Apoptosis induced by lipid-associated membrane proteins from Mycoplasma hyopneumoniae in a porcine lung epithelial cell line with the involvement of caspase 3 and the MAPK pathway

Genet Mol Res. 2015 Sep 25;14(3):11429-43. doi: 10.4238/2015.September.25.10.

Abstract

Lipid-associated membrane proteins (LAMPs) are important in the pathogenicity of the Mycoplasma genus of bacteria. We investigated whether Mycoplasma hyopneumoniae LAMPs have pathogenic potential by inducing apoptosis in a St. Jude porcine lung epithelial cell line (SJPL). LAMPs from a pathogenic strain of M. hyopneumoniae (strain 232) were used in the research. Our investigation made use of diamidino-phenylindole (DAPI) and acridine orange/ethidium bromide (AO/EB) staining, terminal dexynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) analysis, and Annexin-V-propidium iodide staining. After LAMP treatment for 24 h, typical changes were induced, chromosomes were concentrated, apoptotic bodies were observed, the 3'-OH groups of cleaved genomes were exposed, and the percentage of apoptotic cells reached 36.5 ± 11.66%. Caspase 3 and caspase 8 were activated and cytochrome c (cyt c) was released from the mitochondria into the cytoplasm; poly ADP ribose polymerase (PARP) was digested into two fragments; p38 mitogen-activated protein kinase (MAPK) was phosphorylated; and the expression of pro-apoptosis protein Bax increased while the anti-apoptosis protein Bcl-2 decreased. LAMPs also stimulated SJPL cells to produce nitric oxide (NO) and superoxide. This study demonstrated that LAMPs from M. hyopneumoniae can induce apoptosis in SJPL cells through the activation of caspase 3, caspase 8, cyt c, Bax, and p38 MAPK, thereby contributing to our understanding of the pathogenesis of M. hyopneumoniae, which should improve the treatment of M. hyopneumoniae infections.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis*
  • Bacterial Proteins / pharmacology*
  • Caspase 3 / metabolism*
  • Caspase 8 / metabolism
  • Cell Death / drug effects
  • Cell Line
  • Cell Nucleus / drug effects
  • Cell Nucleus / metabolism
  • Cell Survival / drug effects
  • Cytochromes c / metabolism
  • Enzyme Activation / drug effects
  • Epithelial Cells / cytology*
  • Epithelial Cells / drug effects
  • Epithelial Cells / enzymology
  • In Situ Nick-End Labeling
  • Lung / cytology*
  • MAP Kinase Signaling System* / drug effects
  • Models, Biological
  • Mycoplasma hyopneumoniae / metabolism*
  • Nitric Oxide / metabolism
  • Poly(ADP-ribose) Polymerases / metabolism
  • Superoxides / metabolism
  • Sus scrofa
  • bcl-2-Associated X Protein / metabolism
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • Bacterial Proteins
  • bcl-2-Associated X Protein
  • Superoxides
  • Nitric Oxide
  • Cytochromes c
  • Poly(ADP-ribose) Polymerases
  • p38 Mitogen-Activated Protein Kinases
  • Caspase 3
  • Caspase 8