Defective importin β recognition and nuclear import of the sex-determining factor SRY are associated with XY sex-reversing mutations
Defective importin β recognition and nuclear import of the sex-determining factor SRY are associated with XY sex-reversing mutations
复制标题
DOI：
10.1073/pnas.1137864100
复制
发表时间：
2003-06-10
影响因子：
11.1
通讯作者：
Jans, DA
中科院分区：
文献类型：
--
作者：
Harley, VR;Layfield, S;Jans, DA
结构转录因子SRY（Y染色体的性别决定区）在性别决定中起着关键作用，如SRY突变导致人类XY性腺发育不全的事实所示。虽然许多SRY突变降低DNA结合/弯曲活性，但不影响与DNA相互作用的SRY突变如何导致疾病尚不清楚。SRY高迁移率族结构域窝藏两个核定位信号（NLS），在这里，我们研究SRY从四个XY女性与这些信号中的错义突变。在所有情况下，突变体SRY蛋白部分定位于细胞质，而野生型SRY是严格的核。每个NLS可以独立地在体外和体内指导载体蛋白的核转运，其中任一个的突变影响核积累的速率和程度。N-末端NLS功能独立于常规NLS结合输入蛋白（IMP），需要未鉴定的细胞质转运因子，而C-末端NLS由IMP β识别。SRY-R133 W突变体显示作为性别逆转C末端NLS突变的直接结果的IMP β结合减少。在检查的N-末端NLS突变体中，SRY-R62 G出乎意料地显示出IMP β结合的显著降低，而SRY-R75 N和SRY-R76 P显示出正常的IMP β结合，表明IMP非依赖性途径中的缺陷。我们的结论是，SRY通常需要两个不同的NLS依赖的核输入途径，以达到足够的水平，在细胞核的性别决定。这项研究记录了人类疾病的病例，在分子水平上，通过蛋白质在细胞核中积累的能力受损来解释。
The architectural transcription factor SRY (sex-determining region of the Y chromosome) plays a key role in sex determination as indicated by the fact that mutations in SRY are responsible for XY gonadal dysgenesis in humans. Although many SRY mutations reduce DNA-binding/bending activity, it is not clear how SRY mutations that do not affect interaction with DNA contribute to disease. The SRY high-mobility group domain harbors two nuclear localization signals (NLSs), and here we examine SRY from four XY females with missense mutations in these signals. In all cases, mutant SRY protein is partly localized to the cytoplasm, whereas wild-type SRY is strictly nuclear. Each NLS can independently direct nuclear transport of a carrier protein in vitro and in vivo, with mutations in either affecting the rate and extent of nuclear accumulation. The N-terminal NLS function is independent of the conventional NLS-binding importins (IMPs) and requires unidentified cytoplasmic transport factors, whereas the C-terminal NLS is recognized by IMPbeta. The SRY-R133W mutant shows reduced IMPbeta binding as a direct consequence of the sex-reversing C-terminal NLS mutation. Of the N-terminal NLS mutants examined, SRY-R62G unexpectedly shows a marked reduction in IMPbeta binding, whereas SRY-R75N and SRY-R76P show normal IMPbeta binding, suggesting defects in the IMP-independent pathway. We conclude that SRY normally requires the two distinct NLS-dependent nuclear import pathways to reach sufficient levels in the nucleus for sex determination. This study documents cases of human disease being explained, at a molecular level, by the impaired ability of a protein to accumulate in the nucleus.