| 1. |
- Alvarez, Alberto, et al.
(författare)
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Tamoxifen-independent recombination of reporter genes limits lineage tracing and mosaic analysis using CreER(T2) lines
- 2020
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Ingår i: Transgenic research. - : Springer Nature. - 0962-8819 .- 1573-9368. ; 29:1, s. 53-68
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Tidskriftsartikel (refereegranskat)abstract
- The CreER(T2)/loxP system is widely used to induce conditional gene deletion in mice. One of the main advantages of the system is that Cre-mediated recombination can be controlled in time through Tamoxifen administration. This has allowed researchers to study the function of embryonic lethal genes at later developmental timepoints. In addition, CreER(T2) mouse lines are commonly used in combination with reporter genes for lineage tracing and mosaic analysis. In order for these experiments to be reliable, it is crucial that the cell labeling approach only marks the desired cell population and their progeny, as unfaithful expression of reporter genes in other cell types or even unintended labeling of the correct cell population at an undesired time point could lead to wrong conclusions. Here we report that all CreER(T2) mouse lines that we have studied exhibit a certain degree of Tamoxifen-independent, basal, Cre activity. Using Ai14 and Ai3, two commonly used fluorescent reporter genes, we show that those basal Cre activity levels are sufficient to label a significant amount of cells in a variety of tissues during embryogenesis, postnatal development and adulthood. This unintended labelling of cells imposes a serious problem for lineage tracing and mosaic analysis experiments. Importantly, however, we find that reporter constructs differ greatly in their susceptibility to basal CreER(T2) activity. While Ai14 and Ai3 easily recombine under basal CreER(T2) activity levels, mTmG and R26R-EYFP rarely become activated under these conditions and are therefore better suited for cell tracking experiments.
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| 2. |
- Arpa Gonzalez, Enrique Manuel, et al.
(författare)
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Unveiling Photodegradation and Photosensitization Mechanisms of Unconjugated Pterins
- 2023
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Ingår i: Chemistry - A European Journal. - : WILEY-V C H VERLAG GMBH. - 0947-6539 .- 1521-3765. ; 29:29
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Tidskriftsartikel (refereegranskat)abstract
- Unconjugated pterins are ubiquitous molecules that participate in countless enzymatic processes and are potentially involved in the photosensitization of singlet oxygen, amino acids, and nucleotides. Following electronic excitation with UV-A light, some of these pterins degrade, producing hydrogen peroxide as the main side product. This process, which is known to take place in vivo, contributes to oxidative stress and melanocyte destruction in vitiligo. In this work, we present for the first time mechanistic insight into the formation of transient triplet species that simultaneously trigger Type I and Type II photosensitizing processes and the initiation of degradation processes. Our calculations reveal that photodegradation of 6-biopterin, which accumulates in the skin of vitiligo patients, leads to 6-formylpterin through a retro-aldol reaction, and subsequently to 6-carboxypterin through a water-mediated aldehyde oxidation. Additionally, we show that the changes in the photosensitizing potential of these systems with pH come from the modulation of their excited-state redox potentials.
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| 3. |
- Arpa Gonzalez, Enrique Manuel, et al.
(författare)
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Unveiling Photodegradation and Photosensitization Mechanisms of Unconjugated Pterins
- 2023
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Ingår i: Chemistry - A European Journal. - : WILEY-V C H VERLAG GMBH. - 0947-6539 .- 1521-3765.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Invited for the cover of this issue are Enrique M. Arpa (Linkoping University) and Ines Corral (Universidad Autonoma de Madrid). The image depicts two examples where pterin chemistry is relevant, the wing coloration of some butterflies and the cytotoxic action in vitiligo. Read the full text of the article at 10.1002/chem.202300519.
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| 4. |
- Brea, Oriana, et al.
(författare)
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Molecular Modelling of the H-2-Adsorptive Properties of Tetrazolate-Based Metal-Organic Frameworks : From the Cluster Approach to Periodic Simulations
- 2018
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Ingår i: ChemPhysChem. - : Wiley. - 1439-4235 .- 1439-7641. ; 19:11, s. 1349-1357
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen has been proposed as a long-term non-fossil fuel to be used in a future ideal carbon-neutral energetic economy. However, its low volumetric energy density hinders its storage and transportation. Metal-organic frameworks (MOFs) represent very promising materials for this purpose due to their very extended surface areas. Azolates, in particular tetrazolates, are - together with carboxylate functionalities - very common organic linkers connecting metallic secondary building units in MOFs. This study addresses, from a theoretical perspective, the H-2 adsorptive properties of tetrazolate linkers at the molecular level, following a size-progressive approach. Specifically, we have investigated how the physisorption energies and geometries are affected when changing the environment of the linker by considering the azolates in the gas phase, immersed in a finite cluster, or being part of an infinite extended crystal material. Furthermore, we also study the H-2 adsorptive capacity of these linkers within the cluster model.
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| 5. |
- Corpas, Javier, et al.
(författare)
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Interplay between the Directing Group and Multifunctional Acetate Ligand in Pd-Catalyzed anti-Acetoxylation of Unsymmetrical Dialkyl-Substituted Alkynes
- 2022
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Ingår i: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 12:11, s. 6596-6605
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Tidskriftsartikel (refereegranskat)abstract
- The cooperative action of the acetate ligand, the 2-pyridyl sulfonyl (SO2Py) directing group on the alkyne substrate,and the palladium catalyst has been shown to be crucial forcontrolling reactivity, regioselectivity, and stereoselectivity in theacetoxylation of unsymmetrical internal alkynes under mildreaction conditions. The corresponding alkenyl acetates wereobtained in good yields with complete levels of beta-regioselectivityandanti-acetoxypalladation stereocontrol. Experimental andcomputational analyses provide insight into the reasons behindthis delicate interplay between the ligand, directing group, and themetal in the reaction mechanism. In fact, these studies unveil themultiple important roles of the acetate ligand in the coordinationsphere at the Pd center: (i) it brings the acetic acid reagent into close proximity to the metal to allow the simultaneous activation ofthe alkyne and the acetic acid, (ii) it serves as an inner-sphere base while enhancing the nucleophilicity of the acid, and (iii) it acts asan intramolecular acid to facilitate protodemetalation and regeneration of the catalyst. Further insight into the origin of the observedregiocontrol is provided by the mapping of potential energy profiles and distortion-interaction analysis
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| 6. |
- Frye, Maike, et al.
(författare)
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Matrix stiffness controls lymphatic vessel formation through regulation of a GATA2-dependent transcriptional program
- 2018
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Tissue and vessel wall stiffening alters endothelial cell properties and contributes to vascular dysfunction. However, whether extracellular matrix (ECM) stiffness impacts vascular development is not known. Here we show that matrix stiffness controls lymphatic vascular morphogenesis. Atomic force microscopy measurements in mouse embryos reveal that venous lymphatic endothelial cell (LEC) progenitors experience a decrease in substrate stiffness upon migration out of the cardinal vein, which induces a GATA2-dependent transcriptional program required to form the first lymphatic vessels. Transcriptome analysis shows that LECs grown on a soft matrix exhibit increased GATA2 expression and a GATA2-dependent upregulation of genes involved in cell migration and lymphangiogenesis, including VEGFR3. Analyses of mouse models demonstrate a cell-autonomous function of GATA2 in regulating LEC responsiveness to VEGF-C and in controlling LEC migration and sprouting in vivo. Our study thus uncovers a mechanism by which ECM stiffness dictates the migratory behavior of LECs during early lymphatic development.
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| 7. |
- Gardenier, Jason C., et al.
(författare)
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Diphtheria toxin-mediated ablation of lymphatic endothelial cells results in progressive lymphedema
- 2016
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Ingår i: JCI INSIGHT. - : American Society for Clinical Investigation. - 2379-3708. ; 1:15
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Tidskriftsartikel (refereegranskat)abstract
- Development of novel treatments for lymphedema has been limited by the fact that the pathophysiology of this disease is poorly understood. It remains unknown, for example, why limb swelling resulting from surgical injury resolves initially, but recurs in some cases months or years later. Finding answers for these basic questions has been hampered by the lack of adequate animal models. In the current study, we used Cre-lox mice that expressed the human diphtheria toxin receptor (DTR) driven by a lymphatic-specific promoter in order to noninvasively ablate the lymphatic system of the hind limb. Animals treated in this manner developed lymphedema that was indistinguishable from clinical lymphedema temporally, radiographically, and histologically. Using this model and clinical biopsy specimens, we show that the initial resolution of edema after injury is dependent on the formation of collateral capillary lymphatics and that this process is regulated by M2-polarized macrophages. In addition, we show that despite these initial improvements in lymphatic function, persistent accumulation of CD4(+) cells inhibits lymphangiogenesis and promotes sclerosis of collecting lymphatics, resulting in late onset of edema and fibrosis. Our findings therefore provide strong evidence that inflammatory changes after lymphatic injury play a key role in the pathophysiology of lymphedema.
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| 8. |
- Gramolelli, Silvia, et al.
(författare)
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PROX1 is a transcriptional regulator of MMP14
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The transcription factor PROX1 is essential for development and cell fate specification. Its function in cancer is context-dependent since PROX1 has been shown to play both oncogenic and tumour suppressive roles. Here, we show that PROX1 suppresses the transcription of MMP14, a metalloprotease involved in angiogenesis and cancer invasion, by binding and suppressing the activity of MMP14 promoter. Prox1 deletion in murine dermal lymphatic vessels in vivo and in human LECs increased MMP14 expression. In a hepatocellular carcinoma cell line expressing high endogenous levels of PROX1, its silencing increased both MMP14 expression and MMP14-dependent invasion in 3D. Moreover, PROX1 ectopic expression reduced the MMP14-dependent 3D invasiveness of breast cancer cells and angiogenic sprouting of blood endothelial cells in conjunction with MMP14 suppression. Our study uncovers a new transcriptional regulatory mechanism of cancer cell invasion and endothelial cell specification.
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| 9. |
- Huang, Jung-Ju, et al.
(författare)
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Lymph Node Transplantation Decreases Swelling and Restores Immune Responses in a Transgenic Model of Lymphedema
- 2016
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:12
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Secondary lymphedema is a common complication of cancer treatment and recent studies have demonstrated that lymph node transplantation (LNT) can decrease swelling, as well as the incidence of infections. However, although these results are exciting, the mechanisms by which LNT improves these pathologic findings of lymphedema remain unknown. Using a transgenic mouse model of lymphedema, this study sought to analyze the effect of LNT on lymphatic regeneration and T cell-mediated immune responses. Methods We used a mouse model in which the expression of the human diphtheria toxin receptor is driven by the FLT4 promoter to enable the local ablation of the lymphatic system through subdermal hindlimb diphtheria toxin injections. Popliteal lymph node dissection was subsequently performed after a two-week recovery period, followed by either orthotopic LNT or sham surgery after an additional two weeks. Hindlimb swelling, lymphatic vessel regeneration, immune cell trafficking, and T cell-mediated immune responses were analyzed 10 weeks later. Results LNT resulted in a marked decrease in hindlimb swelling, fibroadipose tissue deposition, and decreased accumulation of perilymphatic inflammatory cells, as compared to controls. In addition, LNT induced a marked lymphangiogenic response in both capillary and collecting lymphatic vessels. Interestingly, the resultant regenerated lymphatics were abnormal in appearance on lymphangiography, but LNT also led to a notable increase in dendritic cell trafficking from the periphery to the inguinal lymph nodes and improved adaptive immune responses. Conclusions LNT decreases pathological changes of lymphedema and was shown to potently induce lymphangiogenesis. Lymphatic vessels induced by LNT were abnormal in appearance, but were functional and able to transport antigen-presenting cells. Animals treated with LNT have an increased ability to mount T cell-mediated immune responses when sensitized to antigens in the affected hindlimb.
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| 10. |
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