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Open Access Research article

Function of nuclear transport factor 2 and Ran in the 20E signal transduction pathway in the cotton bollworm, Helicoverpa armigera

Hong-Juan He1, Qian Wang12, Wei-Wei Zheng1, Jin-Xing Wang1, Qi-Sheng Song2 and Xiao-Fan Zhao1*

Author Affiliations

1 School of Life Sciences, the Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, Shandong University, Jinan 250100, Shandong, PR China

2 Division of Plant Sciences, University of Missouri, Columbia, Missouri 65211, USA

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BMC Cell Biology 2010, 11:1  doi:10.1186/1471-2121-11-1

Published: 2 January 2010

Abstract

Background

Nuclear transport factor 2 and small GTPase Ran participate in the nucleo-cytoplasm transport of macromolecules, but their function in the 20-hydroxyecdysone (20E) signal transduction pathway are not well known.

Results

A 703 bp encoding Ntf2 and a 1233 bp encoding Ran full-length cDNAs were cloned from Helicoverpa armigera, and named Ha-Ntf2 and Ha-Ran, respectively. Northern blot and immunoblotting revealed that Ha-Ntf2 had an obviously higher expression levels in the head-thorax and integument of the metamorphically committed larvae. In contrast, the expression of Ha-Ran did not show obvious variation at various developmental stages in four tissues by immunoblotting analysis, except in the midgut, which showed increased expression from 5th-36 h (molting) to 6th-48 h. Both expressions of Ha-Ntf2 and Ha-Ran could be upregulated by 20E in vitro. Immunohistochemistry revealed that Ha-Ntf2 and Ha-Ran were primarily localized in the nucleus of various tissues. Protein binding assay and co-immunoprecipitation indicated that Ha-Ntf2 and Ha-Ran can combine with each other in vitro and in vivo. Knock down of Ha-Ntf2 or Ha-Ran by RNAi resulted in the suppression of other 20E regulated genes including EcR-B1, USP1, E75B, BR-CZ2, HHR3 and Ha-eIF5c. In addition, the knockdown of Ha-Ntf2 resulted in Ha-Ran being prevented in the cytoplasm. The nuclear location of the ecdysone receptor b1 (EcR-B1) was also blocked after the knockdown of Ha-Ntf2 and Ha-Ran.

Conclusion

These evidences suggested that Ha-Ntf2 and Ha-Ran participated in the 20E signal transduction pathway by regulating the location of EcR-B1.