Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY.
Department of Medicine, Division of Hematology and Oncology, University of Alabama at Birmingham School of Medicine, Birmingham, AL.
J Exp Med. 2021 Aug 2;218(8). doi: 10.1084/jem.20201708. Epub 2021 May 25.
A whole-genome CRISPR/Cas9 screen identified ATP2A2, the gene encoding the Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) 2 protein, as being important for V(D)J recombination. SERCAs are ER transmembrane proteins that pump Ca2+ from the cytosol into the ER lumen to maintain the ER Ca2+ reservoir and regulate cytosolic Ca2+-dependent processes. In preB cells, loss of SERCA2 leads to reduced V(D)J recombination kinetics due to diminished RAG-mediated DNA cleavage. SERCA2 deficiency in B cells leads to increased expression of SERCA3, and combined loss of SERCA2 and SERCA3 results in decreased ER Ca2+ levels, increased cytosolic Ca2+ levels, reduction in RAG1 and RAG2 gene expression, and a profound block in V(D)J recombination. Mice with B cells deficient in SERCA2 and humans with Darier disease, caused by heterozygous ATP2A2 mutations, have reduced numbers of mature B cells. We conclude that SERCA proteins modulate intracellular Ca2+ levels to regulate RAG1 and RAG2 gene expression and V(D)J recombination and that defects in SERCA functions cause lymphopenia.
全基因组 CRISPR/Cas9 筛选鉴定出编码肌浆网/内质网 Ca2+-ATP 酶（SERCA）2 蛋白的 ATP2A2 基因对于 V(D)J 重组很重要。SERCAs 是内质网膜蛋白，将 Ca2+从细胞质泵入内质网腔，以维持内质网 Ca2+库并调节依赖细胞质 Ca2+的过程。在 preB 细胞中，由于 RAG 介导的 DNA 切割减少，SERCA2 的缺失导致 V(D)J 重组动力学降低。B 细胞中 SERCA2 的缺乏导致 SERCA3 的表达增加，而 SERCA2 和 SERCA3 的联合缺失导致 ER Ca2+水平降低、细胞质 Ca2+水平升高、RAG1 和 RAG2 基因表达减少，以及 V(D)J 重组严重受阻。B 细胞中缺乏 SERCA2 的小鼠和由 ATP2A2 突变引起的 Darier 病患者的成熟 B 细胞数量减少。我们得出结论，SERCA 蛋白调节细胞内 Ca2+水平以调节 RAG1 和 RAG2 基因表达和 V(D)J 重组，并且 SERCA 功能缺陷导致淋巴细胞减少。
