Correction: Tumor suppressor RARRES1 links tubulin deglutamylation to mitochondrial metabolism and cell survival.

[This corrects the article DOI: 10.18632/oncotarget.26600.].

ARAF recurrent mutation causes central conducting lymphatic anomaly treatable with a MEK inhibitor.

The treatment of lymphatic anomaly, a rare devastating disease spectrum of mostly unknown etiologies, depends on the patient manifestations1. Identifying the causal genes will allow for developing affordable therapies in keeping with precision medicine implementation2. Here we identified a recurrent gain-of-function ARAF mutation (c.640T>C:p.S214P) in a 12-year-old boy with advanced anomalous lymphatic disease unresponsive to conventional sirolimus therapy and in another, unrelated, adult patient. The mutation led to loss of a conserved phosphorylation site. Cells transduced with ARAF-S214P showed elevated ERK1/2 activity, enhanced lymphangiogenic capacity, and disassembly of actin skeleton and VE-cadherin junctions, which were rescued using the MEK inhibitor trametinib. The functional relevance of the mutation was also validated by recreating a lymphatic phenotype in a zebrafish model, with rescue of the anomalous phenotype using a MEK inhibitor. Subsequent therapy of the lead proband with a MEK inhibitor led to dramatic clinical improvement, with remodeling of the patient's lymphatic system with resolution of the lymphatic edema, marked improvement in his pulmonary function tests, cessation of supplemental oxygen requirements and near normalization of daily activities. Our results provide a representative demonstration of how knowledge of genetic classification and mechanistic understanding guides biologically based medical treatments, which in our instance was life-saving.

Tumor suppressor RARRES1 links tubulin deglutamylation to mitochondrial metabolism and cell survival.

RARRES1, a retinoic acid regulated carboxypeptidase inhibitor associated with fatty acid metabolism, stem cell differentiation and tumorigenesis is among the most commonly methylated loci in multiple cancers but has no known mechanism of action. Here we show that RARRES1 interaction with cytoplasmic carboxypeptidase 2 (CCP2) inhibits tubulin deglutamylation, which in turn regulates the mitochondrial voltage dependent anion channel (VDAC1), mitochondrial membrane potential, AMPK activation, energy balance and metabolically reprograms cells and zebrafish to a more energetic and anabolic phenotype. Depletion of RARRES1 also increases expression of stem cell markers, promotes anoikis, anchorage independent growth and insensitivity to multiple apoptotic stimuli. As depletion of CCP2 or inhibition of VDAC1 reverses the effects of RARRES1 depletion on energy balance and cell survival we conclude that RARRES1 modulation of CCP2-modulated tubulin-mitochondrial VDAC1 interactions is a fundamental regulator of cancer and stem cell metabolism and survival.

Sensory neuronal sensitisation occurs through HMGB-1-RAGE and TRPV1 in high-glucose conditions.

Many potential causes for painful diabetic neuropathy have been proposed including actions of cytokines and growth factors. High mobility group protein B1 (HMGB1) is a RAGE (also known as AGER) agonist whose levels are increased in diabetes and that contributes to pain by modulating peripheral inflammatory responses. HMGB1 enhances nociceptive behaviour in naïve animals through an unknown mechanism. We tested the hypothesis that HMGB1 causes pain through direct neuronal activation of RAGE and alteration of nociceptive neuronal responsiveness. HMGB1 and RAGE expression were increased in skin and primary sensory (dorsal root ganglion, DRG) neurons of diabetic rats at times when pain behaviour was enhanced. Agonist-evoked TRPV1-mediated Ca2+ responses increased in cultured DRG neurons from diabetic rats and in neurons from naïve rats exposed to high glucose concentrations. HMGB1-mediated increases in TRPV1-evoked Ca2+ responses in DRG neurons were RAGE- and PKC-dependent, and this was blocked by co-administration of the growth factor splice variant VEGF-A165b. Pain behaviour and the DRG RAGE expression increases were blocked by VEGF-A165b treatment of diabetic rats in vivo Hence, we conclude that HMGB1-RAGE activation sensitises DRG neurons in vitro, and that VEGF-A165b blocks HMGB-1-RAGE DRG activation, which may contribute to its analgesic properties in vivo.

Wnt9a Is Required for the Aortic Amplification of Nascent Hematopoietic Stem Cells.

All mature blood cell types in the adult animal arise from hematopoietic stem and progenitor cells (HSPCs). However, the developmental cues regulating HSPC ontogeny are incompletely understood. In particular, the details surrounding a requirement for Wnt/ß-catenin signaling in the development of mature HSPCs are controversial and difficult to consolidate. Using zebrafish, we demonstrate that Wnt signaling is required to direct an amplification of HSPCs in the aorta. Wnt9a is specifically required for this process and cannot be replaced by Wnt9b or Wnt3a. This proliferative event occurs independently of initial HSPC fate specification, and the Wnt9a input is required prior to aorta formation. HSPC arterial amplification occurs prior to seeding of secondary hematopoietic tissues and proceeds, in part, through the cell cycle regulator myca (c-myc). Our results support a general paradigm, in which early signaling events, including Wnt, direct later HSPC developmental processes.

Aminoacyl-Transfer RNA Synthetase Deficiency Promotes Angiogenesis via the Unfolded Protein Response Pathway.

OBJECTIVE: Understanding the mechanisms regulating normal and pathological angiogenesis is of great scientific and clinical interest. In this report, we show that mutations in 2 different aminoacyl-transfer RNA synthetases, threonyl tRNA synthetase (tars(y58)) or isoleucyl tRNA synthetase (iars(y68)), lead to similar increased branching angiogenesis in developing zebrafish. APPROACH AND RESULTS: The unfolded protein response pathway is activated by aminoacyl-transfer RNA synthetase deficiencies, and we show that unfolded protein response genes atf4, atf6, and xbp1, as well as the key proangiogenic ligand vascular endothelial growth factor (vegfaa), are all upregulated in tars(y58) and iars(y68) mutants. Finally, we show that the protein kinase RNA-like endoplasmic reticulum kinase-activating transcription factor 4 arm of the unfolded protein response pathway is necessary for both the elevated vegfaa levels and increased angiogenesis observed in tars(y58) mutants. CONCLUSIONS: Our results suggest that endoplasmic reticulum stress acts as a proangiogenic signal via unfolded protein response pathway-dependent upregulation of vegfaa.

Characterization of the Cellular Output of a Point-of-Care Device and the Implications for Addressing Critical Limb Ischemia.

Critical limb ischemia (CLI) is a terminal disease with high morbidity and healthcare costs due to limb loss. There are no effective medical therapies for patients with CLI to prevent amputation. Cell-based therapies are currently being investigated to address this unmet clinical need and have shown promising preliminary results. The purpose of this study was to characterize the output of a point-of-care cell separator (MarrowStim P.A.D. Kit), currently under investigation for the treatment of CLI, and compare its output with Ficoll-based separation. The outputs of the MarrowStim P.A.D. Kit and Ficoll separation were characterized using an automated hematology analyzer, colony-forming unit (CFU) assays, and tubulogenesis assays. Hematology analysis indicated that the MarrowStim P.A.D. Kit concentrated the total nucleated cells, mononuclear cells, and granulocytes compared with baseline bone marrow aspirate. Cells collected were positive for VEGFR-2, CD3, CD14, CD34, CD45, CD56, CD105, CD117, CD133, and Stro-1 antigen. CFU assays demonstrated that the MarrowStim P.A.D. Kit output a significantly greater number of mesenchymal stem cells and hematopoietic stem cells compared with cells output by Ficoll separation. There was no significant difference in the number of endothelial progenitor cells output by the two separation techniques. Isolated cells from both techniques formed interconnected nodes and microtubules in a three-dimensional cell culture assay. This information, along with data currently being collected in large-scale clinical trials, will help instruct how different cellular fractions may affect the outcomes for CLI patients.

Identification of Novel Ezrin Inhibitors Targeting Metastatic Osteosarcoma by Screening Open Access Malaria Box.

Ezrin is a member of the ERM (ezrin, radixin, moesin) family of proteins and functions as a linker between the plasma membrane and the actin cytoskeleton. Ezrin is a key driver of tumor progression and metastatic spread of osteosarcoma. We discovered a quinoline-based small molecule, NSC305787, that directly binds to ezrin and inhibits its functions in promoting invasive phenotype. NSC305787 possesses a very close structural similarity to commonly used quinoline-containing antimalarial drugs. On the basis of this similarity and of recent findings that ezrin has a likely role in the pathogenesis of malaria infection, we screened antimalarial compounds in an attempt to identify novel ezrin inhibitors with better efficacy and drug properties. Screening of Medicines for Malaria Venture (MMV) Malaria Box compounds for their ability to bind to recombinant ezrin protein yielded 12 primary hits with high selective binding activity. The specificity of the hits on ezrin function was confirmed by inhibition of the ezrin-mediated cell motility of osteosarcoma cells. Compounds were further tested for phenocopying the morphologic defects associated with ezrin suppression in zebrafish embryos as well as for inhibiting the lung metastasis of high ezrin-expressing osteosarcoma cells. The compound MMV667492 exhibited potent anti-ezrin activity in all biologic assays and had better physicochemical properties for drug-likeness than NSC305787. The drug-like compounds MMV020549 and MMV666069 also showed promising activities in functional assays. Thus, our study suggests further evaluation of antimalarial compounds as a novel class of antimetastatic agents for the treatment of metastatic osteosarcoma.

Rspo1/Wnt signaling promotes angiogenesis via Vegfc/Vegfr3.

Here, we show that a novel Rspo1-Wnt-Vegfc-Vegfr3 signaling pathway plays an essential role in developmental angiogenesis. A mutation in R-spondin1 (rspo1), a Wnt signaling regulator, was uncovered during a forward-genetic screen for angiogenesis-deficient mutants in the zebrafish. Embryos lacking rspo1 or the proposed rspo1 receptor kremen form primary vessels by vasculogenesis, but are defective in subsequent angiogenesis. Endothelial cell-autonomous inhibition of canonical Wnt signaling also blocks angiogenesis in vivo. The pro-angiogenic effects of Rspo1/Wnt signaling are mediated by Vegfc/Vegfr3(Flt4) signaling. Vegfc expression is dependent on Rspo1 and Wnt, and Vegfc and Vegfr3 are necessary to promote angiogenesis downstream from Rspo1-Wnt. As all of these molecules are expressed by the endothelium during sprouting stages, these results suggest that Rspo1-Wnt-VegfC-Vegfr3 signaling plays a crucial role as an endothelial-autonomous permissive cue for developmental angiogenesis.

Arterial-venous specification during development.

The major arteries and veins of the vertebrate circulatory system are formed early in embryonic development, before the onset of circulation, following de novo aggregation of "angioblast" progenitors in a process called vasculogenesis. Initial embryonic determination of artery or vein identity is regulated by variety of genetic factors that work in concert to specify endothelial cell fate, giving rise to 2 distinct components of the circulatory loop possessing unique structural characteristics. Work in multiple in vivo animal model systems has led to a detailed examination of the interacting partners that determine arterial and venous specification. We discuss the hierarchical arrangement of many signaling molecules, including Hedgehog (Hh), vascular endothelial growth factor (VEGF), Notch, and chicken ovalbumin upstream-transcription factor II (COUP-TFII) that promote or inhibit divergent pathways of endothelial cell fate. Elucidation of the functional role of these genetic determinants of blood vessel specification together with the epigenetic factors involved in subsequent modification of arterial-venous identity will allow for potential new therapeutic targets for vascular disorders.

Effect of FGF-binding protein 3 on vascular permeability.

Fibroblast growth factor-binding protein 1 (FGF-BP1 is BP1) is involved in the regulation of embryonic development, tumor growth, and angiogenesis by mobilizing endogenous FGFs from their extracellular matrix storage. Here we describe a new member of the FGF-BP family, human BP3. We show that the hBP3 protein is secreted from cells, binds to FGF2 in vitro and in intact cells, and inhibits FGF2 binding to heparin. To determine the function of hBP3 in vivo, hBP3 was transiently expressed in chicken embryos and resulted in > 50% lethality within 24 h because of vascular leakage. The onset of vascular permeability was monitored by recording the extravasation kinetics of FITC-labeled 40-kDa dextran microperfused into the vitelline vein of 3-day-old embryos. Vascular permeability increased as early as 8 h after expression of hBP3. The increased vascular permeability caused by hBP3 was prevented by treatment of embryos with PD173074, a selective FGFR kinase inhibitor. Interestingly, a C-terminal 66-amino acid fragment (C66) of hBP3, which contains the predicted FGF binding domain, still inhibited binding of FGF2 to heparin similar to full-length hBP3. However, expression of the C66 fragment did not increase vascular permeability on its own, but required the administration of exogenous FGF2 protein. We conclude that the FGF binding domain and the heparin binding domain are necessary for the hBP3 interaction with endogenous FGF and the activation of FGFR signaling in vivo.

Expression of a fibroblast growth factor-binding protein during the development of adenocarcinoma of the pancreas and colon.

The activity of growth factors is crucial for tumor progression. We previously characterized a secreted fibroblast growth factor-binding protein (FGF-BP1) as a chaperone molecule, which enhances the biological functions of FGFs by releasing FGFs from the extracellular matrix. Here, we characterize the frequency and pattern of FGF-BP1 expression during the malignant progression of pancreas and colorectal carcinoma. For this, we generated monoclonal antibodies that detect FGF-BP1 protein in formalin-fixed, paraffin-embedded tissues and applied in situ hybridization to detect FGF-BP1 mRNA in adjacent tissue sections. FGF-BP1 protein and mRNA were found up-regulated (>70% positive) in parallel (r = 0.70, P < 0.0001) in colon adenoma (n = 9) as well as primary (n = 46) and metastatic (n = 71) colorectal cancers relative to normal colon epithelia (all P < 0.0001, versus normal). Similarly, pancreatitis (n = 17), pancreatic intraepithelial neoplasia (n = 80), and pancreatic adenocarcinoma (n = 67) showed a significant up-regulation of FGF-BP1 compared with normal pancreas (n = 42; all P < 0.0001, relative to normal). Furthermore, the biological activity of FGF-BP1 is neutralized by one of the antibodies, suggesting the potential for antibody-based therapeutic targeting. We propose that the up-regulation of the secreted FGF-BP1 protein during initiation of pancreas and colon neoplasia could make this protein a possible serum marker indicating the presence of high-risk premalignant lesions.

Identification of the fibroblast growth factor (FGF)-interacting domain in a secreted FGF-binding protein by phage display.

Fibroblast growth factor-binding proteins (FGF-BP) are secreted carrier proteins that release fibroblast growth factors (FGFs) from the extracellular matrix storage and thus enhance FGF activity. Here we have mapped the interaction domain between human FGF-BP1 and FGF-2. For this, we generated T7 phage display libraries of N-terminally and C-terminally truncated FGF-BP1 fragments that were then panned against immobilized FGF-2. From this panning, a C-terminal fragment of FGF-BP1 (amino acids 193-234) was identified as the minimum binding domain for FGF. As a recombinant protein, this C-terminal fragment binds to FGF-2 and enhances FGF-2-induced signaling in NIH-3T3 fibroblasts and GM7373 endothelial cells, as well as mitogenesis and chemotaxis of NIH-3T3 cells. The FGF interaction domain in FGF-BP1 is distinct from the heparin-binding domain (amino acids 110-143), and homology modeling supports the notion of a distinct domain in the C terminus that is conserved across different species. This domain also contains conserved positioning of cysteine residues with the Cys-214/Cys-222 positions in the human protein predicted to participate in disulfide bridge formation. Phage display of a C214A mutation of FGF-BP1 reduced binding to FGF-2, indicating the functional significance of this disulfide bond. We concluded that the FGF interaction domain is contained in the C terminus of FGF-BP1.

Producing accurate platelet counts for platelet rich plasma: validation of a hematology analyzer and preparation techniques for counting.

Platelet rich plasma (PRP) has been shown to clinically accelerate healing of both soft and hard tissues. As a result, it has gained increasing popularity. However, the clinical effectiveness of each type of PRP preparation method can vary in technique and efficiency, and current methods to evaluate the platelet concentration efficiency of PRP systems have several limitations. Therefore, the purpose of this study was to validate an automated hematology analyzer, the Cell-Dyn 3700, to accurately count platelets in concentration ranges of approximately 2,000,000-4,800,000 platelets/microL. PRP platelets were counted by way of a manual counting method and on the Cell-Dyn 3700, and the statistical evaluation indicated no difference between the groups (P > 0.05). Dilution of the PRP was not required, and accurate platelet counts could be achieved up to platelet concentrations of 4,800,000 platelets/microL. PRPs must be resuspended on a rocker for at least 5 minutes before platelet counts, and the entire PRP sample must be resuspended to allow for equal distribution of platelets before counting. With use of the validated Cell-Dyn 3700, a platelet concentrate system was used to prepare 153 PRPs. The baseline whole blood platelet concentration (328,000 platelets/microL +/- 69,000 platelets/microL) and the average PRP samples (2,645,000 platelets/microL +/- 680,000 platelets/microL) were compared, resulting in an eightfold increase in concentration and an average platelet percent recovery of approximately 76%. Automated hematology analyzers can be used to accurately count platelets in PRP given the system has been validated appropriately and the PRP samples are prepared properly to provide adequate platelet suspension.