scholarly journals Class II phosphatidylinositol 3-kinase-C2α is essential for Notch signaling by regulating the endocytosis of γ-secretase in endothelial cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shota Shimizu ◽  
Kazuaki Yoshioka ◽  
Sho Aki ◽  
Yoh Takuwa
Keyword(s):  
Endothelial Cells ◽  
Cell Surface ◽  
Notch Signaling ◽  
Cell Fate ◽  
Target Genes ◽  
Vascular Endothelial Cells ◽  
Class Ii ◽  
Vegf Receptor ◽  
Phosphatidylinositol 3 Kinase ◽  
Phosphatidylinositol 3

AbstractThe class II α-isoform of phosphatidylinositol 3-kinase (PI3K-C2α) plays a crucial role in angiogenesis at least in part through participating in endocytosis and, thereby, endosomal signaling of several cell surface receptors including VEGF receptor-2 and TGFβ receptor in vascular endothelial cells (ECs). The Notch signaling cascade regulates many cellular processes including cell proliferation, cell fate specification and differentiation. In the present study, we explored a role of PI3K-C2α in Delta-like 4 (Dll4)-induced Notch signaling in ECs. We found that knockdown of PI3K-C2α inhibited Dll4-induced generation of the signaling molecule Notch intracellular domain 1 (NICD1) and the expression of Notch1 target genes including HEY1, HEY2 and NOTCH3 in ECs but not in vascular smooth muscle cells. PI3K-C2α knockdown did not inhibit Dll4-induced endocytosis of cell surface Notch1. In contrast, PI3K-C2α knockdown as well as clathrin heavy chain knockdown impaired endocytosis of Notch1-cleaving protease, γ-secretase complex, with the accumulation of Notch1 at the perinuclear endolysosomes. Pharmacological blockage of γ-secretase also induced the intracellular accumulation of Notch1. Taken together, we conclude that PI3K-C2α is required for the clathrin-mediated endocytosis of γ-secretase complex, which allows for the cleavage of endocytosed Notch1 by γ-secretase complex at the endolysosomes to generate NICD1 in ECs.

scholarly journals Dehydroepiandrosterone Protects Vascular Endothelial Cells against Apoptosis through a Gαi Protein-Dependent Activation of Phosphatidylinositol 3-Kinase/Akt and Regulation of Antiapoptotic Bcl-2 Expression

Endocrinology ◽  
2007 ◽  
Vol 148 (7) ◽  
pp. 3068-3076 ◽  
Author(s):  
Dongmin Liu ◽  
Hongwei Si ◽  
Kathryn A. Reynolds ◽  
Wei Zhen ◽  
Zhenquan Jia ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Estrogen Receptor ◽  
Vascular Function ◽  
Vascular Endothelial Cells ◽  
Specific Inhibitor ◽  
Vascular Endothelial ◽  
Phosphatidylinositol 3 Kinase ◽  
Antiapoptotic Effect ◽  
Dose Dependent ◽  
Phosphatidylinositol 3

The adrenal steroid dehydroepiandrosterone (DHEA) may improve vascular function, but the mechanism is unclear. In the present study, we show that DHEA significantly increased cell viability, reduced caspase-3 activity, and protected both bovine and human vascular endothelial cells against serum deprivation-induced apoptosis. This effect was dose dependent and maximal at physiological concentrations (0.1–10 nm). DHEA stimulation of bovine aortic endothelial cells resulted in rapid and dose-dependent phosphorylation of Akt, which was blocked by LY294002, a specific inhibitor of phosphatidylinositol 3-kinase (PI3K), the upstream kinase of Akt. Accordingly, inhibition of PI3K or transfection of the cells with dominant-negative Akt ablated the antiapoptotic effect of DHEA. The induced Akt phosphorylation and subsequent cytoprotective effect of DHEA were dependent on activation of Gαi proteins, but were estrogen receptor independent, because these effects were blocked by pertussis toxin but not by the estrogen receptor inhibitor ICI182,780 or the aromatase inhibitor aminoglutethimide. Finally, DHEA enhanced antiapoptotic Bcl-2 protein expression, its promoter activity, and gene transcription attributable to the activation of the PI3K/Akt pathway. Neutralization of Bcl-2 by antibody transfection significantly decreased the antiapoptotic effect of DHEA. These findings provide the first evidence that DHEA acts as a survival factor for endothelial cells by triggering the Gαi-PI3K/Akt-Bcl-2 pathway to protect cells against apoptosis. This may represent an important mechanism underlying the vascular protective effect of DHEA.

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

2021 ◽  
Vol 9 ◽  
Author(s):  
Abdellah Akil ◽  
Ana K. Gutiérrez-García ◽  
Rachael Guenter ◽  
J. Bart Rose ◽  
Adam W. Beck ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Tumor Progression ◽  
Notch Signaling ◽  
Cell Fate ◽  
Tumor Angiogenesis ◽  
Vascular Endothelial Cells ◽  
Notch Pathway ◽  
Vascular Endothelial ◽  
Cell Fate Determination ◽  
Fate Determination

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.

scholarly journals Vascular Notch Signaling in Stress Hematopoiesis

2021 ◽  
Vol 8 ◽  
Author(s):  
Can Huang ◽  
Dawei Yang ◽  
George W. Ye ◽  
Charles A. Powell ◽  
Peipei Guo
Keyword(s):  
Endothelial Cells ◽  
Notch Signaling ◽  
Cell Fate ◽  
Stromal Cell ◽  
Vascular Endothelial Cells ◽  
Cell Lineage ◽  
Transgenic Animals ◽  
Cell Types ◽  
Vascular Endothelial ◽  
Hematopoietic Stem

Canonical Notch signaling is one of the most conserved signaling cascades. It regulates cell proliferation, cell differentiation, and cell fate maintenance in a variety of biological systems during development and cancer (Fortini, 2009; Kopan and Ilagan, 2009; Andersson et al., 2011; Ntziachristos et al., 2014). For the hematopoietic system, during embryonic development, Notch1 is essential for the emergence of hematopoietic stem cells (HSCs) at the aorta-gornado-mesonephro regions of the dorsal aorta. At adult stage, Notch receptors and Notch targets are expressed at different levels in diverse hematopoietic cell types and influence lineage choices. For example, Notch specifies T cell lineage over B cells. However, there has been a long-lasting debate on whether Notch signaling is required for the maintenance of adult HSCs, utilizing transgenic animals inactivating different components of the Notch signaling pathway in HSCs or niche cells. The aims of the current mini-review are to summarize the evidence that disapproves or supports such hypothesis and point at imperative questions waiting to be addressed; hence, some of the seemingly contradictory findings could be reconciled. We need to better delineate the Notch signaling events using biochemical assays to identify direct Notch targets within HSCs or niche cells in specific biological context. More importantly, we call for more elaborate studies that pertain to whether niche cell type (vascular endothelial cells or other stromal cell)-specific Notch ligands regulate the differentiation of T cells in solid tumors during the progression of T-lymphoblastic lymphoma (T-ALL) or chronic myelomonocytic leukemia (CMML). We believe that the investigation of vascular endothelial cells' or other stromal cell types' interaction with hematopoietic cells during homeostasis and stress can offer insights toward specific and effective Notch-related therapeutics.

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