MFAP4 Promotes Vascular Smooth Muscle Migration, Proliferation and Accelerates Neointima Formation.

Arterial injury stimulates remodeling responses that, when excessive, lead to stenosis. These responses are influenced by integrin signaling in vascular smooth muscle cells (VSMCs). Microfibrillar-associated protein 4 (MFAP4) is an integrin ligand localized to extracellular matrix fibers in the vascular wall. The role of MFAP4 in vascular biology is unknown. We aimed to test the hypothesis that MFAP4 would enhance integrin-dependent VSMC activation. We produced Mfap4-deficient (Mfap4(-/-)) mice and performed carotid artery ligation to explore the role of MFAP4 in vascular biology in vivo. Furthermore, we investigated the effects of MFAP4 in neointimal formation ex vivo and in primary VSMC and monocyte cultures in vitro. When challenged with carotid artery ligation, Mfap4(-/-) mice exhibited delayed neointimal formation, accompanied by early reduction in the number of proliferating medial and neointimal cells, as well as infiltrating leukocytes. Delayed neointimal formation was associated with decreased cross-sectional area of ligated Mfap4(-/-) carotid arteries resulting in lumen narrowing 28 days after ligation. MFAP4 blockade prohibited the formation of neointimal hyperplasia ex vivo. Moreover, we demonstrated that MFAP4 is a ligand for integrin αVβ3 and mediates VSMC phosphorylation of focal adhesion kinase, migration, and proliferation in vitro. MFAP4-dependent VSMC activation was reversible by treatment with MFAP4-blocking antibodies and inhibitors of focal adhesion kinase and downstream kinases. In addition, we showed that MFAP4 promotes monocyte chemotaxis in integrin αVβ3-dependent manner. MFAP4 regulates integrin αVβ3-induced VSMC proliferation and migration, as well as monocyte chemotaxis, and accelerates neointimal hyperplasia after vascular injury.

Schlosser A ，Pilecki B ，Hemstra LE ，Kejling K ，Kristmannsdottir GB ，Wulf-Johansson H ，Moeller JB ，Füchtbauer EM ，Nielsen O ，Kirketerp-Møller K ，Dubey LK ，Hansen PB ，Stubbe J ，Wrede C ，Hegermann J ，Ochs M ，Rathkolb B ，Schrewe A ，Bekeredjian R ，Wolf E ，Gailus-Durner V ，Fuchs H ，Hrabě de Angelis M ，Lindholt JS ，Holmskov U ，Sorensen GL ... -  《-》

BubR1 insufficiency inhibits neointimal hyperplasia through impaired vascular smooth muscle cell proliferation in mice.

BubR1, a cell cycle-related protein, is an essential component of the spindle checkpoint that regulates cell division. Mice with BubR1 expression reduced to 10% of the normal level display a phenotype characterized by progeria; however, the involvement of BubR1 in vascular diseases is still unknown. We generated mice in which BubR1 expression was reduced to 20% (BubR1(L/L) mice) of that in wild-type mice (BubR1(+/+)) to investigate the effects of BubR1 on arterial intimal hyperplasia. Ten-week-old male BubR1(L/L) and age-matched wild-type littermates (BubR1(+/+)) were used in this study. The left common carotid artery was ligated, and histopathologic examinations were conducted 4 weeks later. Bone marrow transplantation was also performed. Vascular smooth muscle cells (VSMCs) were isolated from the thoracic aorta to examine cell proliferation, migration, and cell cycle progression. Severe neointimal hyperplasia was observed after artery ligation in BubR1(+/+) mice, whereas BubR1(L/L) mice displayed nearly complete inhibition of neointimal hyperplasia. Bone marrow transplantation from all donors did not affect the reconstitution of 3 hematopoietic lineages, and neointimal hyperplasia was still suppressed after bone marrow transplantation from BubR1(+/+) mice to BubR1(L/L) mice. VSMC proliferation was impaired in BubR1(L/L) mice because of delayed entry into the S phase. VSMC migration was unaffected in these BubR1(L/L) mice. p38 mitogen-activated protein kinase-inhibited VSMCs showed low expression of BubR1, and BubR1-inhibited VSMCs showed low expression of p38. BubR1 may represent a new target molecule for treating pathological states of vascular remodeling, such as restenosis after angioplasty.

Kyuragi R ，Matsumoto T ，Harada Y ，Saito S ，Onimaru M ，Nakatsu Y ，Tsuzuki T ，Nomura M ，Yonemitsu Y ，Maehara Y ... -  《-》

Mindin regulates vascular smooth muscle cell phenotype and prevents neointima formation.

Zhu LH ，Huang L ，Zhang X ，Zhang P ，Zhang SM ，Guan H ，Zhang Y ，Zhu XY ，Tian S ，Deng K ，Li H ... -  《-》

Thrombospondin-1 activates medial smooth muscle cells and triggers neointima formation upon mouse carotid artery ligation.

Moura R ，Tjwa M ，Vandervoort P ，Cludts K ，Hoylaerts MF ... -  《-》

Deletion of Hyaluronan Synthase 3 Inhibits Neointimal Hyperplasia in Mice.

Hyaluronan (HA) is a polymeric glucosaminoglycan that forms a provisional extracellular matrix in diseased vessels. HA is synthesized by 3 different HA synthases (HAS1, HAS2, and HAS3). Aim of this study was to unravel the role of the HAS3 isoenzyme during experimental neointimal hyperplasia. Neointimal hyperplasia was induced in Has3-deficient mice by ligation of the carotid artery. HA in the media of Has3-deficient mice was decreased 28 days after ligation, and neointimal hyperplasia was strongly inhibited. However, medial and luminal areas were unaffected. Cell density, proliferation, and apoptosis were not altered, suggesting a proportional decrease of both, the number of cells and extracellular matrix. In addition, endothelial function as determined by acetylcholine-induced relaxation of aortic rings, immunoblotting of endothelial nitric oxide synthase, and arterial blood pressure were not affected. Furthermore, the oxidative stress response was not affected as determined in total protein extracts from aortae. Transcriptome analysis comparing control versus ligated carotid arteries hinted toward a mitigated differential regulation of various signaling pathways in Has3-deficient mice in response to ligation that were related to vascular smooth muscle cell (VSMC) migration, including focal adhesions, integrins, mitogen-activated protein kinase, and phosphatidylinositol signaling system. Lentiviral overexpression of HAS3 in VSMC supported the migratory phenotype of VSMC in response to platelet-derived growth factor BB in vitro. Accordingly, knockdown of HAS3 reduced the migratory response to platelet-derived growth factor BB and in addition decreased the expression of PDGF-B mRNA. HAS3-mediated HA synthesis after vessel injury supports seminal signaling pathways in activation of VSMC, increases platelet-derived growth factor BB-mediated migration, and in turn enhances neointimal hyperplasia in vivo.

Kiene LS ，Homann S ，Suvorava T ，Rabausch B ，Müller J ，Kojda G ，Kretschmer I ，Twarock S ，Dai G ，Deenen R ，Hartwig S ，Lehr S ，Köhrer K ，Savani RC ，Grandoch M ，Fischer JW ... -  《-》