Mutations within Sox2/SOX2 are associated with abnormalities in the hypothalamo-pituitary-gonadal axis in mice and humans
Daniel Kelberman, … , Iain C.A.F. Robinson, Mehul T. Dattani
Daniel Kelberman, … , Iain C.A.F. Robinson, Mehul T. Dattani
Published September 1, 2006
Citation Information: J Clin Invest. 2006;116(9):2442-2455. https://doi.org/10.1172/JCI28658.
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Research Article Endocrinology

Mutations within Sox2/SOX2 are associated with abnormalities in the hypothalamo-pituitary-gonadal axis in mice and humans

Abstract

The transcription factor SOX2 is expressed most notably in the developing CNS and placodes, where it plays critical roles in embryogenesis. Heterozygous de novo mutations in SOX2 have previously been associated with bilateral anophthalmia/microphthalmia, developmental delay, short stature, and male genital tract abnormalities. Here we investigated the role of Sox2 in murine pituitary development. Mice heterozygous for a targeted disruption of Sox2 did not manifest eye defects, but showed abnormal anterior pituitary development with reduced levels of growth hormone, luteinizing hormone, and thyroid-stimulating hormone. Consequently, we identified 8 individuals (from a cohort of 235 patients) with heterozygous sequence variations in SOX2. Six of these were de novo mutations, predicted to result in truncated protein products, that exhibited partial or complete loss of function (DNA binding, nuclear translocation, or transactivation). Clinical evaluation revealed that, in addition to bilateral eye defects, SOX2 mutations were associated with anterior pituitary hypoplasia and hypogonadotropic hypogonadism, variable defects affecting the corpus callosum and mesial temporal structures, hypothalamic hamartoma, sensorineural hearing loss, and esophageal atresia. Our data show that SOX2 is necessary for the normal development and function of the hypothalamo-pituitary and reproductive axes in both humans and mice.

Authors

Daniel Kelberman, Karine Rizzoti, Ariel Avilion, Maria Bitner-Glindzicz, Stefano Cianfarani, Julie Collins, W. Kling Chong, Jeremy M.W. Kirk, John C. Achermann, Richard Ross, Danielle Carmignac, Robin Lovell-Badge, Iain C.A.F. Robinson, Mehul T. Dattani

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Figure 5

Functional analysis of SOX2 mutants.

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Functional analysis of SOX2 mutants. (A) Loss of the HMG box results in ...
(A) Loss of the HMG box results in impaired nuclear localization. Cells were transfected with 50 ng plasmid construct containing wild-type or mutant SOX2 fused to an N-terminal FLAG epitope, fixed, and stained with anti-FLAG antibody; nuclei were counterstained with DAPI. Wild-type SOX2 showed predominantly nuclear staining. Mutant proteins lacking the HMG box (c.60insG and c.70del20) showed a majority of staining in the cytoplasm and impaired nuclear localization. Mutant proteins retaining the HMG box showed staining similar to wild-type. (B) SOX2 mutants show variable DNA binding. Identical amounts of in vitro translated wild-type (lanes 3 and 10) or individual variant SOX2 proteins (lanes 4–8 and 11–13) were incubated with a radiolabeled DNA probe. Specific binding of SOX2 to the probe was demonstrated by duplicate experiments using in vitro translated empty vector (lane 2) or 100 times excess cold probe (lane 9). (C) SOX2 mutants show impaired transcriptional activation. Expression constructs containing wild-type or variant SOX2 (10–50 ng) were cotransfected with 20 ng luciferase reporter construct containing part of the proximal promoter of HESX1. Wild-type SOX2 led to dose-dependent activation of the reporter (up to 20-fold activation), whereas mutant truncated SOX2 proteins showed impaired activation correlating with the extent of the truncation (dashed arrow). c.60insG, c.70del20, and L97P showed similar levels of activation to empty expression vector. In all experiments described here, c.479delA showed identical results to Y160X (not shown). Results are mean ± SD of 3 independent experiments performed in triplicate.