| 1. |
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| 2. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 3. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 4. |
- Chang, Ya-Ting, et al.
(författare)
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Antenatal imatinib treatment reduces pulmonary vascular remodeling in a rat model of congenital diaphragmatic hernia
- 2012
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Ingår i: American Journal of Physiology - Lung cellular and Molecular Physiology. - : American Physiological Society. - 1040-0605 .- 1522-1504. ; 302:11, s. L1159-L1166
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Tidskriftsartikel (refereegranskat)abstract
- The pathophysiology of congenital diaphragmatic hernia (CDH) is constituted by pulmonary hypoplasia and pulmonary hypertension (PH). We previously reported successful treatment with imatinib of a patient with CDH. This study examines the effect of antenatal imatinib administration on the pulmonary vasculature in a rat model of CDH. Pregnant rats were given nitrofen to induce CDH. Controls were given olive oil. Half of the CDH fetuses and half of the controls were treated with imatinib antenatally E17-E21, rendering four groups: Control, Control+Imatinib, CDH, and CDH+Imatinib. Lung sections were obtained for morphometry and immunohistochemistry, and protein was purified for Western blot. Effects of nitrofen and imatinib on Ki-67, caspase-3, PDGF-B, and PDGF receptors were analyzed. Imatinib significantly reduced medial wall thickness in pulmonary arteries of rats with CDH. It also normalized lumen area and reduced the proportion of fully muscularized arteries. Imatinib also caused medial thinning in the control group. Cell proliferation was increased in CDH, and this proliferation was significantly reduced by imatinib. PDGF-B and PDGFR-beta were upregulated in CDH, and imatinib treatment resulted in a downregulation. PDGFR-alpha remained unchanged in CDH but was significantly downregulated by imatinib. Antenatal imatinib treatment reduces development of medial wall thickness and restores lumen area in pulmonary arteries in nitrofen-induced CDH. The mechanism is reduced cell proliferation. Imatinib is an interesting candidate for antenatal therapy for PH in CDH, but potential side effects need to be investigated and more specific targeting of PDGF signaling is needed.
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| 5. |
- Chang, Ya-Ting, et al.
(författare)
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Perlecan heparan sulfate deficiency impairs pulmonary vascular development and attenuates hypoxic pulmonary hypertension
- 2015
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Ingår i: Cardiovascular Research. - : Oxford University Press (OUP). - 0008-6363 .- 1755-3245. ; 107:1, s. 20-31
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Tidskriftsartikel (refereegranskat)abstract
- Aims Excessive vascular cell proliferation is an important component of pulmonary hypertension (PH). Perlecan is the major heparan sulfate (HS) proteoglycan in the vascular extracellular matrix. It binds growth factors, including FGF2, and either restricts or promotes cell proliferation. In this study, we have explored the effects of perlecan HS deficiency on pulmonary vascular development and in hypoxia-induced PH. Methods and results In normoxia, Hspg2(Delta 3/Delta 3) mice, deficient in perlecan HS, had reduced pericytes and muscularization of intra-acinar vessels. Pulmonary angiography revealed a peripheral perfusion defect. Despite these abnormalities, right ventricular systolic pressure (RVSP) and myocardial mass remained normal. After 4 weeks of hypoxia, increases in the proportion of muscularized vessels, RVSP, and right ventricular hypertrophy were significantly less in Hspg2(Delta 3/Delta 3) compared with wild type. The early phase of hypoxia induced a significantly lower increase in fibroblast growth factor receptor-1 (FGFR1) protein level and receptor phosphorylation, and reduced pulmonary artery smooth muscle cell (PASMC) proliferation in Hspg2(Delta 3/Delta 3). At 4 weeks, FGF2 mRNA and protein were also significantly reduced in Hspg2(Delta 3/Delta 3) lungs. Ligand and carbohydrate engagement assay showed that perlecan HS is required for HS-FGF2-FGFR1 ternary complex formation. In vitro, proliferation assays showed that PASMC proliferation is reduced by selective FGFR1 inhibition. PASMC adhesion to fibronectin was higher in Hspg2(Delta 3/Delta 3) compared with wild type. Conclusions Perlecan HS chains are important for normal vascular arborization and recruitment of pericytes to pulmonary vessels. Perlecan HS deficiency also attenuates hypoxia-induced PH, where the underlying mechanisms involve impaired FGF2/FGFR1 interaction, inhibition of PASMC growth, and altered cell-matrix interactions.
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| 6. |
- Chang, Ya-Ting
(författare)
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Vascular remodeling in pulmonary hypertension
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Pulmonary hypertension (PH) is a progressive obliterative vasculopathy with multifactorial etiology and high mortality rate. Endothelial dysfunction, excessive vascular remodeling, inflammation and in situ thrombosis contribute to increased vascular resistance and gradual occlusion of pulmonary vessels. Sustained high pressure in the pulmonary circulation increases right heart afterload and ultimately results in right heart failure. Current pharmacological treatments, like endothelin receptor antagonists, prostacyclin analogues, and phosphodiesterase-5 inhibitors, are primarily vasodilators and exert limited effects on vascular remodeling. Survival has improved, but far from enough, and the demand for lung transplantation has not been reduced. Excessive growth of pulmonary artery smooth muscle cells (PASMCs) contributes to intimal hyperplasia, medial wall thickening, and plexiform lesions, the main features of vascular remodeling in PH. It is therefore important to explore factors which can control PASMC growth in order to identify potential targets for regression of PH. Here, the roles of growth factors and proteoglycans in vascular remodeling were investigated in animal models of PH as well as in tissue specimens from patients. In a rat model of PH associated with congenital diaphragmatic hernia, up-regulation of PDGF-B was found. Prenatal PDGF-B inhibition by imatinib, a tyrosine kinase inhibitor, was demonstrated to inhibit PASMC proliferation and to reduce pulmonary vascular remodeling in fetal rat lungs. In a murine model of hypoxia-induced PH, increased perlecan deposition was observed. Genetically modified mice expressing heparan sulfate-deficient perlecan developed less PH, accompanied by decreased pulmonary vascular remodeling and reduced right ventricular hypertrophy. In addition, defective mural cell recruitment in pulmonary vessels was observed in heparan sulfate-deficient mice. A possible mechanism is impaired interaction between FGF-2 and its receptor and a pro-proliferative function for perlecan heparan sulfate in pulmonary vessels. The role of PDGF-B retention motifs, the C-terminal region of PDGF-B that interacts with heparan sulfate, was also explored. Hypoxia-induced PH was reduced in PDGF-B retention motif knockout, possibly due to defective retention of PDGF-B in the extracellular matrix and disturbed recruitment of mural cells. Metabolic labeling experiments showed that a majority of the proteoglycans secreted by human PASMCs are decorated with chondroitin sulfate. Lung tissue sections from patients with PH revealed versican accumulation in vascular lesions. In vitro, mechanical strain and hypoxia increased versican production in PASMCs. The results suggested that versican is a pro-proliferative element in the vascular remodeling of PH. In summary, this thesis work emphasizes the role of growth factors and proteoglycans, and interactions between the two, in the regulation of PASMC growth during PH development. Inhibition of growth factor activity or specific targeting of important functional domains of proteoglycans may be effective anti-remodeling strategies for future PH treatment.
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| 7. |
- Chang, Ya-Ting, et al.
(författare)
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Versican accumulates in vascular lesions in pulmonary arterial hypertension
- 2016
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Ingår i: PULMONARY CIRCULATION. - : Wiley. - 2045-8932 .- 2045-8940. ; 6:3, s. 347-359
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Tidskriftsartikel (refereegranskat)abstract
- Pulmonary arterial hypertension (PAH) is a lethal condition for which there is no effective curative pharmacotherapy. PAH is characterized by vasoconstriction, wall thickening of pulmonary arteries, and increased vascular resistance. Versican is a chondroitin sulfate proteoglycan in the vascular extracellular matrix that accumulates following vascular injury and promotes smooth-muscle cell proliferation in systemic arteries. Here, we investigated whether versican may play a similar role in PAH. Paraffin-embedded lung sections from patients who underwent lung transplantation to treat PAH were used for immunohistochemistry. The etiologies of PAH in the subjects involved in this study were idiopathic PAH, scleroderma, and congenital heart disease (atrial septal defect) with left-to-right shunt. Independent of the underlying etiology, increased versican immunostaining was observed in areas of medial thickening, in neointima, and in plexiform lesions. Western blot of lung tissue lysates confirmed accumulation of versican in patients with PAH. Double staining for versican and CD45 showed only occasional colocalization in neointima of high-grade lesions and plexiform lesions. In vitro, metabolic labeling with [S-35] sulfate showed that human pulmonary artery smooth-muscle cells (hPASMCs) produce mainly chondroitin sulfate glycosaminoglycans. In addition, hypoxia, but not cyclic stretch, was demonstrated to increase both versican messenger RNA expression and protein synthesis by hPASMCs. Versican accumulates in vascular lesions of PAH, and the amount of versican correlates more with lesion severity than with underlying etiology or inflammation. Hypoxia is a possible regulator of versican accumulation, which may promote proliferation of pulmonary smooth-muscle cells and vascular remodeling in PAH.
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| 8. |
- Gotha, Lara, et al.
(författare)
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Heparan sulfate side chains have a critical role in the inhibitory effects of perlecan on vascular smooth muscle cell response to arterial injury
- 2014
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Ingår i: American Journal of Physiology: Heart and Circulatory Physiology. - : American Physiological Society. - 1522-1539 .- 0363-6135. ; 307:3, s. 337-345
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Tidskriftsartikel (refereegranskat)abstract
- Perlecan is a proteoglycan composed of a 470-kDa core protein linked to three heparan sulfate (HS) glycosaminoglycan chains. The intact proteoglycan inhibits the smooth muscle cell (SMC) response to vascular injury. Hspg2(Delta 3/Delta 3) (M Delta 3/Delta 3) mice produce a mutant perlecan lacking the HS side chains. The objective of this study was to determine differences between these two types of perlecan in modifying SMC activities to the arterial injury response, in order to define the specific role of the HS side chains. In vitro proliferative and migratory activities were compared in SMC isolated from M Delta 3/Delta 3 and wild-type mice. Proliferation of M Delta 3/Delta 3 SMC was 1.5x greater than in wild type (P < 0.001), increased by addition of growth factors, and showed a 42% greater migratory response than wild-type cells to PDGF-BB (P < 0.001). In M Delta 3/Delta 3 SMC adhesion to fibronectin, and collagen types I and IV was significantly greater than wild type. Addition of DRL-12582, an inducer of perlecan expression, decreased proliferation and migratory response to PDGF-BB stimulation in wild-type SMC compared with M Delta 3/Delta 3. In an in vivo carotid artery wire injury model, the medial thickness, medial area/lumen ratio, and macrophage infiltration were significantly increased in the M Delta 3/Delta 3 mice, indicating a prominent role of the HS side chain in limiting vascular injury response. Mutant perlecan that lacks HS side chains had a marked reduction in the inhibition of in vitro SMC function and the in vivo arterial response to injury, indicating the critical role of HS side chains in perlecan function in the vessel wall.
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| 9. |
- Tannenberg, Philip, et al.
(författare)
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Extracellular retention of PDGF-B directs vascular remodeling in mouse hypoxia-induced pulmonary hypertension
- 2018
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Ingår i: American Journal of Physiology - Lung cellular and Molecular Physiology. - : AMER PHYSIOLOGICAL SOC. - 1040-0605 .- 1522-1504. ; 314:4, s. 1593-1605
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Tidskriftsartikel (refereegranskat)abstract
- Pulmonary hypertension (PH) is a lethal condition, and current vasodilator therapy has limited effect. Antiproliferative strategies targeting platelet-derived growth factor (PDGF) receptors, such as imatinib, have generated promising results in animal studies. Imatinib is, however, a nonspecific tyrosine kinase inhibitor and has in clinical studies caused unacceptable adverse events. Further studies are needed on the role of PDGF signaling in PH. Here, mice expressing a variant of PDGF-B with no retention motif (Pdgfb(ret/ret)), resulting in defective binding to extracellular matrix, were studied. Following 4 wk of hypoxia, right ventricular systolic pressure, right ventricular hypertrophy, and vascular remodeling were examined. Pdgfb(ret/ret) mice did not develop PH, as assessed by hemodynamic parameters. Hypoxia did, however, induce vascular remodeling in Pdgfb(ret/ret) mice; but unlike the situation in controls where the remodeling led to an increased concentric muscularization of arteries, the vascular remodeling in Pdgfb(ret/ret) mice was characterized by a diffuse muscularization, in which cells expressing smooth muscle cell markers were found in the interalveolar septa detached from the normally muscularized intra-acinar vessels. Additionally, fewer NG2-positive perivascular cells were found in Pdgfb(ret/ret) lungs, and mRNA analyses showed significantly increased levels of Il6 following hypoxia, a known promigratory factor for pericytes. No differences in proliferation were detected at 4 wk. This study emphasizes the importance of extracellular matrix-growth factor interactions and adds to previous knowledge of PDGF-B in PH pathobiology. In summary, Pdgfb(ret/ret) mice have unaltered hemodynamic parameters following chronic hypoxia, possibly secondary to a disorganized vascular muscularization.
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