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Modulation of Estrogen Response Element-Driven Gene Expressions and Cellular Proliferation with Polar Directions by Designer Transcription Regulators

Muyan, Mesut
Gupur, Gizem
Yasar, Pelin
Ayaz, Gamze
User, Sirma Damla
Kazan, Hasan Huseyin
Huang, Yanfang
Estrogen receptor a (ER alpha), as a ligand-dependent transcription factor, mediates 17 beta-estradiol (E2) effects. ERa is a modular protein containing a DNA binding domain (DBD) and transcription activation domains (AD) located at the amino-and carboxyl-termini. The interaction of the E2-activated ERa dimer with estrogen response elements (EREs) of genes constitutes the initial step in the ERE-dependent signaling pathway necessary for alterations of cellular features. We previously constructed monomeric transcription activators, or monotransactivators, assembled from an engineered ERE-binding module (EBM) using the ER alpha-DBD and constitutively active ADs from other transcription factors. Monotransactivators modulated cell proliferation by activating and repressing ERE-driven gene expressions that simulate responses observed with E2-ER alpha. We reasoned here that integration of potent heterologous repression domains (RDs) into EBM could generate monotransrepressors that alter ERE-bearing gene expressions and cellular proliferation in directions opposite to those observed with E2-ER alpha or monotransactivators. Consistent with this, monotransrepressors suppressed reporter gene expressions that emulate the ERE-dependent signaling pathway. Moreover, a model monotransrepressor regulated DNA synthesis, cell cycle progression and proliferation of recombinant adenovirus infected ER-negative cells through decreasing as well as increasing gene expressions with polar directions compared with E2-ER alpha or monotransactivator. Our results indicate that an 'activator' or a 'repressor' possesses both transcription activating/enhancing and repressing/decreasing abilities within a chromatin context. Offering a protein engineering platform to alter signal pathway-specific gene expressions and cell growth, our approach could also be used for the development of tools for epigenetic modifications and for clinical interventions wherein multigenic de-regulations are an issue.