Gonadotropin-regulated testicular RNA helicase (GRTH/Ddx25) is a transport protein involved in gene-specific mRNA export and protein translation during spermatogenesis
Gonadotropin-regulated testicular RNA helicase (GRTH/Ddx25) is a transport protein involved in gene-specific mRNA export and protein translation during spermatogenesis
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DOI：
10.1074/jbc.m605086200
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发表时间：
2006-11-17
影响因子：
4.8
通讯作者：
Dufau, Maria L.
中科院分区：
文献类型：
--
作者：
Sheng, Yi;Tsai-Morris, Chon-Hwa;Dufau, Maria L.
促性腺激素调节的睾丸RNA解旋酶（GRTH/Ddx 25）是DEAD盒蛋白家族的成员之一，在精子发生过程中起重要作用。GRTH存在于减数分裂的精母细胞和圆形精子细胞的细胞质和细胞核中，并作为mRNP颗粒的组分发挥作用，暗示其在生殖细胞中的转录后调节作用。在这项研究中，GRTH抗体的N-或C-末端序列特异性显示出不同的亚细胞表达的GRTH 56-和61-kDa的种类，分别在细胞核和细胞质中，啮齿动物睾丸和转染的COS 1细胞。56 kDa的核物质与CRM 1相互作用，并参与mRNA的运输。磷酸化的细胞质61-kDa物质与多聚核糖体相关。对COS-1细胞的共聚焦研究表明，GRTH-GFP通过用RNA聚合酶抑制剂或核蛋白输出抑制剂处理而保留在细胞核中。这表明GRTH是一种与RNA输出相关的穿梭蛋白。N端富含亮氨酸的区域（61-74个氨基酸）被鉴定为参与CRM 1依赖的核输出途径的核输出信号。缺失分析鉴定了14个氨基酸的GRTH序列（100-114个氨基酸）作为核定位信号。GRTH选择性地调节生殖细胞中包括组蛋白4和HMG 2在内的特定基因的翻译。此外，GRTH以基因特异性方式参与RNA信息（PGK 2、tACE和TP 2）的核输出。这些研究有力地表明，哺乳动物GRTH/Ddx 25基因是一个多功能的RNA解旋酶，是精子成熟的重要调节因子。
Gonadotropin-regulated testicular RNA helicase (GRTH/Ddx25), a member of the DEAD-box protein family, is essential for completion of spermatogenesis. GRTH is present in the cytoplasm and nucleus of meiotic spermatocytes and round spermatids and functions as a component of mRNP particles, implicating its post-transcriptional regulatory roles in germ cells. In this study, GRTH antibodies specific to N- or C- terminal sequences showed differential subcellular expression of GRTH 56- and 61-kDa species in nucleus and cytoplasm, respectively, of rodent testis and transfected COS1 cells. The 56-kDa nuclear species interacted with CRM1 and participated in mRNA transport. The phosphorylated cytoplasmic 61-kDa species was associated with polyribosomes. Confocal studies on COS-1 cells showed that GRTH-GFP was retained in the nucleus by treatment with a RNA polymerase inhibitor or the nuclear protein export inhibitor. This indicated that GRTH is a shuttling protein associated with RNA export. The N- terminal leucine-rich region (61-74 amino acids) was identified as the nuclear export signal that participated in CRM1-dependent nuclear export pathway. Deletion analysis identified a 14-amino acid GRTH sequence (100-114 amino acids) as a nuclear localization signal. GRTH selectively regulated the translation of specific genes including histone 4 and HMG2 in germ cells. In addition, GRTH participated in the nuclear export of RNA messages (PGK2, tACE, and TP2) in a gene-specific manner. These studies strongly indicate that the mammalian GRTH/Ddx25 gene is a multifunctional RNA helicase that is an essential regulator of sperm maturation.