Astrocyte gene expression and translation in an in vivo FASD mouse model

PROJECT SUMMARY The effects of developmental alcohol exposure on astrocytes remains largely unknown, despite the extensive and growing evidence of the roles played by these cells both in the developing and adult brain. This gap in knowledge is due in part to the challenges of studying these cells in vivo. We propose to employ new technologies allowing the study of astrocytes in vivo to gain mechanistic insights into astrocytic functions altered by developmental alcohol exposure to advance the pace of our discoveries of the roles played by astrocytes in Fetal Alcohol Spectrum Disorders (FASD). We propose to use the Aldh1l1-EGFP-Rpl10a mice that allow for the selective pull down of actively translating RNA from astrocytes by the translating ribosome affinity purification (TRAP) method and for the isolation of astrocyte-specific nuclei by Fluorescent-Activated Cell Sorting (FACS). Hence, this system allows to analyze changes in both astrocyte-specific nuclear RNA expression and astrocyte-specific RNA translation by RNA-seq. We hypothesize that neonatal alcohol exposure induces extensive changes in the translation of genes involved in several astrocyte-mediated processes in vivo and on molecular stuctures mainly contributed by astrocytes, such as the extracellular matrix (ECM) that modulate some of these processes. We also hypothesize that changes in translation are in part driven by changes in transcription and in part independent from transcription. Additionally, the proposed studies will assess astrocyte heterogeneity in their response to developmental alcohol exposure across developmental stages, sexes, and brain regions. The cell type-specificity of the proposed studies will help to disentangle astrocyte function and dysfunction in FASD from contributions of other cell types. We are particularly interested in alterations involving the ECM as we have reported that several proteins of the ECM play important roles in neuronal development and are dysregulated by ethanol. We expect the results of our proposed Aims to be very impactful to the FASD field. We will study the prefrontal cortex (PFC) and hippocampus (HPC) of developing (PD7) and adult (PD90) female and male Aldh1l1-EGFP-Rpl10a mice. Aim 1: To identify changes in the astrocyte nuclear transcriptome induced by neonatal ethanol exposure by FACS sorting of astrocyte nuclei followed by RNA-seq and pathway analysis. Aim 2: To identify changes in the astrocyte translatome induced by neonatal ethanol exposure by TRAP-RNA-seq and integrate these findings with transcriptome data. Aim 3: To explore the dysregulation of the astrocyte ECM network that underlies some of the developmental effects of ethanol by TRAP-qPCR, Fluorescence In Situ Hybridization (FISH)-RNAscope, Western blot, and immunohistochemistry to validate at both mRNA and protein levels ethanol-induced changes in ECM proteins. The proposed studies address NIH/NIAA priorities as they will provide mechanistic insights into astrocyte functions altered by developmental alcohol exposure in the developing and adult brain which are likely involved in behavioral abnormalities and mental illnesses developed by adults with FASD.