Impaired protein stability and nuclear localization of NOBOX variants associated with premature ovarian insufficiency

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Animals
  • CHO Cells
  • Cell Nucleus / genetics*
  • Cricetulus
  • Female
  • Forkhead Box Protein L2
  • Forkhead Transcription Factors / genetics
  • Forkhead Transcription Factors / metabolism*
  • Genetic Predisposition to Disease
  • HEK293 Cells
  • Heterozygote
  • Homeodomain Proteins / genetics*
  • Humans
  • Menopause, Premature / genetics*
  • Mice
  • Mice, Knockout
  • Middle Aged
  • Primary Ovarian Insufficiency / epidemiology
  • Primary Ovarian Insufficiency / genetics*
  • Primary Ovarian Insufficiency / pathology
  • Protein Aggregates / genetics
  • Protein Stability*
  • Transcription Factors / genetics*


  • FOXL2 protein, human
  • Forkhead Box Protein L2
  • Forkhead Transcription Factors
  • Homeodomain Proteins
  • NOBOX protein, human
  • Protein Aggregates
  • Transcription Factors