Haemoglobin graphic
Structure of human hemoglobin. The proteins’ α and β subunits are in red and blue, and the iron-containing heme groups in green. From PDB 1GZX Proteopedia Hemoglobin

The focus of our laboratory is to analyze mechanisms regulating gene expression during erythroid cell differentiation. The beta-globin genes are regulated by a locus control region (LCR). The LCR is composed of several DNase I hypersensitive (HS) sites that together mediate chromatin structure alterations and high-level transcription throughout erythroid development. The human beta-globin gene locus consists of five genes that are expressed in a developmental stage specific manner in erythroid cells. During development the different proteins encoded by the beta-globin gene locus (ε, Aγ, Gγ, δ, and βglobin) dimerize with a-globin subunits to form hemoglobin. The beta-type globin genes are expressed at extremely high levels in erythroid cells which is mediated by the LCR.

LCR graphic
Artwork by Shermi Liang PhD., based on reference sequences NG_000007.3 & NG_000006.1 on NCBI.

Results from our previous work suggest that the individual LCR HS elements interact to generate a higher order structure, referred to as the LCR holocomplex, and that this complex communicates in a stage-specific manner with individual globin genes. We also found that the LCR recruits transcription complexes and proposed that the LCR serves as the primary site of transcription complex recruitment and assembly in the beta-globin gene locus. We use transgenic mice and cell culture to identify and functionally characterize cis-regulatory DNA elements and trans-acting components involved in the regulation of the beta-globin genes. We utilize artificial DNA binding domains to modulate and characterize the function of transcription factor binding sites in the beta-globin gene locus. We also use a variety of molecular techniques, including chromatin immunoprecipitation (ChIP), ChIP-sequencing, shRNA mediated knockdown, and overexpression of dominant negative transcription factors to analyze transcription factor function and globin gene regulation.