Ferrari Ilaria, Bouilly Justine, Beau Isabelle, Guizzardi Fabiana, Ferlin Alberto, Pollazzon Marzia, Salerno Mariacarolina, Binart Nadine, Persani Luca, Rossetti Raffaella
Laboratory of Endocrine and Metabolic Research, IRCCS Istituto Auxologico Italiano, Milan, Italy.
Inserm U1185, Le Kremlin-Bicêtre, France.
Hum Mol Genet. 2016 Dec 1;25(23):5223-5233. doi: 10.1093/hmg/ddw342.
Premature ovarian insufficiency (POI) is a clinical syndrome defined by a loss of ovarian activity before the age of 40. Its pathogenesis is still largely unknown, but increasing evidences support a genetic basis in most cases. Among these, heterozygous mutations in NOBOX, a homeobox gene encoding a transcription factor expressed specifically by oocyte and granulosa cells within the ovary, have been reported in ∼6% of women with sporadic POI. The pivotal role of NOBOX in early folliculogenesis is supported by findings in knock-out mice. Here, we report the genetic screening of 107 European women with idiopathic POI, recruited in various settings, and the molecular and functional characterization of the identified variants to evaluate their involvement in POI onset. Specifically, we report the identification of two novel and two recurrent heterozygous NOBOX variants in 7 out of 107 patients, with a prevalence of 6.5% (upper 95% confidence limit of 11.17%). Furthermore, immunolocalization, Western Blot and transcriptional assays conducted in either HEK293T or CHO cells revealed that all the studied variants (p.R44L, p.G91W, p.G111R, p.G152R, p.K273*, p.R449* and p.D452N) display variable degrees of functional impairment, including defects in transcriptional activity, autophagosomal degradation, nuclear localization or protein instability. Several variants conserve the ability to interact with FOXL2 in intracellular aggregates. Their inability to sustain gene expression, together with their likely aberrant effects on protein stability and degradation, make the identified NOBOX mutations a plausible cause of POI onset.
卵巢早衰（POI）是一种临床综合征，定义为40岁之前卵巢功能丧失。其发病机制在很大程度上仍不清楚，但越来越多的证据支持大多数病例存在遗传基础。其中，在散发性POI女性中，约6%的患者存在NOBOX基因杂合突变，NOBOX是一种同源框基因，编码一种在卵巢内由卵母细胞和颗粒细胞特异性表达的转录因子。敲除小鼠的研究结果支持了NOBOX在早期卵泡发生中的关键作用。在此，我们报告了对107名来自不同背景的欧洲特发性POI女性进行的基因筛查，以及对所鉴定变异体的分子和功能特征分析，以评估它们在POI发病中的作用。具体而言，我们报告在107例患者中的7例中鉴定出两个新的和两个复发的NOBOX杂合变异体，患病率为6.5%（95%置信上限为11.17%）。此外，在HEK293T或CHO细胞中进行的免疫定位、蛋白质印迹和转录分析表明，所有研究的变异体（p.R44L、p.G91W、p.G111R、p.G152R、p.K273*、p.R449*和p.D452N）均表现出不同程度的功能损害，包括转录活性、自噬体降解、核定位或蛋白质稳定性方面的缺陷。几个变异体在细胞内聚集体中保留了与FOXL2相互作用的能力。它们无法维持基因表达，以及对蛋白质稳定性和降解可能产生的异常影响，使得所鉴定的NOBOX突变成为POI发病的一个合理原因。
