HBS1L-MYB intergenic variants modulate fetal hemoglobin via long-range MYB enhancers
Ralph Stadhouders, … , Swee Lay Thein, Eric Soler
Ralph Stadhouders, … , Swee Lay Thein, Eric Soler
Published March 10, 2014
Citation Information: J Clin Invest. 2014;124(4):1699-1710. https://doi.org/10.1172/JCI71520.
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Research Article Hematology

HBS1L-MYB intergenic variants modulate fetal hemoglobin via long-range MYB enhancers

Abstract

Genetic studies have identified common variants within the intergenic region (HBS1L-MYB) between GTP-binding elongation factor HBS1L and myeloblastosis oncogene MYB on chromosome 6q that are associated with elevated fetal hemoglobin (HbF) levels and alterations of other clinically important human erythroid traits. It is unclear how these noncoding sequence variants affect multiple erythrocyte characteristics. Here, we determined that several HBS1L-MYB intergenic variants affect regulatory elements that are occupied by key erythroid transcription factors within this region. These elements interact with MYB, a critical regulator of erythroid development and HbF levels. We found that several HBS1L-MYB intergenic variants reduce transcription factor binding, affecting long-range interactions with MYB and MYB expression levels. These data provide a functional explanation for the genetic association of HBS1L-MYB intergenic polymorphisms with human erythroid traits and HbF levels. Our results further designate MYB as a target for therapeutic induction of HbF to ameliorate sickle cell and β-thalassemia disease severity.

Authors

Ralph Stadhouders, Suleyman Aktuna, Supat Thongjuea, Ali Aghajanirefah, Farzin Pourfarzad, Wilfred van IJcken, Boris Lenhard, Helen Rooks, Steve Best, Stephan Menzel, Frank Grosveld, Swee Lay Thein, Eric Soler

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Figure 3

Erythroid TFs bind intergenic enhancer regions and are required for MYB expression.

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Erythroid TFs bind intergenic enhancer regions and are required for MYB ...
(A) Alignment of LDB1-binding sites (HEPs) to enhancer chromatin signature, DNaseI-HS, and footprinting data from erythroid (K562) and endothelial (HUVEC) cell lines. (B) Table summarizing the comparison between LDB1 sites (HEPs) and enhancer marks (K562). Arrowheads denote conserved sites with highly enriched enhancer signatures. (C) H3K27 acetylation as measured by ChIP-qPCR in HEPs for indicated LDB1-binding sites (n = 2). Enrichments were corrected for total H3 levels and normalized to the AMY2A promoter (AMY prom.). (D) Luciferase reporter assays in MEL cells measuring (n = 3) enhancer activity of the –84-kb and –71-kb elements. Promoter activity without enhancer (empty) was set to 1. (E and F) Gene expression analysis (n = 3) on K562 cells depleted for the indicated TFs by RNAi. A scrambled shRNA was used as control (Ctrl). Error bars display SEM.