The –3.9 kb DHS of the chicken lysozyme locus harbors an enhancer element with unusual chromatin reorganizing activity

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Colleges, School and Institutes


Tissue specific regulation of the chicken lysozyme locus is achieved by a combination of positive and negative cis-regulatory elements. Here we describe the molecular characterization of a newly discovered enhancer element located −3.9 kb upstream of the transcription start. The −3.9 kb enhancer is activated early in macrophage differentiation, as indicated by chromatin reorganization in macrophage precursor cells. Interestingly, enhancer activation leads to nucleosome phasing. Tissue specificity of expression is achieved by a combination of 5′-sequences with ubiquitous enhancer activity and 3′-flanking sequences. The 5′-half contains binding sites for members of the nuclear factor I transcription family and a yet unknown protein. We could show by in vivo footprinting that the ubiquitously expressed factors occupy their binding sites only in lysozyme expressing cells. We conclude that a specific chromatin architecture may be responsible for the differential activity of the enhancer.


Original languageEnglish
Pages (from-to)63-77
Issue number1
Publication statusPublished - 5 Aug 1999


  • Chromatin domain, Macrophage specific gene expression, Nuclear factor I, Nucleosome phasing