Cooperative interaction of chicken lysozyme enhancer sub-domains partially overlapping with a steroid receptor binding site

Abstract

Expression of the lysozyme gene is a marker for the differentiation of macrophages, lysozyme transcription being gradually increased during maturation. We have analyzed the fine structure and function of two macrophage-specific enhancer elements of the chicken lysozyme gene (E-2.7 kb and E-0.2 kb). Both increase their activities upon LPS induction, both contain multiple binding sites for similar or identical nuclear factors and both can be divided into two functional modules. For the E-0.2 kb enhancer we found a synergistic activity of the modules to be dependent on their distance. Binding sites for nuclear proteins within enhancer E-0.2 kb overlap substantially with the previously identified progesterone/glucocorticoid receptor binding site, which is required for steroid induction of lysozyme transcription in the oviduct.

Developmentally Regulated Recruitment of Transcription Factors and Chromatin Modification Activities to Chicken Lysozyme cis-Regulatory Elements In Vivo

“…Preliminary experiments with LPS-stimulated HD11 cells indicate that at least one of the Sp1 consensus sequences at the promoter is recognized by Sp1 itself (P. Lefevre and C. Bonifer, unpublished observation). This confirms earlier in vitro binding studies (3).…”

Role of Positive and Negative Cis-regulatory Elements in the Transcriptional Activation of the Lysozyme Locus in Developing Macrophages of Transgenic Mice

“…The isolated cell populations were cultivated under macrophage growth promoting conditions in the presence of M-CSF and interleukin-3 (IL-3) for a period of 6 days. Bacterial lipopolysaccharide (LPS) is known to promote macrophage activation and has been shown to stimulate expression of the chicken lysozyme gene in chicken and mouse macrophages (10,20,27,31). To examine at which stage of differentiation the cells acquire LPS responsiveness, cultures were treated with LPS for 12 h, either immediately after isolation or after 5 days of culture.…”

COUP-TF acts as a competitive repressor for estrogen receptor-mediated activation of the mouse lactoferrin gene.

“…ER, upon binding to the consensus palindromic estrogen response element (ERE), is able to confer estrogen-stimulated transcription. Recent studies show that the response elements for steroid hormones could also act together with other transcription factor-binding elements to bring about hormone-dependent responses (1,8,12,50,60). The trans activation of these genes is initiated by the interaction between ER and other transcription factors and their respective cognated elements.…”

“…ER, upon binding to the consensus palindromic estrogen response element (ERE), is able to confer estrogen-stimulated transcription. Recent studies show that the response elements for steroid hormones could also act together with other transcription factor-binding elements to bring about hormone-dependent responses (1,8,12,50,60). The trans activation of these genes is initiated by the interaction between ER and other transcription factors and their respective cognated elements. In addition to the steroid hormone receptors that responded to well-known ligands, a large collection of orphan receptors that share structural homology has been isolated, although the particular ligand has not yet been identified (28,51,57,58).…”