title: Silencing of uncoupling protein 2 by small interfering RNA aggravates mitochondrial dysfunction in cardiomyocytes under septic conditions.
abstract: Uncoupling protein 2 (UCP2) regulates the production of mitochondrial reactive oxygen species (ROS) and cellular energy transduction under physiological or pathological conditions. In this study, we aimed to determine whether mitochondrial UCP2 plays a protective role in cardiomyocytes under septic conditions. In order to mimic the septic condition, rat embryonic cardiomyoblast-derived H9C2 cells were cultured in the presence of lipopolysaccharide (LPS) plus peptidoglycan G (PepG) and small interfering RNA (siRNA) against UCP2 (siUCP2) was used to suppress UCP2 expression. Reverse transcription quantitative-polymerase chain reaction (RT-qPCR), western blot analysis, transmission electron microscopy (TEM), confocal microscopy and flow cytometry (FCM) were used to detect the mRNA levels, protein levels, mitochondrial morphology and mitochondrial membrane potential (MMP or ΔΨm) in qualitative and quantitative analyses, respectively. Indicators of cell damage [lactate dehydrogenase (LDH), creatine kinase (CK), interleukin (IL)-6 and tumor necrosis factor (TNF)-α in the culture supernatant] and mitochondrial function [ROS, adenosine triphosphate (ATP) and mitochondrial DNA (mtDNA)] were detected. Sepsis enhanced the mRNA and protein expression of UCP2 in the H9C2 cells, damaged the mitochondrial ultrastructure, increased the forward scatter (FSC)/side scatter (SSC) ratio, increased the CK, LDH, TNF-α and IL-6 levels, and lead to the dissipation of MMP, as well as the overproduction of ROS; in addition, the induction of sepsis led to a decrease in ATP levels and the deletion of mtDNA. The silencing of UCP2 aggravated H9C2 cell damage and mitochondrial dysfunction. In conclusion, our data demonstrate that mitochondrial morphology and funtion are damaged in cardiomyocytes under septic conditions, while the silencing of UCP2 using siRNA aggravated this process, indicating that UCP2 may play a protective role in cardiomyocytes under septic conditions.
authors: Department of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China.
authors: Guilang
authors: G
authors: Zheng
authors: Department of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China.
authors: Juanjuan
authors: J
authors: Lyu
authors: Department of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China.
authors: Shu
authors: S
authors: Liu
authors: Department of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China.
authors: Jinda
authors: J
authors: Huang
authors: Department of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China.
authors: Cui
authors: C
authors: Liu
authors: Department of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China.
authors: Dan
authors: D
authors: Xiang
authors: Department of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China.
authors: Meiyan
authors: M
authors: Xie
authors: Department of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China.
authors: Qiyi
authors: Q
authors: Zeng
mesh_terms: D000818:Animals; D002460:Cell Line; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000633:toxicity; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects / Q000235:genetics; D008929:Mitochondria, Heart / Q000378:metabolism* / Q000648:ultrastructure; D051336:Mitochondrial Membranes / Q000378:metabolism / Q000648:ultrastructure; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000648:ultrastructure; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000494:pharmacology*; D051381:Rats; D018805:Sepsis / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000071246:Uncoupling Protein 2
chemical_list: D007473:Ion Channels; D008070:Lipopolysaccharides; D024101:Mitochondrial Proteins; D009124:Muscle Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C000604391:Ucp2 protein, rat; D000071246:Uncoupling Protein 2