Survivin prevents apoptosis by binding to caspase-3 in astrocytes infected with the BeAn strain of Theiler's murine encephalomyelitis virus.

This paper reports the upregulation of the gene coding for the apoptosis regulator family member "surviving" in SJL/J mouse brain astrocyte cultures infected with the BeAn strain of TMEV. cRNA from mock- and TMEV-infected SJL/J astrocytes was hybridised to an Affymetrix whole murine genome DNA microarray. Analysis revealed the upregulation of two sequences coding for the survivin protein in infected cells; this was confirmed by RT-PCR and qPCR. Western blotting showed an increase in the synthesis of survivin and caspase-3 after infection. Unexpectedly, no enzymatic activity was detected in BeAn-infected cell lysates in caspase-3-specific colorimetric assays. Cross-linking experiments showed survivin and caspase-3 to exist as a complex containing one molecule of caspase-3 (17 kDa) and one of either 16 kDa or 14 kDa survivin. The neutralization of caspase-3 by survivin-containing lysates was demonstrated using recombinant caspase-3. Brains from TMEV-infected mice, but not from naïve mice, contained survivin mRNA during the acute phase of encephalitis. The present results suggest that astrocytes infected by the BeAn strain do not undergo apoptosis due to the production of survivin.