title: Unique Distal Enhancers Linked to the Mouse Tnfsf11 Gene Direct Tissue-Specific and Inflammation-Induced Expression of RANKL.
abstract: Receptor activator of nuclear factor κB ligand (RANKL) is expressed by a number of cell types to participate in diverse physiological functions. We have previously identified 10 distal RANKL enhancers. Earlier studies have shown that RL-D5 is a multifunctional RANKL enhancer. Deletion of RL-D5 from the mouse genome leads to lower skeletal and lymphoid tissue RANKL, causing a high bone mass phenotype. Herein, we determine the physiological role and lineage specificity of 2 additional RANKL enhancers, RL-D6 and RL-T1, which are located 83 and 123 kb upstream of the gene's transcriptional start site, respectively. Lack of RL-D6 or RL-T1 did not alter skeletal RANKL or bone mineral density up to 48 weeks of age. Although both RL-D5 and RL-T1 contributed to activation induction of T-cell RANKL, RL-T1 knockout mice had drastically low lymphocyte and lymphoid tissue RANKL levels, indicating that RL-T1 is the major regulator of lymphocyte RANKL. Moreover, RL-T1 knockout mice had lower circulating soluble RANKL, suggesting that lymphocytes are important sources of circulating soluble RANKL. Under physiological conditions, lack of RL-D6 did not alter RANKL expression. However, lack of RL-D5 or RL-D6, but not of RL-T1, blunted the oncostatin M and lipopolysaccharide induction of RANKL ex vivo and in vivo, suggesting that RL-D5 and RL-D6 coregulate the inflammation-mediated induction of RANKL in osteocytes and osteoblasts while lack of RL-D6 did not alter secondary hyperparathyroidism or lactation induction of RANKL or bone loss. These results suggest that although RL-D5 mediates RANKL expression in multiple lineages, other cell type- or factor-specific enhancers are required for its appropriate control, demonstrating the cell type-specific and complex regulation of RANKL expression.
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706.
authors.forename: M
authors.initials: M
authors.lastname: Onal
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706.
authors.forename: H C
authors.initials: HC
authors.lastname: St John
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706.
authors.forename: A L
authors.initials: AL
authors.lastname: Danielson
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706.
authors.forename: J W
authors.initials: JW
authors.lastname: Markert
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706.
authors.forename: E M
authors.initials: EM
authors.lastname: Riley
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706.
authors.forename: J W
authors.initials: JW
authors.lastname: Pike
mesh_terms: D000818:Animals; D019070:Cell Lineage / Q000235:genetics; D002478:Cells, Cultured; D004742:Enhancer Elements, Genetic; D005260:Female; D005786:Gene Expression Regulation; D007249:Inflammation / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009928:Organ Specificity / Q000235:genetics; D011485:Protein Binding; D053245:RANK Ligand / Q000235:genetics* / Q000378:metabolism*
chemical_list: D053245:RANK Ligand; C505689:Tnfsf11 protein, mouse