title: Reduced expression of citrate synthase leads to excessive superoxide formation and cell apoptosis.
abstract: A/J mice are a mouse model of age-related hearing loss. It has been demonstrated that a mutation in gene of citrate synthase (CS) contributes to the early onset of hearing loss occurring at about one month of age. To understand the effects of a decreased CS activity that results from the mutation in Cs gene on hearing loss in A/J mice, human kidney cell line (293T) was transiently transfected with short hairpin RNA for Cs (shRNA-Cs) to reduce expression of CS. In comparison with those of cells transfected with a scrambled sequence (shRNA-NC), the oxygen consumption rate and adenosine trisphosphate (ATP) production level were decreased in 293T cells transfected with shRNA-Cs. Meanwhile, excessive superoxide production was induced as determined by mitochondrial superoxide formation assay (MitoSOX) and superoxide dismutase 2 (SOD2) detection. Moreover, the expression levels of BIP (binding immunoglobulin protein) and CHOP (CCAAT/enhancer-binding protein-homologous protein), markers of endoplasmic reticulum stress, were upregulated. Furthermore, apoptosis related molecule caspase-3 and the mitochondrial membrane potential were reduced. It is therefore concluded that downregulation of Cs expression in 293T cells leads to low level of ATP production, excessive superoxide formation and cell apoptosis, which implies a possible mechanism for hearing loss in A/J mice.
authors.affiliation: Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai 264003, Shandong, PR China; Department of Neurology, University Hospital of Binzhou Medical University, 661 Second Huanghe Road, Binzhou 256603, Shandong, PR China.
authors.forename: Quanxiang
authors.initials: Q
authors.lastname: Cai
authors.affiliation: Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai 264003, Shandong, PR China; Department of Biochemistry and Molecular Biology, Binzhou Medical University, 346 Guanhai Road, Yantai 264003, Shandong, PR China.
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Zhao
authors.affiliation: Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai 264003, Shandong, PR China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai 264003, Shandong, PR China.
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai 264003, Shandong, PR China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Nie
authors.affiliation: Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai 264003, Shandong, PR China.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.affiliation: Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai 264003, Shandong, PR China.
authors.forename: Tingyan
authors.initials: T
authors.lastname: Liu
authors.affiliation: Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai 264003, Shandong, PR China; Department of Neurology, University Hospital of Binzhou Medical University, 661 Second Huanghe Road, Binzhou 256603, Shandong, PR China. Electronic address: gerli@163.com.
authors.forename: Ruli
authors.initials: R
authors.lastname: Ge
authors.affiliation: Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai 264003, Shandong, PR China; Department of Biochemistry and Molecular Biology, Binzhou Medical University, 346 Guanhai Road, Yantai 264003, Shandong, PR China. Electronic address: hanfengchan@gmail.com.
authors.forename: Fengchan
authors.initials: F
authors.lastname: Han
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D002950:Citrate (si)-Synthase / Q000235:genetics* / Q000378:metabolism; D004195:Disease Models, Animal; D000091342:Endoplasmic Reticulum Chaperone BiP; D057809:HEK293 Cells; D034381:Hearing Loss / Q000235:genetics; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D053078:Membrane Potential, Mitochondrial; D008805:Mice, Inbred A; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism / Q000502:physiology; D034622:RNA Interference; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D051742:Transcription Factor CHOP / Q000378:metabolism; D000099156:Superoxide Dismutase 2
chemical_list: D000255:Adenosine Triphosphate; D053148:Caspase 3; D002950:Citrate (si)-Synthase; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D013482:Superoxide Dismutase; D013481:Superoxides; D051742:Transcription Factor CHOP; D000099156:Superoxide Dismutase 2; C497249:DDIT3 protein, human
keywords: Age-related hearing loss; Apoptosis; Citrate synthase; Oxidative stress; RNA interference