title: The cytoprotective effect of biglycan core protein involves Toll-like receptor 4 signaling in cardiomyocytes.
abstract: OBJECTIVE
  Exogenously administered biglycan (core protein with high-molecular weight glycosaminoglycan chains) has been shown to protect neonatal cardiomyocytes against simulated ischemia/reperfusion injury (SI/R), however, the mechanism of action is not clear. In this study we aimed to investigate, which structural component of biglycan is responsible for its cardiocytoprotective effect and to further explore the molecular mechanisms involved in the cytoprotection.
  
  
  RESULTS
  A pilot study was conducted to demonstrate that both native (glycanated) and deglycanated biglycan can attenuate cell death induced by SI/R in a dose-dependent manner in primary neonatal cardiomyocytes isolated from Wistar rats. In separate experiments, we have shown that similarly to glycanated biglycan, recombinant human biglycan core protein (rhBGNc) protects cardiomyocytes against SI/R injury. In contrast, the glycosaminoglycan component dermatan sulfate had no significant effect on cell viability, while chondroitin sulfate further enhanced cell death induced by SI/R. Treatment of cardiomyocytes with rhBGNc reverses the effect of SI/R upon markers of necrosis, apoptosis, mitochondrial membrane potential, and autophagy. We have also shown that pharmacological blockade of Toll-like receptor 4 (TLR4) signaling or its downstream mediators (IRAK1/4, ERK, JNK and p38 MAP kinases) abolished the cytoprotective effect of rhBGNc against SI/R injury. Pretreatment of cardiomyocytes with rhBGNc for 20h resulted in increased Akt phosphorylation and NO production without having significant effect on phosphorylation of ERK1/2, STAT3, and on the production of superoxide. Treatment over 10min and 1h with rhBGNc increased ERK1 phosphorylation, while the SI/R-induced increase in superoxide production was attenuated by rhBGNc. Blockade of NO synthesis also prevented the cardiocytoprotective effect of rhBGNc.
  
  
  CONCLUSIONS
  The core protein of exogenous biglycan protects myocardial cells from SI/R injury via TLR4-mediated mechanisms involving activation of ERK, JNK and p38 MAP kinases and increased NO production. The cytoprotective effect of rhBGNc is due to modulation of SI/R-induced changes in necrosis, apoptosis and autophagy.
authors: Department of Biochemistry, Faculty of Medicine, University of Szeged, Szeged, Hungary.
authors: Renáta
authors: R
authors: Gáspár
authors: Department of Biochemistry, Faculty of Medicine, University of Szeged, Szeged, Hungary.
authors: Márton
authors: M
authors: Pipicz
authors: Department of Biochemistry, Faculty of Medicine, University of Szeged, Szeged, Hungary.
authors: Fatime
authors: F
authors: Hawchar
authors: Department of Biochemistry and Molecular Biology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary.
authors: Dávid
authors: D
authors: Kovács
authors: Stem Cells and Eye Research Laboratory, Department of Ophthalmology, Faculty of Medicine, University of Szeged, Szeged, Hungary.
authors: Luna
authors: L
authors: Djirackor
authors: Department of Biochemistry, Faculty of Medicine, University of Szeged, Szeged, Hungary.
authors: Anikó
authors: A
authors: Görbe
authors: Department of Biochemistry, Faculty of Medicine, University of Szeged, Szeged, Hungary.
authors: Zoltán V
authors: ZV
authors: Varga
authors: Department of Biochemistry and Molecular Biology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary.
authors: Mónika
authors: M
authors: Kiricsi
authors: Stem Cells and Eye Research Laboratory, Department of Ophthalmology, Faculty of Medicine, University of Szeged, Szeged, Hungary; Centre of Eye Research, Department of Ophthalmology, Oslo University Hospital, University of Oslo, Oslo, Norway.
authors: Goran
authors: G
authors: Petrovski
authors: Department of Microbiology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary.
authors: Attila
authors: A
authors: Gácser
authors: Department of Biochemistry, Faculty of Medicine, University of Szeged, Szeged, Hungary.
authors: Csaba
authors: C
authors: Csonka
authors: Department of Biochemistry, Faculty of Medicine, University of Szeged, Szeged, Hungary. Electronic address: csont.tamas@med.u-szeged.hu.
authors: Tamás
authors: T
authors: Csont
mesh_terms: D000818:Animals; D017209:Apoptosis; D001343:Autophagy; D058578:Biglycan / Q000378:metabolism* / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008954:Models, Biological; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D009336:Necrosis / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation; D010865:Pilot Projects; D020011:Protective Agents / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: C546884:BGN protein, human; D058578:Biglycan; D020011:Protective Agents; D011994:Recombinant Proteins; D051197:Toll-Like Receptor 4; D009569:Nitric Oxide; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases
keywords: JUN N-terminal kinase; Mitogen activated protein kinase; Nitric oxide; Protein kinase B; Proteoglycan