Structural Insights into the Organization of the Cavin Membrane Coat Complex

Kovtun, Oleksiy; Tillu, Vikas A.; Jung, WooRam; Leneva, Natalya; Ariotti, Nicholas; Chaudhary, Natasha; Mandyam, Ramya A.; Ferguson, Charles; Morgan, Garry; Johnston, Wayne A.; Harrop, S.J.; Alexandrov, Kirill; Parton, Robert G.; Collins, Brett M.

doi:10.1016/j.devcel.2014.10.002

Cited by 91 publications

(160 citation statements)

References 40 publications

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“…This result is consistent with cavin1 being the PtdSer-sensitive component needed for proper function or stabilization. The polybasic sites of cavin1, HR1 and HR2 domains, were proposed to bind anionic phospholipids, including PtdSer through charge-based interactions (16,17,20,55). In support of this notion, we find that chronic depletion of the majority (Ϸ80%) of PtdSer limits the ability of cavin1 to associate with Cav1 and the PM.…”

Section: Phosphatidylserine Is Required To Support the Formation Of Csupporting

confidence: 73%

Phosphatidylserine dictates the assembly and dynamics of caveolae in the plasma membrane

Hirama

Das

Yang

et al. 2017

Journal of Biological Chemistry

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Edited by Dennis R. VoelkerCaveolae are bulb-shaped nanodomains of the plasma membrane that are enriched in cholesterol and sphingolipids. They have many physiological functions, including endocytic transport, mechanosensing, and regulation of membrane and lipid transport. Caveola formation relies on integral membrane proteins termed caveolins (Cavs) and the cavin family of peripheral proteins. Both protein families bind anionic phospholipids, but the precise roles of these lipids are unknown. Here, we studied the effects of phosphatidylserine (PtdSer), phosphatidylinositol 4-phosphate (PtdIns4P), and phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P 2 ) on caveolar formation and dynamics. Using live-cell, single-particle tracking of GFP-labeled Cav1 and ultrastructural analyses, we compared the effect of PtdSer disruption or phosphoinositide depletion with caveola disassembly caused by cavin1 loss. We found that PtdSer plays a crucial role in both caveola formation and stability. Sequestration or depletion of PtdSer decreased the number of detectable Cav1-GFP puncta and the number of caveolae visualized by electron microscopy. Under PtdSer-limiting conditions, the co-localization of Cav1 and cavin1 was diminished, and cavin1 degradation was increased. Using rapamycin-recruitable phosphatases, we also found that the acute depletion of PtdIns4P and PtdIns (4,5)P 2 has minimal impact on caveola assembly but results in decreased lateral confinement. Finally, we show in a model of phospholipid scrambling, a feature of apoptotic cells, that caveola stability is acutely affected by the scrambling. We conclude that the predominant plasmalemmal anionic lipid PtdSer is essential for proper Cav clustering, caveola formation, and caveola dynamics and that membrane scrambling can perturb caveolar stability.

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Section: Phosphatidylserine Is Required To Support the Formation Of Csupporting

confidence: 73%

Phosphatidylserine dictates the assembly and dynamics of caveolae in the plasma membrane

Hirama

Das

Yang

et al. 2017

Journal of Biological Chemistry

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“…Affinity purification of Cavin1 expressed in HEK293 cells revealed the presence of heterogeneous particles with a mesh-like appearance by cryoEM and 3D electron tomography. These particles bound robustly to liposomes containing phosphatidylserine (PS) or phosphatidic acid, as seen previously using recombinant cavin proteins (10,11), and showed a propensity to form relatively well-ordered lattices of protein on the membrane surface. Interestingly, in this in vitro system the full-length Cavin1 protein could be observed on the interior surface of the vesicles, which Stoeber et al (6) suggest may be because of the occurrence of frequent inward invagination of the PS-containing liposomes.…”

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confidence: 73%

“…Studies by many laboratories in recent years are now beginning to bridge this gulf using approaches that include biochemical isolation, NMR spectroscopy, EM, and X-ray crystallography (6,10,(12)(13)(14)(15)(16)(17). A picture is now emerging of a vesicular structure that possesses much greater complexity than originally thought.…”

mentioning

confidence: 99%

“…CAV1 can be isolated as disk-shaped oligomers ∼15 nm in diameter that are proposed to be underlying building blocks of the caveolar coat. Cavin1 trimerizes through its N-terminal HR1 domain (10), and then can form oligomers arranged in a net-like structure. These oligomers organize into striated patterns on the surface of caveolae in cooperation with the CAV1 protein.…”

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confidence: 99%

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Unraveling the architecture of caveolae

Parton

Collins

2016

Proc. Natl. Acad. Sci. U.S.A.

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The eukaryotic cell surface is composed of many distinct membrane domains that are formed by the cooperative interactions of different proteins and lipids. These domains are important for membrane trafficking and cell signaling and are modulated in turn by changes in the cell environment. Caveolae ("little caves") are ∼60-nm membrane invaginations ( Fig. 1) that are a dominant surface feature of many mammalian cells, including muscle fibers, endothelia, and adipocytes, where they play a role in membrane homeostasis, signaling, and cellular mechanoprotection. Formation of caveolae in vertebrate cells requires two distinct protein families: the membrane-embedded caveolins (CAV1-3) and the peripheral membrane cavins (Cavin1-4). Although the general morphology of caveolae has been known for decades, the atypical structures of the protein subunits has meant that progress has been slow with regards to the high-resolution studies of caveola architecture. By high-resolution scanning electron microscopy (EM) and frozen deepetch transmission EM, caveolae have been shown to be coated with striations (1, 2) or to possess spike-like structures (3), very different from other well-characterized vesicle coats, such as clathrin (4, 5). In PNAS, Stoeber et al. use a combination of biochemical dissection and EM to provide important insights into the underlying architecture of the caveola protein coat (6).The first protein component of caveolae to be identified and shown to be essential for caveola formation was CAV1 (7-9). Subsequently, it was found that both CAV2 and muscle-specific CAV3 homologs are also localized to caveolae. Caveolin proteins are ∼20 kDa and possess two membrane-inserted α-helices with cytoplasmic N-and C-terminal sequences. These proteins form oligomeric complexes at the plasma membrane that line the cytoplasmic leaflet of the invaginated caveola structures. Cavins, although equally important for caveola formation, were only identified in the past decade through proteomic and cellular studies from several groups. Cavins also possess a conserved and unique structural organization, in this case consisting of conserved N-and C-terminal α-helical domains (HR1 and HR2) interspersed by disordered linker sequences (DR1, DR2, DR3) (10). Although recent studies have begun to tease out the functions of these domains in membrane recruitment, remodeling, and protein-protein interactions, our understanding is still limited. For example, how do caveolin oligomers assemble within caveolae, and what drives cavin oligomerization and recruitment to caveolar domains at the cell surface?In their report, Stoeber et al. (6) propose a model for the arrangement of the caveolin and cavin proteins that begins to address some of the ongoing questions in the field. Affinity purification of Cavin1 expressed in HEK293 cells revealed the presence of heterogeneous particles with a mesh-like appearance by cryoEM and 3D electron tomography. These particles bound robustly to liposomes containing phosphatidylserine (PS) or phosphatidic acid, as...

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“…62,66 Near the plasma membrane, Cavs in the Cav-70S complexes are palmitoylated by palmitoyl acyltransferases and, after fusion with the plasma membrane, 62,67,68 cavin proteins aggregate on the cholesterol-rich and Cav-containing lipid rafts and thereby assist the formation of the membrane invaginations typical for caveolae. 62,69,70 The association of NDPK-B with Cav1 and Cav3 was first identified in the zebrafish. Knockdown of NDPK-B specifically caused not only the loss of NDPK-B and the associated heterotrimeric G proteins G s and G i , but also loss of the Cavs.…”

Section: Ndpk-b/nme2 Influences Signal Complex Assembly At the Plasmamentioning

confidence: 99%

Regulation of heterotrimeric G-protein signaling by NDPK/NME proteins and caveolins: an update

Abu-Taha

Heijman

Feng

et al. 2018

Laboratory Investigation

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Heterotrimeric G proteins are pivotal mediators of cellular signal transduction in eukaryotic cells and abnormal G-protein signaling plays an important role in numerous diseases. During the last two decades it has become evident that the activation status of heterotrimeric G proteins is both highly localized and strongly regulated by a number of factors, including a receptor-independent activation pathway of heterotrimeric G proteins that does not involve the classical GDP/GTP exchange and relies on nucleoside diphosphate kinases (NDPKs). NDPKs are NTP/NDP transphosphorylases encoded by the nme/nm23 genes that are involved in a variety of cellular events such as proliferation, migration, and apoptosis. They therefore contribute, for example, to tumor metastasis, angiogenesis, retinopathy, and heart failure. Interestingly, NDPKs are translocated and/or upregulated in human heart failure. Here we describe recent advances in the current understanding of NDPK functions and how they have an impact on local regulation of G-protein signaling.

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Structural Insights into the Organization of the Cavin Membrane Coat Complex

Cited by 91 publications

References 40 publications

Phosphatidylserine dictates the assembly and dynamics of caveolae in the plasma membrane

Phosphatidylserine dictates the assembly and dynamics of caveolae in the plasma membrane

Unraveling the architecture of caveolae

Regulation of heterotrimeric G-protein signaling by NDPK/NME proteins and caveolins: an update

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