Notch2 signaling sensitizes endothelial cells to apoptosis by negatively regulating the key protective molecule survivin

BMPR2 Loss Activates AKT by Disrupting DLL4/NOTCH1 and PPARγ Signaling in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive cardiopulmonary disease characterized by pathologic vascular remodeling of small pulmonary arteries. Endothelial dysfunction in advanced PAH is associated with proliferation, apoptosis resistance, and endothelial to mesenchymal transition (EndoMT) due to aberrant signaling. DLL4, a cell membrane associated NOTCH ligand, plays a pivotal role maintaining vascular integrity. Inhibition of DLL4 has been associated with the development of pulmonary hypertension, but the mechanism is incompletely understood. Here we report that BMPR2 silencing in pulmonary artery endothelial cells (PAECs) activated AKT and suppressed the expression of DLL4. Consistent with these in vitro findings, increased AKT activation and reduced DLL4 expression was found in the small pulmonary arteries of patients with PAH. Increased NOTCH1 activation through exogenous DLL4 blocked AKT activation, decreased proliferation and reversed EndoMT. Exogenous and overexpression of DLL4 induced BMPR2 and PPRE promoter activity, and BMPR2 and PPARG mRNA in idiopathic PAH (IPAH) ECs. PPARγ, a nuclear receptor associated with EC homeostasis, suppressed by BMPR2 loss was induced and activated by DLL4/NOTCH1 signaling in both BMPR2-silenced and IPAH ECs, reversing aberrant phenotypic changes, in part through AKT inhibition. Directly blocking AKT or restoring DLL4/NOTCH1/PPARγ signaling may be beneficial in preventing or reversing the pathologic vascular remodeling of PAH.

Disruption of DLL4/NOTCH1 Causes Dysregulated PPARγ/AKT Signaling in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive cardiopulmonary disease characterized by vascular remodeling of small pulmonary arteries. Endothelial dysfunction in advanced PAH is associated with proliferation, apoptosis resistance, and endothelial to mesenchymal transition (EndoMT) due to aberrant signaling. DLL4, a cell membrane associated NOTCH ligand, activates NOTCH1 signaling and plays a pivotal role maintaining vascular integrity. Inhibition of DLL4 has been associated with the development of pulmonary hypertension, but the mechanism is incompletely understood. Here we report that BMPR2 silencing in PAECs activated AKT and decreased DLL4 expression. DLL4 loss was also seen in lungs of patients with IPAH and HPAH. Over-expression of DLL4 in PAECs induced BMPR2 promoter activity and exogenous DLL4 increased BMPR2 mRNA through NOTCH1 activation. Furthermore, DLL4/NOTCH1 signaling blocked AKT activation, decreased proliferation and reversed EndoMT in BMPR2-silenced PAECs and ECs from IPAH patients. PPARγ, suppressed by BMPR2 loss, was induced and activated by DLL4/NOTCH1 signaling in both BMPR2-silenced and IPAH PAECs, reversing aberrant phenotypic changes, in part through AKT inhibition. Finally, leniolisib, a well-tolerated oral PI3Kδ/AKT inhibitor, decreased cell proliferation, induced apoptosis and reversed markers of EndoMT in BMPR2-silenced PAECs. Restoring DLL4/NOTCH1/PPARγ signaling and/or suppressing AKT activation may be beneficial in preventing or reversing the pathologic vascular remodeling of PAH.

Therapeutic Targeting Notch2 Protects Bone Micro-Vasculatures from Methotrexate Chemotherapy-Induced Adverse Effects in Rats

Intensive cancer chemotherapy is well known to cause bone vasculature disfunction and damage, but the mechanism is poorly understood and there is a lack of treatment. Using a rat model of methotrexate (MTX) chemotherapy (five once-daily dosses at 0.75 mg/kg), this study investigated the roles of the Notch2 signalling pathway in MTX chemotherapy-induced bone micro-vasculature impairment. Gene expression, histological and micro-computed tomography (micro-CT) analyses revealed that MTX-induced micro-vasculature dilation and regression is associated with the induction of Notch2 activity in endothelial cells and increased production of inflammatory cytokine tumour necrosis factor alpha (TNFα) from osteoblasts (bone forming cells) and bone marrow cells. Blockade of Notch2 by a neutralising antibody ameliorated MTX adverse effects on bone micro-vasculature, both directly by supressing Notch2 signalling in endothelial cells and indirectly via reducing TNFα production. Furthermore, in vitro studies using rat bone marrow-derived endothelial cell revealed that MTX treatment induces Notch2/Hey1 pathway and negatively affects their ability in migration and tube formation, and Notch2 blockade can partially protect endothelial cell functions from MTX damage.

Notch Signaling in Vascular Endothelial and Mural Cell Communications

The Notch signaling pathway is a highly versatile and evolutionarily conserved mechanism with an important role in cell fate determination. Notch signaling plays a vital role in vascular development, regulating several fundamental processes such as angiogenesis, arterial/venous differentiation, and mural cell investment. Aberrant Notch signaling can result in severe vascular phenotypes as observed in cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and Alagille syndrome. It is known that vascular endothelial cells and mural cells interact to regulate vessel formation, cell maturation, and stability of the vascular network. Defective endothelial-mural cell interactions are a common phenotype in diseases characterized by impaired vascular integrity. Further refinement of the role of Notch signaling in the vascular junctions will be critical to attempts to modulate Notch in the context of human vascular disease. In this review, we aim to consolidate and summarize our current understanding of Notch signaling in the vascular endothelial and mural cells during development and in the adult vasculature.

Adding a "Notch" to Cardiovascular Disease Therapeutics: A MicroRNA-Based Approach

Dysregulation of the Notch pathway is implicated in the pathophysiology of cardiovascular diseases (CVDs), but, as of today, therapies based on the re-establishing the physiological levels of Notch in the heart and vessels are not available. A possible reason is the context-dependent role of Notch in the cardiovascular system, which would require a finely tuned, cell-specific approach. MicroRNAs (miRNAs) are short functional endogenous, non-coding RNA sequences able to regulate gene expression at post-transcriptional levels influencing most, if not all, biological processes. Dysregulation of miRNAs expression is implicated in the molecular mechanisms underlying many CVDs. Notch is regulated and regulates a large number of miRNAs expressed in the cardiovascular system and, thus, targeting these miRNAs could represent an avenue to be explored to target Notch for CVDs. In this Review, we provide an overview of both established and potential, based on evidence in other pathologies, crosstalks between miRNAs and Notch in cellular processes underlying atherosclerosis, myocardial ischemia, heart failure, calcification of aortic valve, and arrhythmias. We also discuss the potential advantages, as well as the challenges, of using miRNAs for a Notch-based approach for the diagnosis and treatment of the most common CVDs.

Notch2 Suppression Mimicking Changes in Human Pulmonary Hypertension Modulates Notch1 and Promotes Endothelial Cell Proliferation

Pulmonary arterial hypertension (PAH) is a fatal cardiopulmonary disease characterized by increased vascular cell proliferation with resistance to apoptosis and occlusive remodeling of the small pulmonary arteries in humans. The Notch family of proteins are proximal signaling mediators of an evolutionarily conserved pathway that effect cell proliferation, fate determination, and development. In endothelial cells (ECs), Notch receptor 2 (Notch2) has been shown to promote endothelial apoptosis. However, a pro- or anti-proliferative role for Notch2 in pulmonary endothelial proliferation and ensuing PAH is unknown. Herein, we postulated that suppressed Notch2 signaling drives pulmonary endothelial proliferation in the setting of PAH. We observed that levels of Notch2 are ablated in lung and PA tissue samples from PAH patients compared to non-PAH controls. Interestingly, Notch2 expression was attenuated in human pulmonary artery endothelial cells (hPAECs) exposed to vasoactive factors including hypoxia, TGFβ, ET-1, and IGF-1. Gene silencing of Notch2 increased EC proliferation and reduced apoptosis. At the molecular level, Notch2-deficient hPAECs activated Akt, Erk1/2 and anti-apoptotic protein Bcl-2, and reduced levels of p21^cip and Bax. Intriguingly, loss of Notch2 elicits a paradoxical activation of Notch1 and transcriptional upregulation of canonical Notch target genes Hes1, Hey1 and Hey2. Further, reduction in Rb and increased E2F1 binding to the Notch1 promoter appear to explain the upregulation of Notch1. In aggregate, our results demonstrate that loss of Notch2 derepresses Notch1 and elicits aberrant EC hallmarks of PAH. The data underscore a novel role for Notch in the maintenance of endothelial cell homeostasis.

The Notch Pathway: A Link Between COVID-19 Pathophysiology and Its Cardiovascular Complications

COVID-19 is associated with a large number of cardiovascular sequelae, including dysrhythmias, myocardial injury, myocarditis and thrombosis. The Notch pathway is one likely culprit leading to these complications due to its direct role in viral entry, inflammation and coagulation processes, all shown to be key parts of COVID-19 pathogenesis. This review highlights links between the pathophysiology of SARS-CoV2 and the Notch signaling pathway that serve as primary drivers of the cardiovascular complications seen in COVID-19 patients.

Notch Signaling in Vascular Endothelial Cells, Angiogenesis, and Tumor Progression: An Update and Prospective

The Notch signaling pathway plays an essential role in a wide variety of biological processes including cell fate determination of vascular endothelial cells and the regulation of arterial differentiation and angiogenesis. The Notch pathway is also an essential regulator of tumor growth and survival by functioning as either an oncogene or a tumor suppressor in a context-dependent manner. Crosstalk between the Notch and other signaling pathways is also pivotal in tumor progression by promoting cancer cell growth, migration, invasion, metastasis, tumor angiogenesis, and the expansion of cancer stem cells (CSCs). In this review, we provide an overview and update of Notch signaling in endothelial cell fate determination and functioning, angiogenesis, and tumor progression, particularly in the development of CSCs and therapeutic resistance. We further summarize recent studies on how endothelial signaling crosstalk with the Notch pathway contributes to tumor angiogenesis and the development of CSCs, thereby providing insights into vascular biology within the tumor microenvironment and tumor progression.

Liraglutide mends cognitive impairment by averting Notch signaling pathway overexpression in a rat model of polycystic ovary syndrome

AIMS

Polycystic ovary syndrome (PCOS), the rifest endocrine disorder in women, is involved in disrupting many metabolic processes. However, the impact of PCOS on cognitive deficits is still uncertain. Recently, Notch signaling pathway was identified as a key modifier in regulating the pathological process in the ovary and various neurodegenerative disorders. Liraglutide has favourable neuroprotective effects that may protect against the possible cognitive dysfunction in PCOS.

MAIN METHODS

PCOS was induced in rats by administrating Letrozole orally for 21 successive days. Then, Liraglutide (LIR) was administered intraperitoneally for 30 days. Memory was examined using Y-maze, novel object recognition (NOR), and Morris water maze (MWM) tests. Western blotting, enzyme immunoassay, and quantitative real-time PCR were used to examine Notch signaling downstream targets, as well as assessing the expression of the components of various pathways cross talked with Notch signaling in memory impairment. Furthermore, histopathological examination was performed to examine neuronal changes.

KEY FINDINGS

Notch signaling was overexpressed in PCOS rats, which increased Aβ aggregation, apoptosis, and neuroinflammation. Additionally, histopathological examination showed neuronal degeneration, which was marked by diminished acetylcholine levels in the PCOS rats' hippocampi. Finally, serum levels of insulin and testosterone were elevated while estradiol was reduced. Treatment with LIR repaired Notch signaling-attributed changes and improved the PCOS-induced memory impairment in rats.

SIGNIFICANCE

The obtained findings confirm that Notch signaling activation in the hippocampus of rats impairs cognitive functions in PCOS, which is mitigated by LIR. Therefore, LIR may offer a novel therapeutic intervention to impede PCOS-induced dementia.

KRIT1 Deficiency Promotes Aortic Endothelial Dysfunction

Loss-of-function mutations of the gene encoding Krev interaction trapped protein 1 (KRIT1) are associated with the pathogenesis of Cerebral Cavernous Malformation (CCM), a major cerebrovascular disease characterized by abnormally enlarged and leaky capillaries and affecting 0.5% of the human population. However, growing evidence demonstrates that KRIT1 is implicated in the modulation of major redox-sensitive signaling pathways and mechanisms involved in adaptive responses to oxidative stress and inflammation, suggesting that its loss-of-function mutations may have pathological effects not limited to CCM disease. The aim of this study was to address whether KRIT1 loss-of-function predisposes to the development of pathological conditions associated with enhanced endothelial cell susceptibility to oxidative stress and inflammation, such as arterial endothelial dysfunction (ED) and atherosclerosis. Silencing of KRIT1 in human aortic endothelial cells (HAECs), coronary artery endothelial cells (HCAECs), and umbilical vein endothelial cells (HUVECs) resulted in increased expression of endothelial proinflammatory adhesion molecules vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) and in enhanced susceptibility to tumor necrosis factor alpha (TNF-α)-induced apoptosis. These effects were associated with a downregulation of Notch1 activation that could be rescued by antioxidant treatment, suggesting that they are consequent to altered intracellular redox homeostasis induced by KRIT1 loss-of-function. Furthermore, analysis of the aorta of heterozygous KRIT1^+/- mice fed a high-fructose diet to induce systemic oxidative stress and inflammation demonstrated a 1.6-fold increased expression of VCAM-1 and an approximately 2-fold enhanced fat accumulation (7.5% vs 3.6%) in atherosclerosis-prone regions, including the aortic arch and aortic root, as compared to corresponding wild-type littermates. In conclusion, we found that KRIT1 deficiency promotes ED, suggesting that, besides CCM, KRIT1 may be implicated in genetic susceptibility to the development of atherosclerotic lesions.

Notch Signaling Regulates Immune Responses in Atherosclerosis

Atherosclerosis is a chronic autoimmune inflammatory disease that can cause coronary artery disease, stroke, peripheral artery disease, depending on which arteries are affected. At the beginning of atherosclerosis plasma lipoproteins accumulate in the sub-endothelial space. In response, monocytes migrate from the circulation through the endothelium into the intima where they differentiate into macrophages. These early events trigger a complex immune response that eventually involves many cellular subtypes of both innate and adaptive immunity. The Notch signaling pathway is an evolutionary conserved cell signaling system that mediates cell-to-cell communication. Recent studies have revealed that Notch modulate atherosclerosis by controlling macrophages polarization into M1 or M2 subtypes. Furthermore, it is known that Notch signaling controls differentiation and activity of T-helper and cytotoxic T-cells in inflammatory diseases. In this review, we will discuss the role of Notch in modulating immunity in the context of atherosclerosis and whether targeting Notch may represent a therapeutic strategy.

The Use of Nutraceuticals to Counteract Atherosclerosis: The Role of the Notch Pathway

Despite the currently available pharmacotherapies, today, thirty percent of worldwide deaths are due to cardiovascular diseases (CVDs), whose primary cause is atherosclerosis, an inflammatory disorder characterized by the buildup of lipid deposits on the inside of arteries. Multiple cellular signaling pathways have been shown to be involved in the processes underlying atherosclerosis, and evidence has been accumulating for the crucial role of Notch receptors in regulating the functions of the diverse cell types involved in atherosclerosis onset and progression. Several classes of nutraceuticals have potential benefits for the prevention and treatment of atherosclerosis and CVDs, some of which could in part be due to their ability to modulate the Notch pathway. In this review, we summarize the current state of knowledge on the role of Notch in vascular health and its modulation by nutraceuticals for the prevention of atherosclerosis and/or treatment of related CVDs.

Estrogen-mediated protection against coronary heart disease: The role of the Notch pathway

Estrogen regulates a plethora of biological processes, under physiological and pathological conditions, by affecting key pathways involved in the regulation of cell proliferation, fate, survival and metabolism. The Notch receptors are mediators of communication between adjacent cells and are key determinants of cell fate during development and in postnatal life. Crosstalk between estrogen and the Notch pathway intervenes in many processes underlying the development and maintenance of the cardiovascular system. The identification of molecular mechanisms underlying the interaction between these types of endocrine and juxtacrine signaling are leading to a deeper understanding of physiological conditions regulated by these steroid hormones and, potentially, to novel therapeutic approaches to prevent pathologies linked to reduced levels of estrogen, such as coronary heart disease, and cardiotoxicity caused by hormone therapy for estrogen-receptor-positive breast cancer.

Antiapoptotic Molecule Survivin in Transplantation: Helpful or Harmful?

Survivin, an antiapoptotic molecule from inhibitor of apoptosis protein (IAP) family, is most known for its implication in cancer as there are some efforts to apply it for diagnostic as well as therapeutic purposes in oncology. On the other hand, it could be a useful molecule to be positively targeted when trying to save tissue and promote cells viability. Since protecting the allograft from ischemia reperfusion injury and inflammation-induced damage is a considerable objective in transplantation, it is reasonable to take advantage from antiapoptotic agents like survivin in order to achieve this goal. However, survivin's potential ability to induce malignancies makes some concerns about its use in clinic. The other barrier is this molecule's involvement in lymphocytes development and proliferation which might increase the risk of graft rejection due to adaptive immune system overactivation. In this review we summarize the few studies carried out about survivin's effect on graft survival and probable advantages and disadvantages of its overexpression in transplantation.

Notch1 regulates endothelial apoptosis via the ERK pathway in chronic obstructive pulmonary disease

The Notch signaling pathway plays critical role for determining cell fate by controlling proliferation, differentiation, and apoptosis. In the current study, we investigated the roles of the Notch signaling pathway in cigarette smoke (CS)-induced endothelial apoptosis in chronic obstructive pulmonary disease (COPD). We obtained surgical specimens from 10 patients with COPD and 10 control participants. Notch1, 2, and 4 express in endothelial cells, whereas Notch3 mainly localizes in smooth muscle cells. Compared with control groups, we found that the expression of Notch1, 3, and 4 decreased, as well as their target genes Hes1 and Hes2, while the expression of Notch2 and extracellular signal-regulated kinase (ERK)1/2 increased in COPD patients compared with controls, as well as in human pulmonary microvascular endothelial cells (HPMECs) when exposed to CS extract (CSE). Overexpression of Notch1 with N1ICD in HPMECs markedly alleviated the cell apoptosis induced by CSE. The ERK signaling pathway was significantly activated by CSE, which correlated with CSE-induced apoptosis. However, this activation can be abolished by N1ICD overexpression. Furthermore, treatment of PD98059 (ERK inhibitor) significantly alleviated CSE-induced apoptosis, as well as reduced the methylation of mitochondrial transcription factor A (mtTFA) promoter, which was correlated with CS-induced endothelial apoptosis. These results suggest that CS alters Notch signaling in pulmonary endothelial cells. Notch1 protects against CS-induced endothelial apoptosis in COPD through inhibiting the ERK pathway, while the ERK pathway further regulates the methylation of mtTFA promotor.

Notch signaling triggered via the ligand DLL4 impedes M2 macrophage differentiation and promotes their apoptosis

BACKGROUND

Notch signaling controls many cellular processes, including cell fate determination, cell differentiation, proliferation and apoptosis. In mammals, four Notch receptors (Notch 1-4) can interact with five distinct ligands [Jagged1, Jagged2, Delta-like 1 (DLL1), DLL3, and DLL4]. We previously reported that Notch activation is modulated in endothelial cells and monocytes during inflammation and showed that inflammation upregulates DLL4 on endothelial cells. DLL4 promotes differentiation of blood monocytes into proinflammatory M1 macrophages. Here, we further investigated the ability of DLL4 to interfere with the polarization of blood monocytes into immunosuppressive M2 macrophages.

METHODS

Human blood monocytes were differentiated in vitro into M0 macrophages and then polarized into M1 or M2 macrophages with LPS/IFNγ and IL-4, respectively. Polarization steps were performed in the presence of immobilized recombinant DLL4. Immune phenotype and apoptosis of macrophage subsets were analyzed and quantified by flow cytometry. Regulatory effects of DLL4 on gene expression, cell signaling and apoptotic pathways were investigated by QPCR and western blots.

RESULTS

The phenotype of M2 macrophages was subject to specific alterations in the presence of recombinant DLL4. DLL4 inhibits the upregulation of IL-4 induced M2 markers such as CD11b, CD206, and CD200R. Survival of macrophages upon M2 polarization was also strongly reduced in the presence of DLL4. DLL4 induces a caspase3/7-dependent apoptosis during M2 but not M1 macrophage polarization. The Notch ligand DLL1 has no apoptotic effect. Both DLL4 signaling via Notch1 as well as DLL4-mediated apoptosis are Notch-dependent. Fully differentiated M2 macrophages became resistant to DLL4 action. Mechanistically, DLL4 selectively upregulates gene expression in macrophages upon M2 polarization, thereby affecting the Notch pattern (Notch1, 3, Jag1), activity (HES1), and transcription (IRF5, STAT1). The pro-apoptotic effectors Bax and Bak and the BH3-only proteins Bid and Bim seem to convey DLL4 apoptotic signal.

CONCLUSION

Interplay between the DLL4/Notch and IL-4/IL-4R signaling pathways impairs M2 differentiation. Thus, DLL4 may drive a Notch-dependent selection process not only by promoting M1 macrophage differentiation but also by preventing M2 macrophage differentiation through inhibition of M2-specific gene expression and apoptotic cell death.

Estrogen receptor β-dependent Notch1 activation protects vascular endothelium against tumor necrosis factor α (TNFα)-induced apoptosis

Unlike age-matched men, premenopausal women benefit from cardiovascular protection. Estrogens protect against apoptosis of endothelial cells (ECs), one of the hallmarks of endothelial dysfunction leading to cardiovascular disorders, but the underlying molecular mechanisms remain poorly understood. The inflammatory cytokine TNFα causes EC apoptosis while dysregulating the Notch pathway, a major contributor to EC survival. We have previously reported that 17β-estradiol (E2) treatment activates Notch signaling in ECs. Here, we sought to assess whether in TNFα-induced inflammation Notch is involved in E2-mediated protection of the endothelium. We treated human umbilical vein endothelial cells (HUVECs) with E2, TNFα, or both and found that E2 counteracts TNFα-induced apoptosis. When Notch1 was inhibited, this E2-mediated protection was not observed, whereas ectopic overexpression of Notch1 diminished TNFα-induced apoptosis. Moreover, TNFα reduced the levels of active Notch1 protein, which were partially restored by E2 treatment. Moreover, siRNA-mediated knockdown of estrogen receptor β (ERβ), but not ERα, abolished the effect of E2 on apoptosis. Additionally, the E2-mediated regulation of the levels of active Notch1 was abrogated after silencing ERβ. In summary, our results indicate that E2 requires active Notch1 through a mechanism involving ERβ to protect the endothelium in TNFα-induced inflammation. These findings could be relevant for assessing the efficacy and applicability of menopausal hormone treatment, because they may indicate that in women with impaired Notch signaling, hormone therapy might not effectively protect the endothelium.

Notch Signaling in Endothelial Cells: Is It the Therapeutic Target for Vascular Neointimal Hyperplasia?

Blood vessels respond to injury through a healing process that includes neointimal hyperplasia. The vascular endothelium is a monolayer of cells that separates the outer vascular wall from the inner circulating blood. The disruption and exposure of endothelial cells (ECs) to subintimal components initiate the neointimal formation. ECs not only act as a highly selective barrier to prevent early pathological changes of neointimal hyperplasia, but also synthesize and release molecules to maintain vascular homeostasis. After vascular injury, ECs exhibit varied responses, including proliferation, regeneration, apoptosis, phenotypic switching, interacting with other cells by direct contact or secreted molecules and the change of barrier function. This brief review presents the functional role of the evolutionarily-conserved Notch pathway in neointimal hyperplasia, notably by regulating endothelial cell functions (proliferation, regeneration, apoptosis, differentiation, cell-cell interaction). Understanding endothelial cell biology should help us define methods to prompt cell proliferation, prevent cell apoptosis and dysfunction, block neointimal hyperplasia and vessel narrowing.

MiR-18a-5p inhibits endothelial-mesenchymal transition and cardiac fibrosis through the Notch2 pathway

Hyperglycemia plays a crucial role in the pathogenesis of diabetic complications; however, the mechanisms underlying diabetic cardiac fibrosis remain unclear. Endothelial cells are known to contribute to cardiac fibrosis through endothelial-mesenchymal transition (EndMT) under high glucose stimulation. Here we investigated the expression of miR-18a-5p and examined its functional role in human aortic valvular endothelial cells (HAVECs). Using HAVECs, we revealed that miR-18a-5p regulated high glucose-induced EndMT. Moreover, high glucose levels induced Notch2 expression, which promoted EndMT, resulting in the downregulation of vascular endothelial cadherin and CD31 and upregulation of fibroblast-specific protein-1, α-smooth muscle actin, fibronectin, and vimentin. Furthermore, Notch2 was identified as a target of miR-18a-5p. Our data showed that the overexpression of miR-18a-5p could downregulate Notch2 expression and subsequently suppress EndMT. In conclusion, our findings demonstrated that miR-18a-5p/Notch2 signaling pathway participates in the regulation of high glucose-induced EndMT, and may act as a novel promising target for myocardial fibrosis in diabetic cardiomyopathy.

Context-dependent function of ROS in the vascular endothelium: The role of the Notch pathway and shear stress

Reactive oxygen species (ROS) act as signal molecules in several biological processes whereas excessive, unregulated, ROS production contributes to the development of pathological conditions including endothelial dysfunction and atherosclerosis. The maintenance of a healthy endothelium depends on many factors and on their reciprocal interactions; in this framework, the Notch pathway and shear stress (SS) play two lead roles. Recently, evidence of a crosstalk between ROS, Notch, and SS, is emerging. The aim of this review is to describe the way ROS interact with the Notch pathway and SS protecting from-or promoting-the development of endothelial dysfunction. © 2017 BioFactors, 43(4):475-485, 2017.

Annonaceous acetogenins mediated up-regulation of Notch2 exerts growth inhibition in human gastric cancer cells in vitro

Background

Gastric cancer (GC) is a global health problem because of limited treatments and poor prognosis. Annonaceous acetogenins (ACGs) has been reported to exert anti-tumorigenic effects in cancer, yet the mechanism underlying its effects on GC remains largely unknown. Notch signaling plays a critical role in cell proliferation, differentiation and apoptosis. Therefore, it may contribute to the development of GC. This study aims to explore the role of Notch2 in ACGs’ activities in GC cells.

Results

ACGs inhibited GC cells’ viability in a dose dependent manner and led to cell apoptosis and cell cycle arrest in G0/G1 phase with an increased Notch2 expression. Additionally, Notch2 siRNA reduced ACGs-induced cell growth inhibition while Notch2 cDNA transfection did the opposite.

Materials and Methods

ACGs were administrated in GC cells and cell proliferation was assayed by MTS, cell apoptosis and cell cycle were detected by flow cytometry. Additionally, the expression of Notch2 and the downstream target Hes1 were identified by Western blot. Furthermore, Notch2-siRNA transfection and Notch2-cDNA were performed to investigate the role of Notch2 in the antitumor effect of ACGs. Conclusions: Up-regulation of Notch2 by ACGs is a potential therapeutic strategy for GC.

Activation of an endothelial Notch1-Jagged1 circuit induces VCAM1 expression, an effect amplified by interleukin-1β

The Notch1 and Notch4 signaling pathways regulate endothelial cell homeostasis. Inflammatory cytokines induce the expression of endothelial adhesion molecules, including VCAM1, partly by downregulating Notch4 signaling. We investigated the role of endothelial Notch1 in this IL-1β-mediated process. Brief treatment with IL-1β upregulated endothelial VCAM1 and Notch ligand Jagged1. IL-1β decreased Notch1 mRNA levels, but levels of the active Notch1ICD protein remained constant. IL-1β-mediated VCAM1 induction was downregulated in endothelial cells subjected to pretreatment with a pharmacological inhibitor of the γ-secretase, which activates Notch receptors, producing NotchICD. It was also downregulated in cells in which Notch1 and/or Jagged1 were silenced.Conversely, the forced expression of Notch1ICD in naïve endothelial cells upregulated VCAM1 per se and amplified IL-1β-mediated VCAM1 induction. Jagged1 levels increased and Notch4 signaling was downregulated in parallel. Finally, Notch1ICD and Jagged1 expression was upregulated in the endothelium of the liver in a model of chronic liver inflammation.In conclusion, we describe here a cell-autonomous, pro-inflammatory endothelial Notch1-Jagged1 circuit (i) triggering the expression of VCAM1 even in the absence of inflammatory cytokines and (ii) enhancing the effects of IL-1β. Thus, IL-1β regulates Notch1 and Notch4 activity in opposite directions, consistent with a selective targeting of Notch1 in inflamed endothelium.

Factors regulating capillary remodeling in a reversible model of inflammatory corneal angiogenesis

Newly formed microcapillary networks arising in adult organisms by angiogenic and inflammatory stimuli contribute to pathologies such as corneal and retinal blindness, tumor growth, and metastasis. Therapeutic inhibition of pathologic angiogenesis has focused on targeting the VEGF pathway, while comparatively little attention has been given to remodeling of the new microcapillaries into a stabilized, functional, and persistent vascular network. Here, we used a novel reversible model of inflammatory angiogenesis in the rat cornea to investigate endogenous factors rapidly invoked to remodel, normalize and regress microcapillaries as part of the natural response to regain corneal avascularity. Rapid reversal of an inflammatory angiogenic stimulus suppressed granulocytic activity, enhanced recruitment of remodelling macrophages, induced capillary intussusception, and enriched pathways and processes involving immune cells, chemokines, morphogenesis, axonal guidance, and cell motility, adhesion, and cytoskeletal functions. Whole transcriptome gene expression analysis revealed suppression of numerous inflammatory and angiogenic factors and enhancement of endogenous inhibitors. Many of the identified genes function independently of VEGF and represent potentially new targets for molecular control of the critical process of microvascular remodeling and regression in the cornea.

Serum From Advanced Heart Failure Patients Promotes Angiogenic Sprouting and Affects the Notch Pathway in Human Endothelial Cells

It is unknown whether components present in heart failure (HF) patients' serum provide an angiogenic stimulus. We sought to determine whether serum from HF patients affects angiogenesis and its major modulator, the Notch pathway, in human umbilical vein endothelial cells (HUVECs). In cells treated with serum from healthy subjects or from patients at different HF stage we determined: (1) Sprouting angiogenesis, by measuring cells network (closed tubes) in collagen gel. (2) Protein levels of Notch receptors 1, 2, 4, and ligands Jagged1, Delta-like4. We found a higher number of closed tubes in HUVECs treated with advanced HF patients serum in comparison with cells treated with serum from mild HF patients or controls. Furthermore, as indicated by the reduction of the active form of Notch4 (N4IC) and of Jagged1, advanced HF patients serum inhibited Notch signalling in HUVECs in comparison with mild HF patients' serum and controls. The circulating levels of NT-proBNP (N-terminal of the pro-hormone brain natriuretic peptide), a marker for the detection and evalutation of HF, were positively correlated with the number of closed tubes (r = 0.485) and negatively with Notch4IC and Jagged1 levels in sera-treated cells (r = -0.526 and r = -0.604, respectively). In conclusion, we found that sera from advanced HF patients promote sprouting angiogenesis and dysregulate Notch signaling in HUVECs. Our study provides in vitro evidence of an angiogenic stimulus arising during HF progression and suggests a role for the Notch pathway in it. J. Cell. Physiol. 231: 2700-2710, 2016. © 2016 Wiley Periodicals, Inc.

Characterization of Notch Signaling During Osteogenic Differentiation in Human Osteosarcoma Cell Line MG63

Osteogenic differentiation is a multi-step process controlled by a complex molecular framework. Notch is an evolutionarily conserved intercellular signaling pathway playing a prominent role in cell fate and differentiation, although the mechanisms by which this pathway regulates osteogenesis remain controversial. This study aimed to investigate, in vitro, the involvement of Notch pathway during all the developmental stages of osteogenic differentiation in human osteosarcoma cell line MG63. Cells were cultured in basal condition (control) and in osteoinductive medium (OM). Notch inhibitors were also added in OM to block Notch pathway. During osteogenic differentiation, early (alkaline phosphatase activity and collagen type I) and late osteogenic markers (osteocalcin levels and matrix mineralization), as well as the gene expression of the main osteogenic transcription factors (Runx2, Osterix, and Dlx5) increased. Time dependent changes in the expression of specific Notch receptors were identified in OM versus control with a significant reduction in the expression of Notch1 and Notch3 receptors in the early phase of differentiation, and an increase of Notch2 and Notch4 receptors in the late phase. Among Notch nuclear target genes, Hey1 expression was significantly higher in OM than control, while Hes5 expression decreased. Osteogenic markers were reduced and Hey1 was significantly inhibited by Notch inhibitors, suggesting a role for Notch through the canonical pathway. In conclusion, Notch pathway might be involved with a dual role in osteogenesis of MG63, through the activation of Notch2, Notch4, and Hey1, inducing osteoblast differentiation and the depression of Notch1, Notch3, and Hes5, maintaining an undifferentiated status. J. Cell. Physiol. 231: 2652-2663, 2016. © 2016 Wiley Periodicals, Inc.

Notch4 Signaling Confers Susceptibility to TRAIL-Induced Apoptosis in Breast Cancer Cells

Notch signaling has been established as a key regulator of cell fate in development, differentiation, and homeostasis. In breast cancers, increased Notch1 and Notch4 activity have been implicated in tumor progression and, accumulation of the intracellular domain of Notch4 (ICN4), reported in basal breast cancer cells. While, TNF-related apoptosis-inducing ligand (TRAIL) receptor agonists have demonstrated selectively in targeting tumor cells, the majority of primary tumors are resistant to TRAIL. This necessitates the identification of factors that might regulate TRAIL sensitivity. Here we investigate TRAIL sensitivity in tumor cells following the modulation of Notch (1 and 4) activity using siRNA-mediated depletions or ectopic expression of GFP-tagged constructs of the intracellular domains of Notch1 (ICN1) or Notch4 (ICN4). Our findings suggest that Notch4, but not Notch1 signaling, sensitizes breast tumor cells to TRAIL-induced apoptosis. ICN4-induced sensitization to TRAIL is characterized by CBF1-dependence. Apoptosis was mediated via caspase-8 activation and regulated by the Bcl-2 family pro-apoptotic proteins Bak and Bid. Finally, we present evidence that endogenous Notch4 activity regulates susceptibility to TRAIL in basal-like breast cancer cells but not in cell lines of luminal origin. These experiments reveal a hitherto unexplored Notch4-TRAIL signaling axis in breast cancer cells.

Notch signaling mediates crosstalk between endothelial cells and macrophages via Dll4 and IL6 in cardiac microvascular inflammation

Although short-term outcomes have improved with modern era immunosuppression, little progress has been made in long-term graft survival in cardiac transplantation. Antibody-mediated rejection (AMR) is one of the leading causes of graft failure and contributes significantly to poor long-term outcomes. Endothelial cell (EC) injury, intravascular macrophage infiltrate and microvascular inflammation are the histological features of AMR. Nevertheless, mechanisms of AMR remain unclear and treatment is still limited. Here, we investigated the mechanisms underlying vascular and inflammatory cell network involved in AMR at endothelial and macrophage levels, using endomyocardial transplant biopsies and EC/monocyte cocultures. First, we found that AMR associates with changes in Notch signaling at endothelium/monocyte interface including loss of endothelial Notch4 and the acquisition of the Notch ligand Dll4 in both cell types. We showed that endothelial Dll4 induces macrophage polarization into a pro-inflammatory fate (CD40(high)CD64(high)CD200R(low) HLA-DR(low)CD11b(low)) eliciting the production of IL-6. Dll4 and IL-6 are both Notch-dependent and are required for macrophage polarization through selective down and upregulation of M2- and M1-type markers, respectively. Overall, these findings highlight the impact of the graft's endothelium on macrophage recruitment and differentiation upon AMR via Notch signaling. We identified Dll4 and IL-6 as coregulators of vascular inflammation in cardiac transplantation and as potential targets for immunotherapy.

A Switch in Akt Isoforms Is Required for Notch-Induced Snail1 Expression and Protection from Cell Death

Notch activation in aortic endothelial cells (ECs) takes place at embryonic stages during cardiac valve formation and induces endothelial-to-mesenchymal transition (EndMT). Using aortic ECs, we show here that active Notch expression promotes EndMT, resulting in downregulation of vascular endothelial cadherin (VE-cadherin) and upregulation of mesenchymal genes such as those for fibronectin and Snail1/2. In these cells, transforming growth factor β1 exacerbates Notch effects by increasing Snail1 and fibronectin activation. When Notch-downstream pathways were analyzed, we detected an increase in glycogen synthase kinase 3β (GSK-3β) phosphorylation and inactivation that facilitates Snail1 nuclear retention and protein stabilization. However, the total activity of Akt was downregulated. The discrepancy between Akt activity and GSK-3β phosphorylation is explained by a Notch-induced switch in the Akt isoforms, whereby Akt1, the predominant isoform expressed in ECs, is decreased and Akt2 transcription is upregulated. Mechanistically, Akt2 induction requires the stimulation of the β-catenin/TCF4 transcriptional complex, which activates the Akt2 promoter. Active, phosphorylated Akt2 translocates to the nucleus in Notch-expressing cells, resulting in GSK-3β inactivation in this compartment. Akt2, but not Akt1, colocalizes in the nucleus with lamin B in the nuclear envelope. In addition to promoting GSK-3β inactivation, Notch downregulates Forkhead box O1 (FoxO1), another Akt2 nuclear substrate. Moreover, Notch protects ECs from oxidative stress-induced apoptosis through an Akt2- and Snail1-dependent mechanism.

TSG attenuates LPC-induced endothelial cells inflammatory damage through notch signaling inhibition

Lysophosphatidylcholine (LPC) induces inflammation in endothelial cells (ECs) but the mechanism is not fully understood. The Notch signaling pathway is involved in chronic EC inflammation, but its functions in LPC-induced endothelial inflammatory damage and 2,3,5,4'-tetrahydroxystilbene-2-O-β-d-glucoside's (TSG) protective effect during LPC-induced inflammatory damage in human umbilical vein endothelial cells (HUVECs) is largely unknown. We report that Notch signaling activation contributed to LPC-induced injury in HUVECs, and that TSG protected HUVECs from LPC-induced injury by antagonizing Notch signaling activation by LPC. γ-secretase inhibitor (DAPT), a specific inhibitor of the Notch signaling pathway, and Notch1 siRNA were used to inhibit Notch activity. HUVECs were exposed to LPC in the presence or absence of TSG, DAPT, and Notch1 siRNA. LPC treatment of HUVECs resulted in reduced cell viability, and Notch1 and Hes1 upregulation. Either silencing of Notch1 by siRNA or pharmacological inhibition of Notch signaling by DAPT prevented the loss of cell viability, and induction of apoptosis, and enhanced expression Notch1, Hes1 and MCP-1 by LPC in HUVECs. Similarly, TSG reduced LPC stimulation of Notch1, Hes1, and MCP-1 expression, prevented the release of IL-6 and CRP and rescued HUVECs from LPC-induced cell damage. Our data indicate that the Notch signaling pathway is a crucial mediator of endothelial inflammatory damage and that TSG protects against endothelial inflammatory damage by inhibiting the Notch signaling pathway. Our findings suggest that targeting Notch signaling by natural products such as TSG is a promising strategy for the prevention and treatment of chronic inflammation associated diseases, including atherosclerosis. © 2015 IUBMB Life, 68(1):37-50, 2016.

The role of notch in the cardiovascular system: potential adverse effects of investigational notch inhibitors

Targeting the Notch pathway is a new promising therapeutic approach for cancer patients. Inhibition of Notch is effective in the oncology setting because it causes a reduction of highly proliferative tumor cells and it inhibits survival of cancer stem cells, which are considered responsible for tumor recurrence and metastasis. Additionally, since Delta-like ligand 4 (Dll4)-activated Notch signaling is a major modulator of angiogenesis, anti-Dll4 agents are being investigated to reduce vascularization of the tumor. Notch plays a major role in the heart during the development and, after birth, in response to cardiac damage. Therefore, agents used to inhibit Notch in the tumors (gamma secretase inhibitors and anti-Dll4 agents) could potentially affect myocardial repair. The past experience with trastuzumab and other tyrosine kinase inhibitors used for cancer therapy demonstrates that the possible cardiotoxicity of agents targeting shared pathways between cancer and heart and the vasculature should be considered. To date, Notch inhibition in cancer patients has resulted only in mild gastrointestinal toxicity. Little is known about the potential long-term cardiotoxicity associated to Notch inhibition in cancer patients. In this review, we will focus on mechanisms through which inhibition of Notch signaling could lead to cardiomyocytes and endothelial dysfunctions. These adverse effects could contrast with the benefits of therapeutic responses in cancer cells during times of increased cardiac stress and/or in the presence of cardiovascular risk factor.

The disintegrin and metalloproteinase ADAM10 mediates a canonical Notch-dependent regulation of IL-6 through Dll4 in human endothelial cells

Although the involvement of the disintegrin and metalloproteinase ADAM10 in several areas of vascular biology is now clearly established, its role in vascular inflammation and in Notch signaling at the endothelial level remains unclear. In this study, we demonstrated that ADAM10 specifically localizes in the CD31(+) endothelial cells (ECs) in normal human cardiac tissues and in cultured primary arterial ECs. In vitro, ADAM10 drives a specific regulation of the Notch pathway in vascular ECs. Using an ADAM10 gain and loss of function approach we show an ADAM10-dependent regulation of Dll1 and Dll4 expression in association with changes in Hes1 and Hey1 expression. We also identified IL-6, IL-8, MCP-1 and sVCAM-1 as novel targets of ADAM10 upon inflammation. Although Notch pathway does not seem to be required for the production of IL-8, MCP-1 and sVCAM-1, the release of IL-6 by ECs occurred through ADAM10 and a canonical Notch signaling pathway, dependent of γ-secretase activity. Moreover, sustained expression of Dll4 mediated by ADAM10 elicits an increased release of IL-6 suggesting a strong implication of the specific Dll4 signaling in this mechanism. Modulation of IL-6 mediated by ADAM10/Notch signaling required PI3K activity. Thus, our findings suggest that ADAM10/Dll4 signaling is a major signaling pathway in ECs driving inflammatory events involved in inflammation and immune cell recruitment.

Transcriptional regulation of the survivin gene

Survivin, a small member of the inhibitors of the apoptosis protein family, is highly deregulated in cancer. It is weakly expressed in normal tissues but very strongly expressed in malignant lesions. Survivin is involved in cell-cycle progression, especially in the G2/M transition, and has anti-apoptotic activity, which correlates with its strong expression in cases with a poor cancer treatment response and poor outcomes. Several therapies that target the survivin transcript or protein are currently being tested in clinical trials. However, focusing new therapies on the origins of survivin overexpression and targeting these upstream deregulations could be more effective. For this reason, it seems important to make an inventory of the transcriptional (de)regulation of survivin. This review will gather the important points concerning the regulation of survivin mRNA expression: structure of the survivin promoter, epigenetic modifications and genetic abnormalities, transcription factors, and signalling pathways that affect survivin mRNA expression.

Notch activation promotes endothelial survival through a PI3K-Slug axis

RATIONALE

Loss of endothelial viability correlates with initiation and progress of vascular pathology. However, much remains to be learned about pathways required to maintain the balance between cell viability and apoptosis. Notch activation can enhance or inhibit apoptosis but its role in maintaining the endothelium needs further delineation.

OBJECTIVE

This study aims to identify the mechanisms by which Notch activation regulates endothelial viability.

METHODS AND RESULTS

Endothelial cells transduced with active Notch were treated with lipopolysaccharide (LPS) or homocysteine to induce endothelial apoptosis. Notch protected against LPS-induced cell death but exacerbated homocysteine-induced apoptosis. Inhibition of PI3K revealed that ligand-induced activation of endogenous Notch initiates parallel death and survival pathways and exhibits a differential effect on endothelial survival depending on the apoptotic stimulus. PI3K activity regulated the expression of Slug, which was required for survival in Notch-activated endothelial cells. Homocysteine, but not LPS, blocked both PI3K activity and Slug expression in Notch-activated cells, leading to increased endothelial apoptosis.

CONCLUSIONS

Notch signaling leads to activation of parallel survival and apoptotic pathways in endothelial cells. The interaction of Notch with other signaling pathways plays an important contextual role in regulating endothelial viability.

Impact of notch signaling on inflammatory responses in cardiovascular disorders

Notch signaling is a major pathway in cell fate decisions. Since the first reports showing the major role of Notch in embryonic development, a considerable and still growing literature further highlights its key contributions in various pathological processes during adult life. In particular, Notch is now considered as a major player in vascular homeostasis through the control of key cellular functions. In parallel, confounding evidence emerged that inflammatory responses regulate Notch signaling in vitro in endothelial cells, smooth muscle cells or vascular infiltrating cells and in vivo in vascular and inflammatory disorders and in cardiovascular diseases. This review presents how inflammation influences Notch in vascular cells and, reciprocally, emphasizes the functional role of Notch on inflammatory processes, notably by regulating key cell functions (differentiation, proliferation, apoptosis/survival, activation). Understanding how the disparity of Notch receptors and ligands impacts on vasculature biology remains critical for the design of relevant and adequate therapeutic strategies targeting Notch in this major pathological context.

Differential roles of Hath1, MUC2 and P27Kip1 in relation with gamma-secretase inhibition in human colonic carcinomas: a translational study

Hath1, a bHLH transcription factor negatively regulated by the γ-secretase-dependent Notch pathway, is required for intestinal secretory cell differentiation. Our aim was fourfold: 1) determine whether Hath1 is able to alter the phenotype of colon cancer cells that are committed to a differentiated phenotype, 2) determine whether the Hath1-dependent alteration of differentiation is coupled to a restriction of anchorage-dependent growth, 3) decipher the respective roles of three putative tumor suppressor genes Hath1, MUC2 and P27kip1 in this coupling and, 4) examine how our findings translate to primary tumors. Human colon carcinoma cell lines that differentiate along a mucin secreting (MUC2/MUC5AC) and/or enterocytic (DPPIV) lineages were maintained on inserts with or without a γ-secretase inhibitor (DBZ). Then the cells were detached and their ability to survive/proliferate in the absence of substratum was assessed. γ-secretase inhibition led to a Hath1-mediated preferential induction of MUC2 over MUC5AC, without DPPIV modification, in association with a decrease in anchorage-independent growth. While P27kip1 silencing relieved the cells from the Hath1-induced decrease of anchorage-independent growth, MUC2 silencing did not modify this parameter. Hath1 ectopic expression in the Hath1 negative enterocytic Caco2 cells led to a decreased anchorage-independent growth in a P27kip1-independent manner. In cultured primary human colon carcinomas, Hath1 was up-regulated in 7 out of 10 tumors upon DBZ treatment. Parallel MUC2 up-regulation occurred in 4 (4/7) and P27kip1 in only 2 (2/7) tumors. Interestingly, the response patterns of primary tumors to DBZ fitted with the hierarchical model of divergent signalling derived from our findings on cell lines.

Curcumin attenuates endothelial cell oxidative stress injury through Notch signaling inhibition

Previous studies have demonstrated that Notch signaling pathway plays a regulatory role in cellular oxidative stress injury (OSI). In this study, our aim was to explore the role of the Notch signaling pathway in hydrogen peroxide (H(2)O(2))-induced OSI and the protective effect of curcumin during (H(2)O(2))-induced injury in human umbilical vein endothelial cells (HUVECs). DAPT, a specific inhibitor of the Notch signaling pathway, and Notch1 siRNA were used to study Notch activity. Further, HUVECs were exposed to H(2)O(2) in the absence or presence of curcumin. DAPT and Notch1 siRNA significantly inhibited OSI and the expression of Notch1 and Hes1. Curcumin conferred a protective effect on the HUVECs against H(2)O(2), which was evidenced by improved cell viability, adhesive ability and migratory ability and a decreased apoptotic index, decreased production of reactive oxygen species (ROS) and a reduction in several biochemical parameters. Immunofluorescence and Western blotting analyses demonstrated that H(2)O(2) treatment upregulated the expression of Notch1, Hes1, Caspase3, Bax and cytochrome c downregulated the expression of Bcl2, and treatment with curcumin reversed these effects. We demonstrated for the first time that the inhibition of Notch signaling pathway imparts a protective effect against endothelial OSI. The protective effects of curcumin against OSI are at least in part dependent on Notch1 inhibition.

Genome-wide identification of copy number variations in Chinese Holstein

Recent studies of mammalian genomes have uncovered the vast extent of copy number variations (CNVs) that contribute to phenotypic diversity. Compared to SNP, a CNV can cover a wider chromosome region, which may potentially incur substantial sequence changes and induce more significant effects on phenotypes. CNV has been becoming an alternative promising genetic marker in the field of genetic analyses. Here we firstly report an account of CNV regions in the cattle genome in Chinese Holstein population. The Illumina Bovine SNP50K Beadchips were used for screening 2047 Holstein individuals. Three different programes (PennCNV, cnvPartition and GADA) were implemented to detect potential CNVs. After a strict CNV calling pipeline, a total of 99 CNV regions were identified in cattle genome. These CNV regions cover 23.24 Mb in total with an average size of 151.69 Kb. 52 out of these CNV regions have frequencies of above 1%. 51 out of these CNV regions completely or partially overlap with 138 cattle genes, which are significantly enriched for specific biological functions, such as signaling pathway, sensory perception response and cellular processes. The results provide valuable information for constructing a more comprehensive CNV map in the cattle genome and offer an important resource for investigation of genome structure and genomic variation underlying traits of interest in cattle.

Centroblastic diffuse large B cell lymphoma displays distinct expression pattern and prognostic role of apoptosis resistance related proteins

Centroblastic diffuse large B cell lymphoma (DLBCL) samples were analyzed by immunohistochemistry to evaluate the expression of p53, Bcl-2, Survivin, XIAP, and Ki-67. Survivin was the only protein which expression exhibited a trend for impact in progression-free (p = .077) and overall survival (p = .054). In the Mann-Whitney test, Survivin expression correlated with a negative overall survival (p = .045). These results appeared to be intimately related to Survivin cytoplasmic localization. Moreover, the anti-apoptotic proteins Bcl-2 and Survivin were less frequent in centroblastic DLBCL. Our results indicate that centroblastic DLBCL may be a disease with characteristic biology and clinical course and, therefore, specific prognostic factors.

Notch signals in the endothelium and cancer "stem-like" cells: opportunities for cancer therapy

Anti-angiogenesis agents and the identification of cancer stem-like cells (CSC) are opening new avenues for targeted cancer therapy. Recent evidence indicates that angiogenesis regulatory pathways and developmental pathways that control CSC fate are intimately connected, and that endothelial cells are a key component of the CSC niche. Numerous anti-angiogenic therapies developed so far target the VEGF pathway. However, VEGF-targeted therapy is hindered by clinical resistance and side effects, and new approaches are needed. One such approach may be direct targeting of tumor endothelial cell fate determination. Interfering with tumor endothelial cells growth and survival could inhibit not only angiogenesis but also the self-replication of CSC, which relies on signals from surrounding endothelial cells in the tumor microenvironment. The Notch pathway is central to controlling cell fate both during angiogenesis and in CSC from several tumors. A number of investigational Notch inhibitors are being developed. Understanding how Notch interacts with other factors that control endothelial cell functions and angiogenesis in cancers could pave the way to innovative therapeutic strategies that simultaneously target angiogenesis and CSC.

Notch, apoptosis and cancer

Proper embryonic development and normal tissue homeostasis require a series of molecular processes, regulating cell growth, differentiation and apoptosis. Perturbation in any of these processes invariably contributes to the development of cancer. In particular, defects in apoptosis are seen in virtually all types of human cancers. The Notch pathway plays an important role in cell fate determination in both embryonic development and organ homeostasis. Not surprisingly, Notch also plays a role in cancer when it is dysregulated. In this chapter, we will explore how Notch signaling interacts with key pathways that regulate apoptosis in cancer. Particularly, we will focus on the relationship between Notch and proteins responsible for activation of the caspase pathway. Notch regulates apoptosis through extensive networks, involving cell cycle, growth and survival pathways. Thus, we will also examine how apoptosis is modulated by the crosstalk between Notch and other signaling pathways such as p53, NF-κB and PI3K-Akt pathways.

Notch2-induced COX-2 expression enhancing gastric cancer progression

Gastric carcinoma is one of the most common and mortal types of malignancy worldwide. To date, the mechanisms controlling its aggressiveness are not yet fully understood. Notch signal pathway can function as either an oncogene or a tumor suppressor in tumorigenesis. Four members (Notch1-4) of Notch receptors were found in mammals and each exhibits distinct roles in tumor progression. Previous study showed that the activated Notch1 receptor promoted gastric cancer progression through cyclooxygenase-2 (COX-2). This study addressed whether Notch2 signal pathway is also involved in gastric cancer progression. Constitutive expression of Notch2 intracellular domain (N2IC), the activated form of Notch2 receptor, promoted both cell proliferation and xenografted tumor growth of human stomach adenocarcinoma SC-M1 cells. The colony formation, migration, invasion, and wound-healing abilities of SC-M1 cells were enhanced by N2IC expression, whereas these abilities were suppressed by Notch2 knockdown. Similarly, Notch2 knockdown inhibited cancer progressions of AGS and AZ521 gastric cancer cells. Expression of N2IC also caused epithelial-mesenchymal transition in SC-M1 cells. Furthermore, N2IC bound to COX-2 promoter and induced COX-2 expression through a CBF1-dependent manner in SC-M1 cells. The ability of N2IC to enhance tumor progression in SC-M1 cells was suppressed by knockdown of COX-2 or treatment with NS-398, a COX-2 inhibitor. Moreover, the suppression of tumor progression by Notch2 knockdown in SC-M1 cells was reversed by exogenous COX-2 or its major enzymatic product PGE(2) . Taken together, this study is the first to demonstrate that the Notch2-COX-2 signaling axis plays an important role in controlling gastric cancer progression.

The adaptor Lnk (SH2B3): an emerging regulator in vascular cells and a link between immune and inflammatory signaling

A better knowledge of the process by which inflammatory extracellular signals are relayed from the plasma membrane to specific intracellular sites is a key step to understand how inflammation develops and how it is regulated. This review focuses on Lnk (SH2B3) a member, with SH2B1 and SH2B2, of the SH2B family of adaptor proteins that influences a variety of signaling pathways mediated by Janus kinase and receptor tyrosine kinases. SH2B adaptor proteins contain conserved dimerization, pleckstrin homology, and SH2 domains. Initially described as a regulator of hematopoiesis and lymphocyte differentiation, Lnk now emerges as a key regulator in hematopoeitic and non hematopoeitic cells such as endothelial cells (EC) moderating growth factor and cytokine receptor-mediated signaling. In EC, Lnk is a negative regulator of TNF signaling that reduce proinflammatory phenotype and prevent EC from apoptosis. Lnk is a modulator in integrin signaling and actin cytoskeleton organization in both platelets and EC with an impact on cell adhesion, migration and thrombosis. In this review, we discuss some recent insights proposing Lnk as a key regulator of bone marrow-endothelial progenitor cell kinetics, including the ability to cell growth, endothelial commitment, mobilization, and recruitment for vascular regeneration. Finally, novel findings also provided evidences that mutations in Lnk gene are strongly linked to myeloproliferative disorders but also autoimmune and inflammatory syndromes where both immune and vascular cells display a role. Overall, these studies emphasize the importance of the Lnk adaptor molecule not only as prognostic marker but also as potential therapeutic target.

Protective cross talk between activated protein C and TNF signaling in vascular endothelial cells: implication of EPCR, noncanonical NF-κB, and ERK1/2 MAP kinases

Activated protein C (APC) is a natural anticoagulant protease that displays cytoprotective and antiinflammatory activities and has been demonstrated to reduce mortality of patients with severe sepsis. However, APC signaling is not fully understood. This study further investigated the antiinflammatory effects of APC in vascular endothelial cells (EC) and examined the cross talk between APC and TNF signaling. Analysis of the regulatory mechanisms mediated by APC on vascular human EC shows that APC impairs TNF signaling by triggering a preemptive activation of intracellular pathways. We found that APC signaling causes a moderate but significant induction of cell adhesion molecules (CAMs) including VCAM-1 at mRNA and protein levels. Activation of the noncanonical NF-κB and ERK1/2 are both pivotal to APC signaling leading to VCAM-1 expression. APC upregulates TNF receptor-associated factor 2 (TRAF2) and phosphorylates NF-κB p65 at Ser276 and Ser536 independently of IκB degradation. The ultimate protective antiinflammatory effect of APC in response to TNF is associated with a sustained activation of ERK1/2 and Akt while phosphorylation of NF-κB p65 is precluded. Inhibitors of ERK (PD98059 and U0126) abolish the antiinflammatory signal mediated by APC. Blocking antibodies and silencing assays also suggest that, in EC, protease-activated receptor 1 and endothelial protein C receptor (EPCR) both conduct ERK activation and VCAM-1 induction in response to APC. To conclude, APC protects EC by attenuating CAM expression during inflammation. APC engages a regulatory cross talk involving EPCR, ERK, and NF-κB that impairs TNF signaling.

Modulation of the ligand-independent traffic of Notch by Axin and Apc contributes to the activation of Armadillo in Drosophila

There is increasing evidence for close functional interactions between Wnt and Notch signalling. In many instances, these are mediated by convergence of the signalling events on common transcriptional targets, but there are other instances that cannot be accounted for in this manner. Studies in Drosophila have revealed that an activated form of Armadillo, the effector of Wnt signalling, interacts with, and is modulated by, the Notch receptor. Specifically, the ligand-independent traffic of Notch serves to set up a threshold for the amount of this form of Armadillo and therefore for Wnt signalling. In the current model of Wnt signalling, a complex assembled around Axin and Apc allows GSK3 (Shaggy) to phosphorylate Armadillo and target it for degradation. However, genetic experiments suggest that the loss of function of any of these three elements does not have the same effect as elevating the activity of β-catenin. Here, we show that Axin and Apc, but not GSK3, modulate the ligand-independent traffic of Notch. This finding helps to explain unexpected differences in the phenotypes obtained by different ways of activating Armadillo function and provides further support for the notion that Wnt and Notch signalling form a single functional module.

Colony-stimulating factor 2 inhibits induction of apoptosis in the bovine preimplantation embryo

PROBLEM

Addition of colony-stimulating factor 2 (CSF2) to culture medium increases post-transfer survival of bovine embryos. Here we provide evidence that one mechanism by which CSF2 affects the embryo is through inhibition of apoptosis.

METHOD OF STUDY

In the first experiment, genes and pathways whose expression were regulated by CSF2 were identified by microarray analysis. Embryos were treated with 10 ng/ml CSF2 or vehicle at Day 5 after insemination; morulae were selected for microarray analysis at Day 6. In a second experiment, antiapoptotic effects of CSF2 were determined. Embryos were treated with CSF2 or vehicle at Day 5. On Day 6 (24 h after treatment), morulae were cultured for 15 h at either 42°C (a temperature that induces apoptosis) or 38.5°C (cow body temperature).

RESULTS

In the first experiment, a total of 214 genes were differentially regulated and 160 of these could be annotated (67 upregulated genes and 93 downregulated genes). Differentially expressed genes could be placed in 13 biological process ontologies in four functional groups (development and differentiation process, cell communication, apoptosis and cell adhesion). Antiapoptotic effects of CSF2 were confirmed in the second experiment because the magnitude of the increase in TUNEL positive cells caused by heat shock was reduced by CSF2.

CONCLUSION

CSF2 blocks apoptosis in bovine embryos through actions associated with regulation of genes controlling apoptosis.