整合素BmIntegrin β2的结构分析及其对家蚕血细胞的调控作用

Structure and function of BmIntegrin β2 in silkworm, Bombyx mori

摘要:

整合素是一类广泛分布于细胞表面的黏附分子受体，是由α和β两个亚基组成的异源二聚体跨膜蛋白，其是细胞内外信号转导的中间桥梁。在鳞翅目昆虫细胞内，整合素主要表达于血细胞，参与昆虫细胞免疫反应进程。文中首先通过RACE技术等，克隆获得BmIntegrin β2基因cDNA全长序列2 434 bp；并对其蛋白结构域进行了预测，主要包括信号肽、一段较大的胞外域，单次跨膜结构和较短的胞内域；利用qRT-PCR技术检测了家蚕4龄3天和5龄3天的BmIntegrin β2各组织表达图谱，结果显示其主要在血细胞和造血器官中高表达；然后再经原核诱导表达、蛋白纯化及免疫动物后获得BmIntegrin β2抗体。通过对BmIntegrin β2蛋白功能作用的研究发现，BmIntegrin β2抗体可显著地减少浆细胞的数量，这从侧面说明BmIntegrin β2抗体可能抑制了浆细胞的延伸性和粘附能力。该结果不仅为BmIntegrin β2参与家蚕细胞的免疫反应奠定了基础，还提供了一个新的研究视野。

关键词:整合素，BmIntegrin β2，浆细胞，粘附，细胞免疫

Abstract:

Integrins are cell adhesion receptors, which consists of several transmembrane glycoproteins. They are widely distributed on the cell surface and involved in signal transduction pathways. As a heterodimer, each integrin is composed of one α subunit and one β subunit. Integrins are mainly expressed on lepidopteran hemocytes and involved in cell immune response. The full-length cDNA sequence of BmIntegrin β2 was obtained by PCR and RACE, including 2 434 bp. BmIntegrin β2 was predicted to be a transmembrane protein. The BmIntegrin β2 expression profile was detected by qRT-PCR at L4D3 or L5D3 larval stage, and it was highly expressed in hemocyte and hematopoietic organ. Anti-BmIntegrin β2 polyclonal antibody was generated following prokaryotic expression, protein purification and animal immunization, which is highly specific and effective for recognizing BmIntegrin β2 protein through Western blotting. The results of plasmatocytes adhesion experiment showed that BmIntegrin β2 plays an important role on the adhesion and spreading of plasmatocytes to foreign surfaces. This study provides a foundation for further research of the biological function of BmIntegrin β2 gene.

Key words:integrin, BmIntegrin β2, plasmatocytes, adhesion, cellular immunity