Functions Of Zbtb24 In Mouse T Lymphocytes

Immunodeficiency,centromere instability and facial abnormality syndrome（ICF）is an autosomal recessive disease,with the immunological hallmark of antibody deficiency in circulations.Approximately 30%of ICF patients（ICF2）bear zbtb24mutations,resulting in a premature stop codon in most cases.It has been shown that the proliferation of peripheral blood mononuclear cells（PBMCs）is greatly reduced by upon antigen-non-specific stimulations by PHA/anti-CD3 or antigen-specific triggering by tetanus toxoid in vitro.ZBTB24 is a member of the large ZBTB protein family,many of which are capable of regulating the development and/or function of lymphocytes as transcription factors.Given the role of T cells in humoral responses,we hypothesized that ZBTB24 may modulate the in-vivo antibody productions through regulating the function of T cells.In order to study the role of zbtb24 in T cell functions in vivo,we first constructed a T-cell specific zbtb24 overexpressing vector（hCD2-zbtb24-3x Flag-LCR）by inserting the sequence containing zbtb24 fused to the N-terminal of 3x Flag into the vector with human CD2 promoter and its localization sequence.After microinjecting the hCD2-zbtb24-3xFlag-LCR vector into fertilized eggs of C57/bl6 mice,we obtained a transgenic mouse strain with high zbtb24 levels specifically in T cells,but not B cells(here in termed as zbtb24^TOE mice).CD8⁺T cells express significantly high levels of zbtb24 than that in CD4⁺T cells in zbtb24^TOE mice.The overexpression of zbtb24 in T cells has no effect on their development in thymus,as well as their phenotype and cellular numbers in the periphery.Moreover,T cells,purified from control or zbtb24^TOE mice,display comparable proliferation and apoptosis upon in vitro stimulation.Activated zbtb24-overexpressing CD4⁺T cells,but not CD8⁺T cells,seem to secret more IFN-γ.Immuization with CFA/OVA results in significantly higher amounts of OVA-specific Abs in zbtb24^TOE mice.Moreover,the growth of B16-OVA tumor cells are inhibited in zbtb24^TOE mice after immunization with DC pulsed with OVA protein,which is associated with increased number of splenic CD4⁺T cells and circulating OVA-specific Abs.These data indicate that ectopically overexpressed zbtb24 confers an enhanced help ability to CD4⁺T cells,resulting in augmented in vivo humoral and cellular immune reactions.Our study show that zbtb24is capable of regulating the cellular and humoral immune responses through modulating the function of T cells,and thus may play an important role in our body’s immune defense reactions against tumors and infections.