| First Author | Su BH | Year | 2016 |
| Journal | J Pathol | Volume | 238 |
| Issue | 3 | Pages | 412-22 |
| PubMed ID | 26496995 | Mgi Jnum | J:241116 |
| Mgi Id | MGI:5897743 | Doi | 10.1002/path.4664 |
| Citation | Su BH, et al. (2016) Over-expression of prothymosin-alpha antagonizes TGFbeta signalling to promote the development of emphysema. J Pathol 238(3):412-22 |
| abstractText | Emphysema, a major consequence of chronic obstructive pulmonary disease (COPD), is characterized by the permanent airflow restriction resulting from enlargement of alveolar airspace and loss of lung elasticity. Transforming growth factor-beta (TGFbeta) signalling regulates the balance of matrix metalloproteinase (MMP)/tissue inhibitor of matrix metalloproteinase (TIMP) to control matrix homeostasis. Patients with COPD have dysregulated TGFbeta signalling and reduced histone deacetylase (HDAC) activity through epigenetic up-regulation of histone acetylation in the promoters of pro-inflammatory genes. However, the potential link between decreased HDAC activity and dysregulated TGFbeta signalling in emphysema pathogenesis remains to be determined. Prothymosin alpha (ProT), a highly conserved acidic nuclear protein, plays a role in the acetylation of histone and non-histone proteins. The aim of this study was to test the hypothesis that ProT inhibits TGFbeta-Smad signalling through Smad7, thereby contributing to emphysema pathogenesis. We show that ProT enhances Smad7 acetylation by decreasing its association with HDAC and thereby down-regulates TGFbeta-Smad signalling. ProT caused an imbalance between MMP and TIMP through acetylated Smad7 in favour of MMP expression. In addition to interfering with R-Smad activation and targeting receptors for degradation in the cytoplasm, acetylated Smad7 potentiated by ProT competitively antagonized binding of the pSmad2/3-Smad4 complex to the TIMP-3 promoter, resulting in reduced TIMP-3 expression. These effects were detected in ProT-over-expressing cells, lungs of ProT transgenic mice displaying an emphysema phenotype and in emphysema patients. Importantly, increased Smad7 and reduced TIMP-3 were found in the lungs of emphysema patients and mice with cigarette smoke extract (CSE)-induced emphysema. Such effects could be abrogated by silencing endogenous ProT expression. Collectively, our results uncover acetylated Smad7 regulated by ProT as an important determinant in dysregulated TGFbeta signalling that contributes to emphysema pathogenesis. |
