Cookies on this website
We use cookies to ensure that we give you the best experience on our website. If you click 'Continue' we'll assume that you are happy to receive all cookies and you won't see this message again. Click 'Find out more' for information on how to change your cookie settings.

RATIONALE: The evolutionary conserved Tbx3/Tbx5 gene cluster encodes T-box transcription factors that play crucial roles in the development and homeostasis of the cardiac conduction system in human and mouse. Both genes are expressed in overlapping patterns and function in strictly tissue-specific and dose-dependent manners, yet, their regulation is poorly understood. OBJECTIVE: To analyze the mechanism underlying the complex regulation of the Tbx3/Tbx5 cluster. METHODS AND RESULTS: By probing the 3-dimensional architecture of the Tbx3/Tbx5 cluster using high-resolution circular chromosome conformation capture sequencing in vivo, we found that its regulatory landscape is in a preformed conformation similar in embryonic heart, limbs, and brain. Tbx3 and its flanking gene desert form a 1 Mbp loop between CCCTC-binding factor (CTCF)-binding sites that is separated from the neighboring Tbx5 loop. However, Ctcf inactivation did not result in transcriptional regulatory interaction between Tbx3 and Tbx5. Multiple sites within the Tbx3 locus contact the promoter, including sites corresponding to regions known to contain variations in the human genome influencing conduction. We identified an atrioventricular-specific enhancer and a pan-cardiac enhancer that contact the promoter and each other and synergize to activate transcription in the atrioventricular conduction system. CONCLUSIONS: We provide a high-resolution model of the 3-dimensional structure and function of the Tbx3/Tbx5 locus and show that the locus is organized in a preformed, permissive structure. The Tbx3 locus forms a CTCF-independent autonomous regulatory domain with multiple combinatorial regulatory elements that control the precise pattern of Tbx3 in the cardiac conduction system.

Original publication

DOI

10.1161/CIRCRESAHA.115.303591

Type

Journal article

Journal

Circ Res

Publication Date

01/08/2014

Volume

115

Pages

432 - 441

Keywords

anatomy & histology, heart conduction system, 3' Flanking Region, Animals, Binding Sites, Bone Morphogenetic Proteins, CCCTC-Binding Factor, Chromosomes, Artificial, Bacterial, DNA, Circular, Gene Expression Regulation, Developmental, Genes, Reporter, Green Fluorescent Proteins, Heart Conduction System, Mice, Inbred C57BL, Mice, Knockout, Mice, Transgenic, Morphogenesis, Multigene Family, Repressor Proteins, Signal Transduction, T-Box Domain Proteins, Transcription, Genetic, Transcriptional Activation