title: TALE activators regulate gene expression in a position- and strand-dependent manner in mammalian cells.
abstract: Transcription activator-like effectors (TALEs) are a class of transcription factors that are readily programmable to regulate gene expression. Despite their growing popularity, little is known about binding site parameters that influence TALE-mediated gene activation in mammalian cells. We demonstrate that TALE activators modulate gene expression in mammalian cells in a position- and strand-dependent manner. To study the effects of binding site location, we engineered TALEs customized to recognize specific DNA sequences located in either the promoter or the transcribed region of reporter genes. We found that TALE activators robustly activated reporter genes when their binding sites were located within the promoter region. In contrast, TALE activators inhibited the expression of reporter genes when their binding sites were located on the sense strand of the transcribed region. Notably, this repression was independent of the effector domain utilized, suggesting a simple blockage mechanism. We conclude that TALE activators in mammalian cells regulate genes in a position- and strand-dependent manner that is substantially different from gene activation by native TALEs in plants. These findings have implications for optimizing the design of custom TALEs for genetic manipulation in mammalian cells.
authors.affiliation: Department of Biological Sciences, California State University, East Bay, 25800 Carlos Bee Blvd, Hayward, CA 94542, United States. Electronic address: Claudia.stone@csueastbay.edu.
authors.forename: Claudia
authors.initials: C
authors.lastname: Uhde-Stone
authors.affiliation: System Biosciences (SBI), 265 North Whisman Rd., Mountain View, CA 94043, United States. Electronic address: edna.cheung@ucsf.edu.
authors.forename: Edna
authors.initials: E
authors.lastname: Cheung
authors.affiliation: System Biosciences (SBI), 265 North Whisman Rd., Mountain View, CA 94043, United States. Electronic address: BLu@systembio.com.
authors.forename: Biao
authors.initials: B
authors.lastname: Lu
mesh_terms: D020121:5' Untranslated Regions; D001665:Binding Sites / Q000235:genetics; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D057809:HEK293 Cells; D006801:Humans; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D020121:5' Untranslated Regions; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors
keywords: Dual reporter; Genome editing; TAL Effector; TALE; Transcription-activator-like effector