miR-632 Induces DNAJB6 Inhibition Stimulating Endothelial-to-Mesenchymal Transition and Fibrosis in Marfan Syndrome Aortopathy

Abstract

Marfan syndrome (MFS) is a connective tissue disorder caused by FBN1 gene mutations leading to TGF-β signaling hyperactivation, vascular wall weakness, and thoracic aortic aneurysms (TAAs). The pathogenetic mechanisms are not completely understood and patients undergo early vascular surgery to prevent TAA ruptures. We previously reported miR-632 upregulation in MFS TAA tissues compared with non-genetic TAA tissues. DNAJB6 is a gene target of miR-632 in cancer and plays a critical role in blocking epithelial-to-mesenchymal transition by inhibiting the Wnt/β catenin pathway. TGF-β signaling also activates Wnt/β catenin signaling and induces endothelial-to-mesenchymal transition (End-Mt) and fibrosis. We documented that miR-632 upregulation correlated with DNAJB6 expression in both the endothelium and the tunica media of MFS TAA (p < 0.01). Wnt/β catenin signaling, End-Mt, and fibrosis markers were also upregulated in MFS TAA tissues (p < 0.05, p < 0.01 and p < 0.001). Moreover, miR-632 overexpression inhibited DNAJB6, inducing Wnt/β catenin signaling, as well as End-Mt and fibrosis exacerbation (p < 0.05 and p < 0.01). TGF-β1 treatment also determined miR-632 upregulation (p < 0.01 and p < 0.001), with the consequent activation of the aforementioned processes. Our study provides new insights about the pathogenetic mechanisms in MFS aortopathy. Moreover, the high disease specificity of miR-632 and DNAJB6 suggests new potential prognostic factors and/or therapeutic targets in the progression of MFS aortopathy.

miRNA Regulation of Cell Phenotype and Parietal Remodeling in Atherosclerotic and Non-Atherosclerotic Aortic Aneurysms: Differences and Similarities

“…The main pathway responsible for the End-MT is the canonical Transforming Growth Factor β (TGF-β) signaling in association with NOTCH and Wnt/β catenin signaling [ 8 , 23 , 24 ]. End-Mt has been observed in sporadic TAAs but appears to be more accentuated in MFS TAAs [ 7 ]. At the same time, SMCs in the tunica media can dedifferentiate in myofibroblasts, switching from a contractile phenotype to a proliferative/synthetic one.…”

“…Myofibroblasts deposit alcianophilic material like Glycosaminoglycans (GAGs) and collagen, determining fibrosis [ 25 ]. This process is well evidenced in sporadic TAAs and strongly exacerbated in MFS TAAs [ 7 ]. SMCs can also acquire an osteoblast-like phenotype, promoting calcification, especially in BAV TAAs [ 8 , 26 ].…”

“…An important association between the hyperactivation of TGF-β signaling and the pathogenesis of MFS TAA has been reported [ 99 ]. Moreover, several studies identified TGF-β-responsive miRNAs that play a critical role in the phenotypic changes of MFS vascular cells [ 7 , 100 ]. Merck et al analyzed the expression of miR-29b in the ascending aortas of MFS Fbn1 C1039G/+ and wild-type (WT) mice [ 100 ], showing a higher expression of that miRNA in the aortas of Fbn1 C1039G/+ mice.…”

“…In other studies, miR-632 has been proven to be likely involved in MFS pathological aortic remodeling and TGF-β1 signaling [ 7 , 21 ]. First, a differential expression of some specific miRNAs between sporadic and MFS TAA tissues was reported, especially a very important up-regulation of miR-632 [ 21 ].…”

“…All genetic TAAs occur at an early age but their underlying pathogenetic mechanisms can be very different. In fact, MFS TAAs display fibrosis [ 7 ], whereas BAV TAAs show mainly calcification [ 8 ].…”