Homeodomain POU and Abd-A proteins regulate the transcription of pupal genes during metamorphosis of the silkworm, Bombyx mori

Huimin Deng, Jialing Zhang, Yong Li, Sichun Zheng, Lin Liu, Lihua Huang, Wei Hua Xu, Subba R. Palli, Qili Feng

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

Abstract

A cascade of 20-hydroxyecdysone-mediated gene expression and repression initiates larva-to-pupa metamorphosis. We recently showed that two transcription factors, BmPOUM2 and BmβFTZ-F1, bind to the cis-regulatory elements in the promoter of the gene coding for cuticle protein, BmWCP4, and regulate its expression during Bombyx mori metamorphosis. Here we show that downregulation of BmPOUM2 expression by RNA interference during thewandering stage resulted in failure to complete metamorphosis. The thorax epidermis of RNA interference-treated larvae became transparent, wing disc growth and differentiation were arrested, and the larvae failed to spin cocoons. Quantitative real-time PCR analysis showed that expression of the genes coding for pupal-specific wing cuticle proteins BmWCP1, BmWCP2, BmWCP3, BmWCP4, BmWCP5, BmWCP6, BmWCP8, and BmWCP9 were down-regulated in BmPOUM2 dsRNA-treated animals, whereas overexpression of BmPOUM2 protein increased the expression of BmWCP4, BmWCP5, BmWCP6, BmWCP7, and BmWCP8. Pull-down assays, far-Western blot, and electrophoretic mobility shift assay showed that the BmPOUM2 protein interacted with another homeodomain transcription factor, BmAbd-A, to induce the expression of BmWCP4. Immunohistochemical localization of BmPOUM2, BmAbd-A, and BmWCP4 proteins revealed that BmAbd-A and BmPOUM2 proteins are colocalized in the wing disc cell nuclei, whereas BmWCP4 protein is localized in the cytoplasm. Together these data suggest that BmPOUM2 interacts with the homeodomain transcription factor BmAbd-A and regulates the expression of BmWCP4 and probably other BmWCPs to complete the larva-to-pupa transformation. Although homeodomain proteins are known to regulate embryonic development, this study showed that these proteins also regulate metamorphosis.

Original languageEnglish
Pages (from-to)12598-12603
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume109
Issue number31
DOIs
StatePublished - Jul 31 2012

Keywords

  • Ecdysone
  • Juvenile hormone
  • Molt
  • Pupation

ASJC Scopus subject areas

  • General

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