title: Transcriptional regulation of FoxO3 gene by glucocorticoids in murine myotubes.
abstract: Glucocorticoids and FoxO3 exert similar metabolic effects in skeletal muscle. FoxO3 gene expression was increased by dexamethasone (Dex), a synthetic glucocorticoid, both in vitro and in vivo. In C2C12 myotubes the increased expression is due to, at least in part, the elevated rate of FoxO3 gene transcription. In the mouse FoxO3 gene, we identified three glucocorticoid receptor (GR) binding regions (GBRs): one being upstream of the transcription start site, -17kbGBR; and two in introns, +45kbGBR and +71kbGBR. Together, these three GBRs contain four 15-bp glucocorticoid response elements (GREs). Micrococcal nuclease (MNase) assay revealed that Dex treatment increased the sensitivity to MNase in the GRE of +45kbGBR and +71kbGBR upon 30- and 60-min Dex treatment, respectively. Conversely, Dex treatment did not affect the chromatin structure near the -17kbGBR, in which the GRE is located in the linker region. Dex treatment also increased histone H3 and/or H4 acetylation in genomic regions near all three GBRs. Moreover, using chromatin conformation capture (3C) assay, we showed that Dex treatment increased the interaction between the -17kbGBR and two genomic regions: one located around +500 bp and the other around +73 kb. Finally, the transcriptional coregulator p300 was recruited to all three GBRs upon Dex treatment. The reduction of p300 expression decreased FoxO3 gene expression and Dex-stimulated interaction between distinct genomic regions of FoxO3 gene identified by 3C. Overall, our results demonstrate that glucocorticoids activated FoxO3 gene transcription through multiple GREs by chromatin structural change and DNA looping.
authors.affiliation: Endocrinology Graduate Program, University of California Berkeley, Berkeley, California; and Department of Nutritional Sciences and Toxicology, University of California Berkeley, Berkeley, California.
authors.forename: Taiyi
authors.initials: T
authors.lastname: Kuo
authors.affiliation: Department of Nutritional Sciences and Toxicology, University of California Berkeley, Berkeley, California.
authors.forename: Patty H
authors.initials: PH
authors.lastname: Liu
authors.affiliation: Department of Nutritional Sciences and Toxicology, University of California Berkeley, Berkeley, California.
authors.forename: Tzu-Chieh
authors.initials: TC
authors.lastname: Chen
authors.affiliation: Endocrinology Graduate Program, University of California Berkeley, Berkeley, California; and Department of Nutritional Sciences and Toxicology, University of California Berkeley, Berkeley, California.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Lee
authors.affiliation: Department of Nutritional Sciences and Toxicology, University of California Berkeley, Berkeley, California.
authors.forename: Jenny
authors.initials: J
authors.lastname: New
authors.affiliation: Department of Nutritional Sciences and Toxicology, University of California Berkeley, Berkeley, California.
authors.forename: Danyun
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Department of Nutritional Sciences and Toxicology, University of California Berkeley, Berkeley, California.
authors.forename: Cassandra
authors.initials: C
authors.lastname: Lei
authors.affiliation: Department of Nutritional Sciences and Toxicology, University of California Berkeley, Berkeley, California.
authors.forename: Andy
authors.initials: A
authors.lastname: Chau
authors.affiliation: Department of Nutritional Sciences and Toxicology, University of California Berkeley, Berkeley, California.
authors.forename: Yicheng
authors.initials: Y
authors.lastname: Tang
authors.affiliation: Department of Nutritional Sciences and Toxicology, University of California Berkeley, Berkeley, California.
authors.forename: Edna
authors.initials: E
authors.lastname: Cheung
authors.affiliation: Endocrinology Graduate Program, University of California Berkeley, Berkeley, California; and Department of Nutritional Sciences and Toxicology, University of California Berkeley, Berkeley, California walwang@berkeley.edu.
authors.forename: Jen-Chywan
authors.identifier: http://orcid.org/0000-0001-6030-6886
authors.initials: JC
authors.lastname: Wang
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000818:Animals; D002843:Chromatin / Q000187:drug effects / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000187:drug effects* / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects*; D005938:Glucocorticoids / Q000494:pharmacology*; D042421:Histone Code / Q000187:drug effects*; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000187:drug effects* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D011965:Receptors, Glucocorticoid; D020218:Response Elements; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; C474033:FoxO3 protein, mouse; D005938:Glucocorticoids; D011965:Receptors, Glucocorticoid; D003907:Dexamethasone
keywords: FoxO3; chromatin structure; gene transcription; glucocorticoid receptor; glucocorticoids; myotube