Tudor and its domains: germ cell formation from a Tudor perspective

In many metazoan species, germ cell formation requires the germ plasm, a specialized cytoplasm which often con-tains electron dense structures. Genes required for germ cell formation in Drosophila have been isolated predominantlyin screens for maternal-effect mutations. One such gene is tudor (tud); without proper tud function germ cell formationdoes not occur. Unlike other genes involved in Drosophila germ cell specification tud is dispensable for other somaticfunctions such as abdominal patterning. It is not known how TUD contributes at a molecular level to germ cell forma-tion but in tud mutants, polar granule formation is severely compromised, and mitochondrially encoded ribosomal RNAsdo not localize to the polar granule. TUD is composed of 11 repeats of the protein motif called the Tudor domain. Thereare similar proteins to TUD in the germ line of other metazoan species including mice. Probable vertebrate orthologuesof Drosophila genes involved in germ cell specification will be discussed.

Evolutionary dynamics and conserved function of the Tudor domain-containing(TDRD)proteins in teleost fish

Tudor domain-containing(TDRD)proteins,the germline enriched protein family,play essential roles in the process of gametogenesis and genome stability through their interaction with the PIWI-interacting RNA(piRNA)pathway.Several studies have suggested the rapid evolution of the piRNA pathway in teleost lineages with striking reproductive diversity.However,there is still limited information about the function and evolution of Tdrd genes in teleost species.In this study,through genome wide screening,13 Tdrd family genes were identified in economically important aquaculture fish,including spotted sea bass(Lateolabrax maculatus),Asian sea bass(Lates calcarifer),and tongue sole(Cynoglossus semilaevis).With copy number,structure,phylogeny,and synteny analysis,duplication of Tdrd6 and Tdrd7,as well as loss of Stk31 and Tdrd10,were characterized in teleost lineages.Codon based molecular evolution analysis indicated faster evolution of teleost Tdrd genes than that in mammals,potentially associated with the accelerated evolution of the piRNA pathway in teleost lineages.The evolutionary diversity of Tdrd genes was also detected between different teleost lineages.RNA-seq analysis showed that most teleost Tdrd genes were dominantly expressed in gonads,particularly highly expressed in testis,such as Tdrd6,Tdrd7a,Tdrd9,Ecat8,and Tdrd15.The varied expression and evolutionary pattern between the duplicated Tdrd6 and Tdrd7 in teleosts may indicate their functional diversification.All these results suggest a conserved function of teleost Tdrd family in gametogenesis and the piRNA pathway,which could lay a foundation for the evolution of Tdrd genes and be helpful for further deciphering of Tdrd functions in teleosts.

Crystal structure of TDRD3 Tudor domain

The Tudor domain is a small, ～60 amino acid structure motif that serves to mediate intermolecular protein interactions. Recently, both structural and biochemical evidences

葡萄球菌核酸酶样结构蛋白1/SLC7A11抑制铁死亡对骨肉瘤发生发展的影响

目的探讨葡萄球菌核酸酶样结构蛋白1(SND1)对骨肉瘤细胞生物学功能的影响,及其通过SLC7A11调控骨肉瘤细胞铁死亡的作用机制。方法检测人成骨细胞hFOB1.19以及骨肉瘤细胞系Saos-2、U2OS、HOS和143B中SND1的表达水平。采用小干扰RNA敲减骨肉瘤细胞HOS和143B中SND1的表达(si-SND1),采用CCK8法、细胞克隆形成实验、细胞迁移和侵袭实验探究SND1的表达对骨肉瘤细胞生物学功能的影响;调控骨肉瘤细胞中SND1以及SLC7A11基因的表达,探究SND1通过SLC7A1基因对骨肉瘤铁死亡介导的肿瘤细胞凋亡的影响。结果骨肉瘤细胞Saos-2、U2OS、HOS和143B中SND1 mRNA和蛋白的表达水平显著高于人成骨细胞hFOB1.19(P均<0.01)。与对照组比较,si-SND1转染显著降低HOS和143B细胞中SND1的表达水平(P均<0.01),且细胞活性显著降低,克隆形成数量显著减少,细胞迁移和侵袭能力显著降低(P均<0.001)。铁死亡诱导剂Erastin促进骨肉瘤HOS和143B细胞凋亡,而抑制剂Ferrostatin-1刺激上调细胞活性(P均<0.001)。敲减SND-1后使用Erastin可进一步降低骨肉瘤HOS和143B细胞活性,而使用Ferrostatin-1刺激后可显著恢复细胞活性(P均<0.001);Erastin处理后,si-SND1组细胞中铁离子和丙二醛表达增高,谷胱甘肽表达降低(P均<0.001)。体内实验结果显示,敲减SND1可以明显抑制143B裸鼠移植瘤的瘤体质量(P<0.001)。敲减SND1后骨肉瘤HOS和143B细胞中SLC7A11的表达水平显著减少(P均<0.001),且铁死亡水平升高(P<0.001,P=0.020)。结论骨肉瘤细胞中SND1表达显著增高,其可能通过上调SLC7A11的表达抑制铁死亡,进而促进骨肉瘤细胞活性。

Characterization of functional domains of human p100 protein interacting with signal transducer and activator of transcription-6 (STAT-6)

In the present study, the interaction of human p100 protein with signal transducer and activator of transcription-6 (STAT-6) was investigated. It was proved that the staphylococcal nuclease (SN)-like and tudor (TD) domains containing in p100 protein acting as a adaptor to recruit STAT-6 to the basal transcription machinery, enhanced the STAT-6 mediated transcription activity. The interaction between STAT-6 and the p100 protein was mediated by the full-length of the SN-like domain, whereas individual fragments of SN-like domain showed no binding activity to STAT-6. In line with these results, the SN-like domain was directly engaged in the enhancement of STAT-6 mediated activation of gene transcription in vivo. Yet the TD domain had no ability to increase the transcription activation, but it was still required for the sufficient activation of transcription.

运动神经元生存蛋白SMN与Sm蛋白的结合作用

脊髓性肌萎缩症（spinal muscular atrophy，SMA）是一类与运动神经元存活基因（survival of motor neurons gene，SMN gene）突变有关的神经系统变性疾病，而SMN基因的转录产物即为SMN蛋白（survival of motorneurons protein，SMN protein）。SMN蛋白与多种蛋白结合后发挥作用，如SMN-Sm蛋白的相互作用在富含尿嘧啶的小核核糖核蛋白体（uridine—richsmallribonucleo—proteins，UsnRNPs）转运装配中有重要意义。SMN蛋白是通过其Tudor结构域与剪接体sm蛋白的二甲基化修饰的富含精氨酸一氨基乙酸域（ar—ginineandglycine—rich，RG）结合。