A novel genetic strategy reveals unexpected roles of the Swi-Snf-like chromatin-remodeling BAF complex in thymocyte development

Anant Jani, Mimi Wan, Jianmin Zhang, Kairong Cui, Jie Wu, Paula Preston-Hurlburt, Rohini Khatri, Keji Zhao, Tian Chi

Research output: Contribution to journalArticlepeer-review

Abstract

We have developed a general strategy for creating littermates bearing either a tissue- specific point mutation or deletion in any target gene, and used the method to dissect the roles of Brg, the ATPase subunit of the chromatin-remodeling Brg-associated factor (BAF) complex, in early thymocyte development. We found that a point mutation that inactivates the Brg ATPase recapitulates multiple defects previously described for Brg deletion (Chi, T.H., M. Wan, P.P. Lee, K. Akashi, D. Metzger, P. Chambon, C.B. Wilson, and G.R. Crabtree. 2003. Immunity. 19:169-182). However, the point mutant helps reveal unexpected roles of Brg in CD25 repression and CD4 activation. Surprisingly, CD4 activation occurs independently of the Brg ATPase and is perhaps mediated by physical interactions between Brg and the CD4 locus. Our study thus suggests that the BAF complex harbors novel activities that can be necessary and even sufficient for stimulating transcription from an endogenous chromatin template in the absence of Brg-dependent remodeling of that template. We conclude that conditional point mutants, rarely used in mammalian genetics, can help uncover important gene functions undetectable or overlooked in deletion mutants.

Original languageEnglish (US)
Pages (from-to)2813-2825
Number of pages13
JournalJournal of Experimental Medicine
Volume205
Issue number12
DOIs
StatePublished - Nov 12 2008
Externally publishedYes

ASJC Scopus subject areas

  • Immunology
  • Immunology and Allergy
  • Medicine(all)

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