Transcriptome sequencing of 3,3',4,4',5-Pentachlorobiphenyl (PCB126)-treated human preadipocytes demonstrates progressive changes in pathways associated with inflammation and diabetes

Abstract

Polychlorinated biphenyls (PCBs) are persistent organic pollutants that accumulate in adipose tissue and have been associated with cardiometabolic disease. We have previously demonstrated that exposure of human preadipocytes to the dioxin-like PCB126 disrupts adipogenesis via the aryl hydrocarbon receptor (AhR). To further understand how PCB126 disrupts adipose tissue cells, we performed RNAseq analysis of PCB126-treated human preadipocytes over a 3-day time course. The most significant predicted upstream regulator affected by PCB126 exposure at the early time point of 9 h was the AhR. Progressive changes occurred in the number and magnitude of transcript levels of genes associated with inflammation, most closely fitting the pathways of cytokine-cytokine-receptor signaling and the AGE-RAGE diabetic complications pathway. Transcript levels of genes involved in the IL-17A, IL-1β, MAP kinase, and NF-κB signaling pathways were increasingly dysregulated by PCB126 over time. Our results illustrate the progressive time-dependent nature of transcriptional changes caused by toxicants such as PCB126, point to important pathways affected by PCB126 exposure, and provide a rich dataset for further studies to address how PCB126 and other AhR agonists disrupt preadipocyte function. These findings have implications for understanding how dioxin-like PCBs and other dioxin-like compounds are involved in the development of obesity and diabetes.

Keywords: Adipose; AhR; Inflammation; PCB126; Polychlorinated biphenyls; RNAseq.

Figure 1:

Transcript changes in PCB126-exposed preadipocytes over a time course. A. Volcano plots showing differentially expressed genes at 9-hour, 1-Day, or 3-Day post-treatment of preadipocytes with PCB126 (10 μM). Red: Upregulated; Blue: Downregulated. DE Thresholds: p-value:0.05; Log2FC: 0.3 B. Venn diagram illustrating overlap of differentially expressed genes at the different timepoints. Fdr≤0.05.

Figure 2:

Aryl hydrocarbon receptor (AhR) pathway genes altered by PCB126 treatment of preadipocytes at different timepoints. A. Network analysis of AhR regulated genes at 9-hour, 1-day, and 3-day timepoints. Red Oval: Upregulated; Blue Oval: Downregulated; Gray Oval: Unchanged; “A”: Activated; “E”: Expression Inhibited; “I”: Inhibited; →Activation; ┤Inhibition. B. Transcript level changes (log2fold) of genes considered to be in the AhR pathway at different timepoints (9-hour, 1-day, 3-day) of PCB126-exposed preadipocytes compared to vehicle controls at the same timepoints. Fdr≤0.05.

Figure 3:

Network analysis of predicted IL-1β-regulated genes at 9-hour, 1-day, and 3-day timepoints. Red Oval: Upregulated; Blue Oval: Downregulated; Gray Oval: Unchanged; “A”: Activated; “E”: Expression Inhibited; “I”: Inhibited; →Activation; ┤Inhibition.

Figure 4:

AGE-RAGE pathway gene transcript changes induced by PCB126 treatment of preadipocytes. A. Transcript level changes (log2fold) of genes the AGE-RAGE pathway at different timepoints (9-hour, 1-day, 3-day) of PCB126-exposed preadipocytes compared to vehicle controls at the same timepoints. Values represent log2fold change over vehicle control. B. Transcript level changes (log2fold) of AGE-RAGE pathway genes. Fdr<0.05. Pink: 9-hour exposure; Yellow: 1-day exposure; Blue: 3-day exposure.

Figure 5:

PCB126-induced changes in IL-17A pathway genes. A. Transcript level changes (log2fold) of genes in the IL-17A pathway at different timepoints (9-hour, 1-day, and 3-day) of PCB-exposed preadipocytes compared to vehicle controls at the same timepoints. B. Network analysis of IL-17A pathway genes altered by 3 days of PCB126 treatment of preadipocytes. Red Oval: Upregulated; Blue Oval: Downregulated; White Oval: Unchanged; “A”: Activated; “E”: Expression Inhibited; “I”: Inhibited; →Activation; ┤Inhibition. Fdr≤0.05.