Functional Characterization of Glucocorticoid Receptor Variants Is Required to Avoid Misinterpretation of NGS Data
JOURNAL OF THE ENDOCRINE SOCIETY
Authors: Foussier, Loic; Vitellius, Geraldine; Bouligand, Jerome; Arnazit, Larbi; Bouvattier, Claire; Young, Jacques; Trabado, Severine; Lombes, Marc
Abstract
Recent advances in genetic analysis technologies such as next-generation sequencing (NGS) have considerably increased the incidental discovery of genetic abnormalities. Six heterozygous missense mutations of the human glucocorticoid receptor (GR; encoded by the NR3C1 gene) have been identified in the context of genetic screening of endocrine pathologies. GR, a nuclear receptor, hormone-induced transcription factor, is involved in many physiological processes. Nevertheless, the pathogenic significance of incidentally discovered mutations remains obscure. The aim of this work was to characterize these variants by evaluating their functional impact on GR signaling. Six original GR variants, located in exon 2, led to amino acid substitutions of the N-terminal domain of GR (F65V, M86V, A229T, A304E, N374S, and R386Q), excluding mainly the activation function tau core 1 domain, the potential site of functional interaction with transcriptional coregulators. Transient cotransfection in HEK293T cells of mutated GR-expressing vectors and a luciferase reporter established dose-response curves for dexamethasone. This excluded any major transactivation abnormality of the mutated GRs (ligand concentration leading to 50% maximal transactivation capacity approximate to 0.2 nM), with maximal transactivation capacity identical to that of the wild-type (WT) GR and without modification of the potentiation of transcriptional coactivator steroid receptor coactivator 2 except in N374S. Moreover, protein expression of mutated GRs and their cytonuclear translocation studied by immunocytochemistry were almost unchanged compared with WT GR. These results underline the silent nature of these missense GR variants and call for cautious interpretation of the discovery of genetic incidentalomas by NGS in the absence of detailed characterization in order to appropriately assess their functional impact on a particular signaling pathway. Copyright (C) 2019 Endocrine Society
Stress During Pregnancy and Epigenetic Modifications to Offspring DNA A Systematic Review of Associations and Implications for Preterm Birth
JOURNAL OF PERINATAL & NEONATAL NURSING
Authors: Nowak, Alexandra L.; Anderson, Cindy M.; Mackos, Amy R.; Neiman, Emily; Gillespie, Shannon L.
Abstract
Offspring born preterm (ie, before 37 weeks of gestation) are more likely to die or experience long-standing illness than full-term offspring. Maternal genetic variants (ie, heritable, stable variations in the genetic code) and epigenetic modifications (ie, chemical modifications to the genetic code that can affect which genes are turned on or off) in response to stress have been implicated in preterm birth. Fetal genetic variants have been linked to preterm birth though the role of offspring epigenetics in preterm birth remains understudied. This systematic review synthesizes the literature examining associations among stress during pregnancy and epigenetic modifications to offspring DNA, with 25 reports identified. Ten reports examined DNA methylation (ie, addition/removal of methyl groups to/from DNA) across the epigenome. The remainder examined DNA methylation near genes of interest, primarily genes linked to hypothalamic-pituitary-adrenal axis function (NR3C1, FKBP51), growth/immune function (IGF2), and socioemotional regulation (SLC6A4, OXTR). The majority of reports noted associations among stress and offspring DNA methylation, primarily when perceived stress, anxiety, or depression served as the predictor. Findings suggest that differences in offspring epigenetic patterns may play a role in stress-associated preterm birth and serve as targets for novel interventions.