ePubs

• Mechanical testing of mouse carotid arteries: from newborn to adult

  Authors:
  Amin M, Le VP, Wagenseil JE
  
  J Vis Exp. 2012 Feb 23;(60). pii: 3733. doi: 10.3791/3733
  
  http://www.ncbi.nlm.nih.gov/pubmed/22395422

   

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• Measuring left ventricular pressure in late embryonic and neonatal mice

  Authors:
  Le VP, Kovacs A, Wagenseil JE

  J Vis Exp. 2012 Feb 23;(60). pii: 3756. doi: 10.3791/3756

  http://www.ncbi.nlm.nih.gov/pubmed/22395602

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• Elastin in Large Artery Stiffness and Hypertension

  Authors:
  Wagenseil JE, Mecham RP

  J Cardiovasc Transl Res. 2012 Jan 31. [Epub ahead of print]

  http://www.ncbi.nlm.nih.gov/pubmed/22290157

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• Equal modulation of endothelial cell function by four distinct tissue-specific mesenchymal stem cells

  Authors:
  Lin RZ, Moreno-Luna R, Zhou B, Pu WT, Melero-Martin JM

  Angiogenesis 2012; in press

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• Resolvin D1 receptor stereoselectivity and regulation of inflammation and pro-resolving microRNAs

  Authors:
  Krishnamoorthy S, Recchiuti A, Chiang N, Fredman G, Serhan CN.

  Abstract:
  Resolution of acute inflammation is an active process that involves the biosynthesis of specialized proresolving lipid mediators. Among them, resolvin D1 (RvD1) actions are mediated by two G protein-coupled receptors (GPCRs), ALX/FPR2 and GPR32, that also regulate specific microRNAs (miRNAs) and their target genes in novel resolution circuits. We report the ligand selectivity of RvD1 activation of ALX/FPR2 and GPR32. In addition to RvD1, its aspirin-triggered epimer and RvD1 analogs each dose dependently and effectively activated ALX/FPR2 and GPR32 in GPCR-overexpressing β-arrestin systems using luminescence and electric cell-substrate impedance sensing. To corroborate these findings in vivo, neutrophil infiltration in self-limited peritonitis was reduced in human ALX/FPR2-overexpressing transgenic mice that was further limited to 50% by RvD1 treatment with as little as 10 ng of RvD1 per mouse. Analysis of miRNA expression revealed that RvD1 administration significantly up-regulated miR-208a and miR-219 in exudates isolated from ALX/FPR2 transgenic mice compared with littermates. Overexpression of miR-208a in human macrophages up-regulated IL-10. In comparison, in ALX/FPR2 knockout mice, RvD1 neither significantly reduced leukocyte infiltration in zymosan-induced peritonitis nor regulated miR-208a and IL-10 in these mice. Together, these results demonstrate the selectivity of RvD1 interactions with receptors ALX/FPR2 and GPR32. Moreover, they establish a new molecular circuit that is operative in the resolution of acute inflammation activated by the proresolving mediator RvD1 involving specific GPCRs and miRNAs.

  Citation:
  Am J Pathol. 2012; vol. 180, Epub 3/23/12; doi: 10.1016/j.ajpath.2012.01.028.
   
  http://www.ncbi.nlm.nih.gov/pubmed/22449948

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• Resolvin E2 formation and impact in inflammation-resolution

  Authors:
  Oh SF, Dona M, Fredman G, Krishnamoorthy S, Irimia D, Serhan CN

  Abstract:
  Acute inflammation and its resolution are essential processes for tissue protection and homeostasis. In this context, specialized proresolving mediators derived from polyunsaturated fatty acids are of interest. In this study, we report that resolvin E2 (RvE2) from eicosapentaenoic acid is endogenously produced during self-limited murine peritonitis in both the initiation and resolution phases. RvE2 (1-10 nM) carries potent leukocyte-directed actions that include: 1) regulating chemotaxis of human neutrophils; and 2) enhancing phagocytosis and anti-inflammatory cytokine production. These actions appear to be mediated by leukocyte G-protein-coupled receptors as preparation of labeled RvE2 gave direct evidence for specific binding of radiolabeled RvE2 to neutrophils (K(d) 24.7 ± 10.1 nM) and resolvin E1 activation of recombinant G-protein-coupled receptors was assessed. In addition to the murine inflammatory milieu, RvE2 was also identified in plasma from healthy human subjects. RvE2 rapidly downregulated surface expression of human leukocyte integrins in whole blood and dampened responses to platelet-activating factor. Together, these results indicate that RvE2 can stimulate host-protective actions throughout initiation and resolution in the innate inflammatory responses.

  http://www.ncbi.nlm.nih.gov/pubmed/22450811

  Citation:
  J Immunol. 2012; Epub 3/26/12; doi: 10.4049/jimmunol.1103652.

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• Diverse roles for VEGF-A in the nervous system

  Authors:
  

  Mackenzie F, Ruhrberg C.

  Abstract:
  Vascular endothelial growth factor A (VEGF-A) is best known for its essential roles in blood vessel growth. However, evidence has emerged that VEGF-A also promotes a wide range of neuronal functions, both in vitro and in vivo, including neurogenesis, neuronal migration, neuronal survival and axon guidance. Recent studies have employed mouse models to distinguish the direct effects of VEGF on neurons from its indirect, vessel-mediated effects. Ultimately, refining our knowledge of VEGF signalling pathways in neurons should help us to understand how the current use of therapeutics targeting the VEGF pathway in cancer and eye disease might be expanded to promote neuronal health and nerve repair.

  Development. 2012 Apr;139(8):1371-80.  PMID: 22434866 [PubMed - in process]

  http://www.ncbi.nlm.nih.gov/pubmed/22434866

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• Vascular endothelial hyperpermeability induces the clinical symptoms of Clarkson disease (the systemic capillary leak syndrome)

  Authors:
  

  Zhihui Xie, Chandra C. Ghosh, Roshni Patel, Shoko Iwaki,  Donna Gaskins, Celeste Nelson,    Nina Jones,  Philip R. Greipp, Samir M. Parikh  and Kirk M. Druey

  Abstract:
  The systemic capillary leak syndrome (SCLS) is an extremely rare disorder characterized by transient episodes of hypotensive shock and anasarca thought to arise from reversible microvascular barrier dysfunction. Although the high prevalence of a monoclonal gammopathy of unknown significance (MGUS) in SCLS suggests a pathogenic contribution of endogenous immunoglobulins, the mechanisms of vascular hyperpermeability remain obscure. Herein, we report clinical and molecular findings on 23 subjects, the largest SCLS case series to date. Application of episodic SCLS sera, but neither the purified immunoglobulin fraction nor sera obtained from subjects during remission, to human microvascular endothelial cells caused vascular endothelial cadherin (VE-cadherin) internalization, disruption of inter-endothelial junctions, actin stress fiber formation, and increased permeability in complementary functional assays without inducing endothelial apoptosis. Intravenous immunoglobulin (IVIG), one promising therapy for SCLS, mitigated the permeability effects of episodic sera directly. Consistent with the presence of endogenous, non-immunoglobulin, circulating permeability factor(s) constrained to SCLS episodes, we found that two such proteins, vascular endothelial growth factor (VEGF) and angiopoietin 2 (Ang2), were elevated in episodic SCLS sera but not in remission sera. Antibody-based inhibition of Ang2 counteracted permeability induced by episodic SCLS sera. Comparable experiments with anti-VEGF antibody (bevacizumab) yielded less interpretable results, likely due to endothelial toxicity of VEGF withdrawal. Our results support a model of SCLS pathogenesis in which non-immunoglobulin humoral factors such as VEGF and Ang2 contribute to transient endothelial contraction, suggesting a molecular mechanism for this highly lethal disorder.

  Citation:
  Zhihui Xie, Chandra C. Ghosh, Roshni Patel, Shoko Iwaki, Donna Gaskins, Celeste Nelson, Nina Jones, Philip R. Greipp, Samir M. Parikh, and Kirk M. Druey. Vascular endothelial hyperpermeability induces the clinical symptoms of Clarkson disease (the systemic capillary leak syndrome) Blood blood-2011-08-375816; published ahead of print March 12, 2012, doi:10.1182/blood-2011-08-375816

  http://bloodjournal.hematologylibrary.org/content/early/2012/03/12/blood-2011-08-375816.abstract

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• BAZF, a novel component of cullin3-based E3 ligase complex, mediates VEGFR and Notch cross-signalling in angiogenesis

  Authors:
  Ohnuki H, Inoue H, Takemori N, Nakayama H, Sakaue T, Fukuda S, Miwa D, Nishiwaki E, Hatano M, Tokuhisa T, Endo Y, Nose M, Higashiyama S.

  Abstract:
  Angiogenic homeostasis is maintained by a balance between vascular endothelial growth factor (VEGF) and Notch signalling in endothelial cells (ECs). We screened for molecules that might mediate the coupling of VEGF signal transduction with down-regulation of Notch signalling, and identified B-cell chronic lymphocytic leukemia/lymphoma6-associated zinc finger protein (BAZF). BAZF was induced by VEGF-A in ECs to bind to the Notch signalling factor CBF1, and to promote the degradation of CBF1 through polyubiquitination in a CBF1-cullin3 (CUL3) E3 ligase complex. BAZF disruption in vivo decreased endothelial tip cell number and filopodia protrusion, and markedly abrogated vascular plexus formation in the mouse retina, overlapping the retinal phenotype seen in response to Notch activation. Further, impaired angiogenesis and capillary remodeling were observed in skin-wounded BAZF(-/-) mice. We therefore propose that BAZF supports angiogenic sprouting via BAZF-CUL3-based polyubiquitination-dependent degradation of CBF1 to down-regulate Notch signalling.

  Citation:
  
  BAZF, a novel component of cullin3-based E3 ligase complex, mediates VEGFR and Notch cross-signalling in angiogenesis. Ohnuki H, Inoue H, Takemori N, Nakayama H, Sakaue T, Fukuda S, Miwa D, Nishiwaki E, Hatano M, Tokuhisa T, Endo Y, Nose M, Higashiyama S. Department of Biochemistry and Molecular Genetics, Ehime University Graduate School of Medicine, Toon, Japan.  Blood. 2012 Jan 25. PMID: 22279058 [PubMed - as supplied by publisher]

  http://www.ncbi.nlm.nih.gov/pubmed/22279058

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• Caveolae, Fenestrae and Transendothelial Channels Retain PV1 on the Surface of Endothelial Cells

  Authors:
  Tkachenko E, Tse D, Sideleva O, Deharvengt SJ, Luciano MR, Xu Y, McGarry CL, Chidlow J, Pilch PF, Sessa WC, Toomre DK, Stan RV

  Abstract:
  PV1 protein is an essential component of stomatal and fenestral diaphragms, which are formed at the plasma membrane of endothelial cells (ECs), on structures such as caveolae, fenestrae and transendothelial channels. Knockout of PV1 in mice results in in utero and perinatal mortality. To be able to interpret the complex PV1 knockout phenotype, it is critical to determine whether the formation of diaphragms is the only cellular role of PV1. We addressed this question by measuring the effect of complete and partial removal of structures capable of forming diaphragms on PV1 protein level. Removal of caveolae in mice by knocking out caveolin-1 or cavin-1 resulted in a dramatic reduction of PV1 protein level in lungs but not kidneys. The magnitude of PV1 reduction correlated with the abundance of structures capable of forming diaphragms in the microvasculature of these organs. The absence of caveolae in the lung ECs did not affect the transcription or translation of PV1, but it caused a sharp increase in PV1 protein internalization rate via a clathrin- and dynamin-independent pathway followed by degradation in lysosomes. Thus, PV1 is retained on the cell surface of ECs by structures capable of forming diaphragms, but undergoes rapid internalization and degradation in the absence of these structures, suggesting that formation of diaphragms is the only role of PV1.

  Citation:
  Tkachenko E, Tse D, Sideleva O, Deharvengt SJ, Luciano MR, Xu Y, McGarry CL, Chidlow J, Pilch PF, Sessa WC, Toomre DK, Stan RV.  Caveolae, Fenestrae and Transendothelial Channels Retain PV1 on the Surface of Endothelial Cells. PLoS One. 2012;7(3):e32655. Epub 2012 Mar 5.

  http://www.ncbi.nlm.nih.gov/pubmed/22403691

   

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• Heterogeneity in SDF-1 Expression Defines the Vasculogenic Potential of Adult Cardiac Progenitor Cells

  Authors
  

  Claudia O. Rodrigues, Lina A. Shehadeh, Michael Hoosien, Valerie Otero, Ines Chopra, Nicholas F. Tsinoremas3, Nanette H. Bishopric

  Abstract
  Rationale: The adult myocardium has been reported to harbor several classes of multipotent progenitor cells (CPCs) with tri-lineage differentiation potential. It is not clear whether c-kit+CPCs represent a uniform precursor population or a more complex mixture of cell types.
  Objective: To characterize and understand vasculogenic heterogeneity within c-kit+presumptive cardiac progenitor cell populations.
  Methods and Results: c-kit+, sca-1+ CPCs obtained from adult mouse left ventricle expressed stem cell-associated genes,including Oct-4 and Myc, and were self-renewing, pluripotent and clonogenic. Detailed single cell clonal analysis of 17 clones revealed that most (14/17) exhibited trilineage differentiation potential. However, striking morphological differences were observed among clones that were heritable and stable in long-term culture. 3 major groups were identified: round (7/17), flat or spindle-shaped (5/17) and stellate (5/17). Stellate morphology was predictive of vasculogenic differentiation in
  Matrigel. Genome-wide expression studies and bioinformatic analysis revealed clonally stable, heritable differences in stromal cell-derived factor-1 (SDF-1) expression that correlated strongly with stellate morphology and vasculogenic capacity. Endogenous SDF-1 production contributed directly to vasculogenic differentiation: both shRNA-mediated knockdown of SDF-1 and AMD3100, an antagonist of the SDF-1 receptor CXC chemokine Receptor-4 (CXCR4), reduced tubeforming capacity, while exogenous SDF-1 induced tube formation by 2 non-vasculogenic clones. CPCs producing SDF-1 were able to vascularize Matrigel dermal implants in vivo, while CPCs with low SDF-1 production were not.
  Conclusions: Clonogenic c-kit+, sca-1+ CPCs are heterogeneous in morphology, gene expression patterns and
  differentiation potential. Clone-specific levels of SDF-1 expression both predict and promote development of a vasculogenic phenotype via a previously unreported autocrine mechanism.

  Citation: Rodrigues CO, Shehadeh LA, Hoosien M, Otero V, Chopra I, et al. (2011) Heterogeneity in SDF-1 Expression Defines the Vasculogenic Potential of Adult Cardiac Progenitor Cells. PLoS ONE 6(8): e24013. doi:10.1371/journal.pone.0024013

  http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0024013

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• Axl is essential for VEGF-A-dependent activation of PI3K/Akt.

  Authors:
  Guo-Xiang Ruan and Andrius Kazlauskas

  Abstract:
  Herein, we report that vascular endothelial growth factor A (VEGF-A) engages the PI3K/Akt pathway by a previously unknown mechanism that involves three tyrosine kinases. Upon VEGF-A-dependent activation of VEGF receptor-2 (VEGFR-2), and subsequent TSAd-mediated activation of Src family kinases (SFKs), SFKs engage the receptor tyrosine kinase Axl via its juxtamembrane domain to trigger ligand-independent autophosphorylation at a pair of YXXM motifs that promotes association with PI3K and activation of Akt. Other VEGF-A-mediated signalling pathways are independent of Axl. Interfering with Axl expression or function impairs VEGF-A- but not bFGF-dependent migration of endothelial cells. Similarly, Axl null mice respond poorly to VEGF-A-induced vascular permeability or angiogenesis, whereas other agonists induce a normal response. These results elucidate the mechanism by which VEGF-A activates PI3K/Akt, and identify previously unappreciated potential therapeutic targets of VEGF-A-driven processes.

  Citation:
  EMBO J. 2012 Feb 10. doi: 10.1038/emboj.2012.21. [Epub ahead of print]
  PMID:  22327215

  Link:
  http://www.nature.com/emboj/journal/vaop/ncurrent/full/emboj201221a.html

  Submitted by:
  Andrius Kazlauskas

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• Soluble Thrombomodulin Reduces Inflammation and Prevents Microalbuminuria Induced by Chronic Endothelial Activation in Transgenic Mice

  Authors:
  Gangaraju Rajashekhar, Akanksha Gupta, Abby J Marin, Jessica L Friedrich, Antje Willuweit,
  David T Berg, Martin S Cramer, George E. Sandusky, Timothy A Sutton, David P. Basile, Brian Grinnell, and Matthias Clauss

   

  Abstract:
  Chronic kidney disease pathogenesis involves both tubular and vascular injuries. Despite abundant investigations to identify the risk factors, the involvement of chronic endothelial dysfunction in developing nephropathies is insufficiently explored. Previously, soluble thrombomodulin (sTM), a cofactor in the activation of protein C has been shown to protect endothelial function in models of acute kidney injury. In this study, the role for sTM in treating chronic kidney disease was explored by employing a mouse model of chronic vascular activation using the endothelial specific tumor necrosis factor alpha (TNF) expressing (tie2-TNF) mice. Analysis of kidneys from these mice after 3 months showed no apparent phenotype, whereas 6 months old mice demonstrated infiltration of CD45 positive leukocytes accompanied by up-regulated gene expression of inflammatory chemokines, markers of kidney injury, and albuminuria. Intervention with murine sTM with bi-weekly subcutaneous injections during this window of disease development between month 3 and 6 prevented the development of kidney pathology. To better understand the mechanisms of these findings, we determined whether sTM could also prevent chronic endothelial cell activation in vitro. Indeed, treatment with sTM normalized increased chemokine, adhesion molecule expression, and reduced transmigration of monocytes in continuously activated TNF-expressing endothelial cells. Our results suggest that vascular inflammation associated with vulnerable endothelium can contribute to loss in renal function as suggested by the tie2-TNF mice, a unique model for studying the role of vascular activation and inflammation in chronic kidney disease. Further, the ability to restore the endothelial balance by exogenous administration of sTM via downregulation of specific adhesion molecules and chemokines suggests a potential for therapeutic intervention in kidney disease associated with chronic inflammation.

  Link:
  http://ajprenal.physiology.org/content/early/2011/11/23/ajprenal.00558.2011.reprint

  Submitted by:
  Matthias Clauss

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• Convective tissue movements play a major role in avian endocardial morphogenesis.

  Authors: 
  Aleksandrova, A., Czirok, A., Szabo, A., Filla, M.B., Hossain, M.J., Whelan, P.F, Lansford, R.D., and Rongish, B.J.

  Abstract:
  Endocardial cells play a critical role in cardiac development and function, forming the innermost layer of the early (tubular) heart, separated from the myocardium by extracellular matrix (ECM). However, knowledge is limited regarding the interactions of cardiac progenitors and surrounding ECM during dramatic tissue rearrangements and concomitant cellular repositioning events that underlie endocardial morphogenesis. By analyzing the movements of immunolabeled ECM components (fibronectin, fibrillin-2) and TIE1 positive endocardial progenitors in time-lapse recordings of quail embryonic development, we demonstrate that the transformation of the primary heart field within the anterior lateral plate mesoderm (LPM) into a tubular heart involves the precise co-movement of primordial endocardial cells with the surrounding ECM. Thus, the ECM of the tubular heart contains filaments that were associated with the anterior LPM at earlier developmental stages. Moreover, endocardial cells exhibit surprisingly little directed active motility, that is, sustained directed movements relative to the surrounding ECM microenvironment. These findings point to the importance of large-scale tissue movements that convect cells to the appropriate positions during cardiac organogenesis.

  Citation:
  Developmental Biology, doi:10.1016/j.ydbio.2011.12.036 (in press).

  Link:
  http://www.sciencedirect.com/science/article/pii/S0012160611014643

  Submitted by:
  Brenda Rongish

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• Site-Specific MicroRNA-92a Regulation of Kruppel-Like

  Authors:
  Yun Fang and Peter F Davies

  Abstract:
  Endothelial transcription factors Kruppel-like factor 4 (KLF4) and KLF2 are implicated in protection against atherogenesis. Steady-state microRNA (miR) regulation of KLFs in vivo is accessible by screening region-specific endothelial miRs and their targets.  A subset of differentially expressed endothelial miRs was identified in atherosusceptible versus protected regions of normal swine aorta. In silico analyses predicted highly conserved binding sites in the 3'-untranslated region (3'UTR) of KLF4 for 5 miRs of the subset (miR-26a, -26b, -29a, -92a, and -103) and a single binding site for a miR-92a complex in the 3'UTR of KLF2. Of these, only miR-92a knockdown and knock-in resulted in responses of KLF4 and KLF2 expression in human arterial endothelial cells. Dual luciferase reporter assays demonstrated functional interactions of miR-92a with full-length 3'UTR sequences of both KLFs and with the specific binding elements therein. Two evolutionarily conserved miR-92a sites in KLF4 3'UTR and 1 site in KLF2 3'UTR were functionally validated. Knockdown of miR-92a in vitro resulted in partial rescue from cytokine-induced proinflammatory marker expression (monocyte chemotactic protein 1, vascular cell adhesion molecule-1, E-selectin, and endothelial nitric oxide synthase) that was attributable to enhanced KLF4 expression. Leukocyte-human arterial endothelial cell adhesion experiments supported this conclusion. In swine aortic arch endothelium, a site of atherosusceptibility where miR-92a expression was elevated, both KLFs were expressed at low levels relative to protected thoracic aorta. 

  Conclusion:miR-92a co-regulates KLF4 and KLF2 expression in arterial endothelium and contributes to phenotype heterogeneity associated with regional atherosusceptibility and protection in vivo.

  Citation:
  ATVB, Jan 19th 2012

  Link:
  http://atvb.ahajournals.org/content/early/2012/01/19/ATVBAHA.111.244053

  Submitted by:
  Peter F Davies

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• SPECT imaging of peripheral amyloid in mice by targeting hyper-sulfated heparan sulfate proteoglycans with specific scFv antibodies

  Authors
  Jonathan S. Wall, Tina Richey, Alan Stuckey, Robert Donnell, Arie Oosterhof, Toin H. van Kuppevelt, Nicole C. Smits, Stephen J. Kennel

  Abstract
  INTRODUCTION: Amyloid deposits are associated with a broad spectrum of disorders including monoclonal gammopathies, chronic inflammation, and Alzheimer's disease. In all cases, the amyloid pathology contains, in addition to protein fibrils, a plethora of associated molecules, including high concentrations of heparan sulfate proteoglycans (HSPGs).
  METHODS: We have evaluated radioiodinated scFvs that bind HS for their ability to image amyloid deposits in vivo. scFv's with different binding characteristics were isolated by phage display using HS extracted from bovine kidney or mouse and human skeletal muscle glycosaminoglycans (GAGs). Following purification and radioiodination, the biodistribution of (125)I-scFv's was assessed in mice with inflammation-associated AA amyloidosis or in amyloid-free mice by using SPECT imaging, biodistribution measurements and tissue autoradiography.
  RESULTS:  Four different scFv's all showed binding in vivo to amyloid in the spleen, liver and kidney of diseased mice; however, three of the scFv's also bound to sites within these organs in disease free mice. One scFv specific for hypersulfated HSPGs preferentially bound amyloid and did not accumulate in healthy tissues.
  CONCLUSIONS:  These data indicate that HS expressed in amyloid deposits has unique qualities that can be distinguished from HS in normal tissues. A scFv specific for rare hypersulfated HS was used to selectively image AA amyloid in mice with minimal retention in normal tissue.

   

  Copyright © 2011 Elsevier Inc. All rights reserved.

  PMID: 21958847 [PubMed - as supplied by publisher]
  

  Nucl Med Biol. 2011 Sep 27. [Epub ahead of print]

  
  http://www.ncbi.nlm.nih.gov/pubmed/21958847

   

   

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• Semaphorin-PlexinD1 Signaling Limits Angiogenic Potential via the VEGF Decoy Receptor sFlt1

  Authors
  Tomasz Zygmunt, Carl Michael Gay, Jordan Blondelle, Manvendra K. Singh, Kathleen McCrone Flaherty, Paula Casey Means, Lukas Herwig, Alice Krudewig, Heinz-Georg Belting, Markus Affolter, Jonathan A. Epstein, Jesús Torres-Vázquez

  Sprouting angiogenesis expands the embryonic vasculature enabling survival and homeostasis. Yet how the angiogenic capacity to form sprouts is allocated among endothelial cells (ECs) to guarantee the reproducible anatomy of stereotypical vascular beds remains unclear. Here we show that Sema-PlxnD1 signaling, previously implicated in sprout guidance, represses angiogenic potential to ensure the proper abundance and stereotypical distribution of the trunk's segmental arteries (SeAs). We find that Sema-PlxnD1 signaling exerts this effect by antagonizing the proangiogenic activity of vascular endothelial growth factor (VEGF). Specifically, Sema-PlxnD1 signaling ensures the proper endothelial abundance of soluble flt1 (sflt1), an alternatively spliced form of the VEGF receptor Flt1 encoding a potent secreted decoy. Hence, Sema-PlxnD1 signaling regulates distinct but related aspects of angiogenesis: the spatial allocation of angiogenic capacity within a primary vessel and sprout guidance.

  http://www.cell.com/developmental-cell/abstract/S1534-5807%2811%2900267-X

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• Lung endothelial monocyte-activating protein 2

  Lung endothelial monocyte-activating protein 2 is a mediator of cigarette smoke-induced emphysema in mice. Clauss M, Voswinckel R, Rajashekhar G, Sigua NL, Fehrenbach H, Rush NI, Schweitzer KS, Yildirim AO, Kamocki K, Fisher AJ, Gu Y, Safadi B, Nikam S, Hubbard WC, Tuder RM, Twigg HL 3rd, Presson RG, Sethi S, Petrache I. J Clin Invest. 2011 May 16. pii: 43881. doi: 10.1172/JCI43881.

  http://www.ncbi.nlm.nih.gov/pubmed/21576822

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• BKCa and KV channels limit conducted vasomotor responses in rat mesenteric terminal arterioles

  Authors: Bjørn Olav Hald,  Jens Christian Brings Jacobsen, Thomas Hartig Braunstein,
  Ryuji Inoue, Yushi Ito, Preben Graae Sørensen, Niels-Henrik Holstein-Rathlou and Lars Jørn Jensen

  Abstract:  Intracellular Ca2+ signals underlying conducted vasoconstriction to local application of a brief depolarizing KCl stimulus was investigated in rat mesenteric terminal arterioles (<40 μm). Using a computer model of an arteriole segment comprised of coupled endothelial cells (EC) and vascular smooth muscle cells (VSMC) simulations of both membrane potential and intracellular [Ca2+] were performed.  The “characteristic” length constant, λ, was approximated using a modified cable equation in both experiments and simulations. We hypothesized that K+ conductance in the arteriolar wall limit the electrotonic spread of a local depolarization along arterioles by current dissipation across the VSMC plasma membrane. Thus, we anticipated an increased λ by inhibition of voltage-activated K+ channels.  Application of the BKCa channel blocker iberiotoxin (100 nM) onto mesenteric arterioles in vitro and inhibition of BKCa channel current in silico increased λ by 34% and 32%, respectively. Similarly, inhibition of KV channels in vitro (4-aminopyridine, 1 mM) or in silico increased λ by 41% and 21%, respectively. Immunofluorescence microscopy demonstrated expression of BKCa, Kv1.5, Kv2.1, but not Kv1.2, in VSMCs of rat mesenteric terminal arterioles. Our results demonstrate that inhibition of voltage-activated K+ channels enhance vascular-conducted responses to local depolarization in terminal arterioles by increasing the membrane resistance of VSMCs. These data contribute to our understanding of how differential expression patterns of voltage-activated K+ channels may influence conducted vasoconstriction in small arteriolar networks. This finding is potentially relevant to understanding the compromised microcirculatory blood flow in systemic vascular diseases such as diabetes mellitus and hypertension. 

  Keywords: Calcium. Terminal arteriole . Conducted vasoconstriction . Intercellular  communication . Electrotonic conduction . KV channel . BKCa channel . Computer model . Simulation

  Pflugers Arch - Eur J Physiol
  DOI 10.1007/s00424-011-1049-8
  http://www.springerlink.com/content/e2k87188666110v3/

   

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• Potential candidate genomic biomarkers of drug induced vascular injury in the rat

  Authors
  Deidre A. Dalmas, Marshall S. Scicchitano, David Mullins, Angela Hughes-Earle, Kay Tatsuoka, Michal Magid-Slav, Kendall S. Frazier, Heath C. Thomas

  Abstract
  Drug-induced vascular injury is frequently observed in rats but the relevance and translation to humans present a hurdle for drug development. Numerous structurally diverse pharmacologic agents have been shown to induce mesenteric arterial medial necrosis in rats, but no consistent biomarkers have been identified. To address this need, a novel strategy was developed in rats to identify genes associated with the development of drug-induced mesenteric arterial medial necrosis. Separate groups (n = 6/group) of male rats were given 28 different toxicants (30 different treatments) for 1 or 4 days with each toxicant given at 3 different doses (low, mid and high) plus corresponding vehicle (912 total rats). Mesentery was collected, frozen and endothelial and vascular smooth muscle cells were microdissected from each artery. RNA was isolated, amplified and Affymetrix GeneChip® analysis was performed on selectively enriched samples and a novel panel of genes representing those which showed a dose responsive pattern for all treatments in which mesenteric arterial medial necrosis was histologically observed, was developed and verified in individual endothelial cell- and vascular smooth muscle cell-enriched samples. Data were confirmed in samples containing mesentery using quantitative real-time RT-PCR (TaqMan™) gene expression profiling. In addition, the performance of the panel was also confirmed using similarly collected samples obtained from a timecourse study in rats given a well established vascular toxicant (Fenoldopam). Although further validation is still required, a novel gene panel has been developed that represents a strategic opportunity that can potentially be used to help predict the occurrence of drug-induced mesenteric arterial medial necrosis in rats at an early stage in drug development.

  http://www.sciencedirect.com/science/article/pii/S0041008X11003681

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• Cadherins at cell-autonomous membrane contacts control macropinocytosis

  Authors
  Peter J. B. Sabatini, Ming Zhang, Rosalind V. Silverman-Gavrila, and Michelle P. Bendeck

  Cadherins aggregate and stabilize cell–cell junctions through interactions with adjacent cells. In addition, N-cadherin and E-cadherin concentrate at free edges or at the lamellipodia of migrating cells and are found within large vesicles called macropinosomes, which develop from membrane ruffles. The binding properties of cadherins have not previously been associated with the localization of cadherins at membrane ruffles; however, we report that the dorsal, ventral and lateral membrane contacts that occur as a result of the overlap of membrane ruffles aggregate N-cadherin, and that both N-cadherin and E-cadherin promote macropinosome closure and fluid-phase uptake in macropinosomes. These data reveal a previously unsuspected function for cadherin-mediated cell–cell adhesion molecules in the closure of cell-autonomous membrane contacts at membrane ruffles, resulting in macropinocytosis.

  http://jcs.biologists.org/content/124/12/2013.abstract?sid=d397b2e6-76bc-4566-b5ac-691f9c71180a

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• Neurovascular development in the embryonic zebrafish hindbrain

  Authors
  Florian Ulrich, Leung-Hang Ma, Robert G. Baker, Jesús Torres-Vázquez

  The brain is made of billions of highly metabolically active neurons whose activities provide the seat for cognitive, affective, sensory and motor functions. The cerebral vasculature meets the brain's unusually high demand for oxygen and glucose by providing it with the largest blood supply of any organ. Accordingly, disorders of the cerebral vasculature, such as congenital vascular malformations, stroke and tumors, compromise neuronal function and survival and often have crippling or fatal consequences. Yet, the assembly of the cerebral vasculature is a process that remains poorly understood. Here we exploit the physical and optical accessibility of the zebrafish embryo to characterize cerebral vascular development within the embryonic hindbrain. We find that this process is primarily driven by endothelial cell migration and follows a two-step sequence. First, perineural vessels with stereotypical anatomies are formed along the ventro-lateral surface of the neuroectoderm.

  http://www.sciencedirect.com/science/article/pii/S0012160611010979

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• Promotion of avian endothelial cell differentiation by GATA transcription factors

  C.N. Kamei, H. Kempf, R. Yelin, G. Daoud, R.G. James, A.B. Lassar, C.J. Tabin and T.M. Schultheiss. Promotion of avian endothelial cell differentiation by GATA transcription factors. Developmental Biology, 353(1), 29-37, 2011.

  http://www.sciencedirect.com/science/article/pii/S0012160611001151

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