Inhibition of apoptosis by recombinant 30K protein originating from silkworm hemolymph.

In a previous study, we reported that silkworm hemolymph inhibits apoptosis and that the anti-apoptotic component in silkworm hemolymph is a 30K protein. In this study, the 30K protein encoded by 30Kc6 was expressed in Escherichia coli. The recombinant 30K protein was expressed as an inclusion body, and the inclusion body was separated and refolded by affinity column chromatography using a 6xHis tag. We demonstrated that apoptosis is inhibited by supplementing the culture medium with this purified recombinant 30K protein. The recombinant 30K protein inhibited the virus- or chemical-induced apoptosis in human cells as well as insect cells. Apoptosis-inhibitory activity of recombinant 30K protein was comparable to that of whole silkworm hemolymph. The recombinant 30K protein can be effectively used to minimize cell death and consequently increase the productivity by extending the production time of host cells in commercial animal cell culture.