Control of Cardiac Fibroblast Phenotype by the Meox2/Zeb2 Signalling Switch (LB47)

• Published in: The FASEB journal 2014-04, Vol.28 (S1), p.n/a
• Main Authors: Jahan, Fahmida, Northcott, Josette, Cunnington, Ryan, Cheung, David, Rattan, Sunil, Filomeno, Krista, Dixon, Ian, Wigle, Jeffrey
• Format: Article
• Language: English
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.28.1_supplement.lb47

The fibroblast to myofibroblast phenoconversion, which is induced by TGF‐β, is a crucial step during cardiac fibrosis. Activated myofibroblasts increase extracellular matrix (ECM) synthesis, which impairs contraction that results in myocardial stiffening, and eventually heart failure. Meox2, a regulator of cell proliferation and senescence, can block TGF‐β mediated epithelial to mesenchymal transition (EMT). In contrast, Zeb2, a repressor of Meox2, enhances EMT in concert with TGF‐β. However, their roles in the fibroblast to myofibroblast phenoconversion remain elusive. We have shown that Meox2 is more highly expressed in fibroblasts than in myofibroblasts. Conversely, Zeb2 expression is lower in fibroblasts but higher in myofibroblasts. This suggests that Meox2/Zeb2 may regulate the fibroblast phenotype during cardiac fibrosis. We have shown that ectopic expression of Meox2 represses a set of myofibroblast markers. We have successfully knocked down Meox2 protein in primary cells. By confocal microscopy, Meox2 protein was found to be confined to the nuclei of fibroblasts whereas a cytoplasmic distribution was seen in myofibroblasts. By immunoblotting, Zeb2 expression was found to be higher in the nuclei of myofibroblasts. To test if ectopic Zeb2 expression enhances this phenoconversion, we have recently generated an adenoviral Zeb2 expression construct. We anticipate that the Meox2/Zeb2 signalling switch plays a critical role in cardiac fibrosis and findings from this study may provide a basis for developing Meox2 or Zeb2 based novel anti‐fibrotic drugs in the future. Grant Funding Source: Supported by Canadian Institutes of Health Research & Heart and Stroke Foundation of Canada