Differential Gene Expression Patterns in Chicken Cardiomyocytes during Hydrogen Peroxide-Induced Apoptosis

Hydrogen peroxide (H(2)O(2)) is both an exogenous and endogenous cytotoxic agent that can reliably induce apoptosis in numerous cell types for studies on apoptosis signaling pathways. However, little is known of these apoptotic processes in myocardial cells of chicken, a species prone to progressive heart failure. Sequencing of mRNA transcripts (RNA-Seq) allows for the identification of differentially expressed genes under various physiological and pathological conditions to elucidate the molecular pathways involved, including cellular responses to exogenous and endogenous toxins. We used RNA-seq to examine genes differentially expressed during H(2)O(2)-induced apoptosis in primary cultures of embryonic chicken cardiomyocytes. Following control or H(2)O(2) treatment, RNA was extracted and sequencing performed to identify novel transcripts up- or downregulated in the H(2)O(2) treatment group and construct protein−protein interaction networks. Of the 19,268 known and 2,160 novel transcripts identified in both control and H(2)O(2) treatment groups, 4,650 showed significant differential expression. Among them, 55.63% were upregulated and 44.37% downregulated. Initiation of apoptosis by H(2)O(2) was associated with upregulation of caspase-8, caspase-9, and caspase-3, and downregulation of anti-apoptotic genes API5 and TRIA1. Many other differentially expressed genes were associated with metabolic pathways (including ‘Fatty acid metabolism’, ‘Alanine, aspartate, and glutamate metabolism’, and ‘Biosynthesis of unsaturated fatty acids’) and cell signaling pathways (including ‘PPAR signaling pathway’, ‘Adipocytokine signaling pathway’, ‘TGF-beta signaling pathway’, ‘MAPK signaling pathway’, and ‘p53 signaling pathway’). In chicken cardiomyocytes, H(2)O(2) alters the expression of numerous genes linked to cell signaling and metabolism as well as genes directly associated with apoptosis. In particular, H(2)O(2) also affects the biosynthesis and processing of proteins and unsaturated fatty acids. These results highlight the value of RNA-seq for revealing unexpected molecular contributors to oxidative stress responses, thereby identifying novel potential therapeutic targets.