| 1. |
- Dalin, Martin, 1982, et al.
(författare)
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Massive parallel sequencing questions the pathogenic role of missense variants in dilated cardiomyopathy
- 2017
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Ingår i: International Journal of Cardiology. - : Elsevier BV. - 0167-5273 .- 1874-1754. ; 228, s. 742-748
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Tidskriftsartikel (refereegranskat)abstract
- Background: Germline genetic variants are an important cause of dilated cardiomyopathy (DCM). However, recent sequencing studies have revealed rare variants in DCM-associated genes also in individuals without known heart disease. In this study, we investigate variant prevalence and genotype-phenotype correlations in Swedish DCM patients, and compare their genetic variants to those detected in reference cohorts. Methods and results: We sequenced the coding regions of 41 DCM-associated genes in 176 unrelated patients with idiopathic DCM and found 102 protein-altering variants with an allele frequency of <0.04% in reference cohorts; the majority were missense variants not previously described in DCM. Fifty-five (31%) patients had one variant, and 24 (14%) patients had two or more variants in the analysed genes. Detection of genetic variants in any gene, and in LMNA, MYII7 or TTN alone, was associated with early onset disease and reduced transplant-free survival. As expected, nonsense and frameshift variants were more common in DCM patients than in healthy individuals of the reference cohort 1000 Genomes Europeans. Surprisingly however, the prevalence, conservation and pathogenicity scores, and localization of missense variants were similar in DCM patients and healthy reference individuals. Conclusion: To our knowledge, this is the first study to identify correlations between genotype and prognosis when sequencing a large number of genes in unselected DCM patients. The similar distribution of missense variants in DCM patients and healthy reference individuals questions the pathogenic role of many variants, and suggests that results from genetic testing of DCM patients should be interpreted with caution.
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| 2. |
- Dalin, Martin, 1982, et al.
(författare)
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Myocardial KRASG12D expression does not cause cardiomyopathy in mice
- 2014
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Ingår i: Cardiovascular Research. - : Oxford University Press (OUP). - 0008-6363 .- 1755-3245. ; 101:2, s. 229-235
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Tidskriftsartikel (refereegranskat)abstract
- AimsGerm-line mutations in genes encoding components of the RAS/mitogen-activated protein kinase (MAPK) pathway cause developmental disorders called RASopathies. Hypertrophic cardiomyopathy (HCM) is the most common myocardial pathology and a leading cause of death in RASopathy patients. KRAS mutations are found in Noonan and cardio-facio-cutaneous syndromes. KRAS mutations, unlike mutations of RAF1 and HRAS, are rarely associated with HCM. This has been attributed to the fact that germ-line KRAS mutations cause only a moderate up-regulation of the MAPK pathway. Highly bioactive KRAS mutations have been hypothesized to cause severe cardiomyopathy incompatible with life. The aim of this study was to define the impact of KRASG12D expression in the heart.Methods and resultsTo generate mice with endogenous cardiomyocyte-specific KRASG12D expression (cKRASG12D mice), we bred mice with a Cre-inducible allele expressing KRASG12D from its endogenous promoter (Kras2LSL) to mice expressing Cre under control of the cardiomyocyte-specific α-myosin heavy chain promoter (αMHC-Cre). cKRASG12D mice showed high levels of myocardial ERK and AKT signalling. However, surprisingly, cKRASG12D mice were born in Mendelian ratios, appeared healthy, and had normal function, size, and histology of the heart.ConclusionMice with cardiomyocyte-specific KRAS G12D expression do not develop heart pathology. These results challenge the view that the level of MAPK activation correlates with the severity of HCM in RASopathies and suggests that MAPK-independent strategies may be of interest in the development of new treatments for these syndromes. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2013.
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| 3. |
- Le Gal, Kristell, et al.
(författare)
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Antioxidants can increase melanoma metastasis in mice.
- 2015
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Ingår i: Science Translational Medicine. - : American Association for the Advancement of Science (AAAS). - 1946-6242 .- 1946-6234. ; 7:308
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Tidskriftsartikel (refereegranskat)abstract
- Antioxidants in the diet and supplements are widely used to protect against cancer, but clinical trials with antioxidants do not support this concept. Some trials show that antioxidants actually increase cancer risk and a study in mice showed that antioxidants accelerate the progression of primary lung tumors. However, little is known about the impact of antioxidant supplementation on the progression of other types of cancer, including malignant melanoma. We show that administration of N-acetylcysteine (NAC) increases lymph node metastases in an endogenous mouse model of malignant melanoma but has no impact on the number and size of primary tumors. Similarly, NAC and the soluble vitamin E analog Trolox markedly increased the migration and invasive properties of human malignant melanoma cells but did not affect their proliferation. Both antioxidants increased the ratio between reduced and oxidized glutathione in melanoma cells and in lymph node metastases, and the increased migration depended on new glutathione synthesis. Furthermore, both NAC and Trolox increased the activation of the small guanosine triphosphatase (GTPase) RHOA, and blocking downstream RHOA signaling abolished antioxidant-induced migration. These results demonstrate that antioxidants and the glutathione system play a previously unappreciated role in malignant melanoma progression.
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| 4. |
- Liu, Meng, 1976, et al.
(författare)
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Targeting the protein prenyltransferases efficiently reduces tumor development in mice with K-RAS-induced lung cancer
- 2010
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 107:14, s. 6471-6476
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Tidskriftsartikel (refereegranskat)abstract
- RAS and RHO proteins, which contribute to tumorigenesis and metastasis, undergo posttranslational modification with an isoprenyl lipid by protein farnesyltransferase (FTase) or protein geranylgeranyltransferase-I (GGTase-I). Inhibitors of FTase and GGTase-I were developed to block RAS-induced malignancies, but their utility has been difficult to evaluate because of off-target effects, drug resistance, and toxicity. Moreover, the impact of FTase deficiency and combined FTase/GGTase-I deficiency has not been evaluated with genetic approaches. We found that inactivation of FTase eliminated farnesylation of HDJ2 and H-RAS, prevented H-RAS targeting to the plasma membrane, and blocked proliferation of primary and K-RAS(G12D)-expressing fibroblasts. FTase inactivation in mice with K-RAS-induced lung cancer reduced tumor growth and improved survival, similar to results obtained previously with inactivation of GGTase-I. Simultaneous inactivation of FTase and GGTase-I markedly reduced lung tumors and improved survival without apparent pulmonary toxicity. These data shed light on the biochemical and therapeutic importance of FTase and suggest that simultaneous inhibition of FTase and GGTase-I could be useful in cancer therapeutics.
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| 5. |
- Noguera-Salva, M. A., et al.
(författare)
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Role of the C-terminal basic amino acids and the lipid anchor of the G gamma(2) protein in membrane interactions and cell localization
- 2017
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Ingår i: Biochimica Et Biophysica Acta-Biomembranes. - : Elsevier BV. - 0005-2736. ; 1859:9, s. 1536-1547
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Tidskriftsartikel (refereegranskat)abstract
- Heterotrimeric G proteins are peripheral membrane proteins that frequently localize to the plasma membrane where their presence in molar excess over G protein coupled receptors permits signal amplification. Their distribution is regulated by protein-lipid interactions, which has a clear influence on their activity. G beta gamma dimer drives the interaction between G protein heterotrimers with cell membranes. We focused our study on the role of the C-terminal region of the G gamma(2) protein in G protein interactions with cell membranes. The G gamma(2) subunit is modified at cysteine (Cys) 68 by the addition of an isoprenyl lipid, which is followed by the proteolytic removal of the last three residues that leaves an isoprenylated and carboxyl methylated Cys-68 as the terminal amino acid. The role of Cys isoprenylation of the CAAX box has been defined for other proteins, yet the importance of proteolysis and carboxyl methylation of isoprenylated proteins is less clear. Here, we showed that not only geranylgeranylation but also proteolysis and carboxyl methylation are essential for the correct localization of G gamma(2) in the plasma membrane. Moreover, we showed the importance of electrostatic interactions between the inner leaflet of the plasma membrane and the positively charged C-terminal domain of the G gamma(2) subunit (amino acids Arg-62, Lys-64 and Lys-65) as a second signal to reach the plasma membrane. Indeed, single or multiple point mutations at G gamma(2) C-terminal amino acids have a significant effect on G gamma(2) protein-plasma membrane interactions and its localization to charged Ld (liquid disordered) membrane microdomains. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escriba. (C) 2017 Published by Elsevier B.V.
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| 6. |
- Sjögren, Anna-Karin, 1980, et al.
(författare)
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GGTase-I deficiency reduces tumor formation and improves survival in mice with K-RAS-induced lung cancer
- 2007
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Ingår i: J Clin Invest. - 0021-9738. ; 117:5, s. 1294-304
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Tidskriftsartikel (refereegranskat)abstract
- Protein geranylgeranyltransferase type I (GGTase-I) is responsible for the posttranslational lipidation of CAAX proteins such as RHOA, RAC1, and cell division cycle 42 (CDC42). Inhibition of GGTase-I has been suggested as a strategy to treat cancer and a host of other diseases. Although several GGTase-I inhibitors (GGTIs) have been synthesized, they have very different properties, and the effects of GGTIs and GGTase-I deficiency are unclear. One concern is that inhibiting GGTase-I might lead to severe toxicity. In this study, we determined the effects of GGTase-I deficiency on cell viability and K-RAS-induced cancer development in mice. Inactivating the gene for the critical beta subunit of GGTase-I eliminated GGTase-I activity, disrupted the actin cytoskeleton, reduced cell migration, and blocked the proliferation of fibroblasts expressing oncogenic K-RAS. Moreover, the absence of GGTase-I activity reduced lung tumor formation, eliminated myeloproliferative phenotypes, and increased survival of mice in which expression of oncogenic K-RAS was switched on in lung cells and myeloid cells. Interestingly, several cell types remained viable in the absence of GGTase-I, and myelopoiesis appeared to function normally. These findings suggest that inhibiting GGTase-I may be a useful strategy to treat K-RAS-induced malignancies.
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| 7. |
- Yan, G., et al.
(författare)
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Silencing RhoA inhibits migration and invasion through Wnt/β-catenin pathway and growth through cell cycle regulation in human tongue cancer
- 2014
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Ingår i: Acta Biochimica et Biophysica Sinica. - : China Science Publishing & Media Ltd.. - 1672-9145 .- 1745-7270. ; 46:8, s. 682-690
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Tidskriftsartikel (refereegranskat)abstract
- Ras homolog gene family member A (RhoA) has been identified as a critical regulator of tumor aggressive behavior. In this study, we assessed the role of RhoA in the mechanisms underlying growth, migration, and invasion of squamous cell carcinoma of tongue (TSCC). Stable RhoA knockdown of TSCC cell lines SCC-4 and CAL27 were achieved using Lentiviral transfection. The effects of RhoA depletion on cell migration, invasion, and cell proliferation were determined. The possible underlying mechanism of RhoA depletion on TSCC cell line was also evaluated by determining the expression of Galectin-3 (Gal-3), β-catenin, and matrix metalloproteinase-9 (MMP-9) in vivo. Meanwhile, the underlying mechanism of TSCC growth was studied by analysis of cyclin D1/2, p21 CIP1/WAF1, and p27Kip1 protein levels. Immunohistochemical assessments were performed to further prove the alteration of Gal-3 and β-catenin expression. We found that, in mice injected with human TSCC cells in the tongue, RhoA levels were higher in primary tumors and metastasized lymph nodes compared with those in the normal tissues. Silencing of RhoA significantly reduced the tumor growth, decreased the levels of Gal-3, β-catenin, MMP-9, and cyclin D1/2, and increased the levels of p21 CIP1/WAF1 and p27Kip1. In vitro, RhoA knockdown also led to inhibition of cell migration, invasion, and proliferation. Our data suggest that RhoA plays a significant role in TSCC progression by regulating cell migration and invasion through Wnt/β-catenin signaling pathway and cell proliferation through cell cycle regulation, respectively. RhoA might be a novel therapeutic target of TSCC. © 2014 The Author .
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| 8. |
- Akula, Murali K, et al.
(författare)
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Control of the innate immune response by the mevalonate pathway
- 2016
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Ingår i: Nature Immunology. - : Springer Science and Business Media LLC. - 1529-2908 .- 1529-2916. ; 17:8, s. 922-9
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Tidskriftsartikel (refereegranskat)abstract
- Deficiency in mevalonate kinase (MVK) causes systemic inflammation. However, the molecular mechanisms linking the mevalonate pathway to inflammation remain obscure. Geranylgeranyl pyrophosphate, a non-sterol intermediate of the mevalonate pathway, is the substrate for protein geranylgeranylation, a protein post-translational modification that is catalyzed by protein geranylgeranyl transferase I (GGTase I). Pyrin is an innate immune sensor that forms an active inflammasome in response to bacterial toxins. Mutations in MEFV (encoding human PYRIN) result in autoinflammatory familial Mediterranean fever syndrome. We found that protein geranylgeranylation enabled Toll-like receptor (TLR)-induced activation of phosphatidylinositol-3-OH kinase (PI(3)K) by promoting the interaction between the small GTPase Kras and the PI(3)K catalytic subunit p110 delta. Macrophages that were deficient in GGTase I or p110 delta exhibited constitutive release of interleukin 1 beta that was dependent on MEFV but independent of the NLRP3, AIM2 and NLRC4 inflammasomes. In the absence of protein geranylgeranylation, compromised PI(3)K activity allows an unchecked TLR-induced inflammatory responses and constitutive activation of the Pyrin inflammasome.
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| 9. |
- Akula, Murali K, et al.
(författare)
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Protein prenylation restrains innate immunity by inhibiting Rac1 effector interactions
- 2019
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Rho family proteins are prenylated by geranylgeranyltransferase type I (GGTase-I), which normally target proteins to membranes for GTP-loading. However, conditional deletion of GGIase-I in mouse macrophages increases GTP-loading of Rho proteins, leading to enhanced inflammatory responses and severe rheumatoid arthritis. Here we show that heterozygous deletion of the Rho family gene Rac1, but not Rhoa and Cdc42, reverses inflammation and arthritis in GGTase-I-deficient mice. Non-prenylated Rac1 has a high affinity for the adaptor protein Ras GTPase-activating-like protein 1 (Iqgap1), which facilitates both GTP exchange and ubiquitination-mediated degradation of Rac1. Consistently, inactivating lagapl normalizes Rac1 GTP-loading, and reduces inflammation and arthritis in GGTase-I-deficient mice, as well as prevents statins from increasing Rac1 GTP-loading and cytokine production in macrophages. We conclude that blocking prenylation stimulates Rac1 effector interactions and unleashes proinflammatory signaling. Our results thus suggest that prenylation normally restrains innate immune responses by preventing Rac1 effector interactions.
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| 10. |
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