The DDB1-DCAF2 complex is essential for B cell development because it regulates cell cycle progression
The DDB1-DCAF2 complex is essential for B cell development because it regulates cell cycle progression
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DDB1-DCAF2 复合物对于 B 细胞发育至关重要，因为它调节细胞周期进程
DOI：
10.1038/s41423-020-0390-2
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发表时间：
2020-03
影响因子：
24.1
通讯作者：
Wang Lie
中科院分区：
文献类型：
--
作者：
Xue Zhonghui;Guo Jing;Ma Ruoyu;Zhou Lina;Guo Yixin;Cang Yong;Fan Hengyu;Chen Jian;Qian Wenbin;Wang Lie
B细胞在骨髓中的发育对产生大量在适应性免疫反应中发挥关键作用的B细胞至关重要。B细胞由共同淋巴祖细胞(CLPs)发育而来，然后经过一系列分化阶段，包括前B细胞、前B细胞、前B细胞、未成熟B细胞和成熟B细胞。1在PRO-B阶段，细胞进行增殖以扩大PRO-B细胞库，并完成VH到DHJH片段的重组，形成μ链。然而，前B细胞发育所涉及的机制尚不完全清楚。已经有几项关于泛素化修饰在B细胞发育中的关键作用的研究。2，3在此，我们报道了DNA损伤结合蛋白1(DDB1)，它是CUL4-环E3连接酶中的一种适配蛋白，在各种高增殖的前体细胞中高度表达，4参与调节前B细胞的发育。我们最初检测了DDB1在不同时期B细胞前体细胞中的表达。Pro-B细胞表达的DDB1量最高(图2)。S1a)，表明该蛋白可能参与B淋巴细胞的生成。为了进一步探索DDB1在B细胞发育中的作用，我们将DDB1fl/fl小鼠与Mb1Cre小鼠杂交，从晚期前B细胞中删除DDB1。验证了DDB1缺失的效率(图2)。S1b)。值得注意的是，DDB1缺陷小鼠的脾、淋巴结和外周血中的B细胞严重减少(图4)。S1c)。在DDB1缺陷小鼠中检测到很少的血清免疫球蛋白(图4)。S1d)。然后分析骨髓中不同发育阶段的B细胞亚群。处于Pro-B期的细胞数量减少(图1a)。综上所述，这些数据表明，DDB1的中断严重损害了前B细胞阶段的B细胞发育。在Pro-B阶段，IL-7信号提供生存和增殖信号，并调节免疫球蛋白重链的V-DJ重组。5然而，DDB1缺失并未导致PRO-B细胞中IL-7R表达的明显缺陷(图2)。S2A)。在PRO-B阶段，只有VDJ片段成功重排的细胞才进入下一阶段。Pax5是VH-DHJH重组的重要调控因子。DDB1缺失不影响PRO-B细胞中PAX5的表达(图2)S2B)。近端VH节段(VH7183和VHQ52-DHJH)重组完整，远端VH节段(VHGam3)重组完整。8、VH3609和VHJ558至DHJH)在DDB1缺陷的Pro-B细胞中略有减少(图4)。S2C)。这一发现可能解释了DDB1缺陷的Pro-B细胞细胞内μ链适度下降的原因(图3)。S2D)。目前尚不清楚PRO-B细胞的丧失是否是由于细胞凋亡率增加所致。我们进行了Annexin V染色，发现Annexin V阳性的Pro-B细胞的百分比在野生型和DDB1缺陷小鼠之间是相似的(图4。S2E)。因此，DDB1基因缺陷小鼠PRO-B细胞的严重丢失不是由于IL-7R表达的改变、IgH的V-DJ重组或细胞凋亡所致。VH-DHJH重排后PRO-B细胞的增殖对B细胞库的维持至关重要。接下来，我们检查PRO-B细胞的丢失是否由增殖缺陷引起。因此，我们检测了增殖细胞核抗原(增殖细胞核抗原)和Ki67。缺乏DDB1的Pro-B细胞表达更多的增殖细胞核抗原和Ki67(图1b，图1)。S3A)。一贯地，没有DDB1的Pro-B细胞更大(图1c)。细胞周期分析显示，DDB1缺乏导致Pro-B细胞的G2/M期停滞，在S期有轻微的阻滞(图1d)。Western印迹分析也显示…
B cell development in the bone marrow is critical for producing numerous B cells that play an essential role in the adaptive immune response. B cells develop from common lymphoid progenitors (CLPs), which then differentiate through a series of stages, which include prepro-B cells, pro-B cells, pre-B cells, immature B cells, and mature B cells. 1 Within the pro-B stage, cells undergo proliferation to expand the pro-B cell pool and complete the recombination of the VH to DHJH segments to form the μ chain. However, the mechanisms involved in pro-B cell development are not fully understood. There have been several studies about the critical role of ubiquitination modifications in B cell development. 2, 3 Here, we report that DNA damage binding protein 1 (DDB1), an adaptor protein in CUL4-ring E3 ligases that is highly expressed in a variety of highly proliferative precursor cells, 4 is involved in regulating pro-B cell development. We initially examined DDB1 expression in B cell precursors at different stages. Pro-B cells expressed the highest amount of DDB1 (Fig. S1a), indicating that this protein might be involved in B lymphocytopoiesis. To further explore the role of DDB1 in B cell development, we crossed Ddb1 fl/fl mice with Mb1Cre mice to delete DDB1 from late-stage prepro-B cells. The efficiency of DDB1 deletion was verified (Fig. S1b). Strikingly, B cells in the spleen, lymph nodes and peripheral blood were severely decreased in DDB1-deficient mice (Fig. S1c). Few serum immunoglobulins were detectable in DDB1-deficient mice (Fig. S1d). Then, B cell subsets at different developmental stages in the bone marrow were analyzed. The number of cells in the pro-B stage decreased (Fig. 1 a). Together, these data demonstrated that DDB1 disruption severely impaired B cell development at the pro-B cell stage. Within the pro-B stage, IL-7 signaling provides survival and proliferation signaling and regulates the V-DJ recombination of immunoglobulin heavy chain. 5 However, DDB1 deletion did not induce obvious defects in IL-7R expression in pro-B cells (Fig. S2a). During the pro-B stage, only cells with successfully rearranged VDJ segments enter the next stage. PAX5 is an important regulator of VH-DHJH recombination. DDB1 deletion did not affect PAX5 expression in pro-B cells (Fig. S2b). The recombination of DH to JH and proximal VH segments (VH7183 and VHQ52 to DHJH) was intact, while the recombination of distal VH segments (VHGam3. 8, VH3609, and VHJ558 to DHJH) was slightly diminished in DDB1-deficient pro-B cells (Fig. S2c). This finding might explain the modest decrease in the intracellular μ chain in DDB1-deficient pro-B cells (Fig. S2d). It was unclear whether the loss of pro-B cells was resulted from elevated apoptosis. We performed Annexin V staining and found that the percentage of Annexin V-positive pro-B cells was comparable between wild-type and DDB1-deficient mice (Fig. S2e). Therefore, the severe loss of pro-B cells in DDB1-deficient mice was not caused by altered IL-7R expression, V-DJ recombination of IgH or cell apoptosis. The proliferation of pro-B cells following VH-DHJH rearrangement is crucial for the maintenance of the B cell pool. Next, we examined whether the loss of pro-B cells was caused by proliferation defects. Thus, we detected the proliferation markers proliferating cell nuclear antigen (PCNA) and Ki67. DDB1-deficient pro-B cells expressed more PCNA and Ki67 (Fig. 1 b, Fig. S3a). Consistently, pro-B cells without DDB1 were larger (Fig. 1 c). Cell cycle analysis showed that DDB1 deficiency led to G2/M-phase arrest in pro-B cells, with a slight block in S phase (Fig. 1 d). Western blot analysis also showed …
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影响因子：
16
作者：
Abbas T;Shibata E;Park J;Jha S;Karnani N;Dutta A
通讯作者：
Dutta A
内质网驻留 E3 泛素连接酶 Hrd1 控制小鼠 B 细胞发育的关键检查点
影响因子：
4.8
作者：
Yang Yi;Kong Sinyi;Zhang Yana;Melo-Cardenas Johanna;Gao Beixue;Zhang Yusi;Zhang Donna D.;Zhang Bin;Song Jianxun;Thorp Edward;Zhang Kezhong;Zhang Jinping;Fang Deyu
通讯作者：
Fang Deyu
影响因子：
13.8
作者：
Jackson, Sarah;Xiong, Yue
通讯作者：
Xiong, Yue
影响因子：
4.8
作者：
Nishitani, Hideo;Shiomi, Yasushi;Tsurimoto, Toshiki
通讯作者：
Tsurimoto, Toshiki
影响因子：
16.6
作者：
Wang W;Org T;Montel-Hagen A;Pioli PD;Duan D;Israely E;Malkin D;Su T;Flach J;Kurdistani SK;Schiestl RH;Mikkola HK
通讯作者：
Mikkola HK