Anti-Apoptosis Engineering Using a Gene of Bombyx mori

We have previously shown that the addition of silkworm hemolymph to a culture medium increases the longevity of insect and mammalian cells by inhibiting apoptosis. This indicates that the component which inhibits apoptosis is contained in the silkworm hemolymph, The apoptosis-inhibiting component was isolated from silkwonn hemolymph and characterized in our previous study. A database search using the N-terminal amino acid sequence of this component as a template resulted in a 95% homology with a low molecular weight lipoprotein, the so called ’30K protein' of unknown function. In this study, the 30K protein gene was expressed in mammalian and insect cells to confirm the apoptosis-inhibiting effect. The overexpression of 30K protein in mammalian cell inhibited the staurosporin-induced apoptosis by the prevention of the activation of caspase 3. Using an Autographa californicanuclear polyhedrosis virus (AcNPV) system, the 30K protein was overexpressed also in insect cells. The expression of the 30K protein increased the longevity of baculovirus-infected insect cells by inhibiting apoptosis. These results suggest that the 30K protein is a novel anti-apoptotic protein.