title: M and N proteins of SARS coronavirus induce apoptosis in HPF cells.
abstract: BACKGROUND
  SARS-associated coronavirus (SARS-CoV) induced cell apoptosis and its structural proteins may play a role in this process.
  
  
  OBJECTIVE
  To determine whether the structural proteins M and N of SARS-CoV induce apoptosis.
  
  
  METHODS
  We investigated human pulmonary fibroblast (HPF) cells, were transfected with plasmids containing the M or N gene, by TdT-mediated dUTP nick end labeling (TUNEL), Hoechst 33342 staining for nuclei, and observation of morphology.
  
  
  RESULTS
  We found that in the absence of serum about 16.34% of cells transfected by pcDNA3.1-M and 21.72% of N-transfected cells showed typical apoptotic characteristics, significantly different from mock-transfected cells (only 6.23%, p<0.01). Furthermore, the cells that were co-transfected with M and N proteins showed more obvious phenomena of cell death (about 36.03%). There was a statistical significance between M-transfected cells and co-transfected cells (p<0.01), and a remarkable difference between N-transfected cells and co-transfected cells (p<0.01).
  
  
  CONCLUSIONS
  The results show that M and N proteins of SARS-CoV can induce apoptosis of HPF cells. Co-transfection of M and N enhances the induction of apoptosis by M or N alone, which also suggests that the structural proteins of SARS-CoV may play an important role not only in the process of invasion but also in the pathogenetic process in cells.
authors.affiliation: State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100080, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Zhao
authors.forename: Shu-Qun
authors.initials: SQ
authors.lastname: Shi
authors.forename: Ying
authors.initials: Y
authors.lastname: Yang
authors.forename: Jing-Pian
authors.initials: JP
authors.lastname: Peng
mesh_terms: D017209:Apoptosis; D001562:Benzimidazoles; D015153:Blotting, Western; D002478:Cells, Cultured; D000086862:Coronavirus M Proteins; D000086462:Coronavirus Nucleocapsid Proteins; D005347:Fibroblasts / Q000166:cytology*; D005822:Genetic Vectors; D006801:Humans; D020287:In Situ Nick-End Labeling; D008168:Lung / Q000166:cytology*; D019590:Nucleocapsid Proteins / Q000378:metabolism*; D045473:Severe acute respiratory syndrome-related coronavirus; D044967:Serum; D045169:Severe Acute Respiratory Syndrome; D014162:Transfection; D014763:Viral Matrix Proteins / Q000378:metabolism*
chemical_list: D001562:Benzimidazoles; D000086862:Coronavirus M Proteins; D000086462:Coronavirus Nucleocapsid Proteins; C000706237:M protein, SARS-CoV; D019590:Nucleocapsid Proteins; D014763:Viral Matrix Proteins; C017807:bisbenzimide ethoxide trihydrochloride