Fig. 2

Effects of DNA methylation on the transcription efficiency and promoter activity of BmCHSA-2b. a Effect of methyltransferase inhibitor 5-aza-dC on the methylation level of the CpGI2 in the promoter of BmCHSA-2b in the 3-day-old pupal wings (top panel) and epidermis (low panel). Red line: PBS treatment, Blue line: 5-aza-dC treatment. b Effect of 5-aza-dC treatment on the transcription levels of the BmCHSA-2b in the 3-day-old pupal wings (WD) and epidermis (EP). c Effect of 5-aza-dC treatment on the luciferase activity in the Bm12 cells. The cells were transfected with the CpGI2 promoter luciferase vector (pWT-CpGI2-Luc) or the CpGI2-mutated promoter luciferase vector (pMut-CpGI2-Luc) and were added with 1 µL of 1 μg/μL 5-aza-dC. d Electrophoretic mobility shift assay (EMSA) showing the binding of BmDnmt1 protein to the CpGI2 probe. The wild-type and mutant probes were labeled with biotin. The cold probe was the unlabeled wild-type CpGI2 probe. e Effect of BmDnmt1 overexpression on the luciferase activity in the Bm12 cells. The cells were co-transfected with the CpGI2 promoter luciferase vector (pWT-CpGI2-Luc) or the CpGI2-mutated promoter luciferase vector (pMut-CpGI2-Luc) and the BmDnmt1 protein expression vector (pBmDnmt-GFP) or GFP expression vector (pGFPN1, control). (F) Effect of BmDnmt1 RNAi on the luciferase activity in the Bm12 cells. The cells were co-transfected with dsBmDnmt1 or dsgfp (control) and the CpGI2 promoter luciferase vector (pWT-CpGI2-Luc) or the CpGI2-mutated promoter luciferase vector (pMut-CpGI2-Luc), which expresses luciferase under the control of the wild-type or mutant CpGI2 promoter. For the t test: p < 0.01(**). The sequences of the wild-type and mutant CpGI2 are shown in Additional file 10: Table S1