scholarly journals Epigenetic priming by Dot1l in lymphatic endothelial progenitors ensures normal lymphatic development and function

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Hyunjin Yoo ◽  
Young Jae Lee ◽  
Chanhyeok Park ◽  
Dabin Son ◽  
Dong Yoon Choi ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Lymphatic Vessels ◽  
Genetic Studies ◽  
Hematopoietic Stem ◽  
Genetic Ablation ◽  
Multiple Organs ◽  
Expression Of Genes ◽  
Lymphatic Development ◽  
And Function

AbstractProper functioning of the lymphatic system is required for normal immune responses, fluid balance, and lipid reabsorption. Multiple regulatory mechanisms are employed to ensure the correct formation and function of lymphatic vessels; however, the epigenetic modulators and mechanisms involved in this process are poorly understood. Here, we assess the regulatory role of mouse Dot1l, a histone H3 lysine (K) 79 (H3K79) methyltransferase, in lymphatic formation. Genetic ablation of Dot1l in Tie2(+) endothelial cells (ECs), but not in Lyve1(+) or Prox1(+) lymphatic endothelial cells (LECs) or Vav1(+) definitive hematopoietic stem cells, leads to catastrophic lymphatic anomalies, including skin edema, blood–lymphatic mixing, and underdeveloped lymphatic valves and vessels in multiple organs. Remarkably, targeted Dot1l loss in Tie2(+) ECs leads to fully penetrant lymphatic aplasia, whereas Dot1l overexpression in the same cells results in partially hyperplastic lymphatics in the mesentery. Genetic studies reveal that Dot1l functions in c-Kit(+) hemogenic ECs during mesenteric lymphatic formation. Mechanistically, inactivation of Dot1l causes a reduction of both H3K79me2 levels and the expression of genes important for LEC development and function. Thus, our study establishes that Dot1l-mediated epigenetic priming and transcriptional regulation in LEC progenitors safeguard the proper lymphatic development and functioning of lymphatic vessels.

scholarly journals ALK1 signaling regulates early postnatal lymphatic vessel development

Blood ◽  
2010 ◽  
Vol 115 (8) ◽  
pp. 1654-1661 ◽  
Author(s):  
Kyle Niessen ◽  
Gu Zhang ◽  
John Brady Ridgway ◽  
Hao Chen ◽  
Minhong Yan
Keyword(s):  
Endothelial Cells ◽  
Transforming Growth Factor ◽  
Vascular Development ◽  
Lymphatic Vessels ◽  
Transforming Growth Factor Β ◽  
Type I ◽  
Lymphatic Endothelial Cells ◽  
Multiple Organs ◽  
Lymphatic Development

Abstract In vertebrates, endothelial cells form 2 hierarchical tubular networks, the blood vessels and the lymphatic vessels. Despite the difference in their structure and function and genetic programs that dictate their morphogenesis, common signaling pathways have been recognized that regulate both vascular systems. ALK1 is a member of the transforming growth factor-β type I family of receptors, and compelling genetic evidence suggests its essential role in regulating blood vascular development. Here we report that ALK1 signaling is intimately involved in lymphatic development. Lymphatic endothelial cells express key components of the ALK1 pathway and respond robustly to ALK1 ligand stimulation in vitro. Blockade of ALK1 signaling results in defective lymphatic development in multiple organs of neonatal mice. We find that ALK1 signaling regulates the differentiation of lymphatic endothelial cells to influence the lymphatic vascular development and remodeling. Furthermore, simultaneous inhibition of ALK1 pathway increases apoptosis in lymphatic vessels caused by blockade of VEGFR3 signaling. Thus, our study reveals a novel aspect of ALK1 signaling in regulating lymphatic development and suggests that targeting ALK1 pathway might provide additional control of lymphangiogenesis in human diseases.

scholarly journals Mechanosensation and Mechanotransduction by Lymphatic Endothelial Cells Act as Important Regulators of Lymphatic Development and Function

2021 ◽  
Vol 22 (8) ◽  
pp. 3955
Author(s):  
László Bálint ◽  
Zoltán Jakus
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Cell Fate ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Mechanical Forces ◽  
Lymphatic Endothelial Cells ◽  
Lymphatic Development ◽  
And Function ◽  
The Impact

Our understanding of the function and development of the lymphatic system is expanding rapidly due to the identification of specific molecular markers and the availability of novel genetic approaches. In connection, it has been demonstrated that mechanical forces contribute to the endothelial cell fate commitment and play a critical role in influencing lymphatic endothelial cell shape and alignment by promoting sprouting, development, maturation of the lymphatic network, and coordinating lymphatic valve morphogenesis and the stabilization of lymphatic valves. However, the mechanosignaling and mechanotransduction pathways involved in these processes are poorly understood. Here, we provide an overview of the impact of mechanical forces on lymphatics and summarize the current understanding of the molecular mechanisms involved in the mechanosensation and mechanotransduction by lymphatic endothelial cells. We also discuss how these mechanosensitive pathways affect endothelial cell fate and regulate lymphatic development and function. A better understanding of these mechanisms may provide a deeper insight into the pathophysiology of various diseases associated with impaired lymphatic function, such as lymphedema and may eventually lead to the discovery of novel therapeutic targets for these conditions.

scholarly journals T-BET and EOMES Accelerate and Enhance Functional Differentiation of Human Natural Killer Cells

2021 ◽  
Vol 12 ◽  
Author(s):  
Laura Kiekens ◽  
Wouter Van Loocke ◽  
Sylvie Taveirne ◽  
Sigrid Wahlen ◽  
Eva Persyn ◽  
...  
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Cell Biology ◽  
Nk Cell ◽  
Current Knowledge ◽  
Functional Differentiation ◽  
Cell Maturation ◽  
Hematopoietic Stem ◽  
And Function

T-bet and Eomes are transcription factors that are known to be important in maturation and function of murine natural killer (NK) cells. Reduced T-BET and EOMES expression results in dysfunctional NK cells and failure to control tumor growth. In contrast to mice, the current knowledge on the role of T-BET and EOMES in human NK cells is rudimentary. Here, we ectopically expressed either T-BET or EOMES in human hematopoietic progenitor cells. Combined transcriptome, chromatin accessibility and protein expression analyses revealed that T-BET or EOMES epigenetically represses hematopoietic stem cell quiescence and non-NK lineage differentiation genes, while activating an NK cell-specific transcriptome and thereby drastically accelerating NK cell differentiation. In this model, the effects of T-BET and EOMES are largely overlapping, yet EOMES shows a superior role in early NK cell maturation and induces faster NK receptor and enhanced CD16 expression. T-BET particularly controls transcription of terminal maturation markers and epigenetically controls strong induction of KIR expression. Finally, NK cells generated upon T-BET or EOMES overexpression display improved functionality, including increased IFN-γ production and killing, and especially EOMES overexpression NK cells have enhanced antibody-dependent cellular cytotoxicity. Our findings reveal novel insights on the regulatory role of T-BET and EOMES in human NK cell maturation and function, which is essential to further understand human NK cell biology and to optimize adoptive NK cell therapies.

Discovery of Side- and Shear-Dependent miRNAs and mRNAs in Human Aortic Valvular Endothelial Cells

2011 ◽  
Author(s):  
Casey J. Holliday ◽  
Randall F. Ankeny ◽  
Hanjoong Jo ◽  
Robert M. Nerem
Keyword(s):  
Endothelial Cells ◽  
Aortic Valve ◽  
Oscillatory Flow ◽  
Expression Profiles ◽  
Flow Conditions ◽  
Expression Of Genes ◽  
Inflammatory Phenotype ◽  
Cardiovascular Pathologies ◽  
Laminar Shear

Aortic valve (AV) disease is diagnosed by severe symptoms, such as calcification, and typically treated by AV replacement and repair surgeries. The mechanism by which AV disease occurs, specifically the role of the endothelium remains relatively unknown. It is known that disease preferentially occurs on the fibrosa, or aortic side, where it is exposed to disturbed, oscillatory flow, whereas the ventricularis, or side facing the left ventricle, experiences pulsatile, laminar shear and remains non-calcified [1, 2]. Research shows that regulation of miRNAs, short nucleotide segments targeting mRNAs, coincides with cardiovascular pathologies [3] though expression profiles of miRNAs and the mRNAs they modulate in human AV endothelial cells (HAVECs) have not been reported. We hypothesize that disturbed flow conditions present on the fibrosa stimulate ECs to modify expression of genes and miRNAs to induce a pro-inflammatory phenotype.

Investigating The Role Of ARAP3 In The Regulation Of Hematopoietic Stem and Progenitor Cells

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2409-2409
Author(s):  
Yiwen Song ◽  
Sonja Vermeren ◽  
Wei Tong
Keyword(s):  
Endothelial Cells ◽  
Plasma Membrane ◽  
Progenitor Cells ◽  
Hematopoietic Cells ◽  
Conditional Knockout ◽  
Ph Domain ◽  
Hematopoietic Stem ◽  
Normal Peripheral Blood ◽  
Stem And Progenitor Cells

Abstract ARAP3 is a member of the dual Arf-and-Rho GTPase-activating proteins (GAP) family, functioning specifically to inactivate its substrates Arf6 and RhoA GTPases. ARAP3 is translocated to the plasma membrane after PIP3 binding to the first two of its five PH domains, facilitating its GAP activity in a PI3K-mediated manner. Rho family GTPases are found to play critical roles in many aspects of hematopoietic stem and progenitor cells (HSPCs), such as engraftment and migration, while a role for Arf family GTPases in hematopoiesis is less defined. Previous studies found that either exogenous ARAP3 expression in epithelial cells or RNAi-mediated ARAP3 depletion in endothelial cells disrupts F-actin or lamellipodia formation, respectively, resulting in a cell rounding phenotype and failure to spread. This implies that ARAP3 control of Arf6 and RhoA is tightly regulated, and maintaining precise regulation of ARAP3 levels is crucial to actin organization in the cell. Although ARAP3 was first identified in porcine leukocytes, its function in the hematopoietic system is incompletely understood. Germline deletion of Arap3 results in embryonic lethality due to angiogenic defects. Since endothelial cells are important for the emergence of HSCs during embryonic development, early lethality precludes further studying the role of ARAP3 in definitive hematopoiesis. Therefore, we generated several transgenic mouse models to manipulate ARAP3 in the hematopoietic compartment: (1) Arap3fl/fl;Vav-Cretg conditional knockout mice (CKO) deletes ARAP3 specifically in hematopoietic cells, (2) Arap3fl/fl;VE-Cadherin -Cretg CKO mice selectively deletes ARAP3 in embryonic endothelial cells and thereby hematopoietic cells, and (3) Arap3R302,3A/R302,3A germline knock-in mice (KI/KI) mutates the first PH domain to ablate PI3K-mediated ARAP3 activity in all tissues. We found an almost 100% and 90% excision efficiency in the Vav-Cretg- and VEC-Cretg- mediated deletion of ARAP3 in the bone marrow (BM), respectively. However, the CKO mice appear normal in steady-state hematopoiesis, showing normal peripheral blood (PB) counts and normal distributions of all lineages in the BM. Interestingly, we observed an expansion of the Lin-Scal+cKit+ (LSK) stem and progenitor compartment in the CKO mice. This is due to an increase in the multi-potent progenitor (MPP) fraction, but not the long-term or short-term HSC (LT- or ST-HSC) fractions. Although loss of ARAP3 does not alter the frequency of phenotypically-characterized HSCs, we performed competitive BM transplantation (BMT) studies to investigate the functional impact of ARAP3 deficiency. 500 LSK cells from Arap3 CKO (Arap3fl/fl;Vav-Cretg and Arap3fl/fl;VEC-Cretg) or Arap3fl/fl control littermate donors were transplanted with competitor BM cells into irradiated recipients. We observed similar donor-derived reconstitution and lineage repopulation in the mice transplanted with Arap3fl/fl and Arap3 CKO HSCs. Moreover, Arap3 CKO HSCs show normal reconstitution in secondary transplants. Arap3 KI/KI mice are also grossly normal and exhibit an expanded MPP compartment. Importantly, Arap3KI/KI LSKs show impaired reconstitution compared to controls in the competitive BMT assays. Upon secondary and tertiary transplantation, reconstitution in both PB and BM diminished in the Arap3KI/KI groups, in contrast to sustained reconstitution in the control group. Additionally, we observed a marked skewing towards the myeloid lineage in Arap3KI/KI transplanted secondary and tertiary recipients. These data suggest a defect in HSC function in Arap3KI/KI mice. Myeloid-skewed reconstitution also points to the possibility of selection for “myeloid-primed” HSCs and against “balanced” HSCs, as HSCs exhaust during aging or upon serial transplantation. Taken together, our data suggest that ARAP3 plays a non-cell-autonomous role in HSCs by regulating HSC niche cells. Alternatively, the ARAP3 PH domain mutant that is incapable of locating to the plasma membrane in response to PI3K may exert a novel dominant negative function in HSCs. We are investigating mechanistically how ARAP3 controls HSC engraftment and self-renewal to elucidate the potential cell-autonomous and non-cell-autonomous roles of ARAP3 in HSCs. In summary, our studies identify a previously unappreciated role of ARAP3 as a regulator of hematopoiesis and hematopoietic stem and progenitor cell function. Disclosures: No relevant conflicts of interest to declare.

Ablation of adipose-HO-1 expression increases white fat over beige fat through inhibition of mitochondrial fusion and of PGC1α in female mice

2017 ◽  
Vol 31 (1) ◽  
Author(s):  
Shailendra P. Singh ◽  
Ilana Grant ◽  
Aliza Meissner ◽  
Attallah Kappas ◽  
Nader G. Abraham
Keyword(s):  
Adipose Tissue ◽  
Knockout Mouse ◽  
Potential Role ◽  
Mitochondrial Quality Control ◽  
Knockout Mouse Model ◽  
Genetic Ablation ◽  
Beige Fat ◽  
And Function ◽  
White Fat

AbstractBackgroundHmox1 plays an important role in the regulation of mitochondrial bioenergetics and function by regulating cellular heme-derived CO and bilirubin. Previous studies have demonstrated that global disruption of HO-1 in humans and mice resulted in severe organ dysfunction.MethodsWe investigated the potential role of adipose-specific-HO-1 genetic ablation on adipose tissue function, mitochondrial quality control and energy expenditure by generating an adipo-HO-1 knockout mouse model (Adipo-HO-1ResultsAdipo-HO-1ConclusionAblation of adipose tissue-HO-1 abridged PGC1 expression promoted mitochondrial dysfunction and contributed to an increase of pro-inflammatory visceral fat and abrogated beige-cell like phenotype.

scholarly journals Normal Lymphatic Development and Function in Mice Deficient for the Lymphatic Hyaluronan Receptor LYVE-1

2006 ◽  
Vol 27 (2) ◽  
pp. 595-604 ◽  
Author(s):  
Nicholas W. Gale ◽  
Remko Prevo ◽  
Jorge Espinosa ◽  
David J. Ferguson ◽  
Melissa G. Dominguez ◽  
...  
Keyword(s):  
Lymphatic Vessels ◽  
Physiological Role ◽  
Normal Growth ◽  
Skin Inflammation ◽  
Lewis Lung ◽  
Lymphatic Development ◽  
Lymph Node Sinus ◽  
And Function ◽  
Draining Lymph Nodes ◽  
Hyaluronan Receptor

ABSTRACT The hyaluronan receptor LYVE-1 is expressed abundantly on the surfaces of lymphatic vessels and lymph node sinus endothelial cells from early development, where it has been suggested to function both in cell adhesion/transmigration and as a scavenger for hyaluronan turnover. To investigate the physiological role(s) of LYVE-1, we generated mice in which the gene for the receptor was inactivated by replacement with a β-galactosidase reporter. LYVE-1−/− mice displayed an apparently normal phenotype, with no obvious alteration in lymphatic vessel ultrastructure or function and no apparent change in secondary lymphoid tissue structure or cellularity. In addition, the levels of hyaluronan in tissue and blood were unchanged. LYVE-1−/− mice also displayed normal trafficking of cutaneous CD11c+ dendritic cells to draining lymph nodes via afferent lymphatics and normal resolution of oxazolone-induced skin inflammation. Finally, LYVE-1−/− mice supported normal growth of transplanted B16F10 melanomas and Lewis lung carcinomas. These results indicate that LYVE-1 is not obligatory for normal lymphatic development and function and suggest either the existence of compensatory receptors or a role more specific than that previously envisaged.

scholarly journals Chronic hypertension increases aortic endothelial hydraulic conductivity by upregulating endothelial aquaporin-1 expression

2017 ◽  
Vol 313 (5) ◽  
pp. H1063-H1073 ◽  
Author(s):  
Jimmy Toussaint ◽  
Chirag Bharavi Raval ◽  
Tieuvi Nguyen ◽  
Hadi Fadaifard ◽  
Shripad Joshi ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Hydraulic Conductivity ◽  
Water Transport ◽  
Aortic Endothelial Cells ◽  
Rat Models ◽  
Aquaporin 1 ◽  
Hypertensive Rat ◽  
And Function ◽  
Aortic Endothelial

Numerous studies have examined the role of aquaporins in osmotic water transport in various systems, but virtually none have focused on the role of aquaporin in hydrostatically driven water transport involving mammalian cells save for our laboratory’s recent study of aortic endothelial cells. Here, we investigated aquaporin-1 expression and function in the aortic endothelium in two high-renin rat models of hypertension, the spontaneously hypertensive genetically altered Wistar-Kyoto rat variant and Sprague-Dawley rats made hypertensive by two-kidney, one-clip Goldblatt surgery. We measured aquaporin-1 expression in aortic endothelial cells from whole rat aortas by quantitative immunohistochemistry and function by measuring the pressure-driven hydraulic conductivities of excised rat aortas with both intact and denuded endothelia on the same vessel. We used them to calculate the effective intimal hydraulic conductivity, which is a combination of endothelial and subendothelial components. We observed well-correlated enhancements in aquaporin-1 expression and function in both hypertensive rat models as well as in aortas from normotensive rats whose expression was upregulated by 2 h of forskolin treatment. Upregulated aquaporin-1 expression and function may be a response to hypertension that critically determines conduit artery vessel wall viability and long-term susceptibility to atherosclerosis. NEW & NOTEWORTHY The aortic endothelia of two high-renin hypertensive rat models express greater than two times the aquaporin-1 and, at low pressures, have greater than two times the endothelial hydraulic conductivity of normotensive rats. Data are consistent with theory predicting that higher endothelial aquaporin-1 expression raises the critical pressure for subendothelial intima compression and for artery wall hydraulic conductivity to drop.

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