OBJECTIVETo investigate the relation between transdifferentiation of the airway myofibroblasts and the expression level of (trypsinogen16, TG16) in vitro and explore the mechanism of airway basement membrane thickening.

METHODSThe total lung proteins were extracted from normal and OVA-induced asthmatic mice and the protein expression profiles were analyzed with SDS-PAGE. The differentially expressed proteins were isolated for analysis with liquid chromatography-mass spectrometry. TG16 was cloned from mouse lung tissue and subcloned into the expression vector pcDNA3.0 to generate a pcDNA3-TG16 plasmid. The vectors were transfected into mouse embryonic fibroblast 3T3 cells and cultured in MEM in the presence of transforming growth factor-beta1 (TGF-beta1). The mRNA levels of alpha-actin and the housekeeping GAPDH gene were analyzed with RT-PCR. Using RNA interference, TG16 expression was suppressed and the resultant alpha-actin or GAPDH protein levels were analyzed using Western blotting.

RESULTSIn the total lung proteins from OVA-induced mice, a 25 000 Da protein was significantly enhanced in comparison with the protein profiles of normal mice. The protein band was identified to represent the protein of TG16. With TGF-beta1 stimulation, transfection with the plasmid pcDNA3-TG16 significantly suppressed the mRNA expression of alpha-actin (alpha-actin/GAPDH=1.78-/+0.50) in 3T3 cells as compared with the expression in cells transfected with pcDNA3.0 (3.20-/+1.36); transfection of the cells with TG16 stealth RNAi oligonucleotide to decrease TG16 mRNA level upregulated the protein level of alpha-actin (3.60-/+0.44) as compared with the alpha-actin protein level in 3T3 cells transfected with control oligonucleotide (2.78-/+0.50).

CONCLUSIONTG16 can inhibit the expression of alpha-actin in fibroblasts, which might be a protective mechanism in the progression of airway remodeling in asthma.