| 1. |
- Ali, Zaheer, et al.
(författare)
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Intussusceptive Vascular Remodeling Precedes Pathological Neovascularization
- 2019
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Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - : Lippincott Williams & Wilkins. - 1079-5642 .- 1524-4636. ; 39:7, s. 1402-1418
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Tidskriftsartikel (refereegranskat)abstract
- Objective—Pathological neovascularization is crucial for progression and morbidity of serious diseases such as cancer, diabetic retinopathy, and age-related macular degeneration. While mechanisms of ongoing pathological neovascularization have been extensively studied, the initiating pathological vascular remodeling (PVR) events, which precede neovascularization remains poorly understood. Here, we identify novel molecular and cellular mechanisms of preneovascular PVR, by using the adult choriocapillaris as a model.Approach and Results—Using hypoxia or forced overexpression of VEGF (vascular endothelial growth factor) in the subretinal space to induce PVR in zebrafish and rats respectively, and by analyzing choriocapillaris membranes adjacent to choroidal neovascular lesions from age-related macular degeneration patients, we show that the choriocapillaris undergo robust induction of vascular intussusception and permeability at preneovascular stages of PVR. This PVR response included endothelial cell proliferation, formation of endothelial luminal processes, extensive vesiculation and thickening of the endothelium, degradation of collagen fibers, and splitting of existing extravascular columns. RNA-sequencing established a role for endothelial tight junction disruption, cytoskeletal remodeling, vesicle- and cilium biogenesis in this process. Mechanistically, using genetic gain- and loss-of-function zebrafish models and analysis of primary human choriocapillaris endothelial cells, we determined that HIF (hypoxia-induced factor)-1α-VEGF-A-VEGFR2 signaling was important for hypoxia-induced PVR.Conclusions—Our findings reveal that PVR involving intussusception and splitting of extravascular columns, endothelial proliferation, vesiculation, fenestration, and thickening is induced before neovascularization, suggesting that identifying and targeting these processes may prevent development of advanced neovascular disease in the future.Visual Overview—An online visual overview is available for this article.
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| 2. |
- André, Helder
(författare)
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Analysis of HIF-1alpha degradation and function
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- HIF-1 is a heterodimeric complex of two bHLH/PAS transcription factors, HIF- 1alpha and ANRT. In contrast to the constitutively expressed ARNT, HIF-1alpha protein levels are regulated by oxygen tension. Under normoxic conditions, HIF-1alpha is rapidly degraded by the ubiquitinproteasome pathway. Upon exposure to hypoxia, HIF-1alpha is stabilized and translocated to the nucleus where it heterodimerizes with ARNT to bind hypoxia-responsive elements present in target genes. HIF-1 functions as a master regulator of adaptive responses to hypoxia by activating genes that regulate oxygen supply (erythropoietin, VEGF, NOS), cellular metabolism (GLUT-1, PGK-1, LDH-A), and cell growth and apoptosis (TGF-beta3, telomerase). The interaction between the von Hippel-Lindau tumor suppressor gene product (part of an E3 ubiquitin-ligase) and HIF-1alpha has been shown to be regulated by three soluble dioxygenases. These dioxygenases are termed prolyl hydroxylase domain proteins, since they hydroxylate two conserved proline residues (Pro" and/or Pro` within mHIF-1alpha), targeting HIF-1alpha for degradation. Subsequent studies have indicated that mutagenesis of these prolines to alanine residues generates a constitutively stabilized form of HIF-1alpha, allowing the protein to be expressed independently of oxygen levels. Here we have evaluated the expression of mHIF-1alpha and several mutants in cultured cells and examined normoxia-dependent degradation of these proteins. Under certain conditions we observed degradation of these mutants by the ubiquitin-proteasome system. Moreover, PHD1 or PHD3 failed to induce normoxia-dependent degradation of the mHIF-1alpha(P402A/P563A) mutant. pVHLmediated degradation of both mHIF-1alpha and the double Pro mutant proved to be intrinsically dependent on the hydroxylation status of the overexpressed HIF-1alpha proteins. Taken together, these data suggest the existence of yet unraveled mechanisms of degradation of HIF-1alpha. Furthermore, we have investigated the effects on neoangiogenesis by mHlF-1alpha(P402A/P563A), using adenoassociated virus gene delivery to skeletal muscle. Additionally, we have compared these effects to those produced by previously known vascular growth factors, such as the VEGF. mHIF1alpha(P402A/P563A) was shown to be capable of inducing formation of functional neovasculature without increased leakiness (a well-cheracterized side-effect of VEGF). Our data further suggest that the use of the mHIF-1alpha mutant in pro-angiogenic gene therapy may be capable to circumvent most of the present problems in cardiovascular gene transfer studies. This is due to the fact that HIF1alpha is capable of inducing endogenous angiogenic cascades, that lead to the activation of multiple, necessary vasculogenenic growth factors.
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| 3. |
- André, Helder
(författare)
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Assessment of HIF-1alpha function and identification of a novel degradation mechanism
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- HIF-1 is a heterodimeric complex of two bHLH/PAS transcription factors, HIF-1alpha and ARNT. In contrast to the constitutively expressed ARNT, HIF-1alpha protein levels are regulated by oxygen tension. Under normoxic conditions, HIF-1alpha is rapidly degraded by the ubiquitinproteasome pathway. Upon exposure to hypoxia, HIF-1alpha is stabilized and translocated to the nucleus where it heterodimerizes with ARNT and binds hypoxia-responsive elements present in target genes. HIF-1 functions as a master regulator of adaptive responses to hypoxia by activating genes important for physiological processes. These processes range from oxygen supply, cellular metabolism, and cell growth and apoptosis. The interaction between the von Hippel-Lindau tumor suppressor gene product (pVHL, part of an E3 ubiquitin-ligase) and HIF-1alpha has been shown to be regulated by three soluble dioxygenases. These dioxygenases are termed prolyl hydroxylase domain proteins (PHD). They hydroxylate two conserved proline residues (Pro402 and/or Pro563 within mouse HIF-1alpha), targeting HIF-1alpha for degradation. Initially, it was suggested that mutagenesis of these prolines to alanine residues that cannot be hydroxylated generates a constitutively stabilized form of HIF-1alpha, allowing the protein to be expressed independently of oxygen levels. We have investigated the effects on neoangiogenesis by mHIF-1alpha(P402A/P563A), using adeno-associated virus (AAV) gene delivery to skeletal muscle. Additionally, we have compared these effects to those produced by previously known vascular growth factors, such as the VEGF. mHIF-1alpha(P402A/P563A) was shown to be capable of inducing formation of functional neovasculature without increased leakiness (a well-characterized side-effect of VEGF). Our data further suggest that the use of the mHIF-1alpha mutant in pro-angiogenic gene therapy may have the ability to circumvent most of the present problems in cardiovascular gene transfer studies. This is due to the fact that HIF-1alpha is capable of inducing endogenous angiogenic cascades that lead to the activation of multiple and necessary vasculogenic growth factors. We have also evaluated the expression of mHIF-1alpha and mHIF-1alpha(P402A/P563A) in cultured cells and observed normoxia-dependent degradation of these proteins. Our studies show that degradation of these proteins is mediated by the ubiquitin-proteasome system, through a pVHL-dependent mechanism. Furthermore, PHDs failed to induce normoxiadependent degradation of the mHIF-1alpha(P402A/P563A) mutant. pVHL-mediated degradation of both mHIF-1alpha and the double proline mutant proved to be intrinsically independent of the hydroxylation status of the HIF-1alpha proteins. Taken together, these data suggest the existence of yet unraveled mechanisms of degradation of HIF-1alpha. Subsequently, we evaluated the contribution of the small ubiquitin-like modifier (SUMO) and the SUMO-specific protease 1 (SENP1) to HIF-1alpha degradation. Our results show that RNAi directed to SENP1 impairs protein accumulation of both mHIF-1alpha and mHIF- 1alpha(P402A/P563A) at hypoxia. At normoxia, silencing of the SUMO conjugating enzyme (Ubc9) resulted in stabilization of endogenous HIF-1alpha in cells where PHD2 was down regulated. Additionally, silencing of Ubc9 is sufficient to promote stability of the HIF-1alpha double proline mutant at normoxia. In conclusion, our studies indicate that mHIF-1alpha(P402A/P563A) is a bona fide proangiogenic factor with potential therapeutic effects. Still, this protein is regulated in an oxygen-dependent manner by proteasome-mediated degradation. The degradation of mHIF-1alpha(P402A/P563A) proved to be pVHL-dependent yet PHD-independent. Further investigations indicated a role for SUMO modification in the HIF-1alpha degradation pathway. The presence of SUMO moieties on mHIF-1alpha(P402A/P563A) are sufficient for the recruitment of pVHL and thus promote degradation of the protein at normoxia, suggesting SUMOylation as the novel mechanism for degradation of HIF-1alpha.
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| 4. |
- Blust, Kelly, et al.
(författare)
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Integration of stem cell-derived pancreatic aggregates into FN-silk network for in vitro cultivation and in vivo transplantation
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Type 1 diabetes is a life-threatening disease characterized by lifelong insulin dependency and a reduced quality of life. Pancreatic islet transplantation is a promising treatment but is limited by donor shortages and significant islet loss during the procedures. The usage of pancreatic islet-like aggregates derived from pluripotent stem cells (SC-islets) could solve the problem of shortage of islets. Incorporating these SC-islets into a supporting scaffold could protect them during handling.FN-silk, a recombinantly produced spider silk protein functionalized with a cell adhesion motif from fibronectin, can generate 3D networks that mimic the extracellular matrix (ECM). We herein demonstrate a reproducible method for integrating SC-islets well-distributed within stable 3D networks of FN-silk. These SC-islets showed high viability and maintained functionality, with increased glucagon expression and improved beta cell maturation as compared to free SC-islets. Additionally, the support of FN-silk networks enables cultivation of SC-islets under conditions needed for scale-up. Moreover, the integration of the SC-islets into sheets of FN-silk networks facilitates handling during transplantation into the anterior chamber of the eye (ACE) of rabbits. Such transplanted FN-silk incorporated SC-islets were found vascularized six weeks post-transplantation, with sustained insulin and glucagon expression.
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| 5. |
- Gonzalez Dias Carvalho, Patrícia Conceição, et al.
(författare)
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Baseline gene signatures of reactogenicity to Ebola vaccination: a machine learning approach across multiple cohorts
- 2023
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Ingår i: Frontiers in Immunology. - 1664-3224. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The rVSVDG-ZEBOV-GP (Ervebo®) vaccine is both immunogenic and protective against Ebola. However, the vaccine can cause a broad range of transient adverse reactions, from headache to arthritis. Identifying baseline reactogenicity signatures can advance personalized vaccinology and increase our understanding of the molecular factors associated with such adverse events. Methods: In this study, we developed a machine learning approach to integrate prevaccination gene expression data with adverse events that occurred within 14 days post-vaccination. Results and Discussion: We analyzed the expression of 144 genes across 343 blood samples collected from participants of 4 phase I clinical trial cohorts: Switzerland, USA, Gabon, and Kenya. Our machine learning approach revealed 22 key genes associated with adverse events such as local reactions, fatigue, headache, myalgia, fever, chills, arthralgia, nausea, and arthritis, providing insights into potential biological mechanisms linked to vaccine reactogenicity.
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| 6. |
- Householder, John Ethan, et al.
(författare)
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One sixth of Amazonian tree diversity is dependent on river floodplains
- 2024
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Ingår i: NATURE ECOLOGY & EVOLUTION. - 2397-334X. ; 8, s. 901-911
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Tidskriftsartikel (refereegranskat)abstract
- Amazonia's floodplain system is the largest and most biodiverse on Earth. Although forests are crucial to the ecological integrity of floodplains, our understanding of their species composition and how this may differ from surrounding forest types is still far too limited, particularly as changing inundation regimes begin to reshape floodplain tree communities and the critical ecosystem functions they underpin. Here we address this gap by taking a spatially explicit look at Amazonia-wide patterns of tree-species turnover and ecological specialization of the region's floodplain forests. We show that the majority of Amazonian tree species can inhabit floodplains, and about a sixth of Amazonian tree diversity is ecologically specialized on floodplains. The degree of specialization in floodplain communities is driven by regional flood patterns, with the most compositionally differentiated floodplain forests located centrally within the fluvial network and contingent on the most extraordinary flood magnitudes regionally. Our results provide a spatially explicit view of ecological specialization of floodplain forest communities and expose the need for whole-basin hydrological integrity to protect the Amazon's tree diversity and its function.
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| 7. |
- Luize, Bruno Garcia, et al.
(författare)
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Geography and ecology shape the phylogenetic composition of Amazonian tree communities
- 2024
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Ingår i: JOURNAL OF BIOGEOGRAPHY. - 0305-0270 .- 1365-2699. ; 51:7, s. 1163-1184
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Amazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types. Location: Amazonia. Taxon: Angiosperms (Magnoliids; Monocots; Eudicots). Methods: Data for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran's eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny. Results: In the terra firme and v & aacute;rzea forest types, the phylogenetic composition varies by geographic region, but the igap & oacute; and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R-2 = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R-2 = 28%). A greater number of lineages were significant indicators of geographic regions than forest types. Main Conclusion: Numerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions.
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| 8. |
- Meghraoui, Mustapha, et al.
(författare)
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Preface
- 2022
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Ingår i: Advances in Science, Technology and Innovation. - : Springer Nature. - 9783030730253
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Smith, Ross O., et al.
(författare)
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Vascular permeability in retinopathy is regulated by VEGFR2 Y949 signaling to VE-cadherin
- 2020
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Ingår i: eLIFE. - : ELIFE SCIENCES PUBLICATIONS LTD. - 2050-084X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Edema stemming from leaky blood vessels is common in eye diseases such as agerelated macular degeneration and diabetic retinopathy. Whereas therapies targeting vascular endothelial growth factor A (VEGFA) can suppress leakage, side-effects include vascular rarefaction and geographic atrophy. By challenging mouse models representing different steps in VEGFA/VEGF receptor 2 (VEGFR2)-induced vascular permeability, we show that targeting signaling downstream of VEGFR2 pY949 limits vascular permeability in retinopathy induced by high oxygen or by laser-wounding. Although suppressed permeability is accompanied by reduced pathological neoangiogenesis in oxygen-induced retinopathy, similarly sized lesions leak less in mutant mice, separating regulation of permeability from angiogenesis. Strikingly, vascular endothelial (VE)-cadherin phosphorylation at the Y685, but not Y658, residue is reduced when VEGFR2 pY949 signaling is impaired. These findings support a mechanism whereby VE-cadherin Y685 phosphorylation is selectively associated with excessive vascular leakage. Therapeutically, targeting VEGFR2-regulated VE-cadherin phosphorylation could suppress edema while leaving other VEGFR2-dependent functions intact.
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| 10. |
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| 11. |
- ter Steege, Hans, et al.
(författare)
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Mapping density, diversity and species-richness of the Amazon tree flora
- 2023
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Ingår i: COMMUNICATIONS BIOLOGY. - 2399-3642. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution. A study mapping the tree species richness in Amazonian forests shows that soil type exerts a strong effect on species richness, probably caused by the areas of these forest types. Cumulative water deficit, tree density and temperature seasonality affect species richness at a regional scale.
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| 12. |
- Vestweber, Dietmar, et al.
(författare)
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Report from the 2023 workshop on endothelial permeability, edema and inflammation
- 2023
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Ingår i: Nature Cardiovascular Research. - : Springer Nature. - 2731-0590. ; 2:12, s. 1120-1124
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A key consequence of increased and sustained vascular permeability in several inflammatory and cardiovascular disorders is the development of interstitial protein-rich proinflammatory edema. This response remains poorly understood mechanistically and its potential adverse effect on local and systemic diseases is often underestimated. To discuss current findings and identify crucial unresolved questions, a workshop was held in Berlin from 12-15 April 2023. Key topics that were discussed included regulation of endothelial cell junctions, neutrophil-dependent vascular leakage, resolution of edema, exemplar diseases, and anti-edema therapies. This report is a summary of the meeting.
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| 13. |
- Watson, Hunna J., et al.
(författare)
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Common Genetic Variation and Age of Onset of Anorexia Nervosa
- 2022
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Ingår i: BIOLOGICAL PSYCHIATRY: GLOBAL OPEN SCIENCE. - : Elsevier BV. - 2667-1743. ; 2:4, s. 368-378
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Genetics and biology may influence the age of onset of anorexia nervosa (AN). The aims of this study were to determine whether common genetic variation contributes to age of onset of AN and to investigate the genetic associations between age of onset of AN and age at menarche.METHODS: A secondary analysis of the Psychiatric Genomics Consortium genome-wide association study (GWAS) of AN was performed, which included 9335 cases and 31,981 screened controls, all from European ancestries. We conducted GWASs of age of onset, early-onset AN (,13 years), and typical-onset AN, and genetic correlation, genetic risk score, and Mendelian randomization analyses.RESULTS: Two loci were genome-wide significant in the typical-onset AN GWAS. Heritability estimates (single nucleotide polymorphism-h2) were 0.01-0.04 for age of onset, 0.16-0.25 for early-onset AN, and 0.17-0.25 for typical-onset AN. Early-and typical-onset AN showed distinct genetic correlation patterns with putative risk factors for AN. Specifically, early-onset AN was significantly genetically correlated with younger age at menarche, and typical-onset AN was significantly negatively genetically correlated with anthropometric traits. Genetic risk scores for age of onset and early-onset AN estimated from independent GWASs significantly predicted age of onset. Mendelian randomization analysis suggested a causal link between younger age at menarche and early -onset AN.CONCLUSIONS: Our results provide evidence consistent with a common variant genetic basis for age of onset and implicate biological pathways regulating menarche and reproduction.
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