| 1. |
- Haastert-Talini, Kirsten, et al.
(författare)
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Chitosan tubes of varying degrees of acetylation for bridging peripheral nerve defects
- 2013
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Ingår i: Biomaterials. - : Elsevier BV. - 1878-5905 .- 0142-9612. ; 34:38, s. 9886-9904
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Tidskriftsartikel (refereegranskat)abstract
- Biosynthetic nerve grafts are desired as alternative to autologous nerve grafts in peripheral nerve reconstruction. Artificial nerve conduits still have their limitations and are not widely accepted in the clinical setting. Here we report an analysis of fine-tuned chitosan tubes used to reconstruct 10 mm nerve defects in the adult rat. The chitosan tubes displayed low, medium and high degrees of acetylation (DAI: similar to 2%, DA: similar to 5%, DAIII: similar to 20%) and therefore different degradability and microenvironments for the regenerating nerve tissue. Short and long term investigations were performed demonstrating that the chitosan tubes allowed functional and morphological nerve regeneration similar to autologous nerve grafts. Irrespective of the DA growth factor regulation demonstrated to be the same as in controls. Analyses of stereological parameters as well as the immunological tissue response at the implantation site and in the regenerated nerves, revealed that DAI and DAIII chitosan tubes displayed some limitations in the support of axonal regeneration and a high speed of degradation accompanied with low mechanical stability, respectively. The chitosan tubes combine several pre-requisites for a clinical acceptance and DAII chitosan tubes have to be judged as the most supportive for peripheral nerve regeneration. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.
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| 2. |
- Hill, Sandra Malmgren, 1987, et al.
(författare)
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VCP/p97 regulates Beclin-1-dependent autophagy initiation
- 2021
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Ingår i: Nature Chemical Biology. - : Springer Science and Business Media LLC. - 1552-4450 .- 1552-4469. ; 17, s. 448-455
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Tidskriftsartikel (refereegranskat)abstract
- Autophagy is an essential cellular process that removes harmful protein species, and autophagy upregulation may be able to protect against neurodegeneration and various pathogens. Here, we have identified the essential protein VCP/p97 (VCP, valosin-containing protein) as a novel regulator of autophagosome biogenesis, where VCP regulates autophagy induction in two ways, both dependent on Beclin-1. Utilizing small-molecule inhibitors of VCP ATPase activity, we show that VCP stabilizes Beclin-1 levels by promoting the deubiquitinase activity of ataxin-3 towards Beclin-1. VCP also regulates the assembly and activity of the Beclin-1-containing phosphatidylinositol-3-kinase (PI3K) complex I, thus regulating the production of PI(3)P, a key signaling lipid responsible for the recruitment of downstream autophagy factors. A decreased level of VCP, or inhibition of its ATPase activity, impairs starvation-induced production of PI(3)P and limits downstream recruitment of WIPI2, ATG16L and LC3, thereby decreasing autophagosome formation, illustrating an important role for VCP in early autophagy initiation.
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| 3. |
- Meyer, Cora, et al.
(författare)
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Chitosan-film enhanced chitosan nerve guides for long-distance regeneration of peripheral nerves.
- 2016
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Ingår i: Biomaterials. - : Elsevier BV. - 1878-5905 .- 0142-9612. ; 76, s. 33-51
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Tidskriftsartikel (refereegranskat)abstract
- Biosynthetic nerve grafts are developed in order to complement or replace autologous nerve grafts for peripheral nerve reconstruction. Artificial nerve guides currently approved for clinical use are not widely applied in reconstructive surgery as they still have limitations especially when it comes to critical distance repair. Here we report a comprehensive analysis of fine-tuned chitosan nerve guides (CNGs) enhanced by introduction of a longitudinal chitosan film to reconstruct critical length 15 mm sciatic nerve defects in adult healthy Wistar or diabetic Goto-Kakizaki rats. Short and long term investigations demonstrated that the CNGs enhanced by the guiding structure of the introduced chitosan film significantly improved functional and morphological results of nerve regeneration in comparison to simple hollow CNGs. Importantly, this was detectable both in healthy and in diabetic rats (short term) and the regeneration outcome almost reached the outcome after autologous nerve grafting (long term). Hollow CNGs provide properties likely leading to a wider clinical acceptance than other artificial nerve guides and their performance can be increased by simple introduction of a chitosan film with the same advantageous properties. Therefore, the chitosan film enhanced CNGs represent a new generation medical device for peripheral nerve reconstruction.
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| 4. |
- Wrobel, L., et al.
(författare)
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Compounds activating VCP D1 ATPase enhance both autophagic and proteasomal neurotoxic protein clearance
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Enhancing the removal of aggregate-prone toxic proteins is a rational therapeutic strategy for a number of neurodegenerative diseases, especially Huntington's disease and various spinocerebellar ataxias. Ideally, such approaches should preferentially clear the mutant/misfolded species, while having minimal impact on the stability of wild-type/normally-folded proteins. Furthermore, activation of both ubiquitin-proteasome and autophagy-lysosome routes may be advantageous, as this would allow effective clearance of both monomeric and oligomeric species, the latter which are inaccessible to the proteasome. Here we find that compounds that activate the D1 ATPase activity of VCP/p97 fulfill these requirements. Such effects are seen with small molecule VCP activators like SMER28, which activate autophagosome biogenesis by enhancing interactions of PI3K complex components to increase PI(3)P production, and also accelerate VCP-dependent proteasomal clearance of such substrates. Thus, this mode of VCP activation may be a very attractive target for many neurodegenerative diseases. Several neurodegenerative diseases are characterized by the aggregation of cytoplasmic proteins. Here, the authors demonstrate that the small molecule SMER28 activates VCP, which enhances both autophagic and proteasomal clearance of aggregate-prone proteins.
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| 5. |
- Wrobel, L., et al.
(författare)
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SMER28 binding to VCP/p97 enhances both autophagic and proteasomal neurotoxic protein clearance
- 2023
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8627 .- 1554-8635. ; 19:4, s. 1348-1350
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Tidskriftsartikel (refereegranskat)abstract
- The ability to maintain a functional proteome by clearing damaged or misfolded proteins is critical for cell survival, and aggregate-prone proteins accumulate in many neurodegenerative diseases, such as Huntington, Alzheimer, and Parkinson diseases. The removal of such proteins is mainly mediated by the ubiquitin–proteasome system and autophagy, and the activity of these systems declines in disease or with age. We recently found that targeting VCP/p97 with compounds like SMER28 enhances macroautophagy/autophagy flux mediated by the increased activity of the PtdIns3K complex I. Additionally, we found that SMER28 binding to VCP stimulates aggregate-prone protein clearance via the ubiquitin–proteasome system. This concurrent action of SMER28 on both degradation pathways resulted in the selective decrease in disease-causing proteins but not their wild-type counterparts. These results reveal a promising mode of VCP activation to counteract the toxicity caused by aggregate-prone proteins. © 2022 Informa UK Limited, trading as Taylor & Francis Group.
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| 6. |
- Wrobel, L., et al.
(författare)
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VCP/p97 modulates PtdIns3P production and autophagy initiation
- 2021
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8627 .- 1554-8635. ; 17:4, s. 1052-1053
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Tidskriftsartikel (refereegranskat)abstract
- VCP/p97 is an essential multifunctional protein implicated in a plethora of intracellular quality control systems, and abnormal function of VCP is the underlying cause of several neurodegenerative disorders. We reported that VCP regulates the levels of the macroautophagy/autophagy-inducing lipid phosphatidylinositol-3-phosphate (PtdIns3P) by modulating the activity of the BECN1 (beclin 1)-containing phosphatidylinositol 3-kinase (PtdIns3K) complex. VCP stimulates the deubiquitinase activity of ATXN3 (ataxin 3) to stabilize BECN1 protein levels and also interacts with and promotes the assembly and kinase activity of the PtdIns3K complex. Acute inhibition of VCP activity impairs autophagy induction, demonstrated by a diminished PtdIns3P production and decreased recruitment of early autophagy markers WIPI2 and ATG16L1. Thus, VCP promotes autophagosome biogenesis, in addition to its previously described role in autophagosome maturation.
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