Comparative transcriptomic analysis of rabbit interscapular brown adipose tissue whitening under physiological conditions

Figures

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  Figure 1.. BAT converts to white-like adipose tissue of rabbits following birth. (a) Workflow for validation of BAT whitening in rabbits. (b) MRI images of rabbits iBAT and dBAT at different ages. (c) Fat fraction of rabbit iBAT and dBAT. (d) Anatomical images of rabbit dBAT and iBAT at 14 days and 4 months of age. (e) H&E staining results of rabbit iBAT and ingWAT at different ages. Scale bars, 50 µm. (f) UCP1 protein levels of rabbit iBAT and ingWAT at different ages. (g) UCP1 staining of iBAT_D14, ingWAT_D1 and ingWAT_D14 of rabbits. Scale bars, 20 µm. Data represent mean ± SEM, **P < 0.01, ***P < 0.001, ****P < 0.0001.

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  Figure 2.. The transcriptional profile of iBAT shifts towards that of WAT during whitening. (a) PCA of transcriptomes during the whitening of rabbit iBAT with age, ingWAT as a control after iBAT whitening. (b) Heatmap shows correlation between samples. Pearson correlation coefficient is represented in colour. (c) Heatmap shows expression of known marker genes for BAT and WAT in mice and humans. (d) Venn diagram integrating differentially expressed up-regulated genes in human BAT and WAT, mouse brown and white adipocytes and rabbit iBAT_D1 and ingWAT_M4. (e) Venn diagram integrating differentially expressed down-regulated genes in human BAT and WAT, mouse brown and white adipocytes and rabbit iBAT_D1 and ingWAT_M4. (f) Heatmap shows expression of newly identified marker genes for BAT and WAT.

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  Figure 3.. Mitochondrial content is diminished during iBAT whitening in rabbits. (a) Time course differential heatmap. (b) KEGG enrichment analysis of highly expressed genes in iBAT_D1 and iBAT_D14 (Brown Phase). Diagram shows significant enrichment of KEGG pathways (Padjust ≤ 0.05). (c) Heatmap shows changes in genes involved in mitochondrial function during rabbit iBAT whitening. (d) Expression changes of ESRRA and PGC1α. (e) Relative mtDNA copy number of iBAT at 1 day, 14 days, 1 month, 2 months, 3 months and 4 months of age. Data represent mean ± SEM, *P < 0.05, ****P < 0.0001.

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  Figure 4.. Expression of genes involved in angiogenesis and innervation is augmented during rabbit iBAT whitening. (a) Results of temporal expression trend analysis. (b) KEGG enrichment analysis of gene sets including Profiles 15, 16, 25, 8, 24, 22 and 13. Diagram shows significant enrichment of several KEGG pathways (Padjust ≤ 0.05). (c) GO enrichment analysis of gene sets including Profile 15, 16, 25, 8, 24, 22 and 13. Diagram shows significant enrichment of GO pathways (Padjust ≤ 0.05). (d) Heatmap shows expression of marker genes involved in angiogenesis, axon guidance and neuronal markers.

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  Figure 5.. Expression of immune-related genes and infiltration of immune cells are increased during rabbit iBAT whitening. (a) GO enrichment analysis of Profile 15. Diagram shows significant enrichment of several GO pathways (Padjust ≤ 0.05). (b) GO enrichment analysis of differentially expressed up-regulated genes between iBAT_D14 and iBAT_M1. Diagram shows significant enrichment of GO pathways (Padjust ≤ 0.05). (c) Heatmap shows expression of marker genes regulating immune function during rabbit iBAT whitening. (d) GO enrichment analysis of differentially expressed up-regulated genes between iBAT_M1 and iBAT_M4. Diagram shows significant enrichment of several GO identified pathways (Padjust ≤ 0.05). (e) GO enrichment analysis of differentially expressed down-regulated genes between iBAT_M1 and iBAT_M4. Diagram shows significant enrichment of GO identified pathways (Padjust ≤ 0.05). (f) Heatmap shows the intersection of up-regulated genes between iBAT_D14 and iBAT_M1 involved in immune system processes and down-regulated genes between iBAT_M1 and iBAT_M4 involved in immune system processes.

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  Figure 6.. Identification of putative TFs that promote iBAT whitening in rabbits. (a) Heatmap shows expression changes of TFs that may promote iBAT whitening. (b) Heatmap shows expression changes of TFs that regulate lipid biosynthesis.