| 1. |
- Cansby, Emmelie, 1984, et al.
(författare)
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Silencing of STE20-type kinase STK25 in human aortic endothelial and smooth muscle cells is atheroprotective
- 2022
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 5, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies highlight the importance of lipotoxic damage in aortic cells as the major pathogenetic contributor to atherosclerotic disease. Since the STE20-type kinase STK25 has been shown to exacerbate ectopic lipid storage and associated cell injury in several metabolic organs, we here investigate its role in the main cell types of vasculature. We depleted STK25 by small interfering RNA in human aortic endothelial and smooth muscle cells exposed to oleic acid and oxidized LDL. In both cell types, the silencing of STK25 reduces lipid accumulation and suppresses activation of inflammatory and fibrotic pathways as well as lowering oxidative and endoplasmic reticulum stress. Notably, in smooth muscle cells, STK25 inactivation hinders the shift from a contractile to a synthetic phenotype. Together, we provide several lines of evidence that antagonizing STK25 signaling in human aortic endothelial and smooth muscle cells is atheroprotective, highlighting this kinase as a new potential therapeutic target for atherosclerotic disease.
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| 2. |
- Larsson Berglund, Lisa, et al.
(författare)
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Differential effects of soluble and aggregating polyQ proteins on cytotoxicity and type-1 myosin-dependent endocytosis in yeast
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Huntington's disease develops when the polyglutamine (polyQ) repeat in the Huntingtin (Htt) protein is expanded to over 35 glutamines rendering it aggregation-prone. Here, using Htt exon-1 as a polyQ model protein in a genome-wide screen in yeast, we show that the normal and soluble Htt exon-1 is toxic in cells with defects in type-1 myosin-dependent endocytosis. The toxicity of Htt is linked to physical interactions with type-1 myosins, which occur via the Htt proline-rich region, leading to a reduction in actin patch polarization and clathrin-dependent endocytosis. An expansion of the polyQ stretch from 25 to 103 glutamines, which causes Htt aggregation, alleviated Htt toxicity in cells lacking Myo5 or other components involved in early endocytosis. The data suggest that the proline-rich stretch of Htt interacts with type-1 myosin/clathrin-dependent processes and demonstrate that a reduction in the activity of such processes may result in a positive selection for polyQ expansions.
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| 3. |
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| 4. |
- Liu, Beidong, 1972, et al.
(författare)
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The Polarisome Is Required for Segregation and Retrograde Transport of Protein Aggregates
- 2010
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Ingår i: Cell. - 0092-8674. ; 140:2, s. 257-267
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Tidskriftsartikel (refereegranskat)abstract
- The paradigm sirtuin, Sir2p, of budding yeast is required for establishing cellular age asymmetry, which includes the retention of damaged and aggregated proteins in mother cells. By establishing the global genetic interaction network of SIR2 we identified the polarisome, the formin Bni1p, and myosin motor protein Myo2p as essential components of the machinery segregating protein aggregates during mitotic cytokinesis. Moreover, we found that daughter cells can clear themselves of damage by a polarisome- and tropomyosin-dependent polarized flow of aggregates into the mother cell compartment. The role of Sir2p in cytoskeletal functions and polarity is linked to the CCT chaperonin in sir2Δ cells being compromised in folding actin. We discuss the findings in view of recent models hypothesizing that polarity may have evolved to avoid clonal senescence by establishing an aging (soma-like) and rejuvenated (germ-like) lineage.
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| 5. |
- Song, J., et al.
(författare)
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Essential Genetic Interactors of SIR2 Required for Spatial Sequestration and Asymmetrical Inheritance of Protein Aggregates
- 2014
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Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 10:7
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Tidskriftsartikel (refereegranskat)abstract
- Sir2 is a central regulator of yeast aging and its deficiency increases daughter cell inheritance of stress-and aging-induced misfolded proteins deposited in aggregates and inclusion bodies. Here, by quantifying traits predicted to affect aggregate inheritance in a passive manner, we found that a passive diffusion model cannot explain Sir2-dependent failures in mother-biased segregation of either the small aggregates formed by the misfolded Huntingtin, Htt103Q, disease protein or heat-induced Hsp104-associated aggregates. Instead, we found that the genetic interaction network of SIR2 comprises specific essential genes required for mother-biased segregation including those encoding components of the actin cytoskeleton, the actin-associated myosin V motor protein Myo2, and the actin organization protein calmodulin, Cmd1. Co-staining with Hsp104-GFP demonstrated that misfolded Htt103Q is sequestered into small aggregates, akin to stress foci formed upon heat stress, that fail to coalesce into inclusion bodies. Importantly, these Htt103Q foci, as well as the ATPase-defective Hsp104(Y662A)-associated structures previously shown to be stable stress foci, co-localized with Cmd1 and Myo2-enriched structures and super-resolution 3-D microscopy demonstrated that they are associated with actin cables. Moreover, we found that Hsp42 is required for formation of heat-induced Hsp104(Y662A) foci but not Htt103Q foci suggesting that the routes employed for foci formation are not identical. In addition to genes involved in actin-dependent processes, SIR2-interactors required for asymmetrical inheritance of Htt103Q and heat-induced aggregates encode essential sec genes involved in ER-to-Golgi trafficking/ER homeostasis.
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| 6. |
- Brackley, Karen I., 1982, et al.
(författare)
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Activities of the chaperonin containing TCP-1 (CCT): implications for cell cycle progression and cytoskeletal organisation.
- 2009
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Ingår i: Cell Stress and Chaperones. - : Springer Science and Business Media LLC. - 1355-8145 .- 1466-1268. ; 14:1, s. 23-31
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Forskningsöversikt (refereegranskat)abstract
- The chaperonin containing TCP-1 (CCT) is required for the production of native actin and tubulin and numerous other proteins, several of which are involved in cell cycle progression. The mechanistic details of how CCT acts upon its folding substrates are intriguing: whilst actin and tubulin bind in a sequence-specific manner, it is possible that some proteins could use CCT as a more general binding interface. Therefore, how CCT accommodates the folding requirements of its substrates, some of which are produced in a cell cycle-specific manner, is of great interest. The reliance of folding substrates upon CCT for the adoption of their native structures results in CCT activity having far-reaching implications for a vast array of cellular processes. For example, the dependency of the major cytoskeletal proteins actin and tubulin upon CCT results in CCT activity being linked to any cellular process that depends on the integrity of the microfilament and microtubule-based cytoskeletal systems.
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| 7. |
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| 8. |
- Brackley, Karen I., 1982, et al.
(författare)
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Subunits of the chaperonin CCT interact with F-actin and influence cell shape and cytoskeletal assembly
- 2010
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Ingår i: Experimental Cell Research. - 0014-4827. ; 316:4, s. 543-553
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Tidskriftsartikel (refereegranskat)abstract
- The integrity of the cytoskeleton is closely linked to the oligomeric chaperonin containing TCP-1 (CCT) via the folding requirements of actin and tubulin, but the role of CCT in cytoskeletal organization remains unclear. We address this issue by analyzing the effects of targeting CCT subunits via siRNA and assessing their location/assembly state in cultured mammalian cells. Reducing levels of individual CCT subunits implicates CCTepsilon in influencing cell shape and reduced levels of this subunit limit the cells' ability to recover from microfilament depolymerization. Conversely, cells displayed enhanced microtubule regrowth when CCT subunit levels were altered by siRNA. Some CCT subunits co-localize with F-actin, whilst all are predominantly monomeric in extracts enriched for the cytoskeleton. This provides compelling evidence that some CCT subunits as monomers can influence cytoskeletal organization/polymerization. Therefore the activity of CCT may well extend beyond the folding of newly synthesized polypeptides, representing a novel function for CCT subunits distinct from their role in the CCT oligomer.
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| 9. |
- Cuéllar, J., et al.
(författare)
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The Molecular Chaperone CCT Sequesters Gelsolin and Protects it from Cleavage by Caspase-3: CCT-Gelsolin interaction may affect actin dynamics
- 2022
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836. ; 434:5
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Tidskriftsartikel (refereegranskat)abstract
- The actin filament severing and capping protein gelsolin plays an important role in modulation of actin filament dynamics by influencing the number of actin filament ends. During apoptosis, gelsolin becomes constitutively active due to cleavage by caspase-3. In non-apoptotic cells gelsolin is activated by the binding of Ca2+. This activated form of gelsolin binds to, but is not a folding substrate of the molecular chaperone CCT/TRiC. Here we demonstrate that in vitro, gelsolin is protected from cleavage by caspase-3 in the presence of CCT. Cryoelectron microscopy and single particle 3D reconstruction of the CCT:gelsolin complex reveals that gelsolin is located in the interior of the chaperonin cavity, with a placement distinct from that of the obligate CCT folding substrates actin and tubulin. In cultured mouse melanoma B16F1 cells, gelsolin co-localises with CCT upon stimulation of actin dynamics at peripheral regions during lamellipodia formation. These data indicate that localised sequestration of gelsolin by CCT may provide spatial control of actin filament dynamics. © 2021 The Authors
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| 10. |
- Echbarthi, Meriem, et al.
(författare)
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Interactions between monomeric CCTS and p150(Glued): A novel function for CCTS at the cell periphery distinct from the protein folding activity of the molecular chaperone CCT
- 2018
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Ingår i: Experimental Cell Research. - : Elsevier BV. - 0014-4827. ; 370:1, s. 137-149
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Tidskriftsartikel (refereegranskat)abstract
- Chaperonin containing tailless complex polypeptide 1 (CCT) is a molecular chaperone consisting of eight distinct protein subunits, that when oligomeric is essential for the folding of newly synthesized tubulin and actin. In addition to folding, CCT activity includes functions of individual subunits in their monomeric form. For example, when CCTS monomer levels are increased in cultured mammalian cells, numerous cell surface protrusions are formed from retraction fibres, indicating that an underlying function for the CCTS monomer exists. Here, using a yeast two-hybrid screen we identify the dynactin complex component p150Glued as a binding partner for CCT8 and show by siRNA depletion that this interaction is required for the formation of CCT8-induced cell surface protrusions. Intact microtubules are necessary for the formation of the protrusions, consistent with microtubule minus end transport driving the retraction fibre formation and depletion of either p150Glued or the dynactin complex-associated transmembrane protein dynAP prevents the previously observed localization of GFP-CCT8 to the plasma membrane. Wound healing assays reveal that CCTS monomer levels influence directional cell migration and together our observations demonstrate that in addition to the folding activity of CCT in its oligomer form, a monomeric subunit is associated with events that involve the assembled cytoskeleton.
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