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.

SUMOylation of Vps34 by SUMO1 promotes phenotypic switching of vascular smooth muscle cells by activating autophagy in pulmonary arterial hypertension.

INTRODUCTION: Pulmonary arterial hypertension (PAH) is a life-threatening disease without effective therapies. PAH is associated with a progressive increase in pulmonary vascular resistance and irreversible pulmonary vascular remodeling. SUMO1 (small ubiquitin-related modifier 1) can bind to target proteins and lead to protein SUMOylation, an important post-translational modification with a key role in many diseases. However, the contribution of SUMO1 to PAH remains to be fully characterized. METHODS: In this study, we explored the role of SUMO1 in the dedifferentiation of vascular smooth muscle cells (VSMCs) involved in hypoxia-induced pulmonary vascular remodeling and PAH in vivo and in vitro. RESULTS: In a mouse model of hypoxic PAH, SUMO1 expression was significantly increased, which was associated with activation of autophagy (increased LC3b and decreased p62), dedifferentiation of pulmonary arterial VSMCs (reduced α-SMA, SM22 and SM-MHC), and pulmonary vascular remodeling. Similar results were obtained in a MCT-induced PAH model. Overexpression of SUMO1 significantly increased VSMCs proliferation, migration, hypoxia-induced VSMCs dedifferentiation, and autophagy, but these effects were abolished by inhibition of autophagy by 3-MA in aortic VSMCs. Furthermore, SUMO1 knockdown reversed hypoxia-induced proliferation and migration of PASMCs. Mechanistically, SUMO1 promotes Vps34 SUMOylation and the assembly of the Beclin-1-Vps34-Atg14 complex, thereby inducing autophagy, whereas Vps34 mutation K840R reduces Vps34 SUMOylation and inhibits VSMCs dedifferentiation. DISCUSSION: Our data uncovers an important role of SUMO1 in VSMCs proliferation, migration, autophagy, and phenotypic switching (dedifferentiation) involved in pulmonary vascular remodeling and PAH. Targeting of the SUMO1-Vps34-autophagy signaling axis may be exploited to develop therapeutic strategies to treat PAH.

Protein therapy of skeletal muscle atrophy and mechanism by angiogenic factor AGGF1.

BACKGROUND: Skeletal muscle atrophy is a common condition without a pharmacologic therapy. AGGF1 encodes an angiogenic factor that regulates cell differentiation, proliferation, migration, apoptosis, autophagy and endoplasmic reticulum stress, promotes vasculogenesis and angiogenesis and successfully treats cardiovascular diseases. Here, we report the important role of AGGF1 in the pathogenesis of skeletal muscle atrophy and attenuation of muscle atrophy by AGGF1. METHODS: In vivo studies were carried out in impaired leg muscles from patients with lumbar disc herniation, two mouse models for skeletal muscle atrophy (denervation and cancer cachexia) and heterozygous Aggf1+/- mice. Mouse muscle atrophy phenotypes were characterized by body weight and myotube cross-sectional areas (CSA) using H&E staining and immunostaining for dystrophin. Molecular mechanistic studies include co-immunoprecipitation (Co-IP), western blotting, quantitative real-time PCR analysis and immunostaining analysis. RESULTS: Heterozygous Aggf1+/- mice showed exacerbated phenotypes of reduced muscle mass, myotube CSA, MyHC (myosin heavy chain) and α-actin, increased inflammation (macrophage infiltration), apoptosis and fibrosis after denervation and cachexia. Intramuscular and intraperitoneal injection of recombinant AGGF1 protein attenuates atrophy phenotypes in mice with denervation (gastrocnemius weight 81.3 ± 5.7 mg vs. 67.3 ± 5.1 mg for AGGF1 vs. buffer; P < 0.05) and cachexia (133.7 ± 4.7 vs. 124.3 ± 3.2; P < 0.05). AGGF1 expression undergoes remodelling and is up-regulated in gastrocnemius and soleus muscles from atrophy mice and impaired leg muscles from patients with lumbar disc herniation by 50-60% (P < 0.01). Mechanistically, AGGF1 interacts with TWEAK (tumour necrosis factor-like weak inducer of apoptosis), which reduces interaction between TWEAK and its receptor Fn14 (fibroblast growth factor-inducing protein 14). This leads to inhibition of Fn14-induced NF-kappa B (NF-κB) p65 phosphorylation, which reduces expression of muscle-specific E3 ubiquitin ligase MuRF1 (muscle RING finger 1), resulting in increased MyHC and α-actin and partial reversal of atrophy phenotypes. Autophagy is reduced in Aggf1+/- mice due to inhibition of JNK (c-Jun N-terminal kinase) activation in denervated and cachectic muscles, and AGGF1 treatment enhances autophagy in two atrophy models by activating JNK. In impaired leg muscles of patients with lumbar disc herniation, MuRF1 is up-regulated and MyHC and α-actin are down-regulated; these effects are reversed by AGGF1 by 50% (P < 0.01). CONCLUSIONS: These results indicate that AGGF1 is a novel regulator for the pathogenesis of skeletal muscle atrophy and attenuates skeletal muscle atrophy by promoting autophagy and inhibiting MuRF1 expression through a molecular signalling pathway of AGGF1-TWEAK/Fn14-NF-κB. More importantly, the results indicate that AGGF1 protein therapy may be a novel approach to treat patients with skeletal muscle atrophy.

AGGF1 therapy inhibits thoracic aortic aneurysms by enhancing integrin α7-mediated inhibition of TGF-ß1 maturation and ERK1/2 signaling.

Thoracic aortic aneurysm (TAA) is a localized or diffuse dilatation of the thoracic aortas, and causes many sudden deaths each year worldwide. However, there is no effective pharmacologic therapy. Here, we show that AGGF1 effectively blocks TAA-associated arterial inflammation and remodeling in three different mouse models (mice with transverse aortic constriction, Fbn1C1041G/+ mice, and ß-aminopropionitrile-treated mice). AGGF1 expression is reduced in the ascending aortas from the three models and human TAA patients. Aggf1+/- mice and vascular smooth muscle cell (VSMC)-specific Aggf1smcKO knockout mice show aggravated TAA phenotypes. Mechanistically, AGGF1 enhances the interaction between its receptor integrin α7 and latency-associated peptide (LAP)-TGF-ß1, blocks the cleavage of LAP-TGF-ß1 to form mature TGF-ß1, and inhibits Smad2/3 and ERK1/2 phosphorylation in VSMCs. Pirfenidone, a treatment agent for idiopathic pulmonary fibrosis, inhibits TAA-associated vascular inflammation and remodeling in wild type mice, but not in Aggf1+/- mice. In conclusion, we identify an innovative AGGF1 protein therapeutic strategy to block TAA-associated vascular inflammation and remodeling, and show that efficacy of TGF-ß inhibition therapies require AGGF1.

Endothelial cell metabolic memory causes cardiovascular dysfunction in diabetes.

AIMS: The aim of this study was to identify the molecular mechanism for hyperglycaemia-induced metabolic memory in endothelial cells (ECs), and to show its critical importance to development of cardiovascular dysfunction in diabetes. METHODS AND RESULTS: Hyperglycaemia induces increased nuclear factor-κB (NF-κB) signalling, up-regulation of miR-27a-3p, down-regulation of nuclear factor erythroid-2 related factor 2 (NRF2) expression, increased transforming growth factor-ß (TGF-ß) signalling, down-regulation of miR-29, and induction of endothelial-to-mesenchymal transition (EndMT), all of which are memorized by ECs and not erased when switched to a low glucose condition, thereby causing perivascular fibrosis and cardiac dysfunction. Similar metabolic memory effects are found for production of nitric oxide (NO), generation of reactive oxygen species (ROS), and the mitochondrial oxygen consumption rate in two different types of ECs. The observed metabolic memory effects in ECs are blocked by NRF2 activator tert-butylhydroquinone and a miR-27a-3p inhibitor. In vivo, the NRF2 activator and miR-27a-3p inhibitor block cardiac perivascular fibrosis and restore cardiovascular function by decreasing NF-κB signalling, down-regulating miR-27a-3p, up-regulating NRF2 expression, reducing TGF-ß signalling, and inhibiting EndMT during insulin treatment of diabetes in streptozotocin-induced diabetic mice, whereas insulin alone does not improve cardiac function. CONCLUSIONS: Our data indicate that disruption of hyperglycaemia-induced EC metabolic memory is required for restoring cardiac function during treatment of diabetes, and identify a novel molecular signalling pathway of NF-κB/miR-27a-3p/NRF2/ROS/TGF-ß/EndMT involved in metabolic memory.