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- Bandaru, Sashidar
(författare)
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Filamin A in Cardiovascular Remodeling
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Filamin A (FLNA) is a large actin-binding cytoskeletal protein that stabilizes actin networks and integrates them with cell membranes. FLNA is therefore important for cell motility and organ development. We recently discovered that a C-terminal fragment of FLNA (FLNACT) can be cleaved off by calpain and stimulate angiogenesis by transporting transcription factors into the nucleus. However, little is known about the role of FLNA in cell types that participate in the pathogenesis of vascular diseases where angiogenesis typically plays an important role. In this thesis, we defined the impact of inactivating Flna in mouse vascular endothelial cells and macrophages on the pathogenesis of myocardial infarction (MI) and atherosclerosis, respectively—and made several exciting discoveries. In Study I, we induced MI by ligating the left descending coronary artery in wt control mice and mice lacking FLNA in endothelial cells. The Flna-knockout mice developed larger MI lesions than controls, and exhibited larger and thinner left ventricles, impaired cardiac function, elevated plasma levels of the cardiac damage biomarker NT-proBNP, and reduced plasma levels of the angiogenesis-promoting factor VEGF-A. Hearts from the Flna-knockout mice exhibited reduced capillary structures within infarcted regions; and cultured Flna-deficient endothelial cells showed impaired migration and tubular formation, along with reduced levels of the signaling molecules p-ERK and p-AKT and the small GTPase RAC1. In Study II, we first discovered that FLNA expression was higher in human carotid arteries with advanced atherosclerotic plaques than with intermediate plaques. We generated mice lacking FLNA in macrophages and found that their macrophages proliferated and migrated less compared with littermate controls. Moreover, Flna-deficient macrophages exhibited reduced levels of p-ERK and p-AKT, and reduced lipid uptake and increased cholesterol efflux. In two different mouse atherosclerosis models, the knockout of FLNA in macrophages markedly reduced lesion size and number of CD68-positive lesional macrophages. Interestingly, the calpain-cleaved FLNACT fragment interacted strongly with STAT3 in wt macrophages. Inhibiting FLNA cleavage with the calpain inhibitor calpeptin reduced nuclear p-STAT3 levels and subsequent IL-6 secretion in vitro; and reduced atherosclerotic lesions in vivo. We conclude that FLNA interacts with transcription factors and thereby regulates angiogenesis and inflammatory responses which are important events in the progression of MI and atherosclerosis. These findings identify FLNA as an important new mediator of cardiovascular remodeling and as a potential target for therapy.
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- Bandaru, Sashidar, et al.
(författare)
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Targeting filamin A reduces macrophage activity and atherosclerosis. : Filamin A in atherogenesis
- 2019
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Ingår i: Circulation. - 1524-4539. ; 140:1, s. 67-79
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Tidskriftsartikel (refereegranskat)abstract
- The actin-binding protein FLNA (filamin A) regulates signal transduction important for cell locomotion, but the role of macrophage-specific FLNA during atherogenesis has not been explored.We analyzed FLNA expression in human carotid atherosclerotic plaques by immunofluorescence. We also produced mice with Flna-deficient macrophages by breeding conditional Flna-knockout mice ( Flna o/fl) with mice expressing Cre from the macrophage-specific lysosome M promoter ( LC). Atherosclerosis in vivo was studied by transplanting bone marrow from male Flna o/fl/ LC mice to atherogenic low-density lipoprotein receptor-deficient ( Ldlr-/-) mice; and by infecting Flna o/fl and Flna o/fl/ LC mice with AdPCSK9 (adenoviral vector overexpressing proprotein convertase subtilisin/kexin type 9). Furthermore, C57BL/6 mice were infected with AdPCSK9 and then treated with the calpain inhibitor calpeptin to inhibit FLNA cleavage.We found that macrophage FLNA expression was higher in advanced than in intermediate human atherosclerotic plaques. Flna o/fl/ LC macrophages proliferated and migrated less than controls; expressed lower levels of phosphorylated AKT and ERK1/2; exhibited reduced foam cell formation and lipid uptake; and excreted more lipids. The deficiency of Flna in macrophages markedly reduced the size of aortic atherosclerotic plaques in both Ldlr-/-BMT: Flnao/fl/LC and AdPCSK9-infected Flna o/fl/ LC mice. Intima/media ratios and numbers of CD68-positive macrophages in atherosclerotic plaques were lower in Flna-deficient mice than in control mice. Moreover, we found that STAT3 interacts with a calpain-cleaved carboxyl-terminal fragment of FLNA. Inhibiting calpain-mediated FLNA cleavage with calpeptin in macrophages reduced nuclear levels of phosphorylated STAT3, interleukin 6 secretion, foam cell formation, and lipid uptake. Finally, calpeptin treatment reduced the size of atherosclerotic plaques in C57BL/6 mice infected with AdPCSK9.Genetic inactivation of Flna and chemical inhibition of calpain-dependent cleavage of FLNA impaired macrophage signaling and function, and reduced atherosclerosis in mice, suggesting that drugs targeting FLNA may be useful in the treatment of atherosclerosis.
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- Chaudhari, Aditi, et al.
(författare)
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p110alpha hot spot mutations E545K and H1047R exert metabolic reprogramming independently of p110alpha kinase activity : Kinase-independent signaling of p110 alpha mutants
- 2015
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Ingår i: Molecular and Cellular Biology. - 0270-7306 .- 1098-5549. ; 35:19, s. 3258-3273
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Tidskriftsartikel (refereegranskat)abstract
- The phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) catalytic subunit p110α is the most frequently mutated kinase in human cancer, and the hot spot mutations E542K, E545K, and H1047R are the most common mutations in p110α. Very little is known about the metabolic consequences of the hot spot mutations of p110α in vivo. In this study, we used adenoviral gene transfer in mice to investigate the effects of the E545K and H1047R mutations on hepatic and whole-body glucose metabolism. We show that hepatic expression of these hot spot mutations results in rapid hepatic steatosis, paradoxically accompanied by increased glucose tolerance, and marked glycogen accumulation. In contrast, wild-type p110α expression does not lead to hepatic accumulation of lipids or glycogen despite similar degrees of upregulated glycolysis and expression of lipogenic genes. The reprogrammed metabolism of the E545K and H1047R p110α mutants was surprisingly not dependent on altered p110α lipid kinase activity.
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- Mondal, Tanmoy, 1981, et al.
(författare)
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Sense-antisense lncRNA pair encoded by locus 6p22.3 determines neuroblastoma susceptibility via the USP36-CHD7-SOX9 regulatory axis
- 2018
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Ingår i: Cancer Cell. - : Elsevier BV. - 1535-6108 .- 1878-3686. ; 33:3
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Tidskriftsartikel (refereegranskat)abstract
- Trait-associated loci often map to genomic regions encoding long noncoding RNAs (lncRNAs), but the role of these lncRNAs in disease etiology is largely unexplored. We show that a pair of sense/antisense lncRNA (6p22lncRNAs) encoded by CASC15 and NBAT1 located at the neuroblastoma (NB) risk-associated 6p22.3 locus are tumor suppressors and show reduced expression in high-risk NBs. Loss of functional synergy between 6p22lncRNAs results in an undifferentiated state that is maintained by a gene-regulatory network, including SOX9 located on 17q, a region frequently gained in NB. 6p22lncRNAs regulate SOX9 expression by controlling CHD7 stability via modulating the cellular localization of USP36, encoded by another 17q gene. This regulatory nexus between 6p22.3 and 17q regions may lead to potential NB treatment strategies.
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- Salimi, Reza, et al.
(författare)
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Blocking the cleavage of filamin A by calpain inhibitor decreases tumor cell growth
- 2018
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Ingår i: Anticancer Research. - : Anticancer Research USA Inc.. - 0250-7005 .- 1791-7530. ; 38:4, s. 2079-2085
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Tidskriftsartikel (refereegranskat)abstract
- Filamin A (FLNA) is the most abundant and widely expressed isoform of filamin in human tissues. It is cleaved by calpain at the hinge 1 and 2 domains, producing a 90-kDa carboxyl-terminal fragment (FLNACT). Recently, it has been shown that FLNACTmediates cell signaling and transports transcription factors into the cell nucleus. However, the significance of cleavage of FLNA by calpain has not been studied in cancer cell growth. Calpeptin is a chemical inhibitor of both calpain 1 and 2 that cleaves FLNA. In this study, we questioned if inhibiting calpain using calpeptin would decrease tumor cell proliferation, migration, invasion, and colony formation.Human melanoma (A7), prostate cancer (PC3), mouse fibrosarcoma (T241) and endothelial (MS1) cells were assayed for proliferation, migration, invasion and colony formation after treatment with calpeptin. Cell lysates were immunoblotted for FLNA and FLNACTResults: Calpeptin treatment of these cells resulted in a decreased production of FLNACTCalpeptin-treated human and mouse tumor cells displayed impaired proliferation, migration, and colony formation.These data suggest that the cleavage of FLNA by calpain is an important cellular event in the regulation of tumor cell growth.
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