Regulation of cyst wall protein promoters by Myb2 in Giardia lamblia

Yu Chang Huang, Li Hsin Su, Gilbert A. Lee, Pei Wei Chiu, Chao Cheng Cho, Jeng You Wu, Chin Hung Sun

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)


Myb family transcription factors are important in regulating cell proliferation, differentiation, and cell cycle progression. Giardia lamblia differentiates into infectious cysts to survive outside of the host. During encystation, genes encoding cyst wall proteins (CWPs) are coordinately induced. We have identified an encystation-induced Myb2 protein, which binds to the promoter regions of the cwp genes and myb2 itself in vitro. To elucidate the role of Myb2 in G. lamblia, we tested the hypothesis that Myb2 can activate encystation-induced genes. We found that overexpression of Myb2 resulted in an increase of expression of CWP1 at both protein and mRNA levels. Interestingly, the Myb2-overexpressing trophozoites had increased capability to differentiate into cysts. In cotransfection assays, Myb2 was able to transactivate the cwp promoters and its own promoter in vivo, suggesting that its gene can be positively autoregulated. Moreover, deletion of the N- or C-terminal domain resulted in a decrease of transactivation and autoregulation function of Myb2. We also found that the promoter of a newly identified encystation-induced gene, the giardial myeloid leukemia factor-like gene, has the Myb2 binding sites and that its mRNA levels were increased by Myb2 overexpression. Chromatin immunoprecipitation assays confirmed that Myb2 was bound to the promoters with its binding sites. Transfection of the myb2 antisense construct reduced the levels of the cwp1 transcripts and cyst formation. Our results suggest that Myb2 is a potent transactivator of the cwp genes and other endogenous genes and plays an important role in G. lamblia differentiation into cysts.

Original languageEnglish
Pages (from-to)31021-31029
Number of pages9
JournalJournal of Biological Chemistry
Issue number45
Publication statusPublished - Nov 7 2008

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


Dive into the research topics of 'Regulation of cyst wall protein promoters by Myb2 in Giardia lamblia'. Together they form a unique fingerprint.

Cite this