5.4.9 Biological Pathways of Interest From the functional annotation analysis performed in DAVID and IMPALA, there were several common pathways that emerged that were altered in MAB391-treated astrocytes. Both pathway enrichment programs suggest transcriptomic changes in the energy metabolism of IGF1 impaired astrocytes compared with untreated astrocytes. In particular, there is an agreement between the two programs that there is a signifcant downregulation of genes involved in oxidative phosphorylation (using DAVID p=0.015 and in IMPALA p=0.00593). In addition, analysis performed in IMPALA suggested upregulation of a number of pathways in IGF1 impaired astrocytes. One of these was upregulation of genes involved in glycolysis, which might indicate a compensatory mechanism since oxidative phosphorylation was downregulated. Closer inspection of the gene expression profile data revealed that a number of genes involved in synaptic support and antioxidant capacity were altered in the MAB391-treated astrocytes. These changes are discussed in more detail below. Oxidative Phosphorylation Both DAVID and IMPALA enrichment analysis identified the downregulation of genes involved in oxidative phosphorylation in IGF1-impaired astrocytes. Eight genes involved in oxidative phosphorylation were differentially expressed in MAB391-treated astrocytes and these are listed in Five of these eight genes listed encode table 5.13. subunits that form part of complex I of the mitochondrial respiratory chain (NDUFA2, NDUFB3, NDUFAB1, NDUFA1, NDUFB6), which is known to form ROS if not functioning properly (Jastroch et al. 2010). These downregulated genes have also been marked with a red star in a KEGG pathway diagram of oxidative phosphorylation (figure Closer inspection of the clustering analysis performed by DAVID 5.17). revealed 33 genes involved in mitochondrial function were downregulated in astrocytes (table 5.14). Together these results suggest loss of IGF1R results in mitochondrial dysfunction at the transcript level, particularly in the oxidative phosphorylation pathway.
5.4.9 Biological Pathways of Interest From the functional annotation analysis performed in DAVID and IMPALA, there were several common pathways that emerged that were altered in MAB391-treated astrocytes. Both pathway enrichment programs suggest transcriptomic changes in the energy metabolism of IGF1 impaired astrocytes compared with untreated astrocytes. In particular, there is an agreement between the two programs that there is a signifcant downregulation of genes involved in oxidative phosphorylation (using DAVID p=0.015 and in IMPALA p=0.00593). In addition, analysis performed in IMPALA suggested upregulation of a number of pathways in IGF1 impaired astrocytes. One of these was upregulation of genes involved in glycolysis, which might indicate a compensatory mechanism since oxidative phosphorylation was downregulated. Closer inspection of the gene expression profile data revealed that a number of genes involved in synaptic support and antioxidant capacity were altered in the MAB391-treated astrocytes. These changes are discussed in more detail below. Oxidative Phosphorylation Both DAVID and IMPALA enrichment analysis identified the downregulation of genes involved in oxidative phosphorylation in IGF1-impaired astrocytes. Eight genes involved in oxidative phosphorylation were differentially expressed in MAB391-treated astrocytes and these are listed in table 5.13. Five of these eight genes listed encode subunits that form part of complex I of the mitochondrial respiratory chain (NDUFA2, NDUFB3, NDUFAB1, NDUFA1, NDUFB6), which is known to form ROS if not functioning properly (Jastroch et al. 2010). These downregulated genes have also been marked with a red star in a KEGG pathway diagram of oxidative phosphorylation (figure 5.17). Closer inspection of the clustering analysis performed by DAVID revealed 33 genes involved in mitochondrial function were downregulated in astrocytes (table 5.14). Together these results suggest loss of IGF1R results in mitochondrial dysfunction at the transcript level, particularly in the oxidative phosphorylation pathway.