Scaffold functions of 14-3-3 adaptors in B cell immunoglobulin class switch DNA recombination

Tonika Lam, Lisa M. Thomas, Clayton A. White, Guideng Li, Egest J. Pone, Zhenming Xu, Paolo Casali

Research output: Contribution to journalArticle

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Abstract

Class switch DNA recombination (CSR) of the immunoglobulin heavy chain (IgH) locus crucially diversifies antibody biological effector functions. CSR involves the induction of activation-induced cytidine deaminase (AID) expression and AID targeting to switch (S) regions by 14-3-3 adaptors. 14-3-3 adaptors specifically bind to 5′-AGCT-3′ repeats, which make up for the core of all IgH locus S regions. They selectively target the upstream and downstream S regions that are set to undergo S-S DNA recombination. We hypothesized that 14-3-3 adaptors function as scaffolds to stabilize CSR enzymatic elements on S regions. Here we demonstrate that all seven 14-3-3β, 14-3-3ε, 14-3-3γ, 14-3-3η, 14-3-3σ, 14-3-3τ and 14-3-3ζ adaptors directly interacted with AID, PKA-Cα (catalytic subunit) and PKA-RIα (regulatory inhibitory subunit) and uracil DNA glycosylase (Ung). 14-3-3 adaptors, however, did not interact with AID C-terminal truncation mutant AIDΔ(180-198) or AIDF193A and AIDL196A point-mutants (which have been shown not to bind to S region DNA and fail to mediate CSR). 14-3-3 adaptors colocalized with AID and replication protein A (RPA) in B cells undergoing CSR. 14-3-3 and AID binding to S region DNA was disrupted by viral protein R (Vpr), an accessory protein of human immunodeficiency virus type-1 (HIV-1), which inhibited CSR without altering AID expression or germline IH-C H transcription. Accordingly, we demonstrated that 14- 3-3 directly interact with Vpr, which in turn, also interact with AID, PKA-Cα and Ung. Altogether, our findings suggest that 14-3-3 adaptors play important scaffold functions and nucleate the assembly of multiple CSR factors on S regions. They also show that such assembly can be disrupted by a viral protein, thereby allowing us to hypothesize that small molecule compounds that specifically block 14-3-3 interactions with AID, PKA and/or Ung can be used to inhibit unwanted CSR.

Original languageEnglish (US)
Article numbere80414
JournalPLoS One
Volume8
Issue number11
DOIs
StatePublished - Nov 25 2013

Fingerprint

Immunoglobulin Isotypes
Scaffolds
immunoglobulins
Genetic Recombination
B-lymphocytes
B-Lymphocytes
Cells
Switches
DNA
Uracil-DNA Glycosidase
viral proteins
vpr Gene Products
immunoglobulin heavy chains
Immunoglobulin Heavy Chains
Replication Protein A
AICDA (activation-induced cytidine deaminase)
cytidine deaminase
Human Immunodeficiency Virus Proteins
mutants
loci

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

Cite this

Scaffold functions of 14-3-3 adaptors in B cell immunoglobulin class switch DNA recombination. / Lam, Tonika; Thomas, Lisa M.; White, Clayton A.; Li, Guideng; Pone, Egest J.; Xu, Zhenming; Casali, Paolo.

In: PLoS One, Vol. 8, No. 11, e80414, 25.11.2013.

Research output: Contribution to journalArticle

Lam, Tonika ; Thomas, Lisa M. ; White, Clayton A. ; Li, Guideng ; Pone, Egest J. ; Xu, Zhenming ; Casali, Paolo. / Scaffold functions of 14-3-3 adaptors in B cell immunoglobulin class switch DNA recombination. In: PLoS One. 2013 ; Vol. 8, No. 11.
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