title: Lipopolysaccharide effects on the proliferation of NRK52E cells via alternations in gap-junction function.
abstract: BACKGROUND
  Gap junctions regulate proper kidney function by facilitating intercellular communication, vascular conduction, and tubular purinergic signaling. However, no clear relationship has been described between gap-junction function and acute kidney injury induced by the endotoxin lipopolysaccharide (LPS).
  
  
  METHODS
  Normal rat kidney epithelial cells (NRK52E cells) were seeded at high and low densities to promote or impede gap-junction formation, respectively, and establish distinctive levels of intercellular communication in culture. Cells were then challenged with LPS at various concentrations (10-1,000 ng/mL). LPS-induced formation and function of gap junctions were assessed by measuring changes in cell proliferation and colony-forming rates, fluorescent dye transmission to adjacent cells, expression levels of connexin43, and repositioning of confluent cells in response to the gap junction inhibitor oleamide or agonist retinoic acid.
  
  
  RESULTS
  The cell proliferation rate and colony-forming rate of high- and low-density NRK52E cells were decreased upon LPS challenge, in a dose-dependent manner. The colony-forming rate of confluent high-density cells was significantly lower than that of low-density cells. Oleamide treatment raised the LPS-induced colony-forming rate of high-density cells, whereas retinoic acid decreased the rate. Neither oleamide nor retinoic acid significantly affected the LPS-induced colony-forming rate of low-density cells. Fluorescence transmission of high-density cells was reduced by LPS challenge, in a dose-dependent manner, but inclusion of retinoic acid increased the LPS-induced transmission of fluorescence. LPS challenge of either high- or low-density NRK52E cells resulted in down-regulated connexin43 expression.
  
  
  CONCLUSIONS
  Gap-junction function plays an important role in concentration-dependent cytotoxic effect of LPS on normal rat kidney cells in vitro.
authors: Department of Anesthesiology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China. heiziqing@sina.com
authors: Ziqing
authors: Z
authors: Hei
authors: Ailan
authors: A
authors: Zhang
authors: Jing
authors: J
authors: Wei
authors: Xiaoliang
authors: X
authors: Gan
authors: Yanling
authors: Y
authors: Wang
authors: Gangjian
authors: G
authors: Luo
authors: Xiaoyun
authors: X
authors: Li
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects*; D018031:Connexin 43 / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004731:Endotoxins / Q000494:pharmacology; D017629:Gap Junctions / Q000187:drug effects / Q000502:physiology*; D007668:Kidney / Q000166:cytology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D009829:Oleic Acids / Q000494:pharmacology; D051381:Rats; D013234:Stem Cells / Q000187:drug effects / Q000502:physiology; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D018031:Connexin 43; D004731:Endotoxins; D008070:Lipopolysaccharides; D009829:Oleic Acids; D014212:Tretinoin; C044101:endotoxin, Escherichia coli; C029407:oleylamide