Alcohol Effects on the Proteome and Transcriptome of Fetal Neural Stem Cell-Derived Extracellular Vesicles: Mechanism for Alcohol Teratogenesis

项目总结

Project Summary Prenatal alcohol exposure (PAE) can result in decreased neurogenic capacity of neural stem cells (NSCs), which, during the early-to-mid gestation period, give rise to most neurons of the adult brain. This loss of neurogenic capacity explains, in part, neurobehavioral and brain growth deficits associated with Fetal Alcohol Spectrum Disorders (FASD). However, the mechanisms that mediate the persistent effects of episodic PAE on fetal NSCs are unknown. We and others have recently identified a novel class of sub-200 nanometer-sized extracellular vesicles (EVs) secreted by NSCs, as a means for intercellular transfer of biomolecules including proteins and nucleic acids. I hypothesize that EVs constitute endocrine-like organelles that propagate the effects of ethanol throughout the stem cell microenvironment in time and space. My preliminary and published data support the hypotheses that ethanol (i) alters the sequestration of proteins into EVs released by fetal NSCs, in a dose-dependent manner, and, by interfering with protein expression in EVs, (ii) results in loss of stem cell renewal and diminished neurogenesis. Using mass spectrometric and transcriptomic tools and cell and molecular biological analyses of EV function in a murine model, planned and completed studies address the following specific aims: Aim 1 seeks to identify and validate the effects of alcohol exposure on proteins and RNAs in EVs and associated NSCs. My studies show that EVs from parent NSCs exposed to moderate doses of ethanol (Mod-EtoHEVs) exhibit a significant increase in proteins of the Nonsense- Mediated Decay (NMD), whereas EVs obtained following NSC exposure to higher levels of ethanol (Hi-EtoHEVs) overexpress mitochondrial proteins that constitute a Danger-Associated Molecular Pattern (mito-DAMP) signal. These data will be validated and compared to the ethanol-affected intracellular proteome of parent NSCs. Aim 2 will evaluate the mediating role of Mod-EtoHEV-derived NMD on NSC proliferation, differentiation, and death, under basal and ethanol-exposure conditions. Our working hypothesis is that Mod-EtoHEVs transfer NMD components to recipient cells to confer compensatory neuroprotection. Aim 3 will evaluate the mediating role of Hi-EtoHEV-derived mito-DAMP on NSC proliferation, differentiation, and death. Our working hypothesis is that the secretion of a ‘danger’ signal in response to high levels of ethanol exposure triggers a pro-inflammatory cytokine response in recipient NSCs, resulting in impaired neurogenesis. My studies are expected to uncover novel intercellular communication pathways that mediate the effects of PAE on early neural maturation. This training plan will equip me with technical and research methodology skills and develop specific competency with data analytic and statistical approaches for proteome and transcriptome assessment. The plan’s focus on dissecting and disrupting the connection between PAE and FASD integrates well with my career goal to become a scientist with a focus on the role of early environmental mediators of developmental disability.