calpain and Brucellosis

The calcium-dependent protease calpain2 is involved in macrophages apoptosis. Brucella infection-induced up-regulation of intracellular calcium level is an essential factor for the intracellular survival of Brucella within macrophages. Here, we hypothesize that calcium-dependent E3 ubiquitin ligase Nedd4 ubiquitinates calpain2 and inhibits Brucella infection-induced macrophage apoptosis via degradation of calpain2.Our results reveal that Brucella infection induces increases in Nedd4 activity in an intracellular calcium dependent manner. Furthermore, Brucella infection-induced degradation of calpain2 is mediated by Nedd4 ubiquitination of calpain2. Brucella infection-induced calpain2 degradation inhibited macrophages apoptosis. Treatment of Brucella infected macrophages with calcium chelator BAPTA or Nedd4 knock-down decreased Nedd4 activity, prevented calpain2 degradation, and resulted in macrophages apoptosis.

Topics: Analysis of Variance; Animals; Apoptosis; Blotting, Western; Brucella; Brucellosis; Calpain; Cell Line; Densitometry; Electrophoresis, Polyacrylamide Gel; Endosomal Sorting Complexes Required for Transport; Gene Expression Regulation; Humans; Immunoprecipitation; In Situ Nick-End Labeling; Macrophages; Mice; Microscopy, Fluorescence; Nedd4 Ubiquitin Protein Ligases; RNA Interference; Ubiquitin-Protein Ligases; Ubiquitination