title: Dual regulatory effects of non-coding GC-rich elements on the expression of virulence genes in malaria parasites.
abstract: As the primary virulence factor of falciparum malaria, var genes harboring mutually exclusive expression pattern lead to antigenic variation and immune evasion of this pathogen in human host. Although various mechanisms contribute to silence of var genes, little is known of transcriptional activation pathways of a single var gene and maintenance of its active state with other silent var loci. Here, we report a monoallelic expression pattern of the non-coding GC-elements flanking chromosomal internal var genes, and transcript from the active one was required for activation of the var gene in the same array. Meanwhile, GFP reporter assays revealed a repressive effect on the adjacent gene induced by DNA motifs of the insulator-like GC-element, which was linked to heterochromatin subnuclear localization. Taken together, these data for the first time provide experimental evidence of the dual cis- and trans-acting regulatory functions of the GC-elements in both silence and activation of var genes, which would advance our understanding of the complex regulatory network of the virulence gene family in P. falciparum.
authors: Institute for Infectious Diseases and Vaccine Development, Tongji University School of Medicine, 1239 Siping Road, Shanghai 200092, China.
authors: Guiying
authors: G
authors: Wei
authors: Institute for Infectious Diseases and Vaccine Development, Tongji University School of Medicine, 1239 Siping Road, Shanghai 200092, China.
authors: Yuemeng
authors: Y
authors: Zhao
authors: Institute for Infectious Diseases and Vaccine Development, Tongji University School of Medicine, 1239 Siping Road, Shanghai 200092, China. Electronic address: qfzhangsh@aliyun.com.
authors: Qingfeng
authors: Q
authors: Zhang
authors: Institute for Infectious Diseases and Vaccine Development, Tongji University School of Medicine, 1239 Siping Road, Shanghai 200092, China; Department of Tropical Infectious Diseases, Second Military Medical University, 800 Xiang Yin Road, Shanghai 200433, China. Electronic address: wqpan0912@aliyun.com.
authors: Weiqing
authors: W
authors: Pan
mesh_terms: D001483:Base Sequence; D020862:GC Rich Sequence; D015870:Gene Expression; D005786:Gene Expression Regulation; D020868:Gene Silencing; D017125:Genes, Protozoan; D017930:Genes, Reporter; D006801:Humans; D016778:Malaria, Falciparum / Q000469:parasitology; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D010963:Plasmodium falciparum / Q000235:genetics* / Q000472:pathogenicity; D015800:Protozoan Proteins / Q000235:genetics; D022661:RNA, Untranslated / Q000737:chemistry / Q000235:genetics; D014158:Transcription, Genetic; D020506:Untranslated Regions; D014774:Virulence / Q000235:genetics*
chemical_list: D015800:Protozoan Proteins; D022661:RNA, Untranslated; D020506:Untranslated Regions; C085731:erythrocyte membrane protein 1, Plasmodium falciparum
keywords: GC-elements; Malaria; Mutually exclusive expression; Non-coding RNA; Plasmodium falciparum; var genes