| 1. |
- Dodda, Jagan Mohan, et al.
(författare)
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Bioresorbable films of polycaprolactone blended with poly(lactic acid) or poly(lactic-co-glycolic acid)
- 2023
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier. - 0141-8130 .- 1879-0003. ; 248
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Tidskriftsartikel (refereegranskat)abstract
- Recent complications on the use of polypropylene meshes for hernia repair has led to the development of meshes or films, which were based on resorbable polymers such as polycaprolactone (PCL), polylactic acid (PLA) and poly(lactic-co-glycolic acid) (PLGA). These materials are able to create suitable bioactive environment for the growth and development of cells. In this research, we mainly focused on the relations among structure, mechanical performance and biocompatiblity of PCL/PLA and PCL/PLGA and blends prepared by solution casting. The films were characterized regarding the chemical structure, morphology, physicochemical properties, cytotoxicity, biocompatibility and cell growth. All the films showed high tensile strength ranging from 9.5 to 11.8 MPa. SAXS showed that the lamellar stack structure typical for PCL was present even in the blend films while the morphological parameters of the stacks varied slightly with the content of PLGA or PLA in the blends. WAXS indicated preferential orientation of crystallites (and thus, also the lamellar stacks) in the blend films. In vitro studies revealed that PCL/PLGA films displayed better cell adhesion, spreading and proliferation than PCL/PLA and PCL films. Further the effect of blending on the degradation was investigated, to understand the significant variable within the process that could provide further control of cell adhesion. The results showed that the investigated blend films are promising materials for biomedical applications.
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| 2. |
- Hoernke, Maria, et al.
(författare)
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EHD2 restrains dynamics of caveolae by an ATP-dependent, membrane-bound, open conformation
- 2017
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 114:22
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Tidskriftsartikel (refereegranskat)abstract
- The EH-domain-containing protein 2 (EHD2) is a dynamin-related ATPase that confines caveolae to the cell surface by restricting the scission and subsequent endocytosis of these membrane pits. For this, EHD2 is thought to first bind to the membrane, then to oligomerize, and finally to detach, in a stringently regulated mechanistic cycle. It is still unclear how ATP is used in this process and whether membrane binding is coupled to conformational changes in the protein. Here, we show that the regulatory N-terminal residues and the EH domain keep the EHD2 dimer in an autoinhibited conformation in solution. By significantly advancing the use of infrared reflection-absorption spectroscopy, we demonstrate that EHD2 adopts an open conformation by tilting the helical domains upon membrane binding. We show that ATP binding enables partial insertion of EHD2 into the membrane, where G-domain-mediated oligomerization occurs. ATP hydrolysis is related to detachment of EHD2 from the membrane. Finally, we demonstrate that the regulation of EHD2 oligomerization in a membrane-bound state is crucial to restrict caveolae dynamics in cells.
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| 3. |
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| 4. |
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| 5. |
- Liu, Kang-Cheng, et al.
(författare)
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Membrane insertion mechanism of the caveola coat protein Cavin1
- 2022
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 119:25
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Tidskriftsartikel (refereegranskat)abstract
- Caveolae are small plasma membrane invaginations, important for control of membrane tension, signaling cascades, and lipid sorting. The caveola coat protein Cavin1 is essential for shaping such high curvature membrane structures. Yet, a mechanistic understanding of how Cavin1 assembles at the membrane interface is lacking. Here, we used model membranes combined with biophysical dissection and computational modeling to show that Cavin1 inserts into membranes. We establish that initial phosphatidylinositol (4, 5) bisphosphate [PI(4,5)P2]-dependent membrane adsorption of the trimeric helical region 1 (HR1) of Cavin1 mediates the subsequent partial separation and membrane insertion of the individual helices. Insertion kinetics of HR1 is further enhanced by the presence of flanking negatively charged disordered regions, which was found important for the coassembly of Cavin1 with Caveolin1 in living cells. We propose that this intricate mechanism potentiates membrane curvature generation and facilitates dynamic rounds of assembly and disassembly of Cavin1 at the membrane.
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| 6. |
- Mohan, Jagan, et al.
(författare)
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Cavin3 interacts with cavin1 and caveolin1 to increase surface dynamics of caveolae
- 2015
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Ingår i: Journal of Cell Science. - : The Company of Biologists. - 0021-9533 .- 1477-9137. ; 128:5, s. 979-991
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Tidskriftsartikel (refereegranskat)abstract
- Caveolae are invaginations of the cell surface thought to regulate membrane tension, signalling, adhesion and lipid homeostasis due to their dynamic behaviour ranging from stable surface association to dynamic rounds of fission and fusion with the plasma membrane. The caveolae coat is generated by oligomerisation of the membrane protein caveolin and the family of cavin proteins. Here, we show that cavin3 is targeted to caveolae by cavin1 where it interacts with the scaffolding domain of caveolin1 and promote caveolae dynamics. We found that the N-terminal region of cavin3 binds a trimer of the cavin1 N-terminus in competition with a homologous cavin2 region, showing that the cavins form distinct subcomplexes via their N-terminal regions. Our data shows that cavin3 is enriched at deeply invaginated caveolae and that loss of cavin3 in cells results in an increase of stable caveolae and a decrease of caveolae with short duration time at the membrane. We propose that cavin3 is recruited to the caveolae coat by cavin1 to interact with caveolin1 and regulate the duration time of caveolae at the plasma membrane.
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| 7. |
- Mohan, Jagan, 1978-
(författare)
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Regulation of assembly and cell surface dynamics of caveolae
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A typical mammalian cell plasma membrane displays a high level of plasticity counter balanced with stability. The plasma membrane show various kinds of invaginations to meet physiological demands of the cells such as nutrient uptake, receptor signaling etc. An example of one such invagination observed in many cell types is “Caveola”. Caveolae are bulb shaped invaginations of the plasma membrane enriched in sphingolipids and cholesterol. Each individual caveola is in equilibrium with multi caveolar assemblies and exhibits various dynamics ranging from stable association with cell surface to the “kiss and run” type and internalized caveolae called cavicle. The principle protein components of caveolae involve caveolin1, 2 and 3, cavin 1, 2, 3 and 4 along with EHD2, PACSIN2 and dynamin. Caveolin1 acts as the hallmark of caveolae, whereas caveolin3 and cavin4 are limited to muscle cells. Caveolae are appreciated as important plasma membrane structures in maintaining cellular homeostasis of many cell types. Its dysfunction is associated with several human diseases such as cancer, vascular diseases, lipid and muscular dystrophies.This thesis aims to understand the assembly of caveolae and the molecular machineries involved in the regulation of caveolae dynamics. In particular, we have focused on the mechanism of cavin coat assembly, the influence of cavin3 in the regulation of caveolae dynamics, along with the mechanistic cycle of EHD2.Cavins form characteristic striations around caveolae, and in this work we showed that the N-terminus of cavin3 interacts with the trimeric N-terminus of cavin1 in competition with the N-terminus of cavin2 to form cavin sub-complex. We also observed that cavin3 interacts with caveolin1 in a cholesterol dependent manner and cavin3 may promote scission by acting as a positive regulator of caveolae dynamics, opposite to the cellular function of EHD2. The stringent roles of cavin3 and EHD2 control the equilibrium between stably cell surface associated caveolae and the “kiss and run” type of caveolae, undergoing rounds of fission and fusion. Our results demonstrated the molecular composition of the caveolae coat at a domain level with the stoichiometry of cavin sub-complexes. We also showed the function of cavin3 in the regulation of caveolae dynamics at the plasma membrane. Previous work from our lab showed that EHD2 is a dimeric ATPase localised to the caveolae neck and confines caveolae to the cell surface. In the present study, we showed that EHD2 oligomerized in an open conformation stabilized by ATP and in a G-domain loop dependent manner. The oligomerization of EHD2 in cells is finely tuned by the N-terminal region and the C-terminal EH domain, where both of these regions act as negative regulators of membrane binding. Our results showed the stringent regulation of EHD2 oligomerization and its importance with respect to various statuses and/or function of caveolae.In summary, the current study provides a novel insight into the assembly of cavin coat and protein machineries involved in the regulation of caveolae dynamics. In addition, it also contributes to the understanding of the molecular mechanism of ATPase activity of EHD2.
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