Helia N. acid upregulate miRNAs that silence AID expression, thereby modulating specific antibody responses in C57BL/6 mice and autoantibody responses in lupus-prone MRL/mice. Here, using constitutive knockout mice and B cells, we showed that this HDI-mediated downregulation of expression as well as the maturation of antibody and autoantibody responses is Rabbit Polyclonal to Tau (phospho-Ser516/199) usually reversed by estrogen and enhanced by deletion of ER or E2 inhibition. Estrogen’s reversion of HDI-mediated inhibition of and CSR in antibody and autoantibody responses occurred through downregulation of B cell miR-26a, which, as we showed, targets mRNA 3UTR. miR-26a was significantly upregulated by HDIs. Accordingly, enforced expression of miR-26a reduced expression and CSR, while Safinamide miR-26a-sponges (competitive inhibitors of miR-26a) increased expression and CSR. Thus, our findings show that estrogen reverses the HDI-mediated downregulation of AID expression and CSR through selective modulation of miR-26a. They also provide mechanistic insights into the immunomodulatory activity of this hormone and a proof-of-principle for using combined ER inhibitor-HDI as a potential therapeutic approach. in mice and in humans), which is expressed in B cells in a differentiation stage-specific fashion (19C21). As a potent DNA mutator, AID must be tightly regulated to prevent off-targeting effects, which can result in mutations in non-Ig genes, genomic instability, interchromosomal translocations and cellular neoplastic transformation (21). Epigenetic mediators influence gene expression without modifying the genomic sequence. As we have suggested, such mediators, including DNA methylases, histone posttranslational modifiers, such as methyltransferases and acetyltransferases and non-coding RNAs, such as microRNAs (miRNAs), modulate B cell functions. They interact with genetic programs to regulate B cell functions, such as CSR, SHM and plasma cell differentiation, thereby informing the antibody response (1, 2, 22). We have shown that in addition to DNA methylation and histone acetylation in the locus, select miRNAs also provide an important mechanism for modulation of AID expression. miRNAs likely play important functions in B cell development, peripheral differentiation, and autoimmunity (2, 23C25). In B cells, miR-155, miR-181b, and miR-361 repress expression, while miR-30a and miR-125b repress expressionis the gene that encodes Blimp1, the plasma cell differentiation grasp transcription factor (23, 24). By binding to the evolutionarily conserved miRNA target sites in Safinamide the 3UTR of and mRNAs, these miRNAs cause degradation of the mRNA transcripts and/or inhibit their translation (2, 26). As we have also shown, the expression of or promoter (21, 27, 28). At the transcriptional level, we have shown that estrogen-estrogen receptor (ER) complexes bind to three cooperative evolutionarily conserved estrogen response elements (EREs) in the promoter and synergize with the signaling of CD154 or LPS and IL-4 to up-regulate HoxC4 expression, thereby inducing AID and CSR (28). ERs (ER and ER, encoded by and and in the presence of HDIs VPA, butyrate and propionate using mice we generated by crossbreeding mice with mice, as well as anti-estrogen drugs, including fulvestrant (a selective ER degrader, SERD) and Letrozole (an aromatase inhibitor that also inhibits endogenous estrogen synthesis). As epigenetic modifiers, SCFA HDIs inhibit expression and CSR through upregulation of select B cell miRNAs that silence mice and mice. Further, we analyzed how estrogen affected the role of HDIs as epigenetic modifiers, and found that ER bound to ER-binding and host gene promoters, thereby inhibiting the expression of such a miRNA. Thus, estrogen/ER provides an additional layer of epigenetic regulation of AID expression, as mediated by miR-26a that targets mRNA 3UTR. Materials and Methods Mice C57BL/6 (Stock No. 000664), (MRL/MpJ-transgenic (B6; FVB-Tg((sequences in the gene flanking exon 3 that encodes a conserved zinc finger type DNA binding domain name, were obtained from Dr. J.-A. Gustafsson (Karolinska Institutet, Sweden). In BAC transgenic mice, the bacterial recombinase gene was launched in lieu of exon 1 in a supplementary locus and under the control of the promoter/enhancers within the Safinamide BAC transgene (35). mice were generated by crossbreeding with mice. studies, VPA sodium salt (VPA, Sigma-Aldrich) was.