A DIGE approach for the assessment of differential expression of the CHO proteome under sodium butyrate addition: Effect of Bcl-x_L overexpression

Bcl-x_L, a member of the Bcl-2 family, is known to inhibit apoptosis of recombinant Chinese hamster ovary (rCHO) cells induced by the addition of sodium butyrate (NaBu), which is used for the elevated expression of recombinant protein. In order to understand the intracellular effects of Bcl-x_L overexpression on CHO cells treated with NaBu, changes to the proteome caused by controlled Bcl-x_L expression in rCHO cells producing erythropoietin (EPO) in the presence of 3mM NaBu were evaluated using twodimensional differential in-gel electrophoresis (2D-DIGE) and MS analysis. The consequences of Bcl-x_L overexpression were not limited to the apoptotic signaling pathway. Out of eight proteins regulated significantly by Bcl-x_L overexpression in 3mM NaBu addition culture, four proteins were related to cell survival (Iq motif-containing GTPase-activating protein 1), cell proliferation (dihydrolipoamide-S-acetyltransferase, guanine nucleotide binding protein alpha interacting 2), and repair of DNA damage (BRCA and CDKN1A interacting protein). Taken together, a DIGE approach reveals that overexpression of Bcl-x_L not only inhibits apoptosis in the presence of NaBu but also affects cell proliferation and survival in various aspects.