Department of Biosciences and Biomedical Engineering, Indian Institute of Technology, Indore, Madhya Pradesh, 453 552, India.
Sci Rep. 2023 Nov 10;13(1):19615. doi: 10.1038/s41598-023-46448-7.
Activation-induced cytidine deaminase (AID) is the key mediator of antibody diversification in activated B-cells by the process of somatic hypermutation (SHM) and class switch recombination (CSR). Targeting AID to the Ig genes requires transcription (initiation and elongation), enhancers, and its interaction with numerous factors. Furthermore, the HIRA chaperon complex, a regulator of chromatin architecture, is indispensable for SHM. The HIRA chaperon complex consists of UBN1, ASF1a, HIRA, and CABIN1 that deposit H3.3 onto the DNA, the SHM hallmark. We explored whether UBN1 interacts with AID using computational and in-vitro experiments. Interestingly, our in-silico studies, such as molecular docking and molecular dynamics simulation results, predict that AID interacts with UBN1. Subsequently, co-immunoprecipitation and pull-down experiments established interactions between UBN1 and AID inside B-cells. Additionally, a double immunofluorescence assay confirmed that AID and UBN1 were co-localized in the human and chicken B-cell lines. Moreover, proximity ligation assay studies validated that AID interacts with UBN1. Ours is the first report on the interaction of genome mutator enzyme AID with UBN1. Nevertheless, the fate of interaction between UBN1 and AID is yet to be explored in the context of SHM or CSR.
激活诱导胞嘧啶脱氨酶（AID）是通过体细胞超突变（SHM）和类别转换重组（CSR）过程在活化 B 细胞中进行抗体多样化的关键介质。将 AID 靶向 Ig 基因需要转录（起始和延伸）、增强子及其与众多因素的相互作用。此外，HIRA 伴侣复合物是染色质结构的调节剂，对于 SHM 是必不可少的。HIRA 伴侣复合物由 UBN1、ASF1a、HIRA 和 CABIN1 组成，将 H3.3 沉积在 DNA 上，这是 SHM 的标志。我们使用计算和体外实验探索了 UBN1 是否与 AID 相互作用。有趣的是，我们的计算机研究，如分子对接和分子动力学模拟结果，预测 AID 与 UBN1 相互作用。随后，共免疫沉淀和下拉实验确立了 UBN1 和 AID 在 B 细胞内的相互作用。此外，双免疫荧光测定证实 AID 和 UBN1 在人源和鸡源 B 细胞系中共定位。此外，邻近连接测定研究验证了 AID 与 UBN1 相互作用。我们的研究首次报道了基因组突变酶 AID 与 UBN1 的相互作用。然而，UBN1 和 AID 之间相互作用的命运仍有待在 SHM 或 CSR 背景下探索。
