Identification of DRG family regulatory proteins (DFRPs): specific regulation of DRG1 and DRG2
Identification of DRG family regulatory proteins (DFRPs): specific regulation of DRG1 and DRG2
复制标题
DOI：
10.1111/j.1365-2443.2005.00825.x
复制
发表时间：
2005-02-01
期刊：
影响因子：
2.1
通讯作者：
Inoue, J
中科院分区：
文献类型：
--
作者：
Ishikawa, K;Azuma, S;Inoue, J
DRG 1和DRG 2包含GTP结合蛋白的高度保守的亚家族，被认为是细胞生长的关键调节因子。它们的异常表达可触发细胞转化或细胞周期阻滞。我们的目的是阐明其生理功能和调节机制。在这里，我们报告鉴定新的蛋白质，DRG家族调节蛋白（DFRP）1和DFRP 2，通过特异性结合调节DRG蛋白的表达。在瞬时转染实验中，DFRP 1特异性结合DRG 1，DFRP 2优先结合DRG 2。DFRP通过物理缔合为靶DRG蛋白提供稳定性，可能是通过阻断DRG蛋白的蛋白水解之前的多聚泛素化。DFRP在真核生物中高度保守，dfrp1和drg1转录本在非洲爪蟾胚胎和组织中的表达模式相似，表明这些基因在各种类型的真核细胞中协同工作。免疫荧光实验表明，DRG 1和DFRP 1之间的相互作用可能发生在细胞质中。我们产生了dfrp1敲除细胞，发现DRG1的内源性表达受DFRP 1调节，证实DFRP 1是体内DRG1的特异性上调因子。在这些结果的基础上，我们提出，DRG 1和DRG 2的调节不同，尽管它们的结构相似。
DRG1 and DRG2 comprise a highly conserved subfamily of GTP-binding proteins and are thought to act as critical regulators of cell growth. Their abnormal expressions may trigger cell transformation or cell cycle arrest. Our aim is to clarify their physiological functions and regulatory mechanisms. Here we report identification of novel proteins, DRG family regulatory protein (DFRP) 1 and DFRP2, which regulate expression of DRG proteins through specific binding. In transient transfection experiments, DFRP1 specifically binds DRG1, and DFRP2 preferentially binds DRG2. DFRPs provide stability to the target DRG proteins through physical association, possibly by blocking the poly-ubiquitination that would precede proteolysis of DRG proteins. DFRPs are highly conserved in eucaryotes, and the expression patterns of dfrp1 and drg1 transcripts in Xenopus embryos and tissues are similar, indicating that these genes work cooperatively in various types of eukaryotic cells. Immunofluorescence experiments have revealed that the interaction between DRG1 and DFRP1 may occur in the cytoplasm. We generated dfrp1- knockout cells and found that endogenous expression of DRG1 is regulated by DFRP1, confirming that DFRP1 is a specific up-regulator of DRG1 in vivo. On the basis of these results, we propose that DRG1 and DRG2 are regulated differently despite their structural similarities.