Targeting AGGF1 (angiogenic factor with G patch and FHA domains 1) for Blocking Neointimal Formation After Vascular Injury.

Despite recent improvements in angioplasty and placement of drug-eluting stents in treatment of atherosclerosis, restenosis and in-stent thrombosis impede treatment efficacy and cause numerous deaths. Research efforts are needed to identify new molecular targets for blocking restenosis. We aim to establish angiogenic factor AGGF1 (angiogenic factor with G patch and FHA domains 1) as a novel target for blocking neointimal formation and restenosis after vascular injury. AGGF1 shows strong expression in carotid arteries; however, its expression is markedly decreased in arteries after vascular injury. AGGF1+/- mice show increased neointimal formation accompanied with increased proliferation of vascular smooth muscle cells (VSMCs) in carotid arteries after vascular injury. Importantly, AGGF1 protein therapy blocks neointimal formation after vascular injury by inhibiting the proliferation and promoting phenotypic switching of VSMCs to the contractile phenotype in mice in vivo. In vitro, AGGF1 significantly inhibits VSMCs proliferation and decreases the cell numbers at the S phase. AGGF1 also blocks platelet-derived growth factor-BB-induced proliferation, migration of VSMCs, increases expression of cyclin D, and decreases expression of p21 and p27. AGGF1 inhibits phenotypic switching of VSMCs to the synthetic phenotype by countering the inhibitory effect of platelet-derived growth factor-BB on SRF expression and the formation of the myocardin/SRF/CArG-box complex involved in activation of VSMCs markers. Finally, we show that AGGF1 inhibits platelet-derived growth factor-BB-induced phosphorylation of MEK1/2, ERK1/2, and Elk phosphorylation involved in the phenotypic switching of VSMCs, and that overexpression of Elk abolishes the effect of AGGF1. AGGF1 protein therapy is effective in blocking neointimal formation after vascular injury by regulating a novel AGGF1-MEK1/2-ERK1/2-Elk-myocardin-SRF/p27 signaling pathway.

Yao Y ，Hu Z ，Ye J ，Hu C ，Song Q ，Da X ，Yu Y ，Li H ，Xu C ，Chen Q ，Wang QK ... -  《Journal of the American Heart Association》

Angiogenic Factor With G Patch and FHA Domains 1 Is a Novel Regulator of Vascular Injury.

Phenotypic modulation of vascular smooth muscle cells represents a hallmark event in vascular injury. The underlying mechanism is not completely sorted out. We investigated the involvement of angiogenic factor with G patch and FHA domains 1 (Aggf1) in vascular injury focusing on the transcriptional regulation of vascular smooth muscle cell signature genes. We report here that Aggf1 expression was downregulated in several different cell models of phenotypic modulation in vitro and in the vessels after carotid artery ligation in mice. Adenovirus-mediated Aggf1 overexpression dampened vascular injury and normalized vascular smooth muscle cell signature gene expression. Mechanistically, Aggf1 interacted with myocardin and was imperative for the formation of a serum response factor-myocardin complex on gene promoters. In response to injurious stimuli, kruppel-like factor 4 was recruited to the Aggf1 promoter and enlisted histone deacetylase 11 to repress Aggf1 transcription. In accordance, depletion of kruppel-like factor 4 or histone deacetylase 11 restored Aggf1 expression and abrogated vascular smooth muscle cell phenotypic modulation. Finally, treatment of a histone deacetylase 11 inhibitor attenuated vascular injury in mice. Therefore, we have unveiled a previously unrecognized role for Aggf1 in regulating vascular injury.

Zhou B ，Zeng S ，Li N ，Yu L ，Yang G ，Yang Y ，Zhang X ，Fang M ，Xia J ，Xu Y ... -  《-》

Angiogenic factor AGGF1 blocks neointimal formation after vascular injury via interaction with integrin α7 on vascular smooth muscle cells.

Angiogenic factor AGGF1 (AngioGenic factor with G-patch and FHA (Forkhead-Associated) domain 1) blocks neointimal formation (formation of a new or thickened layer of arterial intima) after vascular injury by regulating phenotypic switching of vascular smooth muscle cells (VSMCs). However, the AGGF1 receptor on VSMCs and the underlying molecular mechanisms of its action are unknown. In this study, we used functional analysis of serial AGGF1 deletions to reveal the critical AGGF1 domain involved in VSMC phenotypic switching. This domain was required for VSMC phenotypic switching, proliferation, cell cycle regulation, and migration, as well as the regulation of cell cycle inhibitors cyclin D, p27, and p21. This domain also contains an RDDAPAS motif via which AGGF1 interacts with integrin α7 (ITGA7), but not α8. In addition, we show that AGGF1 enhanced the expression of contractile markers MYH11, α-SMA, and SM22 and inhibited MEK1/2, ERK1/2, and ELK phosphorylation in VSMCs, and that these effects were inhibited by knockdown of ITGA7, but not by knockdown of ITGA8. In vivo, deletion of the VSMC phenotypic switching domain in mice with vascular injury inhibited the functions of AGGF1 in upregulating α-SMA and SM22, inhibiting MEK1/2, ERK1/2, and ELK phosphorylation, in VSMC proliferation, and in blocking neointimal formation. Finally, we show the inhibitory effect of AGGF1 on neointimal formation was blocked by lentivirus-delivered shRNA targeting ITGA7. Our data demonstrate that AGGF1 interacts with its receptor integrin α7 on VSMCs, and this interaction is required for AGGF1 signaling in VSMCs and for attenuation of neointimal formation after vascular injury.

Yu Y ，Li Y ，Peng H ，Song Q ，Da X ，Li H ，He Z ，Ren X ，Xu C ，Yao Y ，Wang QK ... -  《-》

Fibroblast Growth Factor 12 Is a Novel Regulator of Vascular Smooth Muscle Cell Plasticity and Fate.

Vascular smooth muscle cells (VSMCs) modulate their phenotype between synthetic and contractile states in response to environmental changes; this modulation plays a crucial role in the pathogenesis of restenosis and atherosclerosis. Here, we identified fibroblast growth factor 12 (FGF12) as a novel key regulator of the VSMC phenotype switch. Using murine models and human specimens, we found that FGF12 was highly expressed in contractile VSMCs of normal vessel walls but was downregulated in synthetic VSMCs from injured and atherosclerotic vessels. In human VSMCs, FGF12 expression was inhibited at the transcriptional level by platelet-derived growth factor-BB. Gain- and loss-of-function experiments showed that FGF12 was both necessary and sufficient for inducing and maintaining the quiescent and contractile phenotypes of VSMCs. FGF12 inhibited cell proliferation through the p53 pathway and upregulated the key factors involved in VSMC lineage differentiation, such as myocardin and serum response factor. Such FGF12-induced phenotypic change was mediated by the p38 MAPK (mitogen-activated protein kinase) pathway. Moreover, FGF12 promoted the differentiation of mouse embryonic stem cells and the transdifferentiation of human dermal fibroblasts into SMC-like cells. Furthermore, adenoviral infection of FGF12 substantially decreased neointima hyperplasia in a rat carotid artery injury model. In general, FGF family members induce a synthetic VSMC phenotype. Interestingly, the present study showed the unanticipated finding that FGF12 belonging to FGF family, strongly induced the quiescent and contractile VSMC phenotypes and directly promoted VSMC lineage differentiation. These novel findings suggested that FGF12 could be a new therapeutic target for treating restenosis and atherosclerosis.

Song SH ，Kim K ，Jo EK ，Kim YW ，Kwon JS ，Bae SS ，Sung JH ，Park SG ，Kim JT ，Suh W ... -  《-》

Myocardin regulates vascular response to injury through miR-24/-29a and platelet-derived growth factor receptor-β.

Talasila A ，Yu H ，Ackers-Johnson M ，Bot M ，van Berkel T ，Bennett MR ，Bot I ，Sinha S ... -  《-》