Document Detail

A general approach for controlling transcription and probing epigenetic mechanisms: application to the CD4 locus.
MedLine Citation:
PMID:  23293358     Owner:  NLM     Status:  MEDLINE    
Synthetic regulatory proteins such as tetracycline (tet)-controlled transcription factors are potentially useful for repression as well as ectopic activation of endogenous genes and also for probing their regulatory mechanisms, which would offer a versatile genetic tool advantageous over conventional gene targeting methods. In this study, we provide evidence supporting this concept using Cd4 as a model. CD4 is expressed in double-positive and CD4 cells but irreversibly silenced in CD8 cells. The silencing is mediated by heterochromatin established during CD8 lineage development via transient action of the Cd4 silencer; once established, the heterochromatin becomes self-perpetuating independently of the Cd4 silencer. Using a tet-sensitive Cd4 allele harboring a removable Cd4 silencer, we found that a tet-controlled repressor recapitulated the phenotype of Cd4-deficient mice, inhibited Cd4 expression in a reversible and dose-dependent manner, and could surprisingly replace the Cd4 silencer to induce irreversible Cd4 silencing in CD8 cells, thus suggesting the Cd4 silencer is not the (only) determinant of heterochromatin formation. In contrast, a tet-controlled activator reversibly disrupted Cd4 silencing in CD8 cells. The Cd4 silencer impeded this disruption but was not essential for its reversal, which revealed a continuous role of the silencer in mature CD8 cells while exposing a remarkable intrinsic self-regenerative ability of heterochromatin after forced disruption. These data demonstrate an effective approach for gene manipulation and provide insights into the epigenetic Cd4 regulatory mechanisms that are otherwise difficult to obtain.
Mimi Wan; Ravinder Kaundal; Haichang Huang; Jiugang Zhao; Xiaojun Yang; Barbara H Chaiyachati; Sicong Li; Tian Chi
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of immunology (Baltimore, Md. : 1950)     Volume:  190     ISSN:  1550-6606     ISO Abbreviation:  J. Immunol.     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-01-07     Completed Date:  2013-03-14     Revised Date:  2014-04-25    
Medline Journal Info:
Nlm Unique ID:  2985117R     Medline TA:  J Immunol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  737-47     Citation Subset:  AIM; IM    
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MeSH Terms
Antigens, CD4 / genetics*
CD8-Positive T-Lymphocytes / metabolism
Epigenesis, Genetic*
Gene Expression Regulation*
Gene Order
Gene Silencing
Gene Targeting
Mice, Knockout
Silencer Elements, Transcriptional
T-Lymphocytes / metabolism
Transcription, Genetic*
Grant Support
Reg. No./Substance:
0/Antigens, CD4

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