Abstract：
Blimp1 is the master regulator of B cell terminal differentiation in mammals, it inhibits expression of many transcription factors including bcl6, which provides the basis for promoting further development of activated B lymphocytes into plasma cells. Blimp-1 is thought to act as a sequence-specific recruitment factor for chromatin-modifying enzymes including histone deacetylases (HDAC) and methyltransferases to repress target genes. The cDNA of Ccblimp1a (Cyprinus carpio) open reading frame is 2337 bp encoding a protein of 777 amino acids. CcBlimp1a contains a SET domain, two Proline Rich domains, and five ZnF_C2H2 domains. Blimp1 are conserved in vertebrate species. Ccblimp1a transcripts were detected in common carp larvae from 1 dpf (day post fertilization)to 31 dpf. Ccblimp1a expression was up-regulated in peripheral blood leukocytes (PBL) and spleen leukocytes (SPL) of common carp stimulated by intraperitoneal lipopolysaccharide (LPS) injection. Ccblimp1a expression in PBL and SPL of common carp was induced by TNP-LPS and TNP-KLH. The results indicated TNP-LPS induced a rapid response in PBL and TNP-KLH induced much stronger response in SPL and PBL. IHC results showed that CcBlimp1 positive cells were distributed in the head kidney, trunk kidney, liver, and gut. Immunofluorescence stain results showed that CcBlimp1 was expressed in IgM + lymphocytes. The subcellular localization of CcBlimp1 in the nuclei indicated CcBlimp1 may be involved in the differentiation of IgM + lymphocytes. Further study focusing on the function of CcBlimp1 transcriptional repression was performed using dual luciferase assay. The results showed that the transcription repression of CcBlimp1 on bcl6aa promoter was affected by the histone deacetylation inhibitor and was synergized with histone deacetylase 3 (HDAC3). The results of Co-IP in HEK293T and immunoprecipitation in SPL indicated that CcBlimp1 recruited HDAC3 and might be involved in the formation of complexes. These results suggest that CcBlimp1 is an important transcription factor in common carp lymphocytes. Histone deacetylation modification mediated by HDAC3 may have important roles in CcBlimp1 transcriptional repression during the differentiation of lymphocytes.
摘要：
Blimp1是哺乳动物B细胞末端分化的主要调控因子,它抑制包括bcl6在内的许多转录因子的表达，为促进活化的B淋巴细胞进一步发育为浆细胞提供了基础。Blimp-1被认为是染色质修饰酶（包括组蛋白脱乙酰酶（HDAC）和甲基转移酶）的序列特异性募集因子，以抑制靶基因。Ccblimp1a（Cyprinuscarpio）开放阅读框的cDNA为2337bp，编码777个氨基酸的蛋白质。CcBlimp1a包含一个SET域，两个脯氨酸丰富的域，和五个ZnF_C2H2结构域。Blimp1在脊椎动物物种中是保守的。从1dpf（受精后第1天）到31dpf，在鲤鱼幼虫中检测到Ccblimp1a转录本。腹腔注射脂多糖(LPS)刺激鲤鱼外周血白细胞(PBL)和脾白细胞(SPL)中Ccblimp1a表达上调。TNP-LPS和TNP-KLH诱导鲤鱼PBL和SPL中Ccblimp1a的表达。结果表明，TNP-LPS在PBL中诱导了快速反应，TNP-KLH在SPL和PBL中诱导了更强的反应。免疫组化结果显示，CcBlimp1阳性细胞分布于头肾，躯干肾,肝脏,和直觉。免疫荧光染色结果显示CcBlimp1在IgM+淋巴细胞中表达。CcBlimp1在细胞核中的亚细胞定位表明CcBlimp1可能参与IgM淋巴细胞的分化。使用双荧光素酶测定进行关注CcBlimp1转录抑制功能的进一步研究。结果表明，CcBlimp1对bcl6aa启动子的转录抑制受到组蛋白去乙酰化抑制剂的影响，并与组蛋白去乙酰化酶3（HDAC3）协同作用。HEK293T中的Co-IP和SPL中的免疫沉淀结果表明，CcBlimp1募集了HDAC3，可能参与了复合物的形成。这些结果表明，CcBlimp1是鲤鱼淋巴细胞中重要的转录因子。HDAC3介导的组蛋白去乙酰化修饰可能在淋巴细胞分化过程中CcBlimp1转录抑制中起重要作用。
