Airway smooth muscle cells from ovalbumin-sensitized mice show increased proliferative response to TGFβ1 due to upregulation of Smad3 and TGFβRII

ABSTRACT

Objective: This study aimed to elucidate the role of Transforming growth factor (TGF)-β1 signaling in the proliferation of airway smooth muscle cells (ASMCs). Background: TGF-β1 is an important cytokine in airway remodeling in asthma. However, results of studies focusing on the effect of TGFβ1 on proliferation of ASMCs are controversial. Methods: An allergic model that mimics airway remodeling in chronic asthma was established and primary ASMCs were cultured. Cell proliferation was detected by viable cell counting and Cell Counting Kit (CCK)-8 analysis. Expression and phosphorylation of Smad3, type 1 TGFβ receptor (TGFβRI), type 2 TGFβ receptor (TGFβRII), extracellular signal-regulated kinase (ERK)-1/2, p38 mitogen-activated protein kinase (MAPK), C-Jun N-terminal kinase (JNK) and AKT were detected by western blot. siRNAs were used to knock down Smad3 and TGFβRII. Results: Smad3 and TGFβRII were up-regulated in primary ASMCs isolated from ovalbumin (OVA)-sensitized mice as compared with ASMCs isolated from unsensitized control mice, which persisted for at least four passages. TGFβ1 stimulated proliferation of ASMCs isolated from OVA-sensitized mice, which was inhibited by specific siRNA targeting Smad3 or TGFβRII. However ASMCs from control mice showed no proliferative response to TGFβ1. TGFβ1-induced proliferation of ASMCs from OVA-sensitized mice was markedly attenuated by PD-98059, a specific ERK1/2 inhibitor. TGFβ1 induced ERK1/2 phosphorylation within 15 minute, which was partially blocked by specific inhibitor of Smad3 (SIS3). Conclusions: ASMCs isolated from OVA-sensitized mice showed hyper-proliferation upon TGFβ1 stimulation. This might have been associated with up-regulated Smad3 and TGFβRII and mediated by ERK1/2 downstream to Smad3.

KEYWORDS:

• Airway smooth muscle cell
• asthma
• ERK1/2
• Smad3
• TGFβ1

Acknowledgments

The authors thank coworker of Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation for technical support. We also thank Animal Experiments Center of Sun Yat-sen University for the experimentation on animals.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Funding

This work was supported by the National Natural Science Foundation of China (81370120, 81500018) and by the Guangdong Natural Science Foundation (S2013010014803).