Research Paper Volume 13, Issue 15 pp 19442—19459

CC16-TNF-α negative feedback loop formed between Clara cells and normal airway epithelial cells protects against diesel exhaust particles exposure-induced inflammation

C/EBPα regulates CC16 secretion via Munc18b in CC16+ cells. After transfection of CC16+ cells with pcDNA-ctrl, pcDNA-C/EBPα, pcDNA-C/EBPα+si-Munc18b, si-ctrl, si-C/EBPα, or si-C/EBPα+ pcDNA-CC16, cells are cultured for 48 h, and then cells and culture supernatants are collected. (A, B) The effects of C/EBPα overexpression or knockdown on CC16 mRNA and protein released into the culture media are detected by RT-PCR and ELISA. (C, D) The effects of C/EBPα overexpression or knockdown on Munc18b mRNA and protein expression are detected by RT-PCR and western blot assay. (E, F) The increase of CC16 secretion induced by C/EBPα overexpression is abolished by Munc18b knockdown, while the decrease of CC16 secretion induced by C/EBPα knockdown is not affected by CC16 overexpression. **P P ##P  vs. pcDNA-C/EBPα group.

Figure 3. C/EBPα regulates CC16 secretion via Munc18b in CC16+ cells. After transfection of CC16+ cells with pcDNA-ctrl, pcDNA-C/EBPα, pcDNA-C/EBPα+si-Munc18b, si-ctrl, si-C/EBPα, or si-C/EBPα+ pcDNA-CC16, cells are cultured for 48 h, and then cells and culture supernatants are collected. (A, B) The effects of C/EBPα overexpression or knockdown on CC16 mRNA and protein released into the culture media are detected by RT-PCR and ELISA. (C, D) The effects of C/EBPα overexpression or knockdown on Munc18b mRNA and protein expression are detected by RT-PCR and western blot assay. (E, F) The increase of CC16 secretion induced by C/EBPα overexpression is abolished by Munc18b knockdown, while the decrease of CC16 secretion induced by C/EBPα knockdown is not affected by CC16 overexpression. **P < 0.01 and ***P < 0.001 vs. pcDNA-ctrl or si-ctrl group; ##P < 0.01 vs. pcDNA-C/EBPα group.