Wang Bo, Merillat Sean A, Vincent Michael, Huber Amanda K, Basrur Venkatesha, Mangelberger Doris, Zeng Li, Elenitoba-Johnson Kojo, Miller Richard A, Irani David N, Dlugosz Andrzej A, Schnell Santiago, Scaglione Kenneth Matthew, Paulson Henry L
From the Departments of Neurology, Neuroscience Graduate Program, and.
From the Departments of Neurology.
J Biol Chem. 2016 Feb 5;291(6):3030-42. doi: 10.1074/jbc.M115.676601. Epub 2015 Nov 24.
UBE2W ubiquitinates N termini of proteins rather than internal lysine residues, showing a preference for substrates with intrinsically disordered N termini. The in vivo functions of this intriguing E2, however, remain unknown. We generated Ube2w germ line KO mice that proved to be susceptible to early postnatal lethality without obvious developmental abnormalities. Although the basis of early death is uncertain, several organ systems manifest changes in Ube2w KO mice. Newborn Ube2w KO mice often show altered epidermal maturation with reduced expression of differentiation markers. Mirroring higher UBE2W expression levels in testis and thymus, Ube2w KO mice showed a disproportionate decrease in weight of these two organs (~50%), suggesting a functional role for UBE2W in the immune and male reproductive systems. Indeed, Ube2w KO mice displayed sustained neutrophilia accompanied by increased G-CSF signaling and testicular vacuolation associated with decreased fertility. Proteomic analysis of a vulnerable organ, presymptomatic testis, showed a preferential accumulation of disordered proteins in the absence of UBE2W, consistent with the view that UBE2W preferentially targets disordered polypeptides. These mice further allowed us to establish that UBE2W is ubiquitously expressed as a single isoform localized to the cytoplasm and that the absence of UBE2W does not alter cell viability in response to various stressors. Our results establish that UBE2W is an important, albeit not essential, protein for early postnatal survival and normal functioning of multiple organ systems.
UBE2W使蛋白质的N端泛素化，而非内部赖氨酸残基，且更倾向于以具有内在无序N端的底物为作用对象。然而，这种有趣的E2酶在体内的功能仍不清楚。我们培育出了Ube2w种系敲除小鼠，结果表明这些小鼠出生后早期易死亡，且无明显发育异常。尽管早期死亡的原因尚不确定，但多个器官系统在Ube2w敲除小鼠中出现了变化。新生的Ube2w敲除小鼠常表现出表皮成熟改变，分化标志物表达降低。与睾丸和胸腺中较高的UBE2W表达水平相对应，Ube2w敲除小鼠这两个器官的重量出现了不成比例的下降（约50%），这表明UBE2W在免疫和雄性生殖系统中发挥功能作用。事实上，Ube2w敲除小鼠表现出持续性中性粒细胞增多，同时伴有G-CSF信号增强，以及与生育力下降相关的睾丸空泡化。对一个易损器官——症状前睾丸进行蛋白质组分析，结果显示在缺乏UBE2W的情况下无序蛋白质会优先积累，这与UBE2W优先靶向无序多肽的观点一致。这些小鼠还让我们确定UBE2W以单一异构体的形式普遍表达，定位于细胞质，且缺乏UBE2W不会改变细胞对各种应激源的活力。我们的结果表明，UBE2W是一种对出生后早期存活和多个器官系统正常功能很重要的蛋白质，尽管并非必不可少。
