The genomic underpinnings of apoptosis in the silkworm, Bombyx mori

Min-Hui Pan,Zi-Shu Yu,Jin-Ye Zhang,Zhi-Ya Sun,Di Liu,Dan-Hong Zhao,Cheng Lu,Shu-Jing Huang

doi:10.1186/1471-2164-11-611

Abstract

BackgroundApoptosis is regulated in an orderly fashion by a series of genes, and has a crucial role in important physiological processes such as growth development, immunological response and so on. Recently, substantial studies have been undertaken on apoptosis in model animals including humans, fruit flies, and the nematode. However, the lack of genomic data for silkworms limits their usefulness in apoptosis studies, despite the advantages of silkworm as a representative of Lepidoptera and an effective model system. Herein we have identified apoptosis-related genes in the silkworm Bombyx mori and compared them to those from insects, mammals, and nematodes.ResultsFrom the newly assembled genome databases, a genome-wide analysis of apoptosis-related genes in Bombyx mori was performed using both nucleotide and protein Blast searches. Fifty-two apoptosis-related candidate genes were identified, including five caspase family members, two tumor necrosis factor (TNF) superfamily members, one Bcl-2 family member, four baculovirus IAP (inhibitor of apoptosis) repeat (BIR) domain family members and 1 RHG (Reaper, Hid, Grim, and Sickle; Drosophila cell death activators) family member. Moreover, we identified a new caspase family member, BmCaspase-New, two splice variants of BmDronc, and Bm3585, a mammalian TNF superfamily member homolog. Twenty-three of these apoptosis-related genes were cloned and sequenced using cDNA templates isolated from BmE-SWU1 cells. Sequence analyses revealed that these genes could have key roles in apoptosis.ConclusionsBombyx mori possesses potential apoptosis-related genes. We hypothesized that the classic intrinsic and extrinsic apoptotic pathways potentially are active in Bombyx mori. These results lay the foundation for further apoptosis-related study in Bombyx mori.

Highlights

Apoptosis is regulated in an orderly fashion by a series of genes, and has a crucial role in important physiological processes such as growth development, immunological response and so on
We hypothesized that the classic intrinsic and extrinsic apoptotic pathways potentially are active in Bombyx mori
We have identified one member of the Bcl-2 family, two members of the tumor necrosis factor (TNF) superfamily (TNFSF), and four members of the baculovirus IAP repeat (BIR) domain family in Bombyx mori (Table 1)

Summary

Introduction

Apoptosis is regulated in an orderly fashion by a series of genes, and has a crucial role in important physiological processes such as growth development, immunological response and so on. Substantial studies have been undertaken on apoptosis in model animals including humans, fruit flies, and the nematode. We have identified apoptosis-related genes in the silkworm Bombyx mori and compared them to those from insects, mammals, and nematodes. Programmed cell death [1], as well as cell proliferation and cell differentiation, has a crucial role in biological growth and development. There are two primary programmed cell death signaling pathways [2], apoptosis [3]. Apoptotic mechanisms are being clarified in model organisms using completed genome sequences, especially in nematodes, fruit flies and humans. Two primary apoptotic signaling pathways have been described: the extrinsic pathway, which is initiated by the tumor necrosis factor (TNF)/

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