| 1. |
- Larsson, Elin, et al.
(author)
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An EH-domain switching mechanism regulates stable membrane association of EHD2
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Other publication (other academic/artistic)abstract
- EHD2 is a dimeric ATPase known to stabilise the surface connection of the characteristic small invaginations of the cell surface termed caveolae. EHD2 oligomerises into rings around lipid membranes thereby controlling their shape. Here, we have analysed the domain interactions and mechanism that control the stable membrane association of EHD2 at caveolae. We have found that the N-terminus of EHD2, which is buried in the core protein and obstruct assembly, has to be relieved by an EH domain dependent mechanism. The binding between the EH domain and a loop in the GTPase domain of EHD2 was required for stable membrane association, but the loop in itself was not sufficient for specific recruitment to caveolae. A positively charged stretch in the EH domain is proposed to bind to lipids and thereby influence the exchange rate of EHD2. Taken together, we propose a stringent regulatory mechanism for the assembly of EHD2 involving switching of the EH domain position to release the N-terminus and facilitate oligomerisation.
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| 2. |
- Mohan, Jagan, et al.
(author)
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Cavin3 interacts with cavin1 and caveolin1 to increase surface dynamics of caveolae
- 2015
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In: Journal of Cell Science. - : The Company of Biologists. - 0021-9533 .- 1477-9137. ; 128:5, s. 979-991
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Journal article (peer-reviewed)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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| 3. |
- Morén, Björn, 1983-
(author)
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Caveolae associated proteins and how they effect caveolae dynamics
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Caveolae are a type of invaginated membrane domain that has been shown to be involved in several disease states, including lipodystrophy, muscular dystrophies and cancer. Several of these diseases are caused by the lack of caveolae or caveolae-related signaling deficiencies in the tissues in which the caveolar domain are abundant such as lung, adipose, muscle and their related endothelial cells. Caveolae are formed through the assembly of the membrane inserted protein caveolin, cholesterol and the recently described family of cavin proteins, which together form the caveolae coat. The work in this thesis focuses on understanding the protein components and mechanisms that control the biogenesis and dynamics of caveolae.We have found that the protein EHD2 is an important regulator and stabilizer of the caveolar domain at the cell membrane. EHD2 is a dimeric ATPase known to oligomerize into ring-like structures around lipid membranes to control their shape. We have characterized the domain interactions involved in the specific targeting and assembly of this protein at caveolae. We propose a stringent regulatory mechanism for the assembly of EHD2 involving ATP binding and switching of the EH domain position to release the N-terminus and facilitate oligomerization in the presence of membrane species. We show that loss of EHD2 in cells results in hyper- dynamic caveolae and that caveolae stability at the membrane can be restored by reintroducing EHD2 into these cells.In a study of the protein cavin-3, which is known to be an integral component of the caveolar coat, we showed that this protein is targeted to caveolae via direct binding to the caveolar core protein caveolin1. Furthermore, we show that cavin-3 is enriched at deeply invaginated caveolae and regulate the duration time of caveolae at the cell surface.In combination with a biochemical and cellbiological approach, the advanced fluorescence microscopy techniques, like Fluorescence Recovery After Photobleaching (FRAP), Total Internal Reflection microscopy (TIRF), combined with correlative Atomic Force Microscopy (AFM) have allowed us to characterize distinct caveolae-associated proteins and their respective functions at caveolae.
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