Prenatal alcohol exposure (PAE) programs the fetal hypothalamic-pituitary-adrenal (HPA) axis, resulting in HPA dysregulation and hyperresponsiveness to stressors in adulthood. Molecular mechanisms mediating these alterations are not fully understood. Disturbances in one-carbon metabolism, a source of methyl donors for epigenetic processes, contributes to alcoholic liver disease. We assessed whether PAE affects one-carbon metabolism (including Mtr, Mat2a, Mthfr, and Cbs mRNA) and programming of HPA function genes (Nr3c1, Nr3c2, and Slc6a4) in offspring from ethanol-fed (E), pair-fed (PF), and ad libitum-fed control (C) dams. At gestation day 21, plasma total homocysteine and methionine concentrations were higher in E compared with C dams, and E fetuses had higher plasma methionine concentrations and lower whole brain Mtr and Mat2a mRNA compared with C fetuses. In adulthood (55 days), hippocampal Mtr and Cbs mRNA was lower in E compared with C males, whereas Mtr, Mat2a, Mthfr, and Cbs mRNA were higher in E compared with C females. We found lower Nr3c1 mRNA and lower nerve growth factor inducible protein A (NGFI-A) protein in the hippocampus of E compared with PF females, whereas hippocampal Slc6a4 mRNA was higher in E than C males. By contrast, hypothalamic Slc6a4 mRNA was lower in E males and females compared with C offspring. This was accompanied by higher hypothalamic Slc6a4 mean promoter methylation in E compared with PF females. These findings demonstrate that PAE is associated with alterations in one-carbon metabolism and has long-term and region-specific effects on gene expression in the brain. These findings advance our understanding of mechanisms of HPA dysregulation associated with PAE.
The low-density lipoprotein receptor (Ldlr) is a key molecule involved with lipid clearance. The Ldlr Ϫ/Ϫ mouse has been used extensively as a model for studying atherosclerosis.
Pseudohypoparathyrodism (PHP) is a disorder caused by mutations in the guanine nucleotide-binding α-subunit (GNAS). We sought to determine the genetic origin of PHP1a in one affected family. We identified the previously reported Gsα R231H mutation in family members affected with PHP1a. DNA analysis found that the two clinically affected sons are heterozygous for the mutation. The sons have PHP1a, manifesting obesity, intellectual disability, hypogonadism, hypothyroidism and elevated PTH levels. Initial DNA sequencing did not detect the mutation in either parent. However, their mother displayed some features of PHP, including elevated PTH levels and asymmetrical metacarpal shortening. Using molecular cloning, we detected the mutation at low levels in the mother's leukocyte DNA, consistent with somatic mosaicism and her mildly affected status. Thus, we have identified additional cases of PHP1a caused by the Gsα R231H mutation. In this family, the mother has a milder phenotype due in part to somatic mosaicism, whereas the two affected sons have full PHP1a. Though somatic mosaicism for activating GNAS mutations is known to occur in McCune-Albright syndrome, this is the first report confirming somatic mosaicism for a hypofunctioning GNAS mutation in a PHP kindred.
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