Two Novel 30K Proteins Overexpressed in Baculovirus System and Their Antiapoptotic Effect in Insect and Mammalian Cells

Abstract

The 30K family of proteins is important in energy metabolism and may play a role in inhibiting cellular apoptosis in silkworms (Bombyx mori). Several 30K-family proteins have been identified. In this study, two new silkworm genes, referred to as Slp (NM 001126256) and Lsp-t (NM 001043443), were analyzed by a bioinformatics approach according to the sequences of 30K proteins previously reported in the silkworm. Both Slp and Lsp-t shared more than 41% amino acid sequence homology with the reported 30K proteins and displayed a conserved domain consistent with that of lipoprotein-11. Additionally, the cDNA sequences of both Slp and Lsp-t were obtained from the fat bodies of silkworm larvae by reverse transcription polymerase chain reaction. Both genes were expressed in BmN cells using the Bac-to-Bac system. Purified Slp and Lsp-t were added to cultured BmN and human umbilical vein endothelial cells (HUVEC) that were treated with H2O2. Both Slp and Lsp-t significantly enhanced the viability and suppressed DNA fragmentation in H2O2 treated BmN and HUVEC cells. This study suggested that Slp and Lsp-t exhibit similar biological activities as their known 30K-protein counterparts and mediate an inhibitory effect against H2O2-induced apoptosis.