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A Novel E2F-Iike Protein Involved in Transcriptional Activation of Cyst Wall Protein Genes in Giardia Iamblia.

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Title: A Novel E2F-Iike Protein Involved in Transcriptional Activation of Cyst Wall Protein Genes in Giardia Iamblia.
Authors: Li-Hsin Su1, Yu-Jiao Pan1, Yu-Chang Huang1, Chao-Cheng Cho1, Chia-Wei Chen1, Shao-Wei Huang1, Sheng-Fung Chuang1, Chin-Hung Sun1 chinhsun@ntu.edu.tw
Source: Journal of Biological Chemistry. 9/30/2011, Vol. 286 Issue 39, p34101-34120. 20p.
Subjects: Genetic transcription, Giardia lamblia, Gene expression, Messenger RNA, Cysts (Pathology), Cell proliferation
Abstract: Giardia lamblia differentiates into resistant walled cysts for survival outside the host and transmission. During encystation, synthesis of cyst wall proteins is coordinately induced. The E2F family of transcription factors in higher eukaryotes is involved in cell cycle progression and cell differentiation. We asked whether Giardia has E2F-like genes and whether they influence gene expression during Giardia encystation. Blast searches of the Giardia genome database identified one gene (e2fl) encod- ing a putatiLve E2F protein with two putative DNA-binding domains. We found that the e2fl gene expression levels in- creased significantly during encystation. Epitope-tagged E2F1 was found to localize to nuclei. Recombinant E2F1 specifically bound to the thyrnidine kinase and cwpl -3 gene promoters. E2F1 contains several key residues for DNA binding, and muta- tion analysis revealed that its binding sequence is similar to those of the known E2F family proteins. The E2F1-binding sequences were positive cis-acting elements of the thymidine kinase and cwpl promoters. We also found that E2F1 transacti- vated the thyrnidine kinase and cwpl promoters through its binding sequences in vivo. Interestingly, E2F1 overexpression resulted in a significant increase of the levels of CWP1 protein, cwpl-3 gene mRNA, and cyst formation. We also found E2F1 can interact with Myb2, a transcription factor that coordinate up-regulates the cwpl-3 genes during encystation. Our results suggest that: E2F family has been conserved during evolution and that E211 is an important transcription factor in regulation of the Giardia cwp genes, which are key to Giardia differentia- tion into cysts. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:Giardia lamblia differentiates into resistant walled cysts for survival outside the host and transmission. During encystation, synthesis of cyst wall proteins is coordinately induced. The E2F family of transcription factors in higher eukaryotes is involved in cell cycle progression and cell differentiation. We asked whether Giardia has E2F-like genes and whether they influence gene expression during Giardia encystation. Blast searches of the Giardia genome database identified one gene (e2fl) encod- ing a putatiLve E2F protein with two putative DNA-binding domains. We found that the e2fl gene expression levels in- creased significantly during encystation. Epitope-tagged E2F1 was found to localize to nuclei. Recombinant E2F1 specifically bound to the thyrnidine kinase and cwpl -3 gene promoters. E2F1 contains several key residues for DNA binding, and muta- tion analysis revealed that its binding sequence is similar to those of the known E2F family proteins. The E2F1-binding sequences were positive cis-acting elements of the thymidine kinase and cwpl promoters. We also found that E2F1 transacti- vated the thyrnidine kinase and cwpl promoters through its binding sequences in vivo. Interestingly, E2F1 overexpression resulted in a significant increase of the levels of CWP1 protein, cwpl-3 gene mRNA, and cyst formation. We also found E2F1 can interact with Myb2, a transcription factor that coordinate up-regulates the cwpl-3 genes during encystation. Our results suggest that: E2F family has been conserved during evolution and that E211 is an important transcription factor in regulation of the Giardia cwp genes, which are key to Giardia differentia- tion into cysts. [ABSTRACT FROM AUTHOR]
ISSN:00219258
DOI:10.1074/jbc.M111.280206