title: Antiapoptotic Effect of Recombinant HMGB1 A-box Protein via Regulation of microRNA-21 in Myocardial Ischemia-Reperfusion Injury Model in Rats.
abstract: The ~80 amino acid A box DNA-binding domain of high mobility group box 1 (HMGB1) protein antagonizes proinflammatory responses during myocardial ischemia reperfusion (I/R) injury. The exact role of microRNA-21 (miR-21) is unknown, but its altered levels are evident in I/R injury. This study examined the roles of HMGB1 A-box and miR-21 in rat myocardial I/R injury model. Sixty Sprague-Dawley rats were randomly divided into six equal groups: (1) Sham; (2) I/R; (3) Ischemic postconditioning (IPost); (4) AntagomiR-21 post-treatment; (5) Recombinant HMGB1 A-box pretreatment; and (6) Recombinant HMGB1 A-box + antagomiR-21 post-treatment. Hemodynamic indexes, arrhythmia scores, ischemic area and infarct size, myocardial injury, and related parameters were studied. Expression of miR-21 was detected by real-time quantitative polymerase chain reaction (qRT-PCR) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was used to quantify apoptosis. Left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP), maximal rate of pressure rise (+dp/dtmax), and decline (-dp/dtmax) showed clear reduction upon treatment with recombinant HMGB1 A-box. Arrhythmia was relieved and infarct area decreased in the group pretreated with recombinant HMGB1 A-box, compared with other groups. Circulating lactate dehydrogenase (LDH) and malondialdehyde (MDA) levels increased in response to irreversible cellular injury, while creatine kinase MB isoenzymes (CK-MB) and superoxide dismutase (SOD) activities were reduced in the I/R group, which was reversed following recombinant HMGB1 A-box treatment. Interestingly, pretreatment with recombinant HMGB1 A-box showed the most dramatic reductions in miR-21 levels, compared with other groups. Significantly reduced apoptotic index (AI) was seen in recombinant HMGB1 A-box pretreatment group and recombinant HMGB1 A-box + antagomiR-21 post-treatment group, with the former showing a more dramatic lowering in AI than the latter. Bax, caspase-8, and CHOP showed reduced expression, and Bcl-2 and p-AKT levels were upregulated in recombinant HMGB1 A-box pretreatment group. Thus, recombinant HMGB1 A-box treatment protects against I/R injury and the mechanisms may involve inhibition of miR-21 expression.
authors: Department of Thoracic and Cardiovascular Surgery, Fifth Affiliated Hospital of Sun Yat-Sen University , Zhuhai, People's Republic of China .
authors: Qiang
authors: Q
authors: Han
authors: Department of Thoracic and Cardiovascular Surgery, Fifth Affiliated Hospital of Sun Yat-Sen University , Zhuhai, People's Republic of China .
authors: Hua-Yong
authors: HY
authors: Zhang
authors: Department of Thoracic and Cardiovascular Surgery, Fifth Affiliated Hospital of Sun Yat-Sen University , Zhuhai, People's Republic of China .
authors: Bei-Long
authors: BL
authors: Zhong
authors: Department of Thoracic and Cardiovascular Surgery, Fifth Affiliated Hospital of Sun Yat-Sen University , Zhuhai, People's Republic of China .
authors: Bing
authors: B
authors: Zhang
authors: Department of Thoracic and Cardiovascular Surgery, Fifth Affiliated Hospital of Sun Yat-Sen University , Zhuhai, People's Republic of China .
authors: Hua
authors: H
authors: Chen
mesh_terms: D000818:Animals; D017209:Apoptosis; D053181:Caspase 8 / Q000378:metabolism; D004353:Drug Evaluation, Preclinical; D024243:HMGB1 Protein / Q000494:pharmacology / Q000627:therapeutic use*; D006439:Hemodynamics; D057775:Ischemic Postconditioning; D008297:Male; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D015428:Myocardial Reperfusion Injury / Q000188:drug therapy*; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000494:pharmacology / Q000627:therapeutic use; D015398:Signal Transduction; D051742:Transcription Factor CHOP / Q000378:metabolism; D014693:Ventricular Fibrillation / Q000188:drug therapy*; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism
chemical_list: C494828:Bax protein, rat; C497251:Ddit3 protein, rat; D024243:HMGB1 Protein; C104200:Hbp1 protein, rat; D035683:MicroRNAs; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins; D051028:bcl-2-Associated X Protein; C546082:mirn21 microRNA, rat; D051742:Transcription Factor CHOP; D051057:Proto-Oncogene Proteins c-akt; C505528:Casp8 protein, rat; D053181:Caspase 8; D018631:ras Proteins