title: Inhibition of gap junction intercellular communication is involved in silica nanoparticles-induced H9c2 cardiomyocytes apoptosis via the mitochondrial pathway.
abstract: Gap junction intercellular communication (GJIC) between cardiomyocytes is essential for synchronous heart contraction and relies on connexin-containing channels. Connexin 43 (Cx43) is a major component involved in GJIC in heart tissue, and its abnormal expression is closely associated with various cardiac diseases. Silica nanoparticles (SNPs) are known to induce cardiovascular toxicity. However, the mechanisms through which GJIC plays a role in cardiomyocytes apoptosis induced by SNPs remain unknown. The aim of the present study is to determine whether SNPs-decreased GJIC promotes apoptosis in rat cardiomyocytes cell line (H9c2 cells) via the mitochondrial pathway using CCK-8 Kit, scrape-loading dye transfer technique, Annexin V/PI double-staining assays, and Western blot analysis. The results showed that SNPs elicited cytotoxicity in H9c2 cells in a time- and concentration-dependent manner. SNPs also reduced GJIC in H9c2 cells in a concentration-dependent manner through downregulation of Cx43 and upregulation of P-Cx43. Inhibition of gap junctions by gap junction blocker carbenoxolone disodium resulted in decreased survival and increased apoptosis, whereas enhancement of the gap junctions by retinoic acid led to enhanced survival but decreased apoptosis. Furthermore, SNPs-induced apoptosis through the disrupted functional gap junction was correlated with abnormal expressions of the proteins involved in the mitochondrial pathway-related apoptosis such as Bcl-2/Bax, cytochrome C, Caspase-9, and Caspase-3. Taken together, our results provide the first evidence that SNPs-decreased GJIC promotes apoptosis in cardiomyocytes via the mitochondrial pathway. In addition, downregulation of GJIC by SNPs in cardiomyocytes is mediated through downregulation of Cx43 and upregulation of P-Cx43. These results suggest that in rat cardiomyocytes cell line, GJIC plays a protective role in SNPs-induced apoptosis and that GJIC may be one of the targets for SNPs-induced biological effects.
authors.affiliation: Department of Toxicology, Shandong Academy of Occupational Health and Occupational Medicine, Shandong Academy of Medical Sciences.
authors.forename: Zhong-Jun
authors.initials: ZJ
authors.lastname: Du
authors.affiliation: Department of Respiratory Medicine, Qilu Children's Hospital of Shandong University, Jinan.
authors.forename: Guan-Qun
authors.initials: GQ
authors.lastname: Cui
authors.affiliation: Department of Toxicology, Shandong Academy of Occupational Health and Occupational Medicine, Shandong Academy of Medical Sciences.
authors.forename: Juan
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Radiation Chemistry and Toxicology, School of Public Health, Jilin University, Changchun, People's Republic of China.
authors.forename: Xiao-Mei
authors.initials: XM
authors.lastname: Liu
authors.affiliation: Department of Toxicology, Shandong Academy of Occupational Health and Occupational Medicine, Shandong Academy of Medical Sciences.
authors.forename: Zhi-Hu
authors.initials: ZH
authors.lastname: Zhang
authors.affiliation: Department of Toxicology, Shandong Academy of Occupational Health and Occupational Medicine, Shandong Academy of Medical Sciences.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Jia
authors.affiliation: National Research Centre for Environmental Toxicology-Entox, The University of Queensland, Brisbane, QLD, Australia.
authors.forename: Jack C
authors.initials: JC
authors.lastname: Ng
authors.affiliation: Department of Toxicology, Shandong Academy of Occupational Health and Occupational Medicine, Shandong Academy of Medical Sciences; National Research Centre for Environmental Toxicology-Entox, The University of Queensland, Brisbane, QLD, Australia.
authors.forename: Cheng
authors.initials: C
authors.lastname: Peng
authors.affiliation: Department of Toxicology, Shandong Academy of Occupational Health and Occupational Medicine, Shandong Academy of Medical Sciences.
authors.forename: Cun-Xiang
authors.initials: CX
authors.lastname: Bo
authors.affiliation: Department of Toxicology, Shandong Academy of Occupational Health and Occupational Medicine, Shandong Academy of Medical Sciences.
authors.forename: Hua
authors.initials: H
authors.lastname: Shao
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002450:Cell Communication / Q000187:drug effects; D002460:Cell Line; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000378:metabolism; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects*; D012822:Silicon Dioxide / Q000494:pharmacology*; D013997:Time Factors; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D014212:Tretinoin; D012822:Silicon Dioxide
keywords: cardiotoxicity; cell death; connexin 43; gap junction; silica nanoparticles