells when transfected with the miR-21 mimic. MiR-21 overexpression alone did not induce ROS or DNA fragmentation; however, in conjunction with palmitate exposure, miR-21 mimic reduced ROS and DNA fragmentation. Moreover, palmitate administration overcame the antioxidant effect of 3 mM N-acetylcysteine to significantly inhibit apoptosis, DNA fragmentation, and caspase-3 activity. The exposure to palmitate greatly reduced p65 and p-p38 expression in the nucleus. A p38 inhibitor had no effect on the expression of Bcl-2 and cleaved caspase-3 in H9c2 cells alone; however, when combined with exposure to palmitate the p38 inhibitor induced Bcl-2 expression and inhibited caspase-3 activity. The p38 inhibitor by itself did not induce apoptosis, ROS production, or DNA fragmentation in H9c2 cells, but when palmitate was included with the p38 inhibitor, apoptosis, ROS production, and DNA fragmentation were reduced.
Conclusion:
miR-21 protects cardiomyocytes from apoptosis that is induced by palmitate through the caspase-3/NF-κB signal pathways.
Insights
MicroRNA-21 (miR-21) protects heart cells from palmitate-induced apoptosis. This study reveals miR-21
Area of Science:
- Cardiovascular Biology
- Molecular Biology
- Cell Biology
Background:
- Cardiomyocyte apoptosis is a key factor in heart disease.
- MicroRNAs (miRNAs) play crucial roles in regulating cellular processes, including apoptosis.
- The specific role of microRNA-21 (miR-21) in palmitate-induced cardiomyocyte apoptosis requires further elucidation.
Purpose of the Study:
- To investigate the protective role of miR-21 against palmitate-induced cardiomyocyte apoptosis.
- To elucidate the underlying molecular mechanisms involved in miR-21's function.
Main Methods:
- H9c2 embryonic rat heart-derived cells were utilized.
- Cell viability was assessed using MTT assays.
- Apoptosis, reactive oxygen species (ROS), and DNA fragmentation were evaluated using flow cytometry and ELISA.
- mRNA and protein expression of apoptosis-related factors were analyzed via RT-PCR and Western blot.
Main Results:
- Palmitate exposure significantly reduced miR-21 expression and increased cardiomyocyte apoptosis.
- miR-21 inhibition exacerbated apoptosis, while miR-21 overexpression conferred protection.
- miR-21 overexpression reduced ROS and DNA fragmentation in palmitate-treated cells.
- Palmitate exposure decreased nuclear p65 and p-p38 expression, and p38 inhibition mimicked miR-21's protective effects.
Conclusions:
- miR-21 plays a critical protective role in cardiomyocytes against palmitate-induced apoptosis.
- The protective mechanism involves the modulation of caspase-3 and NF-κB signaling pathways.
- Targeting miR-21 may offer a therapeutic strategy for managing conditions involving palmitate-induced cardiac injury.
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