Transcriptional, metabolic and epigenetic changes associated with in utero diesel exhaust particulate exposure

Thesis (Ph.D.)--University of Washington, 2017In utero exposure to diesel exhaust air pollution has been associated with increased adult susceptibility to heart failure in mice but the mechanisms by which this exposure promotes susceptibility are poorly understood. To identify potential transcriptional effects that mediate this susceptibility, we have performed RNA-seq analysis on neonatal cardiomyocytes from mice exposed to diesel exhaust in utero, as well as on adult hearts that have undergone transverse aortic constriction. We have identified a neonatal cardiomyocyte dysregulation of 300 genes, including many involved in cardiac metabolism. In the adult hearts, we have identified three target genes, Mir133a-2, Ptprf and Pamr1, which demonstrate dysregulation after exposure and aortic constriction. These target genes in the heart are the first to be identified that likely play an important role in mediating adult sensitivity to heart failure. We followed up on the identified neonatal transcriptional dysregulation by determining whether cardiomyocytes from mice exposed in utero to diesel exhaust have impaired metabolic activity. We observed that the neonatal cardiomyocytes exhibit reduced metabolic activity as measured by pyruvate/glutamate-fueled oxygen consumption. However, the adult mitochondria showed a conflicting increase in metabolic activity as measured by pyruvate/glutamate-fueled respiration, as well as an increased mitochondrial load as measured by the ratio of mitochondrial:genomic DNA. We subsequently examined for DNA methylation modifications both in global regulatory regions and at these candidate loci in neonatal cardiomyocytes after in utero exposure to diesel exhaust and found hypomethylation both globally at CpG-rich regions and in the first exon of GM6307, the gene miR133a-2 is intronically embedded in. We have shown a change in DNA methylation within cardiomyocytes as a result of in utero exposure to diesel exhaust. Taken together, we have demonstrated that in utero exposure to diesel exhaust alters the neonatal cardiomyocyte transcriptional and epigenetic landscapes, as well as the metabolic capability of these cells, and that when these mice undergo heart failure as adults, there are changes in gene expression related to both heart failure and the in utero exposure