Fig. 3.

Knockdown of Irx3 repressed the differentiation of SVFs toward beige adipocytes in vitro.

(A–B) (A) Relative mRNA and (B) protein levels of Irx3 in SVFs from IWAT were efficiently knocked down after a 3-day infection of mouse Irx3 lentiviral shRNA (n = 3 for each group). (C–D) (C) Oil Red O staining and (D) TG concentration of the mature beige adipocytes under eight-day differentiation (n = 6 for each group). (E) Relative mRNA expression of Ucp1, Cidea, Pgc-1α, C/ebpβ, and Prdm16 at different time points during beige adipocyte differentiation from IWAT SVFs (n = 3–4 for different groups). (F–G) (F) Relative mRNA (n = 4) and (G) protein expression of brown adipocyte marker genes of the induced beige adipocytes from mouse IWAT SVTs for eight days with the infection of mouse Irx3 lentiviral shRNA, with or without CL-316,243 activation. (H) Relative mRNA expression of adipocyte differentiation-related genes in beige adipocytes (n = 4). (I) Relative mRNA expression of the indicated genes in the induced brown adipocytes from mouse BAT SVFs for eight days, with the infection of mouse Irx3 lentiviral shRNA (n = 4). (J) Relative mRNA levels of IRX3 in SVFs from human sWAT after a 3-day infection of human IRX3 lentiviral shRNA (left), and the mRNA levels of brown adipocyte marker genes in the SVFs under 2-day differentiation (n = 4). (K) OCR measurement of the beige adipocytes under 5-day differentiation, with the infection of mouse Irx3 lentiviral shRNA (n = 5). (L–N) (L) Ucp1 promoter-luciferase reporter activity was measured in HEK293T cells transfected with pEGFP-C1 vector or IRX3 for 48 h. (M) Schematic diagram of the mutant mouse Ucp1 promoter deleting ACATGTGT among the − 3470 to − 3463 bp region proximal to the TSS of the Ucp1 gene. (N) Transcriptional activity of wild-type or mutant Ucp1 promoter was measured with IRX3 overexpression. (O) qPCR of Ucp1 promoter binding region which was recruited by Irx3 antibody in 8-day induced beige adipocytes, as analyzed by ChIP. Fold enrichment of Ucp1 promoter was given (n = 3). For the measurement of luciferase activity, cells were seeded on 24-well plate and transfected with 800 ng pEGFP-C1 vector or IRX3, 200 ng Ucp1 promoter construct, and 1 ng pRL-SV40, followed by the harvest for luciferase activity assessment using a dual-luciferase reporter assay system (Promega). Luciferase activity was corrected for Renilla luciferase activity (n = 3–4 for each group). For qPCR data, mRNA expression was normalized to 36b4 for mouse genes and βACTIN for human genes. SVF cells were isolated from IWAT and BAT of C57BL/6J mice or human sWAT wherever mentioned, and IRX3 shRNA were introduced to cells 24 h after seeding. Data were presented as mean ± s.e.m. *P < 0.05, **P < 0.01, ***P < 0.001. The results are representative of at least three independent experiments. NT, no targeting.