Developmental regulation of the murine beta-globin locus

Thursday, October 11, 2012 — Poster Session III
10:00 a.m. – Noon	Natcher Conference Center, Building 45	NIDDK	EPIGEN/TRANS/CHROM-3

* FARE Award Winner

Authors

• JH Oum
• I Som
• S Eszterhas
• J Little
• Q Gong
• S Fiering
• A Dean

Abstract

RNA polymerase II (pol II) tracking and chromatin looping are non-exclusive models of gene activation by distant enhancers. The mouse β-globin locus is a prominent system for the study of long-range gene activation. All the β-like globin genes are activated by the locus control region (LCR) 60 kb upstream of β-major but only 6 kb from εy. Chromatin looping occurs between the LCR and β-major but whether this mechanism also activates the more proximal εy gene is unknown. We investigated the hypothesis that pol II tracking activates εy by inserting the chicken HS4 insulator (cHS4) between the gene and the LCR in mouse ES cells by homologous recombination. We found that εy and β-major transcripts were reduced 50-80% in differentiated cHS4 ES cells compared to WT ES cells. However, unlike in human erythroid cells, intergenic transcription between the LCR and εy was very low in WT ES cells. Nevertheless, in cHS4 ES cells, intergenic transcripts accumulated near the CTCF binding site in cHS4, suggesting that pol II stalls at this region. We are currently analyzing pol II occupancy in the ES cell globin loci as well as the consequences of exchanging the cHS4 insulator for a transcription terminator.

back to top