| 1. |
- Andersson, Stefanie, 1989, et al.
(författare)
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Genome-wide imaging screen uncovers molecular determinants of arsenite-induced protein aggregation and toxicity
- 2021
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Ingår i: Journal of Cell Science. - : The Company of Biologists. - 0021-9533 .- 1477-9137. ; 134:11
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Tidskriftsartikel (refereegranskat)abstract
- The toxic metalloid arsenic causes widespread misfolding and aggregation of cellular proteins. How these protein aggregates are formed in vivo, the mechanisms by which they affect cells and how cells prevent their accumulation is not fully understood. To find components involved in these processes, we performed a genome-wide imaging screen and identified Saccharomyces cerevisiae deletion mutants with either enhanced or reduced protein aggregation levels during arsenite exposure. We show that many of the identified factors are crucial to safeguard protein homeostasis (proteostasis) and to protect cells against arsenite toxicity. The hits were enriched for various functions including protein biosynthesis and transcription, and dedicated follow-up experiments highlight the importance of accurate transcriptional and translational control for mitigating protein aggregation and toxicity during arsenite stress. Some of the hits are associated with pathological conditions, suggesting that arsenite-induced protein aggregation may affect disease processes. The broad network of cellular systems that impinge on proteostasis during arsenic stress identified in this current study provides a valuable resource and a framework for further elucidation of the mechanistic details of metalloid toxicity and pathogenesis. This article has an associated First Person interview with the first authors of the paper.
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| 2. |
- Biquand, A, et al.
(författare)
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Titin M-line insertion sequence 7 is required for proper cardiac function in mice
- 2021
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Ingår i: Journal of cell science. - : The Company of Biologists. - 1477-9137 .- 0021-9533. ; 134:18
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Tidskriftsartikel (refereegranskat)abstract
- Titin is a giant sarcomeric protein that is involved in a large number of functions, with a primary role in skeletal and cardiac sarcomere organization and stiffness. The titin gene (TTN) is subject to various alternative splicing events, but in the region that is present at the M-line, the only exon that can be spliced out is Mex5, which encodes for the insertion sequence 7 (is7). Interestingly, in the heart, the majority of titin isoforms are Mex5+, suggesting a cardiac role for is7. Here, we performed comprehensive functional, histological, transcriptomic, microscopic and molecular analyses of a mouse model lacking the Ttn Mex5 exon (ΔMex5), and revealed that the absence of the is7 is causative for dilated cardiomyopathy. ΔMex5 mice showed altered cardiac function accompanied by increased fibrosis and ultrastructural alterations. Abnormal expression of excitation–contraction coupling proteins was also observed. The results reported here confirm the importance of the C-terminal region of titin in cardiac function and are the first to suggest a possible relationship between the is7 and excitation–contraction coupling. Finally, these findings give important insights for the identification of new targets in the treatment of titinopathies.
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| 3. |
- Bullock, Simon L., et al.
(författare)
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Meeting report - Nuclear and cytoplasmic molecular machines at work
- 2020
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Ingår i: Journal of Cell Science. - : The Company of Biologists. - 0021-9533 .- 1477-9137. ; 133:7
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Tidskriftsartikel (refereegranskat)abstract
- This report summarizes an international conference on molecular machines convened at New York University, Abu Dhabi by Piergiorgio Percipalle, George Shubeita and Serdal Kirmizialtin. The meeting was conceived around the epistemological question of what do we understand, or not understand (if we have open minds), about the degree to which cells operate by the individual actions of single enzymes or non-catalytic protein effectors, versus combinations of these in which their heterotypic association creates an entity that is more finely tuned and efficient - a machine. This theme was explored through a vivid series of talks, summarizing the latest findings on macromolecular complexes that operate in the nucleus or cytoplasm.
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| 4. |
- Burrinha, Tatiana, et al.
(författare)
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Up-regulation of APP endocytosis by neuronal aging drives amyloid dependent-synapse loss
- 2021
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Ingår i: Journal of Cell Science. - : The Company of Biologists. - 0021-9533 .- 1477-9137. ; 134:9
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Tidskriftsartikel (refereegranskat)abstract
- Neuronal aging increases the risk of late-onset Alzheimer's disease. During normal aging, synapses decline, and β-amyloid (Aβ) accumulates intraneuronally. However, little is known about the underlying cell biological mechanisms. We studied normal neuronal aging using normal aged brain and aged mouse primary neurons that accumulate lysosomal lipofuscin and show synapse loss. We identify the up-regulation of amyloid precursor protein (APP) endocytosis as a neuronal aging mechanism that potentiates APP processing and Aβ production in vitro and in vivo. The increased APP endocytosis may contribute to the observed early endosomes enlargement in the aged brain. Mechanistically, we show that clathrin-dependent APP endocytosis requires F-actin and that clathrin and endocytic F-actin increase with neuronal aging. Finally, Aβ production inhibition reverts synaptic decline in aged neurons while Aβ accumulation, promoted by endocytosis up-regulation in younger neurons, recapitulates aging-related synapse decline. Overall, we identify APP endocytosis up-regulation as a potential mechanism of neuronal aging and, thus, a novel target to prevent late-onset Alzheimer's disease.
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| 5. |
- Corkery, Dale, et al.
(författare)
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Vibrio cholerae cytotoxin MakA induces noncanonical autophagy resulting in the spatial inhibition of canonical autophagy
- 2021
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Ingår i: Journal of Cell Science. - : The Company of Biologists. - 0021-9533 .- 1477-9137. ; 134:5
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Tidskriftsartikel (refereegranskat)abstract
- Autophagy plays an essential role in the defense against manymicrobial pathogens as a regulator of both innate and adaptive immunity. Some pathogens have evolved sophisticated mechanisms that promote their ability to evade or subvert host autophagy. Here, we describe a novel mechanism of autophagy modulation mediated by the recently discovered Vibrio cholerae cytotoxin, motility-associatedkilling factor A (MakA). pH-dependent endocytosis of MakA by host cells resulted in the formation of a cholesterol-rich endolysosomal membrane aggregate in the perinuclear region. Aggregate formation induced the noncanonical autophagy pathway driving unconventional LC3 (herein referring to MAP1LC3B) lipidation on endolysosomal membranes. Subsequent sequestration of the ATG12-ATG5-ATG16L1 E3-like enzyme complex, required for LC3 lipidation at the membranous aggregate, resulted in an inhibition of both canonical autophagy and autophagy-related processes, including the unconventional secretion of interleukin-1β (IL-1β). These findings identify a novel mechanismof host autophagy modulation and immune modulation employed by V. cholerae during bacterial infection.
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| 6. |
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| 7. |
- Englund, JI, et al.
(författare)
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Laminin matrix adhesion regulates basal mammary epithelial cell identity
- 2022
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Ingår i: Journal of cell science. - : The Company of Biologists. - 1477-9137 .- 0021-9533. ; 135:23
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Tidskriftsartikel (refereegranskat)abstract
- Mammary epithelium is a bilayered ductal network composed of luminal and basal epithelial cells, which together drive the growth and functional differentiation of the gland. Basal mammary epithelial cells (MECs) exhibit remarkable plasticity and progenitor activity that facilitate epithelial expansion. However, their activity must be tightly regulated to restrict excess basal cell activity. Here, we show that adhesion of basal cells to laminin α5-containing basement membrane matrix, which is produced by luminal cells, presents such a control mechanism. Adhesion to laminin α5 directs basal cells towards a luminal cell fate, and thereby results in a marked decrease of basal MEC progenitor activity in vitro and in vivo. Mechanistically, these effects are mediated through β4-integrin and activation of p21 (encoded by CDKN1A). Thus, we demonstrate that laminin matrix adhesion is a key determinant of basal identity and essential to building and maintaining a functional multicellular epithelium.
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| 8. |
- Habicht, Juri, et al.
(författare)
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UNC-45A Breaks MT Lattice Independent of its Effect on Non-Muscle Myosin II
- 2020
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Ingår i: Journal of Cell Science. - : The Company of Biologists. - 0021-9533 .- 1477-9137.
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Tidskriftsartikel (refereegranskat)abstract
- In invertebrates, UNC-45 regulates myosin stability and functions. Vertebrates have two distinct isoforms of the protein: UNC-45B, expressed in muscle cells only and UNC-45A, expressed in all cells and implicated in regulating both Non-Muscle Myosin II (NMII)- and microtubule (MT)-associated functions. Here we show that both, in vitro and in cells, UNC-45A binds to the MT lattice leading to MT bending, breakage and depolymerization. Furthermore, we show that UNC-45A destabilizes MTs independent of its NMII C-terminal binding domain and even in presence of the NMII inhibitor blebbistatin. These findings identified UNC-45A as a novel type of MT-severing protein with a not mutually exclusive but rather dual role in regulating NMII activity and MT stability. Because many human diseases, from cancer to neurodegenerative diseases, are caused by or associated with deregulation of MT stability our findings have profound implications in both, the biology of MTs as well as the biology of human diseases and possible therapeutic implications for their treatment.
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| 9. |
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| 10. |
- Junghans, Victoria, et al.
(författare)
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Effects of a local auxiliary protein on the two-dimensional affinity of a TCR-peptide MHC interaction
- 2020
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Ingår i: Journal of Cell Science. - : The Company of Biologists Ltd.. - 0021-9533 .- 1477-9137. ; 133:15
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Tidskriftsartikel (refereegranskat)abstract
- The affinity of T-cell receptors (TCRs) for major histocompatibility complex molecules (MHCs) presenting cognate antigens likely determines whether T cells initiate immune responses, or not. There exist few measurements of two-dimensional (2D) TCR-MHC interactions, and the effect of auxiliary proteins on binding is unexplored. Here, Jurkat T-cells expressing the MHC molecule HLA-DQ8-glia-α1 and the ligand of an adhesion protein (rat CD2) were allowed to bind supported lipid bilayers (SLBs) presenting fluorescently-labelled L3-12 TCR and rat CD2, allowing measurements of binding unconfounded by cell signaling effects or co-receptor binding. The 2D Kd for L3-12 TCR binding to HLA-DQ8-glia-α1, 14±5 molecules/μm2, was only marginally influenced by including CD2 up to ∼200 bound molecules/μm2 but higher CD2 densities reduced the affinity up to 1.9-fold. Cell-SLB contact size increased steadily with ligand density without affecting binding for contacts up to ∼20% of total cell area but beyond this lamellipodia appeared, giving an apparent increase in bound receptors of up to 50%. Our findings show how parameters other than the specific protein-protein interaction can influence binding behavior at cell-cell contacts.
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