ABSTRACT: FUNDC1 protein levels were reduced in PH lung vessels from clinical subjects and animal models. Global Fundc1 deficiency exacerbated PH, while its overexpression is protective. The effect of FUNDC1 was mediated by endothelial cells rather than smooth muscle cells. Further, inducible loss of endothelial Fundc1 in postnatal mice was sufficient to cause PH spontaneously, whereas augmenting endothelial Fundc1 protected against PH before and after the onset of disease. Mechanistically, Fundc1 deficiency impaired basal mitophagy in endothelial cells, leading to accumulation of dysfunctional mitochondria, metabolic reprogramming towards aerobic glycolysis, pseudohypoxia and senescence, likely via a mtROS-HIF2α signaling pathway. Subsequently, Fundc1-deficient endothelial cells increased IGFBP2 secretion that drove pulmonary arterial remodeling to instigate PH. Finally, proof-of-principle in vivo studies showed significant efficacy on PH amelioration by targeting endothelial mitophagy, pseudohypoxia, senescence or IGFBP2.
Project description:FUNDC1 protein levels were reduced in PH lung vessels from clinical subjects and animal models. Global Fundc1 deficiency exacerbated PH, while its overexpression is protective. The effect of FUNDC1 was mediated by endothelial cells rather than smooth muscle cells. Further, inducible loss of endothelial Fundc1 in postnatal mice was sufficient to cause PH spontaneously, whereas augmenting endothelial Fundc1 protected against PH before and after the onset of disease. Mechanistically, Fundc1 deficiency impaired basal mitophagy in endothelial cells, leading to accumulation of dysfunctional mitochondria, metabolic reprogramming towards aerobic glycolysis, pseudohypoxia and senescence, likely via a mtROS-HIF2α signaling pathway. Subsequently, Fundc1-deficient endothelial cells increased IGFBP2 secretion that drove pulmonary arterial remodeling to instigate PH. Finally, proof-of-principle in vivo studies showed significant efficacy on PH amelioration by targeting endothelial mitophagy, pseudohypoxia, senescence or IGFBP2. We then performed gene expression profiling analysis using data obtained from RNA-seq of 2 different cells .
Project description:This experiment was conducted to identify mRNA transcripts alteration in muscle from skeletal muscle-sepcific Fundc1-knockout mice. The following abstract from the submitted manuscript describes the major findings of this work. Mitophagy directs muscle-adipose crosstalk to alleviate dietary obesity. Tingting Fu, Zhisheng Xu, Lin Liu, Qiqi Guo, Hao Wu, Xijun Liang, Danxia Zhou, Liwei Xiao, Lei Liu, Yong Liu, Min-Sheng Zhu, Quan Chen and Zhenji Gan. The quality of mitochondria in skeletal muscle is essential for maintaining metabolic homeostasis during adaptive stress responses. However, the precise control mechanism of muscle mitochondrial quality and its physiological impacts remain unclear. Here, we demonstrate that FUNDC1, a mediator of mitophagy, plays a critical role in controlling muscle mitochondrial quality as well as metabolic homeostasis. Skeletal muscle-specific ablation of FUNDC1 in mice resulted in LC3-mediated mitophagy defect, leading to impaired mitochondrial energetics. This caused decreased muscle fat utilization and endurance capacity during exercise. Interestingly, mice lacking muscle FUNDC1 were protected against high-fat diet-induced obesity with improved systemic insulin sensitivity and glucose tolerance despite reduced muscle mitochondrial energetics. Mechanistically, FUNDC1 deficiency elicited a retrograde response in muscle that upregulated FGF21 expression, thereby promoting the thermogenic remodeling of adipose tissue. Thus, these findings reveal a pivotal role of FUNDC1-dependent mitochondrial quality-control in mediating the muscle-adipose dialogue to regulate systemic metabolism.
Project description:Uncontrolled accumulation of pulmonary artery smooth muscle cells (PASMC) to the non-muscularized distal pulmonary arterioles (PAs) is one of the major characteristics of pulmonary hypertension (PH). Cellular senescence contributes to aging and lung diseases associated with PH and links to PH progression. However, the mechanism by which cellular senescence controls vascular remodeling in PH is not fully understood. Here, we have demonstrated that endothelial senescence mediates PH pathology by increasing platelet-derived growth factor (PDGFB) expression. The levels of senescence markers p16INK4A and senescence-associated β-galactosidase (SA-β-gal) are higher in PA endothelial cells (ECs) isolated from IPAH patients compared to those from healthy individuals. Hypoxia-induced accumulation of α-smooth muscle actin (αSMA)-positive cells to the PAs is attenuated in p16INK4Afl/fl-Cdh5(PAC)-CreERT2 mice after tamoxifen induction. We have reported that endothelial TWIST1 mediates hypoxia-induced vascular remodeling by increasing PDGFB expression. Transcriptomic analyses of idiopathic pulmonary arterial hypertension (IPAH) patient lung ECs or hypoxia-induced mouse lung ECs reveal the alteration of senescence-related gene expression and interaction with TWIST1. Increases in the levels of PDGFB and TWIST1 in hypoxia-treated mouse lung ECs or IPAH patient lung ECs are attenuated by knocking down p16INK4A expression or treating with senolytic reagents. Knockdown of p16INK4A also suppresses accumulation of αSMA–positive cells to the supplemented ECs in the gel. Exosomes collected from hypoxia-treated mouse lung ECs stimulate SMC DNA synthesis and migration in vitro and in the gel implanted on the mouse lungs, while p16INK4A knockdown in ECs inhibits the effects. These results suggest that endothelial senescence controls αSMA–positive cell proliferation and migration in PH through TWIST1-PDGFB signaling.
Project description:Studies of diabetic glomerular injury raise the possibility of developing useful early biomarkers and therapeutic approaches for the treatment of type 2 diabetic nephropathy (T2DN). In this study, it is found that FGF13 expression is induced in glomerular endothelial cells (GECs) during T2DN progression, and endothelial-specific deletion of Fgf13 potentially alleviates T2DN damage. Fgf13 deficiency restores the expression of Parkin both in the cytosolic, mitochondrial, and nuclear fractions under diabetic conditions, resulting in improved mitochondrial homeostasis and endothelial barrier integrity due to promotion of mitophagy and inhibition of apoptosis. Additionally, it is confirmed that the beneficial effects of Fgf13 deficiency on T2DN are abolished by endothelial-specific double deletion of Fgf13 and Prkn. The effects of Fgf13 deficiency on mitophagy and apoptosis via Parkin-dependent regulation may be distinct and separable events under diabetic conditions. These data show that the bifunctional role of Fgf13 deficiency in promoting mitophagy and inhibiting apoptosis through Parkin can shape mitochondrial homeostasis regulation in GECs and T2DN progression. Acting as a potential biomarker and therapeutic target for prevention and control of T2DN, mechanistically understanding of the biofunction of FGF13 may also be of relevance to the pathogenesis of other FGF13- and Parkin-associated diseases.
Project description:SRY-Box Transcription Factor 17 (SOX17) enhancers variants and mutations are found in patients with pulmonary arterial hypertension (PAH). In human PAH pulmonary endothelial cells, there is a significant downregulation of SOX17 expression. We hypothesized that SOX17 deficiency contributes to the pathogenesis of PAH and found that mice with endothelial specific disruption (ecKO Sox17) developed spontaneous pulmonary hypertension (PH) and exacerbated hypoxia-induced PH. Loss of SOX17 in lung ECs induced endothelial dysfunctions including upregulation of cell cycle programming and paracrine effect, proliferative and anti-apoptotic phenotypes, impaired cellular junction and BMP signaling. E2F Transcription Factor 1 (E2F1) signaling was showed to mediate the SOX17 deficiency-induced EC dysfunction. Pharmacological inhibition of E2F1 in ecKO Sox17 mice attenuated PH and cell cycle programming. Our study demonstrated that endothelial SOX17 deficiency induces PH through E2F1 and targeting E2F1 signaling represents a promising approach in PAH patients.
Project description:Uncontrolled accumulation of pulmonary artery smooth muscle cells (PASMC) to the distal pulmonary arterioles (PAs) is one of the major characteristics of pulmonary hypertension (PH). Cellular senescence contributes to aging and lung diseases associated with PH and links to PH progression. However, the mechanism by which cellular senescence controls vascular remodeling in PH is not fully understood. The levels of senescence marker, p16INK4A and senescence-associated β-galactosidase (SA-β-gal) activity are higher in PA endothelial cells (ECs) isolated from idiopathic pulmonary arterial hypertension (IPAH) patients compared to those from healthy individuals. Hypoxia-induced accumulation of α-smooth muscle actin (αSMA)-positive cells to the PAs is attenuated in p16fl/fl-Cdh5(PAC)-CreERT2 (p16iΔEC) mice after tamoxifen induction. We have reported that endothelial TWIST1 mediates hypoxia-induced vascular remodeling by increasing platelet-derived growth factor (PDGFB) expression. Transcriptomic analyses of IPAH patient or hypoxia-induced mouse lung ECs reveal the alteration of senescence-related gene expression and their interaction with TWIST1. Knockdown of p16INK4A attenuates the expression of PDGFB and TWIST1 in IPAH patient PAECs or hypoxia-treated mouse lungs and suppresses accumulation of αSMA–positive cells to the supplemented ECs in the gel implanted on the mouse lungs. Hypoxia-treated mouse lung EC-derived exosomes stimulate DNA synthesis and migration of PASMCs in vitro and in the gel implanted on the mouse lungs, while p16iΔEC mouse lung EC-derived exosomes inhibit the effects. These results suggest that endothelial senescence controls αSMA–positive cell proliferation and migration in PH through TWIST1-PDGFB signaling.
Project description:Erythropoietin (EPO) drives erythropoiesis and is secreted mainly by the kidney upon hypoxic or anemic stress. The paucity of EPO production in renal EPO-producing cells (REPs) causes renal anemia, one of the most common complications of chronic nephropathies. Although mitochondrial dysfunction is commonly observed in several renal and hematopoietic disorders, the mechanism by which mitochondrial quality control impacts renal anemia remains elusive. In this study, we showed that FUNDC1, a mitophagy receptor, plays a critical role in EPO-driven erythropoiesis induced by stresses. Mechanistically, EPO production is impaired in REPs in Fundc1-/- mice upon stresses, and the impairment is caused by the accumulation of damaged mitochondria, which consequently leads to the elevation of the reactive oxygen species (ROS) level and triggers inflammatory responses by up-regulating proinflammatory cytokines. These inflammatory factors promote the myofibroblastic transformation of REPs, resulting in the reduction of EPO production. We therefore provide a link between aberrant mitophagy and deficient EPO generation in renal anemia. Our results also suggest that the mitochondrial quality control safeguards REPs under stresses, which may serve as a potential therapeutic strategy for the treatment of renal anemia.
Project description:SRY-Box Transcription Factor 17 (SOX17) enhancers variants and mutations are found in patients with pulmonary arterial hypertension (PAH). In human PAH pulmonary microvascular endothelial cells (HPMVEC), there is a significant downregulation of SOX17 expression. We hypothesized that SOX17 deficiency contributes to the pathogenesis of PAH and found that mice with endothelial specific disruption (ecKO Sox17) developed spontaneous pulmonary hypertension (PH) and exacerbated hypoxia-induced PH. Loss of SOX17 in lung ECs induces cell cycle programming, proliferative and anti-apoptotic phenotypes, a process mediated by the activation of E2F Transcription Factor 1 (E2F1) signaling. Pharmacological inhibition of E2F1 in ecKO Sox17 mice attenuated PH and cell cycle programming. Our study demonstrated that endothelial SOX17 deficiency induces PH and targeting E2F1 signaling represents a promising approach in PAH patients.