Journal Article

Premature aortic smooth muscle cell differentiation contributes to matrix dysregulation in Marfan Syndrome

Lang, Haili, Purcell, Laura N., Karpisek, Andrew, Dale, Matthew, Meisinger, Trevor, Carson, Jeffrey S., Liu, Zhibo, Batra, Rishi, Mietus, Constance J., Harding, Paul, Casale, George, Xiong, Wanfen, Pipinos, Iraklis, Fitzgerald, Matthew P., Koutakis, Panagiotis, Baxter, B. Timothy

2017

Overview

Thoracic aortic aneurysm and dissection are life-threatening complications of Marfan syndrome (MFS). Studies of human and mouse aortic samples from late stage MFS demonstrate increased TGF-β activation/signaling and diffuse matrix changes. However, the role of the aortic smooth muscle cell (SMC) phenotype in early aneurysm formation in MFS has yet to be fully elucidated. As our objective, we investigated whether an altered aortic SMC phenotype plays a role in aneurysm formation in MFS. We describe previously unrecognized concordant findings in the aortas of a murine model of MFS, mgR, during a critical and dynamic phase of early development. Using Western blot, gelatin zymography, and histological analysis, we demonstrated that at postnatal day (PD) 7, before aortic TGF-β levels are increased, there is elastic fiber fragmentation/disorganization and increased levels of MMP-2 and MMP-9. Compared to wild type (WT) littermates, aortic SMCs in mgR mice express higher levels of contractile proteins suggesting a switch to a more mature contractile phenotype. In addition, tropoelastin levels are decreased in mgR mice, a finding consistent with a premature switch to a contractile phenotype. Proliferation assays indicate a decrease in the proliferation rate of mgR cultured SMCs compared to WT SMCs. KLF4, a regulator of smooth muscle cell phenotype, was decreased in aortic tissue of mgR mice. Finally, overexpression of KLF4 partially reversed this phenotypic change in the Marfan SMCs. This study indicates that an early phenotypic switch appears to be associated with initiation of important metabolic changes in SMCs that contribute to subsequent pathology in MFS.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Aneurysm / Animal models / Animals / Aorta / Aorta, Thoracic - metabolism / Aorta, Thoracic - pathology / Aortic Aneurysm, Thoracic - genetics / Aortic Aneurysm, Thoracic - metabolism / Aortic Aneurysm, Thoracic - pathology / Aortic aneurysms / Apoptosis / Biology / Biology and Life Sciences / Bone morphogenetic proteins / Cell Differentiation / Cell Proliferation / Complications / Coronary vessels / Dissection / Elastic Tissue - metabolism / Elastic Tissue - pathology / Extracellular Matrix - metabolism / Extracellular Matrix - pathology / Gelatin / Gelatinase A / Gelatinase B / Gene expression / Gene Expression Regulation / Genotype & phenotype / Growth factors / Humans / Kinases / KLF4 protein / Kruppel-Like Transcription Factors - genetics / Kruppel-Like Transcription Factors - metabolism / Marfan syndrome / Marfan Syndrome - genetics / Marfan Syndrome - metabolism / Marfan Syndrome - pathology / Marfan's syndrome / Matrix Metalloproteinase 2 - genetics / Matrix Metalloproteinase 2 - metabolism / Matrix Metalloproteinase 9 - genetics / Matrix Metalloproteinase 9 - metabolism / Medical research / Medicine and Health Sciences / Mice / Mice, Transgenic / Muscle contraction / Myocytes, Smooth Muscle - metabolism / Myocytes, Smooth Muscle - pathology / Phenotype / Primary Cell Culture / Proteins / Research and Analysis Methods / Rodents / Signal Transduction / Smooth muscle / Surgery / Thorax / Transforming Growth Factor beta - genetics / Transforming Growth Factor beta - metabolism / Transforming growth factors / Tropoelastin / Tropoelastin - genetics / Tropoelastin - metabolism