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- Batool, Tahira
(författare)
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Heparan sulfate dependent cell signaling and associated pathophysiology : Implications in tumorigenesis and embryogenesis
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Heparan sulfate proteoglycans (HSPGs) consist of a protein core to which several linear, negatively charged heparan sulfate (HS) chains are covalently attached. HSPGs are expressed on the cell surface and in the extra-cellular matrix (ECM) where they have diverse biological functions, for example co-receptor functions. The diverse functions of HS are linked to structural variability of the polysaccharide. In this thesis, I investigated HS structure-function relationship by using different cell and animal models of one HS-biosynthetic enzyme, glucuronyl C5-epimerase (Hsepi) and one enzyme responsible for post synthetic modification, heparanase.Deletion of Hsepi in mice resulted in neonatal lethality, with multiple organ defects, indicating the importance of HS in embryogenesis. Up-regulated expression of heparanase is found in most human tumor tissues, correlating with increased metastatic potential and decreased survival of cancer patients.In the first project, I focused on the effects of HS on cancer associated cell signaling and found that heparanase overexpression attenuated TGF-β1 stimulated Smad phosphorylation in tumor cells because of increased sulfation degree and turnover rate of HS.Heparanase role in cancer progression has led to clinical trials where inhibition of heparanase activity is currently being evaluated as a potential cancer treatment. Heparin, a HS-related polysaccharide, is being used to inhibit heparanase activity. In my second project, we studied the effect of low molecular weight heparin (LMWH) on cisplatin resistance of ovarian cancer cells (A2780cis). LMWH treatment of A2780cis cells reduced Wnt-activity in these cells and consequently reduce the drug resistance.In paper III, we continued exploring the HS/heparanase role in cancer by using heparanase overexpressing mice (Hpa-tg). We found Lewis Lung Carcinoma (LLC2) cells showed faster growth, bigger tumors and more metastasis in the Hpa-tg mice as compared to wild-type (WT) mice, because of suppressed antitumor immunity in the Hpa-tg mice.In paper IV and V, we studied the structure-function relationship of HS by using Hsepi-/- mice model. Hsepi-/- results in HS-chains lacking IdoA, which makes the chain rigid and consequently affects its co-receptor function. Skeletal malformation in Hsepi-/- mice, led us in paper IV to investigate bone morphogenic protein (BMP), an important signal molecule during embryogenesis and known to interact with HS. We found upregulation of a number of BMPs and expression of P-smad1/5/8, but reduced expression of inhibitory Smads and Gremlin1 in the Hsepi-/- MEF cells. The study indicated that the developmental defects in Hsepi mice could be contributed by a higher BMP signaling. In paper V we investigated the lung of the Hsepi-/- mice. The distal lung of 17.5 days old embryos remained populated by epithelial tubules, because of impaired differentiation of type I cells of the lungs. Potential mechanisms behind the failure of type I cell formation was identified to be reduced vascularization and a sustained signaling of Smad pathways.
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- Digre, Andreas, 1987-
(författare)
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Implications of Heparan Sulfate and Heparanase in Inflammatory Diseases
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Heparan sulfate (HS), an unbranched sulfated carbohydrate chain, and the HS-degrading enzyme heparanase play important roles in physiological and pathological processes during all stages of life, from early embryogenesis to ageing. Accumulated information shows that HS and heparanase are involved in inflammatory processes and associated diseases, e.g. rheumatoid arthritis (RA) and Alzheimer’s disease.In this thesis I have investigated the role of HS and heparanase (Hpa) in inflammatory-related pathologies. In the first project, Hpa overexpressing mice (Hpa-tg) were induced with a murine model of RA. We found a pro-inflammatory role of Hpa through enhancing the activity of T-cells and innate immune cells, which contributed to an augmented severity of clinical symptoms in the Hpa-tg mice.In my second project, we revealed co-current interaction of heparin with both ApoA1 and SAA of HDL isolated from plasma of inflamed mouse. Mass spectrometry analysis indicated close proximity of ApoA1 and SAA on the HDL surface, providing a molecular and structural mechanism for the simultaneous binding of heparin to apoA1 and SAA.In my third project, we investigated the role of Hpa in AA amyloid formation and resolution in mice in a model of AA-amyloidosis. We found a similar degree of amyloid formation in Hpa-KO mice compared to the wildtype control mice, but the resolution process was faster in Hpa-KO mice. The rapid clearance of deposited SAA in Hpa-KO mice was associated with upregulated expression of matrix metalloproteases. The results suggest an associated function of ECM proteases with heparanase in the process of AA amyloid resolution.In my fourth project, we found that overexpression of heparanase impaired inflammation associated beta amyloid (Aβ) clearance in the brain of an Alzheimer’s disease mouse model. Examination of the cytokine profile of brain lysates revealed an overall lower inflammatory reaction in the double transgenic (tgHpa*Swe) mice compared to single APP-tg (tg-Swe) mice in response to LPS-induced inflammation.
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- Ikeda, Fumiyo, et al.
(författare)
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SHARPIN forms a linear ubiquitin ligase complex regulating NF-κB activity and apoptosis.
- 2011
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 471:7340, s. 637-641
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Tidskriftsartikel (refereegranskat)abstract
- SHARPIN is a ubiquitin-binding and ubiquitin-like-domain-containing protein which, when mutated in mice, results in immune system disorders and multi-organ inflammation. Here we report that SHARPIN functions as a novel component of the linear ubiquitin chain assembly complex (LUBAC) and that the absence of SHARPIN causes dysregulation of NF-κB and apoptotic signalling pathways, explaining the severe phenotypes displayed by chronic proliferative dermatitis (cpdm) in SHARPIN-deficient mice. Upon binding to the LUBAC subunit HOIP (also known as RNF31), SHARPIN stimulates the formation of linear ubiquitin chains in vitro and in vivo. Coexpression of SHARPIN and HOIP promotes linear ubiquitination of NEMO (also known as IKBKG), an adaptor of the IκB kinases (IKKs) and subsequent activation of NF-κB signalling, whereas SHARPIN deficiency in mice causes an impaired activation of the IKK complex and NF-κB in B cells, macrophages and mouse embryonic fibroblasts (MEFs). This effect is further enhanced upon concurrent downregulation of HOIL-1L (also known as RBCK1), another HOIP-binding component of LUBAC. In addition, SHARPIN deficiency leads to rapid cell death upon tumour-necrosis factor α (TNF-α) stimulation via FADD- and caspase-8-dependent pathways. SHARPIN thus activates NF-κB and inhibits apoptosis via distinct pathways in vivo.
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- Marto, João Pedro, et al.
(författare)
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Safety and Outcome of Revascularization Treatment in Patients With Acute Ischemic Stroke and COVID-19: The Global COVID-19 Stroke Registry.
- 2023
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Ingår i: Neurology. - 1526-632X. ; 100:7
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Tidskriftsartikel (refereegranskat)abstract
- COVID-19-related inflammation, endothelial dysfunction, and coagulopathy may increase the bleeding risk and lower the efficacy of revascularization treatments in patients with acute ischemic stroke (AIS). We aimed to evaluate the safety and outcomes of revascularization treatments in patients with AIS and COVID-19.This was a retrospective multicenter cohort study of consecutive patients with AIS receiving intravenous thrombolysis (IVT) and/or endovascular treatment (EVT) between March 2020 and June 2021 tested for severe acute respiratory syndrome coronavirus 2 infection. With a doubly robust model combining propensity score weighting and multivariate regression, we studied the association of COVID-19 with intracranial bleeding complications and clinical outcomes. Subgroup analyses were performed according to treatment groups (IVT-only and EVT).Of a total of 15,128 included patients from 105 centers, 853 (5.6%) were diagnosed with COVID-19; of those, 5,848 (38.7%) patients received IVT-only and 9,280 (61.3%) EVT (with or without IVT). Patients with COVID-19 had a higher rate of symptomatic intracerebral hemorrhage (SICH) (adjusted OR 1.53; 95% CI 1.16-2.01), symptomatic subarachnoid hemorrhage (SSAH) (OR 1.80; 95% CI 1.20-2.69), SICH and/or SSAH combined (OR 1.56; 95% CI 1.23-1.99), 24-hour mortality (OR 2.47; 95% CI 1.58-3.86), and 3-month mortality (OR 1.88; 95% CI 1.52-2.33). Patients with COVID-19 also had an unfavorable shift in the distribution of the modified Rankin score at 3 months (OR 1.42; 95% CI 1.26-1.60).Patients with AIS and COVID-19 showed higher rates of intracranial bleeding complications and worse clinical outcomes after revascularization treatments than contemporaneous non-COVID-19 patients receiving treatment. Current available data do not allow direct conclusions to be drawn on the effectiveness of revascularization treatments in patients with COVID-19 or to establish different treatment recommendations in this subgroup of patients with ischemic stroke. Our findings can be taken into consideration for treatment decisions, patient monitoring, and establishing prognosis.The study was registered under ClinicalTrials.gov identifier NCT04895462.
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- Mehić, Merima, 1987-
(författare)
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Regulation of Hyaluronan Synthesis and Signaling via CD44 in Cancer
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hyaluronan is a ubiquitous glycosaminoglycan which is an important constituent of the extracellular matrix (ECM). In addition to organizing the extracellular matrix and regulating tissue homeostasis, hyaluronan, by binding to its main cell surface receptor CD44, is involved in intracellular signaling pathways regulating major cellular processes during development, wound healing, inflammation and cancer. Accumulation of hyaluronan in cancer promotes progression of the disease and correlates with poor prognosis. This thesis focuses on the regulation of hyaluronan synthesis and its signaling in normal and cancer cells.Cancer cells in solid tumors are surrounded by stroma, which has an essential role in the growth and metastasis of tumors. Prominent members of the tumor stroma are fibroblasts, which synthesize ECM components, such as hyaluronan, and secrete growth factors, and activate intracellular signaling pathways. We demonstrate a cross-talk between the receptors for platelet-derived growth factor BB (PDGF-BB), transforming growth factor β (TGFβ) and CD44 in dermal fibroblasts. We found that PDGF-BB can activate the Smad signaling pathway downstream of the TGFβ receptor I (TβRI), and that PDGF-BB-induced migration depends on TβRI. CD44 forms a ternary complex with the receptors for PDGF-BB and TGFβ, and negatively regulates their signaling. Furthermore, we demonstrate that TGFβ stimulation of mammary epithelial cells transcriptionally upregulates hyaluronan synthase 2 (HAS2), which is essential for TGFβ-induced epithelial-mesenchymal transition (EMT); in this process, polarized epithelial cells adapt a mesenchymal phenotype which facilitates migration and invasion.HAS2 protein activity and stability is regulated by posttranslational modifications, including ubiquitination. We investigated the ubiquitination of HAS2 in aggressive breast cancer cells, whose metastasizing capability depends on HAS2-synthesized hyaluronan. We identified two deubiquitinating enzymes, USP4 and USP17, which target HAS2 and affect its activity and stability.In summary, these studies increase the knowledge about the regulation of hyaluronan production and its role in cancer progression.
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