Project description:Vasculogenesis involves the differentiation of vascular endothelial progenitors de novo from undifferentiated mesoderm, their migration and coalescence to form the major embryonic vessels and the acquisition of arterial or venous identity. Vascular Endothelial Growth Factor (Vegf) signaling plays multiple roles during vascular development. However, its function during embryonic vasculogenesis has been controversial. Previous studies have implicated Vegf signaling in either regulating arteriovenous specification or overall vascular endothelial differentiation. To clarify the role of Vegf in embryonic vasculogenesis and identify its downstream targets, we used chemical inhibitors of Vegf receptor (Vegfr) signaling in zebrafish embryos as well as zebrafish genetic mutants. A high level of chemical inhibition of Vegfr signaling resulted in the reduction of overall vascular endothelial marker gene expression, including downregulation of both arterial and venous markers, ultimately leading to the apoptosis of vascular endothelial cells. In contrast, a low level of Vegfr inhibition specifically blocked arterial specification while the expression of venous markers appeared largely unaffected or increased. Inhibition of Vegfr signaling prior to the initiation of vasculogenesis reduced overall vascular endothelial differentiation, while inhibition of Vegfr signaling starting at mid-somitogenesis stages largely inhibited arterial specification. Conversely, Vegf overexpression resulted in the expansion of both arterial and pan-endothelial markers, while the expression of several venous-specific markers was downregulated. We further show that Vegf signaling affects overall endothelial differentiation by modulating the expression of the ETS transcription factor etv2/ etsrp. etv2 expression was downregulated in Vegfr- inhibited embryos, and expanded in Vegfaa-overexpressing embryos. Furthermore, vascular-specific overexpression of etv2 in Vegfr-inhibited embryos rescued defects in vascular endothelial differentiation. Similarly, vegfaa genetic mutants displayed a combination of the two phenotypes observed with chemical Vegfr inhibition: the expression of arterial and pan-endothelial markers including etv2 was downregulated while the expression of most venous markers was either expanded or unchanged. Based on these results we propose a revised model which explains the different phenotypes observed upon inhibition of Vegf signaling: low levels of Vegf signaling promote overall vascular endothelial differentiation and cell survival by upregulating etv2 expression, while high levels of Vegf signaling promote arterial and inhibit venous specification.
Project description:Hyperglycemia is reported to accelerate endothelial cell senescence that contributes to diabetic complications. The underlying mechanism, however, remains elusive. We previously demonstrated AQR as a susceptibility gene for type 2 diabetes mellitus (T2DM) and showed that it was increased in multiple tissues in models with T2DM or metabolic syndrome. This study aimed to investigate the role of AQR in hyperglycemia-induced senescence and its underlying mechanism. Here, we retrieved several datasets of the aging models and found the expression of AQR was increased by high glucose and by aging across species, including C. elegans (whole-body), rat (cardiac tissues), and monkey (blood). we validated the increased AQR expression in senescent human umbilical vein endothelial cells (HUVECs). When overexpressed, AQR promoted the endothelial cell senescence, confirmed by an increased number of cells stained with senescence-associated beta-galactosidase and upregulation of CDKN1A (P21) as well as the prohibited cellular colony formation and G2/M phase arrest. To explore the mechanism by which AQR regulated the cellular senescence, transcriptomic analyses of HUVECs with the overexpression and knockdown of the AQR were performed. We identified 52 co-expressed genes that were enriched, in the terms of plasminogen activation, innate immunity, immunity, and antiviral defense. Among co-expressed genes, PLAU was selected to evaluate its contribution to senescence for its highest strength in the enrichment of the biological process. We demonstrated that the knockdown of PLAU rescued senescence-related phenotypes, endothelial cell activation, and inflammation in models induced by AQR or TNF-α. These findings, for the first time, indicate that AQR/PLAU is a critical signaling axis in the modulation of endothelial cell senescence, revealing a novel link between hyperglycemia and vascular dysfunction. The study may have implications in the prevention of premature vascular aging associated with T2DM.
Project description:Aberrant blood vessel formation contributes to a wide variety of pathologies, and factors that regulate angiogenesis are attractive therapeutic targets. Endothelial and smooth muscle cell-derived neuropilin-like protein (ESDN) is a neuropilin-related transmembrane protein expressed in ECs; however, its potential effect on VEGF responses remains undefined. Here, we generated global and EC-specific Esdn knockout mice and demonstrated that ESDN promotes VEGF-induced human and murine EC proliferation and migration. Deletion of Esdn in the mouse interfered with adult and developmental angiogenesis, and knockdown of the Esdn homolog (dcbld2) in zebrafish impaired normal vascular development. Loss of ESDN in ECs blunted VEGF responses in vivo and attenuated VEGF-induced VEGFR-2 signaling without altering VEGF receptor or neuropilin expression. Finally, we found that ESDN associates with VEGFR-2 and regulates its complex formation with negative regulators of VEGF signaling, protein tyrosine phosphatases PTP1B and TC-PTP, and VE-cadherin. These findings establish ESDN as a regulator of VEGF responses in ECs that acts through a mechanism distinct from neuropilins. As such, ESDN may serve as a therapeutic target for angiogenesis regulation.
Project description:Endothelial activation by proinflammatory cytokines is closely associated to the pathogenesis of atherosclerosis and other vascular diseases; however, the molecular mechanisms controlling endothelial activation are not fully understood. Here we identify TRIM14 as a new positive regulator of endothelial activation via activating NF-κB signal pathway. TRIM14 is highly expressed in human vascular endothelial cells (ECs) and markedly induced by inflammatory stimuli such as TNF-α, IL-1β, and LPS. Overexpression of TRIM14 significantly increased the expression of adhesion molecules such as VCAM-1, ICAM-1, E-selectin, and cytokines such as CCL2, IL-8, CXCL-1, and TNF-α in activated ECs and by which it facilitated monocyte adhesion to ECs. Conversely, knockdown of TRIM14 has opposite effect on endothelial activation. Upon TNF-α stimulation, TRIM14 is recruited to IKK complex via directly binding to NEMO and promotes the phosphorylation of IκBα and p65, which is dependent on its K63-linked ubiquitination. Meanwhile, p65 can directly bind to the promoter regions of human TRIM14 gene and control its mRNA transcription. Finally, TRIM14 protein level is significantly upregulated in mouse and human atheroma compared to normal arteries. Taken together, these results indicate that TRIM14-NF-κB forms a positive feedback loop to enhance EC activation and TRIM14 may be a potential therapeutic target for vascular inflammatory diseases such as atherosclerosis.
Project description:Glomerular endothelial cells (GEnCs) dysfunction occurs at the early stage of diabetic nephropathy (DN). One of its characteristics is endothelial-to-mesenchymal transition (EndMT). Heparanase (HPSE) is the only known mammalian endoglycosidase capable of degrading heparin sulfates and has a prominent role in DN pathogenesis. However, whether HPSE induces EndMT of GEnCs remains unknown. This study aimed to determine the effect and potential mechanism of HPSE on GEnCs phenotype under high-glucose conditions. In the early development of streptozotocin (STZ)-induced diabetic mice, HPSE overexpression was positively correlated with renal injury and the number of GEnCs undergoing EndMT, which was characterized by loss of endothelial marker CD31 and gain of mesenchymal markers including α-SMA and Snail1/2 by double immunofluorescence staining. Bioinformatics analysis revealed a positive correlation between HPSE and ERK. The counts of double positive staining of CD31 and p-ERK1/2 was significantly increased in the glomeruli of STZ-induced diabetic mice compared with sham mice. In cultured GEnCs, high glucose dramatically upregulated the expressions of HPSE and p-ERK1/2, both of which were markedly blocked by HPSE siRNA. Furthermore, recombinant mouse HPSE (rmHPSE) promoted the expressions of mesenchymal markers and p-ERK1/2 in a dosage- and time-dependent manner. U0126, a specific MEK/ERK inhibitor, significantly inhibited either high glucose or rmHPSE-induced EndMT of GEnCs. These data indicate that high glucose induces EndMT of GEnCs at least partially through upregulating HPSE and that HPSE promotes EndMT of GEnCs via activating ERK signaling. This study improves understanding the crucial role of HPSE in DN development and progression.
Project description:Endothelial cells (ECs) senescence is critical for vascular dysfunction, which leads to age-related disease. DHCR24, a 3β-hydroxysterol δ 24 reductase with multiple functions other than enzymatic activity, has been involved in age-related disease. However, little is known about the relationship between DHCR24 and vascular ECs senescence. We revealed that DHCR24 expression is chronologically decreased in senescent human umbilical vein endothelial cells (HUVECs) and the aortas of aged mice. ECs senescence in endothelium-specific DHCR24 knockout mice was characterized by increased P16 and senescence-associated secretory phenotype, decreased SIRT1 and cell proliferation, impaired endothelium-dependent relaxation, and elevated blood pressure. In vitro, DHCR24 knockdown in young HUVECs resulted in a similar senescence phenotype. DHCR24 deficiency impaired endothelial migration and tube formation and reduced nitric oxide (NO) levels. DHCR24 suppression also inhibited the caveolin-1/ERK signaling, probably responsible for increased reactive oxygen species production and decreased eNOS/NO. Conversely, DHCR24 overexpression enhanced this signaling pathway, blunted the senescence phenotype, and improved cellular function in senescent cells, effectively blocked by the ERK inhibitor U0126. Moreover, desmosterol accumulation induced by DHCR24 deficiency promoted HUVECs senescence and inhibited caveolin-1/ERK signaling. Our findings demonstrate that DHCR24 is essential in ECs senescence.
Project description:Endothelial-to-mesenchymal transition (EndMT) is now widely considered a pivotal contributor to cancer progression. In this study, we show that the Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) is a sufficient cause of EndMT, potentially helping to explain the aggressiveness of KS that occurs commonly in AIDS patients. Upon KSHV infection, primary dermal microvascular endothelial cells lost expression of endothelial markers and acquired expression of mesenchymal markers, displaying new invasive and migratory properties along with increased survival. KSHV activated Notch-induced transcription factors Slug and ZEB1, and canonical Notch signaling was required for KSHV-induced EndMT. In contrast, KSHV did not utilize the TGFβ signaling pathway, which has also been linked to EndMT. Within KS lesions, KSHV-infected spindle cells displayed features compatible with KSHV-induced EndMT including a complex phenotype of endothelial and mesenchymal properties, Notch activity, and nuclear ZEB1 expression. Our results show that KSHV engages the EndMT program to increase the invasiveness and survival of infected endothelial cells, traits that likely contribute to viral persistence and malignant progression. One important implication of our findings is that therapeutic approaches to disrupt the Notch pathway may offer novel approaches for KS treatment.
Project description:p130Cas is a polyvalent adapter protein essential for cardiovascular development, and with a key role in cell movement. In order to identify the pathways by which p130Cas exerts its biological functions in endothelial cells we mapped the p130Cas interactome and its dynamic changes in response to VEGF using high-resolution mass spectrometry and reconstruction of protein interaction (PPI) networks with the aid of multiple PPI databases. VEGF enriched the p130Cas interactome in proteins involved in actin cytoskeletal dynamics and cell movement, including actin-binding proteins, small GTPases and regulators or binders of GTPases. Detailed studies showed that p130Cas association of the GTPase-binding scaffold protein, IQGAP1, plays a key role in VEGF chemotactic signaling, endothelial polarization, VEGF-induced cell migration, and endothelial tube formation. These findings indicate a cardinal role for assembly of the p130Cas interactome in mediating the cell migratory response to VEGF in angiogenesis, and provide a basis for further studies of p130Cas in cell movement.
Project description:The transcription factor Krüppel-like factor 4 (KLF4) has been implicated in regulating cell proliferation, migration and differentiation in a variety of human cells and is one of four factors required for the induction of pluripotent stem cell reprogramming. However, its role has not been addressed in ocular neovascular diseases. This study investigated the role of KLF4 in angiogenesis and underlying molecular mechanisms in human retinal microvascular endothelial cells (HRMECs). The functional role of KLF4 in HRMECs was determined following lentiviral vector mediated inducible expression and shRNA knockdown of KLF4. Inducible expression of KLF4 promotes cell proliferation, migration and tube formation. In contrast, silencing KLF4 inhibits cell proliferation, migration, tube formation and induces apoptosis in HRMECs. KLF4 promotes angiogenesis by transcriptionally activating VEGF expression, thus activating the VEGF signaling pathway in HRMECs.
Project description:While emerging evidence suggests the link between endothelial activation of TGF-β signaling, induction of endothelial-to-mesenchymal transition (EndMT), and cardiovascular disease (CVD), the molecular underpinning of this connection remains enigmatic. Here, we report aberrant expression of H19 lncRNA and TET1 in endothelial cells (ECs) of human atherosclerotic coronary arteries. Using primary human umbilical vein endothelial cells (HUVECs) and aortic endothelial cells (HAoECs) we show that TNF-α, a known risk factor for endothelial dysfunction and CVD, induces H19 expression which in turn activates TGF-β signaling and EndMT via a TET1-dependent epigenetic mechanism. We also show that H19 regulates TET1 expression at the posttranscriptional level. Further, we provide evidence that this H19/TET1-mediated regulation of TGF-β signaling and EndMT occurs in mouse pulmonary microvascular ECs in vivo under hyperglycemic conditions. We propose that endothelial activation of the H19/TET1 axis may play an important role in EndMT and perhaps CVD.