Figure 7: siRNA Knock-Down of Thyroid Receptor Expression Inhibits Dust-Induced Triglyceride Accumulation.

3T3-L1 cells were transfected with either no siRNA, a negative control (scrambled) siRNA, or TRα and TRβ siRNAs and were then induced to differentiate as described in Methods. Cells were assessed after ten days of differentiation while exposed to set concentrations (16-fold dilutions of maximal concentrations) of nine select indoor house dust extracts. (A) Raw triglyceride accumulation per well relative to maximal response for rosiglitazone, (B) increase in pre-adipocyte proliferation (DNA content) relative to vehicle control, and (C) percent normalized triglyceride accumulation per cell relative to maximal rosiglitazone response (normalized to DNA content). The left bar in each pair depicts the response induced by the dust extract alone, while the right bar in each pair depicts the activity induced by the dust extract following transfection with TRα and TRβ siRNAs. Data presented as mean ± SEM from two independent experiments of four biological replicates. # = p < 0.10, * = p < 0.05, ** = p < 0.01 indicate statistical differences between TR siRNA and dust control samples as per one-way ANOVA and Dunnett’s posthoc test in GraphPad Prism 7.0. No significant differences were observed between the dust control samples and the negative control (scrambled) siRNA; see Supplemental Figures 7 and 8 for additional details on these results.