家蚕自噬受体蛋白Bmp62与Bmref(2)P形成聚集体的研究

Aggregate Formation of Silkworm Autophagic Adaptors Bmp62 and Bmref(2)P

p62聚集体在自噬体形成和抗氧化应激过程中起着十分重要的作用。人源p62通过PB1结构域自我寡聚。家蚕基因组只含有一个p62基因。该基因表达两个蛋白,即Bmp62和Bmref(2)P。Bmref(2)P比Bmp62缺少PB1结构域。在家蚕细胞中瞬时表达Bmp62和Bmref(2)P,发现Bmp62和Bmref(2)P在细胞质中共定位且形成聚集体。为研究Bmp62和Bmref(2)P各结构域在聚集体形成中的作用,构建Bmp62和Bmref(2)P的缺失突变体并与eGFP融合表达,发现缺失氨基酸残基1—101的Bmref(2)P在细胞质中弥散分布且不能形成聚集体,而含有PB1的Bmp62缺失突变体都能在细胞质中形成聚集体。对p62同源蛋白的结构域进行分析发现,部分p62不含有PB1结构域。

p62 aggregates exert important roles in the formation of autophagosome and anti-oxidative stress response.Self-oligomerization of Homo sapiens p62 is mediated by the PB1 domain.The Bombyx mori genome contains only one p62 gene expressing two proteins,Bmp62 and Bmref(2)P.Bmref(2)P lacks the PB1 domain compared to Bmp62.Bmp62 and Bmref(2)P were expressed transiently in BmN cell.The results showed that these proteins co-localized and formed aggregates in the cytoplasm.To explore the distinct roles of Bmp62 and Bmref(2)P domains in formation of aggregates,several deletion mutants of Bmp62 and Bmref(2)P were constructed to be fused in frame with eGFP.Chimeric eGFP-Bmref(2)P lacking amino acid residues 1—101 of Bmref(2)P showed far fewer aggregates but diffuse distribution,whereas those deletion mutants containing PB1 domain of Bmp62 displayed aggregate structures in the cytoplasm.Domain analysis of p62 homologues showed that some p62 homologues did not contain PB1 domain.