Accumulating evidence has suggested that a suboptimal early life environment produces multigenerational developmental defects. A proposed mechanism is stable inheritance of DNA methylation. Here we show that maternal bisphenol A (BPA) exposure in C57BL/6 mice produces multigenerational metabolic phenotypes in their offspring. Using various methods including dual-energy X-ray absorptiometry analyses, glucose tolerance tests, and perifusion islet studies, we showed that exposure to 10 μg/kg/d and 10 mg/kg/d BPA in pregnant F0 mice was associated with higher body fat and perturbed glucose homeostasis in F1 and F2 male offspring but not female offspring. To provide insight into the mechanism of the multigenerational metabolic abnormalities, we investigated the maternal metabolic milieu and inheritance of DNA methylation across generations. We showed that maternal glucose homeostasis during pregnancy was altered in the F0 but not F1 female mice. The results suggested that a compromised maternal metabolic milieu may play a role in the health of the F1 offspring but cannot account for all of the observed multigenerational phenotypes. We further demonstrated that the metabolic phenotypes in the F1 and F2 BPA male offspring were linked to fetal overexpression of the imprinted Igf2 gene and increased DNA methylation at the Igf2 differentially methylated region 1. Studies in H19(Δ3.8/+) mouse mutants supported the role of fetal Igf2 overexpression in altered adult glucose homeostasis. We conclude that early life BPA exposure at representative human exposure levels can perturb metabolic health across multiple generations in the mouse through stable inheritance of DNA methylation changes at the Igf2 locus.

Increasing evidence has highlighted the critical role of early life environment in shaping the future health outcomes of an individual. Moreover, recent studies have revealed that early life perturbations can affect the health of subsequent generations. Hypothesized mechanisms of multi- and transgenerational inheritance of abnormal developmental phenotypes include epigenetic misregulation in germ cells. In this review, we will focus on the available data demonstrating the ability of endocrine disrupting chemicals (EDCs), including bisphenol A (BPA), phthalates, and parabens, to alter epigenetic marks in rodents and humans. These epigenetic marks include DNA methylation, histone post-translational modifications, and non-coding RNAs. We also review the current evidence for multi- and transgenerational inheritance of abnormal developmental changes in the offspring following EDC exposure. Based on published results, we conclude that EDC exposure can alter the mouse and human epigenome, with variable tissue susceptibilities. Although increasing data suggest that exposure to EDCs is linked to transgenerational inheritance of reproductive, metabolic, or neurological phenotypes, more studies are needed to validate these observations and to elucidate further whether these developmental changes are directly associated with the relevant epigenetic alterations.

Background:Exposure to the environmental endocrine disruptor bisphenol A (BPA) is ubiquitous and associated with the increased risk of diabetes and obesity. However, the underlying mechanisms remain unknown. We recently demonstrated that perinatal BPA exposure is associated with higher body fat, impaired glucose tolerance, and reduced insulin secretion in first- (F1) and second-generation (F2) C57BL/6J male mice offspring.Objective:We sought to determine the multigenerational effects of maternal bisphenol A exposure on mouse pancreatic islets.Methods:Cellular and molecular mechanisms underlying these persistent changes were determined in F1 and F2 adult offspring of F0 mothers exposed to two relevant human exposure levels of BPA (10μg/kg/d-LowerB and 10mg/kg/d-UpperB).Results:Both doses of BPA significantly impaired insulin secretion in male but not female F1 and F2 offspring. Surprisingly, LowerB and UpperB induced islet inflammation in male F1 offspring that persisted into the next generation. We also observed dose-specific effects of BPA on islets in males. UpperB exposure impaired mitochondrial function, whereas LowerB exposure significantly reduced β-cell mass and increased β-cell death that persisted in the F2 generation. Transcriptome analyses supported these physiologic findings and there were significant dose-specific changes in the expression of genes regulating inflammation and mitochondrial function. Previously we observed increased expression of the critically important β-cell gene, Igf2 in whole F1 embryos. Surprisingly, increased Igf2 expression persisted in the islets of male F1 and F2 offspring and was associated with altered DNA methylation.Conclusion:These findings demonstrate that maternal BPA exposure has dose- and sex-specific effects on pancreatic islets of adult F1 and F2 mice offspring. The transmission of these changes across multiple generations may involve either mitochondrial dysfunction and/or epigenetic modifications. https://doi.org/10.1289/EHP1674

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Rhesus (rh) but not human (hu) TRIM5α potently restricts human immunodeficiency virus (HIV)-1 infection. It is not clear why huTRIM5α fails to effectively block HIV infection, but it is thought to have a lower affinity for the viral core. Using primary human CD4 T cells, we investigated the ability of huTRIM5α, rhTRIM5α, and the huTRIM5αR323-332 B30.2/SPRY patch-mutant to form cytoplasmic bodies, postulated as key components of the HIV-1 restriction apparatus. Both rhTRIM5α and huTRIM5αR323-332 formed pronounced cytoplasmic bodies, whereas cytoplasmic bodies in T cells overexpressing huTRIM5α were present but more difficult to detect. As expression of all three TRIM5α orthologs was similar at the RNA level, we next investigated the role of protein stability in conferring TRIM5α-mediated HIV-1 restriction. Both steady-state and pulse-chase experiments revealed that the huTRIM5α protein was much less stable than rhTRIM5α, and this difference correlated with higher self-ubiquitination activity. Using a stabilized form of huTRIM5α in which the steady-state expression level was more similar to rhTRIM5α, we observed comparable HIV-1 restriction activity in multi-round HIV-1 challenge assays. Lastly, primary human CD4 T cells expressing a stabilized huTRIM5α were protected from HIV-1-mediated destruction in vivo, indicating that efforts to stabilize huTRIM5α should have significant long-term therapeutic value.

Fetal exposure to endocrine disrupting chemicals (EDCs) has been associated with adverse neurobehavioral outcomes across the lifespan and can persist across multiple generations of offspring. However, the underlying mechanisms driving these changes are not well understood. We investigated the molecular perturbations associated with EDC-induced behavioral changes in first (F1) and second (F2) filial generations, using the model EDC bisphenol A (BPA). C57BL/6J dams were exposed to BPA from preconception until lactation through the diet at doses (10 μg/kg bw/d-lower dose or 10 mg/kg bw/d-upper dose) representative of human exposure levels. As adults, F1 male offspring exhibited increased depressive-like behavior, measured by the forced swim test, while females were unaffected. These behavioral changes were limited to the F1 generation and were not associated with altered maternal care. Transcriptome analysis by RNA-sequencing in F1 control and upper dose BPA-exposed adult male hippocampus revealed neurotransmitter systems as major pathways disrupted by developmental BPA exposure. High performance liquid chromatography demonstrated a male-specific reduction in hippocampal serotonin. Administration of the selective serotonin reuptake inhibitor fluoxetine (20 mg/kg bw) rescued the depressive-like phenotype in males exposed to lower, but not upper, dose BPA, suggesting distinct mechanisms of action for each exposure dose. Finally, high resolution mass spectrometry revealed reduced circulating levels of the neuroactive steroid dehydroepiandrosterone in BPA-exposed males, suggesting another potential mechanism underlying the depressive-like phenotype. Thus, behavioral changes associated with early life BPA exposure may be mediated by sex-specific disruptions in the serotonergic system and/or sex steroid biogenesis in male offspring.

In mammals, the extraembryonic tissues, which include the placenta, are crucial for embryonic development and growth. Because the placenta is no longer needed for postnatal life, however, it has been relatively understudied as a tissue of interest in biomedical research. Recently, increased efforts have been placed on understanding the placenta and how it may play a key role in human health and disease. In this review, we discuss two very different types of environmental exposures--assisted reproductive technologies and in utero exposure to endocrine disrupting chemicals. We summarize the current literature on their effects on placental development in both rodent and human, and comment on the potential use of placental biomarkers as predictors of offspring health outcomes.

Exposure to the endocrine disruptor bisphenol A (BPA) is ubiquitous and associated with health abnormalities that persist in subsequent generations. However, transgenerational effects of BPA on metabolic health are not widely studied. In a maternal C57BL/6J mice (F0) exposure model using BPA doses that are relevant to human exposure levels (10 μg/kg/day, LowerB; 10 mg/kg/day, UpperB), we showed male- and dose-specific effects on pancreatic islets of the first (F1) and second generation (F2) offspring relative to controls (7% corn oil diet; Control). In this study, we determined the transgenerational effects (F3) of BPA on metabolic health and pancreatic islets in our model. Adult F3 LowerB and UpperB male offspring had increased body weight relative to Controls, however glucose tolerance was similar in the three groups. F3 LowerB, but not UpperB, males had reduced ß-cell mass and smaller islets which was associated with increased glucose stimulated insulin secretion. Similar to F1 and F2 BPA male offspring, staining for markers of T-cells and macrophages (CD3 and F4/80) was increased in pancreas of F3 LowerB and UpperB male offspring, which was associated with changes in cytokine levels. In contrast to F3 BPA males, LowerB and UpperB female offspring had comparable body weight, glucose tolerance and insulin secretion as Controls. Thus, maternal BPA exposure resulted in fewer metabolic defects in F3 than F1 and F2 offspring, and these were sex- and dose-specific.