| 1. |
- Arruda, Lucas C. M., et al.
(författare)
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A novel CD34-specific T-cell engager efficiently depletes acute myeloid leukemia and leukemic stem cells in vitro and in vivo
- 2022
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Ingår i: Haematologica. - : Ferrata Storti Foundation (Haematologica). - 0390-6078 .- 1592-8721. ; 107:8, s. 1786-1795
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Tidskriftsartikel (refereegranskat)abstract
- Less than a third of patients with acute myeloid leukemia (AML) are cured by chemotherapy and/or hematopoietic stem cell transplantation, highlighting the need to develop more efficient drugs. The low efficacy of standard treatments is associated with inadequate depletion of CD34(+) blasts and leukemic stem cells, the latter a drug-resistant subpopulation of leukemia cells characterized by the CD34(+)CD38(-) phenotype. To target these drug-resistant primitive leukemic cells better, we have designed a CD34/CD3 bi-specific T-cell engager (BTE) and characterized its anti-leukemia potential in vitro, ex vivo and in vivo. Our results show that this CD34-specific BTE induces CD34-dependent T-cell activation and subsequent leukemia cell killing in a dose-dependent manner, further corroborated by enhanced T-cell-mediated killing at the singlecell level. Additionally, the BTE triggered efficient T-cell-mediated depletion of CD34(+) hematopoietic stem cells from peripheral blood stem cell grafts and CD34(+) blasts from AML patients. Using a humanized AML xenograft model, we confirmed that the CD34-specific BTE had in vivo efficacy by depleting CD34(+) blasts and leukemic stem cells without side effects. Taken together, these data demonstrate that the CD34-specific BTE has robust antitumor effects, supporting development of a novel treatment modality with the aim of improving outcomes of patients with AML and myelodysplastic syndromes.
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| 2. |
- Mim, Carsten, et al.
(författare)
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Structure versus function : Are new conformations of pannexin 1 yet to be resolved?
- 2021
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Ingår i: The Journal of General Physiology. - : Rockefeller University Press. - 0022-1295 .- 1540-7748. ; 153:5
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Tidskriftsartikel (refereegranskat)abstract
- Pannexin 1 (Panx1) plays a decisive role in multiple physiological and pathological settings, including oxygen delivery to tissues, mucociliary clearance in airways, sepsis, neuropathic pain, and epilepsy. It is widely accepted that Panx1 exerts its role in the context of purinergic signaling by providing a transmembrane pathway for ATP. However, under certain conditions, Panx1 can also act as a highly selective membrane channel for chloride ions without ATP permeability. A recent flurry of publications has provided structural information about the Panx1 channel. However, while these structures are consistent with a chloride selective channel, none show a conformation with strong support for the ATP release function of Panx1. In this Viewpoint, we critically assess the existing evidence for the function and structure of the Panx1 channel and conclude that the structure corresponding to the ATP permeation pathway is yet to be determined. We also list a set of additional topics needing attention and propose ways to attain the large-pore, ATP-permeable conformation of the Panx1 channel.
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| 3. |
- de Rivero Vaccari, J. P., et al.
(författare)
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Mechanism of action of IC 100, a humanized IgG4 monoclonal antibody targeting apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC)
- 2023
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Ingår i: Translational Research. - : Elsevier BV. - 1931-5244 .- 1878-1810. ; 251, s. 27-40
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Tidskriftsartikel (refereegranskat)abstract
- Inflammasomes are multiprotein complexes of the innate immune response that recognize a diverse range of intracellular sensors of infection or cell damage and recruit the adaptor protein apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) into an inflammasome signaling complex. The recruitment, polymerization and cross-linking of ASC is upstream of caspase-1 activation and interleukin-1β release. Here we provide evidence that IC 100, a humanized IgG4κ monoclonal antibody against ASC, is internalized into the cell and localizes with endosomes, while another part is recycled and redistributed out of the cell. IC 100 binds intracellular ASC and blocks interleukin-1β release in a human whole blood cell inflammasome assay. In vitro studies demonstrate that IC 100 interferes with ASC polymerization and assembly of ASC specks. In vivo bioluminescence imaging showed that IC 100 has broad tissue distribution, crosses the blood brain barrier, and readily penetrates the brain and spinal cord parenchyma. Confocal microscopy of fluorescent-labeled IC 100 revealed that IC 100 is rapidly taken up by macrophages via a mechanism utilizing the Fc region of IC 100. Coimmunoprecipitation experiments and confocal immunohistochemistry showed that IC 100 binds to ASC and to the atypical antibody receptor Tripartite motif-containing protein-21 (TRIM21). In A549 WT and TRIM21 KO cells treated with either IC 100 or IgG4κ isotype control, the levels of intracellular IC 100 were higher than in the IgG4κ-treated controls at 2 hours, 1 day and 3 days after administration, indicating that IC 100 escapes degradation by the proteasome. Lastly, electron microscopy studies demonstrate that IC 100 binds to ASC filaments and alters the architecture of ASC filaments. Thus, IC 100 readily penetrates a variety of cell types, and it binds to intracellular ASC, but it is not degraded by the TRIM21 antibody-dependent intracellular neutralization pathway.
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| 4. |
- Gowrisankaran, Sindhuja, et al.
(författare)
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Cells Control BIN1-Mediated Membrane Tubulation by Altering the Membrane Charge
- 2020
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Ingår i: Journal of Molecular Biology. - : ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD. - 0022-2836 .- 1089-8638. ; 432:4, s. 1235-1250
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Tidskriftsartikel (refereegranskat)abstract
- The Bridging integrator 1 (BIN1)/Amphiphysin/Rvs (BAR) protein family is an essential part of the cell's machinery to bend membranes. BIN1 is a muscle-enriched BAR protein with an established role in muscle development and skeletal myopathies. Here, we demonstrate that BIN1, on its own, is able to form complex interconnected tubular systems in vitro, reminiscent of t-tubule system in muscle cells. We further describe how BIN1's electrostatic interactions regulate membrane bending: the ratio of negatively charged lipids in the bilayer altered membrane bending and binding properties of BIN1 and so did the manipulation of BIN1's surface charge. We show that the electrostatically mediated BIN1 membrane binding depended on the membrane curvature-it was less affected in liposomes with high curvature. Curiously, BIN1 membrane binding and bending was diminished in cells where the membrane's charge was experimentally reduced. Membrane bending was also reduced in BIN1 mutants where negative or positive charges in the BAR domain have been eliminated. This phenotype, characteristic of BIN1 mutants linked to myopathies, was rescued when the membrane charge was made more negative. The latter findings also show that cells can control tubulation at their membranes by simply altering the membrane charge and through it, the recruitment of BAR proteins and their interaction partners (e.g. dynamin).
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| 5. |
- Kerr, A. G., et al.
(författare)
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The long noncoding RNA ADIPINT regulates human adipocyte metabolism via pyruvate carboxylase
- 2022
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- The pleiotropic function of long noncoding RNAs is well recognized, but their direct role in governing metabolic homeostasis is less understood. Here, we describe a human adipocyte-specific lncRNA, ADIPINT, that regulates pyruvate carboxylase, a pivotal enzyme in energy metabolism. We developed an approach, Targeted RNA-protein identification using Orthogonal Organic Phase Separation, which identifies that ADIPINT binds to pyruvate carboxylase and validated the interaction with electron microscopy. ADIPINT knockdown alters the interactome and decreases the abundance and enzymatic activity of pyruvate carboxylase in the mitochondria. Reduced ADIPINT or pyruvate carboxylase expression lowers adipocyte lipid synthesis, breakdown, and lipid content. In human white adipose tissue, ADIPINT expression is increased in obesity and linked to fat cell size, adipose insulin resistance, and pyruvate carboxylase activity. Thus, we identify ADIPINT as a regulator of lipid metabolism in human white adipocytes, which at least in part is mediated through its interaction with pyruvate carboxylase.
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| 6. |
- Sporny, Michael, et al.
(författare)
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Structural Evidence for an Octameric Ring Arrangement of SARM1
- 2019
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Ingår i: Journal of Molecular Biology. - : ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD. - 0022-2836 .- 1089-8638. ; 431:19, s. 3591-3605
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Tidskriftsartikel (refereegranskat)abstract
- SARM1 induces axonal degeneration in response to various insults and is therefore considered an attractive drug target for the treatment of neuro-degenerative diseases as well as for brain and spinal cord injuries. SARM1 activity depends on the integrity of the protein's SAM domains, as well as on the enzymatic conversion of NAD + to ADPR (ADP Ribose) products by the SARM1's TIR domain. Therefore, inhibition of either SAM or TIR functions may constitute an effective therapeutic strategy. However, there is currently no SARM1-directed therapeutic approach available because of an insufficient structural and mechanistic understanding of this protein. In this study, we found that SARM1 assembles into an octameric ring. This arrangement was not described before in other SAM proteins, but is reminiscent of the apoptosome and inflammasome well-known apoptotic ring-like oligomers. We show that both SARM1 and the isolated tandem SAM(1-2) domains form octamers in solution, and electron microscopy analysis reveals an octameric ring of SARM1. We determined the crystal structure of SAM(1-2) and found that it also forms a closed octameric ring in the crystal lattice. The SAM(1-2) ring interactions are mediated by complementing "lock and key" hydrophobic grooves and inserts and electrostatic charges between the neighboring protomers. We have mutated several interacting SAM1-2 interfaces and measured how these mutations affect SARM1 apoptotic activity in cultured cells, and in this way identified critical oligomerization sites that facilitate cell death. These results highlight the importance of oligomerization for SARM1 function and reveal critical epitopes for future targeted drug development. Elsevier Ltd. All rights reserved.
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