Hippocampal DNA Methylation in a Mouse Model of Fetal Alcohol Spectrum Disorder That Includes Maternal Separation Stress Only Partially Explains Changes in Gene Expression

Abstract

Fetal alcohol spectrum disorder (FASD) is characterized by developmental and behavioral deficits caused by maternal drinking during pregnancy. Children born with FASD often face additional stresses, including maternal separation, that add yet additional deficits. The mechanism associated with this interaction is not known. We have used a mouse model for prenatal ethanol exposure and maternal separation to demonstrate that the combination of the two treatments results in more than additive deficits. Furthermore, the behavioral deficits are associated with changes in hippocampal gene expression that persist into adulthood. What initiates and maintains these changes remains to be established and forms the focus of this report. Specifically, MeDIP-Seq was used to assess if changes in promoter DNA methylation are affected by exposure to prenatal ethanol and maternal separation including its relationship to gene expression. The novel results show that different sets of genes implicated by promoter DNA methylation are affected by both treatments independently, and a relatively unique set of genes are affected by the combination of the two treatments. Prenatal ethanol exposure leads to altered promoter DNA methylation at genes important for transcriptional regulation. Maternal separation leads to changes at genes important for histone methylation and immune response, and the combination of two treatments results in DNA methylation changes at genes important for neuronal migration and immune response. Our dual results from the same hippocampal samples suggest there is minimal complementarity between changes in promoter DNA methylation and gene expression, although genes involved tend to be critical for brain development and function. While remaining to be validated, such results argue that mechanisms beyond promoter DNA methylation must be involved in lasting gene expression alterations leading to behavioral deficits implicated in FASD. They may facilitate early and reliable diagnosis, as well as novel strategies for the amelioration of FASD-related deficits.

Epigenetic Impacts of Early Life Stress in Fetal Alcohol Spectrum Disorders Shape the Neurodevelopmental Continuum

“…In our mouse model of continuous PAE, we found altered promoter methylation at genes important for transcriptional regulation. Specifically, PAE led to decreased promoter methylation of polycomb repressive complex 1 members, including chromobox 4 and 8 ( Cbx4 , Cbx8 ) polycomb group ring finger 6 ( Pcgf6 ), and ring finger protein 1 ( Ring1 ), as well as transcription factor II D complex members general transcription factor II A, 2 ( Gtf2a2 ), and TATA-box binding protein associated factors 8, 10, and 11 ( Taf8 , Taf10 , Taf11 ; Alberry and Singh, 2020 ). Additionally, there is decreased promoter methylation of nine members of the RNA polymerase II transcription factor complex, including the aforementioned Gtf2a2 , Taf8 , Taf10 , Taf11 , as well as pygopus 2 ( Pygo2 ), nuclear transcription factor-Y gamma ( Nfyc ), peroxisome proliferator activator receptor delta ( Ppard ), and nuclear receptor subfamily 1, group H, member 4 and group D, member 2 ( Nr1h4 , Nr1d2 ; Alberry and Singh, 2020 ).…”

“…Using a mouse model combining PAE and ELS, we found different sets of genes with altered promoter methylation following prenatal ethanol exposure, postnatal maternal separation stress, and the combination of treatments (Alberry and Singh, 2020 ). The combination of PAE and ELS results in decreased promoter methylation of genes critical for neuronal migration, including sema domain, transmembrane domain (TM), and cytoplasmic domain, (semaphorin) 6A ( Sema6a ), unc-51-like kinase 4 ( Ulk4 ), disabled 2 interacting protein ( Dab2ip ), and rho/rac guanine nucleotide exchange factor (GEF) 2 ( Arhgef2 ).…”

“…The combination of PAE and ELS results in decreased promoter methylation of genes critical for neuronal migration, including sema domain, transmembrane domain (TM), and cytoplasmic domain, (semaphorin) 6A ( Sema6a ), unc-51-like kinase 4 ( Ulk4 ), disabled 2 interacting protein ( Dab2ip ), and rho/rac guanine nucleotide exchange factor (GEF) 2 ( Arhgef2 ). Conversely, the combination of PAE and ELS led to increased promoter methylation of genes important for immune response, including 21 members of the cytokine-cytokine receptor interaction KEGG pathway (Alberry and Singh, 2020 ). While there is a minimal correspondence between promoter DNA methylation and gene expression, genes involved are critical for brain development and function.…”

“…In an FASD model that includes PAE and ELS in adult mouse hippocampus both hyper- and hypo-methylation in the protocadherin region as well as decreased gene expression resulted from PAE (Alberry and Singh, 2020 ; Alberry et al, 2020 ). ELS alone and the combination of PAE and ELS resulted in hypermethylation of the locus and decreased expression of a transcript (Alberry and Singh, 2020 ; Alberry et al, 2020 ). Interestingly, transcripts from this locus were within a gene co-expression module that correlates with treatment and anxiety-like behavior (Alberry et al, 2020 ).…”

Study on the Regulatory Effects of GA3 on Soybean Internode Elongation

“…[ 13 ]. Moreover, the application of GA 3 significantly increases the overall height and length of internodes of plants and reduces internode mechanical strength [ 14 , 15 , 16 , 17 , 18 ]. The stimulatory effect of GAs on plant internode length is closely related to the endogenous levels of GAs [ 19 ].…”