ACE-inhibition induces a cardioprotective transcriptional response in the metabolic syndrome heart

Figure 1. (A) Chow-Ruskey Venn diagram of number and overlap of differentially expressed genes when comparing WT to DKO mice and when comparing the effect of ACE-I in both animal models. (B) Comparison analysis of top 10 pathways most affected based on p-value (relative number of genes differential versus total members of the pathway). (C) Comparison analysis of top 10 pathways most severely up (orange) or down (blue) regulated. Observed up or down regulation is compared to known changes that are either activating or inhibiting, as derived from the literature and compiled in the Ingenuity® Knowledge Base.

Figure 2. Integrin linked kinase (ILK) signaling. This pathway illustrates cytoskeletal changes and effects through integrin contacts with the extracellular matrix. (A) Differential gene expression in DKO mice versus WT mice. Red = upregulated, green = downregulated. A = activation, C = causes, E = Expression, EC = Enzyme Catalysis, I = inhibition, PP = Protein-Protein binding, RE = Reaction. (B) Differential gene expression in DKO mice after ACE-I. Red = upregulated, green = downregulated. A = activation, C = causes, E = Expression, EC = Enzyme Catalysis, I = inhibition, PP = Protein-Protein binding, RE = Reaction.

Figure 3. Rho GTPase family signaling. (A) Differential gene expression in DKO mice versus WT mice. (B) Differential gene expression in DKO mice after ACE-I. GTPases regulate a wide range of biological processes. The mammalian GTPase family currently consists of three subfamilies: Rho, Rac and Cdc42 and each affect numerous downstream molecules that mediate effects on the cytoskeleton and gene expression. The small GTPases act as molecular switches, cycling between an active GTP-bound state and an inactive GDP-bound state. A number of proteins have been identified as targets of Rho with ROCK being a prominent target. ROCK phosphorylates MLC, which plays an important role in actomyosin contractility. ROCK also activates LIMK, which results in Cofilin inactivation and leads to actin polymerization. Rac and Cdc42 also bind to PI3K, thus activating the PI3K/AKT signaling pathway. Red = upregulated, green = downregulated. A = activation, C = causes, E = Expression, EC = Enzyme Catalysis, I = inhibition, P = (de−)Phosphorylation, PP = Protein-Protein binding, RE = Reaction.

Figure 4. Atherosclerosis signaling. (A) Differential gene expression in DKO mice versus WT mice. (B) Differential gene expression in DKO mice after ACE-I. Monocytes adhere to endothelial cells and migrate into the intima of the blood vessel where they differentiate into macrophages. Atherogenic lipoproteins such as oxidized LDL play an initiating role in this adhesion. Macrophages take up oxidized LDL through scavenger receptors on their cell surface to form foam cells. Such lipid laden foam cells in the intima form a “fatty streak”. Foam cells secrete pro-inflammatory cytokines as well as MMPs. This in turn amplifies the local inflammatory response and stimulates SMC proliferation and migration toward the lesion, leading to formation of the thick fibrous cap of the stable plaque. Red = upregulated, green = downregulated. E = Expression (includes metabolism/synthesis for chemicals), EC = Enzyme Catalysis, L = Molecular cleavage or degradation, LO = Localization, O = Oxidized, PP = Protein-Protein binding, RE = Reaction, TR = Translocation.

Figure 5. Acute phase response. (A) Differential gene expression in DKO mice versus WT mice. (B) Differential gene expression in DKO mice after ACE-I. The acute phase response is a rapid inflammatory response that can –amongst others- be triggered by tissue injury. It consists of an increase in inflammatory factors and a change in concentration of several plasma proteins (the acute phase proteins). Red = upregulated, green = downregulated. E = Expression, I = inhibition, PP = Protein-Protein binding.

Figure 6. Pathways significantly changed when comparing DKO with WT mice. Only differential transcription factors are plotted in a network representation to show involvement in pathways. Red and green color indicate up- and downregulation, respectively.

Figure 7. (A) Gene expression activity for IPA transcription factor prediction for all 4 conditions. FPKM values have been scaled across experimental conditions for convenient visualization ranging from low (0) to high (1) relative expression levels; (B) i-Cis-Target based transcription factor binding site enrichment analysis.

Figure 8. Schematic representation of main effects on pathways in the metabolic syndrome hearts (DKO) versus WT hearts and for both mouse models the effect of ACE-I. Red = upregulated pathway, green = downregulated pathway.