Destabilization and Mislocalization of POU3F4 by C-Terminal Frameshift Truncation and Extension Mutation
Destabilization and Mislocalization of POU3F4 by C-Terminal Frameshift Truncation and Extension Mutation
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DOI：
10.1002/humu.22232
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发表时间：
2013-02-01
期刊：
影响因子：
3.9
通讯作者：
Park, Woong-Yang
中科院分区：
文献类型：
--
作者：
Choi, Byung Yoon;Kim, Do-Hwan;Park, Woong-Yang
大多数x连锁非综合征性听力损失是由POU结构域3类转录因子4基因（POU3F4）的各种类型突变引起的。我们在韩国患者中发现了五种独特的错义和移码截断和扩展突变。两个错义突变（p.Thr211Met和p.Gln229Arg）干扰了转录活性。两个移码扩展突变p.Thr354GlnfsX115和p.X362ArgextX113位于POU结构域和c端核定位信号（NLS）之外。POU3F4蛋白水平较低，可通过蛋白酶体抑制剂MG132体外恢复。这些突变的POU3F4蛋白完全定位于细胞质，没有转录活性。POU3F4的移码突变（p.l u317phefsx12）导致横跨POU结构域和NLS的c端44个氨基酸被截断。这种移码截断突变蛋白位于细胞核和细胞质中，蛋白水平较低。即使在MG132存在的情况下，该突变体也具有转录活性。根据这些结果，我们得出结论，POU3F4 c端移码截断和延伸突变导致细胞质定位，随后由于结构畸变导致蛋白体降解，从而导致转录失活，从而导致非综合征性听力损失。
Most X-linked nonsyndromic hearing loss is caused by various types of mutations of the POU domain class 3 transcription factor 4 gene (POU3F4). We found five unique missense and frameshift truncation and extension mutations in Korean patients. Two missense mutations (p.Thr211Met and p.Gln229Arg) disturbed transcriptional activity. Two frameshift extension mutations (p.Thr354GlnfsX115 and p.X362ArgextX113) were located outside of POU domain and nuclear localization signal (NLS) at the C-terminus. POU3F4 protein levels were low and could be restored by MG132, a proteasome inhibitor, in vitro. These mutant POU3F4 proteins were exclusively localized to the cytoplasm and did not have transcriptional activity. Frameshift mutation (p.Leu317PhefsX12) in POU3F4 leads to the truncation of the C-terminal 44 amino acids spanning the POU domain and NLS. This frameshift truncation mutant protein was located in both the nucleus and cytoplasm and was present at low protein levels. This mutant was also transcriptionally inactive, even in the presence of MG132. From these results, we conclude that frameshift truncation and extension mutations in the C-terminus of POU3F4 lead to cytoplasmic localization and subsequent proteosomal degradation due to structural aberrations, which cause transcriptional inactivity and thus nonsyndromic hearing loss.