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International Journal of Medical... 2023Lung cancer is one of the most frequently diagnosed cancers worldwide. Due to its late diagnosis, it remains the leading cause of cancer-related deaths. Despite it is... (Review)
Review
Lung cancer is one of the most frequently diagnosed cancers worldwide. Due to its late diagnosis, it remains the leading cause of cancer-related deaths. Despite it is mostly associated to tobacco smoking, recent data suggested that genetic factors are of the highest importance. In this context, different processes meaningful for the development and progression of lung cancer such endocytosis, protein secretion and signal transduction, are controlled by membrane rafts. These highly ordered membrane domains contain proteins such as caveolins and flotillins, which were traditionally considered scaffold proteins but have currently been given a preponderant role in lung cancer. Here, we summarize current knowledge regarding the involvement of caveolins and flotillins in lung cancer from a molecular point of view.
Topics: Humans; Caveolins; Lung Neoplasms; Membrane Proteins; Membrane Microdomains
PubMed: 37928877
DOI: 10.7150/ijms.87836 -
Current Opinion in Cell Biology Jun 2024Caveolae are atypical plasma membrane invaginations that take part in lipid sorting and regulation of oxidative and mechanical plasma membrane stress. Caveola formation... (Review)
Review
Caveolae are atypical plasma membrane invaginations that take part in lipid sorting and regulation of oxidative and mechanical plasma membrane stress. Caveola formation requires caveolin, cavin, and specific lipid types. The recent advances in understanding the structure and assembly of caveolin and cavin complexes within the membrane context have clarified the fundamental processes underlying caveola biogenesis. In addition, the curvature of the caveola membrane is controlled by the regulatory proteins EHD2, pacsin2, and dynamin2, which also function to restrain the scission of caveolae from the plasma membrane (PM). Here, this is integrated with novel insights on caveolae as lipid and mechanosensing complexes that can dynamically flatten or disassemble to counteract mechanical, and oxidative stress.
Topics: Humans; Caveolae; Cell Membrane; Animals; Caveolins
PubMed: 38788266
DOI: 10.1016/j.ceb.2024.102371 -
Biophysical Journal Jun 2024Annexin A2 (A2)-induced microdomain formation is a key step in biological processes such as Ca-mediated exocytosis in neuroendocrine cells. In this work, a total of 15...
Annexin A2 (A2)-induced microdomain formation is a key step in biological processes such as Ca-mediated exocytosis in neuroendocrine cells. In this work, a total of 15 coarse-grained molecular dynamics simulations were performed on vesicle models having a diameter of approximately 250 Å for 15 μs each using the Martini2 force field. Five simulations were performed in the presence of 10 A2, 5 in the presence of A2 but absence of PIP, and 5 simulations in the absence of A2 but presence of PIP. Consistent results were generated among the simulations. A2-induced PIP microdomain formation was observed and shown to occur in three phases: A2-vesicle association, localized A2-induced PIP clustering, and A2 aggregation driving PIP microdomain formation. The relationship between A2 aggregation and PIP microdomain formation was quantitatively described using a novel method which calculated the variance among protein and lipid positions via the Fréchet mean. A large reduction in PIP variance was observed in the presence of A2 but not in its absence. This reduction in PIP variance was proportional to the reduction observed in A2 variance and demonstrates that the observed PIP microdomain formation is dependent upon A2 aggregation. The three-phase model of A2-induced microdomain formation generated in this work will serve as a valuable guide for further experimental studies and the development of novel A2 inhibitors. No microdomain formation was observed in the absence of A2 and minimal A2-membrane interaction was observed in the absence of PIP.
PubMed: 38859585
DOI: 10.1016/j.bpj.2024.06.006 -
Biomacromolecules Feb 2024Considerable attention has been dedicated to lipid rafts due to their importance in numerous cell functions such as membrane trafficking, polarization, and signaling....
Considerable attention has been dedicated to lipid rafts due to their importance in numerous cell functions such as membrane trafficking, polarization, and signaling. Next to studies in living cells, artificial micrometer-sized vesicles with a minimal set of components are established as a major tool to understand the phase separation dynamics and their intimate interplay with membrane proteins. In parallel, mixtures of phospholipids and certain amphiphilic polymers simultaneously offer an interface for proteins and mimic this segregation behavior, presenting a tangible synthetic alternative for fundamental studies and bottom-up design of cellular mimics. However, the simultaneous insertion of complex and sensitive membrane proteins is experimentally challenging and thus far has been largely limited to natural lipids. Here, we present the co-reconstitution of the proton pump oxidase and the proton consumer ATP synthase in hybrid polymer/lipid giant unilamellar vesicles (GUVs) via fusion/electroformation. Variations of the current method allow for tailored reconstitution protocols and control of the vesicle size. In particular, mixing of protein-free and protein-functionalized nanosized vesicles in the electroformation film results in larger GUVs, while separate reconstitution of the respiratory enzymes enables higher ATP synthesis rates. Furthermore, protein labeling provides a synthetic mechanism for phase separation and protein sequestration, mimicking lipid- and protein-mediated domain formation in nature. The latter means opens further possibilities for re-enacting phenomena like supercomplex assembly or symmetry breaking and enriches the toolbox of bottom-up synthetic biology.
Topics: Unilamellar Liposomes; Polymers; Phospholipids; Membrane Proteins; Membrane Microdomains; Adenosine Triphosphate
PubMed: 38190609
DOI: 10.1021/acs.biomac.3c00972 -
MBio Aug 2023The obligate intracellular bacterium inserts a family of inclusion membrane (Inc) proteins into the membrane of its vacuole (the inclusion). The Inc CpoS is a critical...
The obligate intracellular bacterium inserts a family of inclusion membrane (Inc) proteins into the membrane of its vacuole (the inclusion). The Inc CpoS is a critical suppressor of host cellular immune surveillance, but the underlying mechanism remained elusive. By complementing a mutant with various natural orthologs and variants of CpoS, we linked distinct molecular interactions of CpoS to distinct functions. Unexpectedly, we found CpoS to be essential for the formation of inclusion membrane microdomains that control the spatial organization of multiple Incs involved in signaling and modulation of the host cellular cytoskeleton. While the function of CpoS in microdomains was uncoupled from its role in the suppression of host cellular defenses, we found the ability of CpoS to interact with Rab GTPases to be required not only for the manipulation of membrane trafficking, such as to mediate transport of ceramide-derived lipids (sphingolipids) to the inclusion, but also for the inhibition of Stimulator of interferon genes (STING)-dependent type I interferon responses. Indeed, depletion of Rab35 phenocopied the exacerbated interferon responses observed during infection with CpoS-deficient mutants. Overall, our findings highlight the role of Inc-Inc interactions in shaping the inclusion microenvironment and the modulation of membrane trafficking as a pathogenic immune evasion strategy. IMPORTANCE is a prevalent bacterial pathogen that causes blinding ocular scarring and urogenital infections that can lead to infertility and pregnancy complications. Because can only grow within its host cell, boosting the intrinsic defenses of human cells may represent a novel strategy to fight pathogen replication and survival. Hence, CpoS, a protein known to block host cellular defenses, or processes regulated by CpoS, could provide new opportunities for therapeutic intervention. By revealing CpoS as a multifunctional virulence factor and by linking its ability to block host cellular immune signaling to the modulation of membrane trafficking, the present work may provide a foundation for such rationale targeting and advances our understanding of how intracellular bacteria can shape and protect their growth niche.
Topics: Humans; Bacterial Proteins; Chlamydia trachomatis; Chlamydia Infections; Immune Evasion; Interferon Type I; HeLa Cells; Host-Pathogen Interactions
PubMed: 37530528
DOI: 10.1128/mbio.03190-22 -
International Journal of Molecular... Nov 2023Resistance to anticancer drugs is a problem in the treatment of pancreatic ductal carcinoma (PDAC) and overcoming it is an important issue. Recently, it has been...
Resistance to anticancer drugs is a problem in the treatment of pancreatic ductal carcinoma (PDAC) and overcoming it is an important issue. Recently, it has been reported that statins induce apoptosis in cancer cells but the mechanism has not been completely elucidated. We investigated the antitumor mechanisms of statins against PDAC and their impact on resistance to gemcitabine (GEM). Lovastatin (LOVA) increased mitochondrial oxidative stress in PDAC cells, leading to apoptosis. LOVA reduced lipid rafts in the plasma membrane and mitochondria, suppressed the activation of epithelial growth factor receptor (EGFR) and AKT in plasma membrane rafts, and reduced B-cell lymphoma 2 (BCL2)-Bcl-2-associated X protein (BAX) binding and the translocation of F1F0 ATPase in mitochondrial rafts. In the three GEM-resistant cell lines derived from MIA and PANC1, the lipid rafts in the cell membrane and the mitochondria were increased to activate EGFR and AKT and to increase BCL2-BAX binding, which suppressed apoptosis. LOVA abrogated these anti-apoptotic effects by reducing the rafts in the resistant cells. By treating the resistant cells with LOVA, GEM sensitivity improved to the level of the parental cells. Therefore, cholesterol rafts contribute to drug resistance in PDAC. Further clinical research is warranted on overcoming anticancer drug resistance by statin-mediated intracellular cholesterol regulation.
Topics: Humans; bcl-2-Associated X Protein; Lovastatin; Proto-Oncogene Proteins c-akt; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Apoptosis; Antineoplastic Agents; Cell Membrane; Gemcitabine; Pancreatic Neoplasms; Membrane Microdomains; Carcinoma, Pancreatic Ductal; ErbB Receptors; Mitochondria; Cholesterol; Cell Line, Tumor
PubMed: 38069135
DOI: 10.3390/ijms242316814 -
BioRxiv : the Preprint Server For... May 2024Fungal plasma membrane proteins represent key therapeutic targets for antifungal agents, yet their structure and spatial distribution in the native context remain poorly...
Fungal plasma membrane proteins represent key therapeutic targets for antifungal agents, yet their structure and spatial distribution in the native context remain poorly characterized. Herein, we employ an integrative multimodal approach to elucidate the structural and functional organization of plasma membrane protein complexes in , focusing on prominent and essential membrane proteins, the polysaccharide synthase β-(1,3)-glucan synthase (GS) and the proton pump Pma1. Cryo-electron tomography (cryo-ET) and live cell imaging reveal that GS and Pma1 are heterogeneously distributed into distinct plasma membrane microdomains. Treatment with caspofungin, an echinocandin antifungal that targets GS, alters the plasma membrane and disrupts the native distribution of GS and Pma1. Based on these findings, we propose a model for echinocandin action that considers how drug interactions with the plasma membrane environment lead to inhibition of GS. Our work underscores the importance of interrogating the structural and dynamic characteristics of fungal plasma membrane proteins to understand function and facilitate precisely targeted development of novel antifungal therapies.
PubMed: 38854035
DOI: 10.1101/2024.05.29.596243 -
FEBS Open Bio Sep 2023Intracellular organelles carry out many of their functions by engaging in extensive interorganellar communication through specialized membrane contact sites (MCSs)... (Review)
Review
Intracellular organelles carry out many of their functions by engaging in extensive interorganellar communication through specialized membrane contact sites (MCSs) formed where two organelles tether to each other or to the plasma membrane (PM) without fusing. In recent years, these ubiquitous membrane structures have emerged as central signaling hubs that control a multitude of cellular pathways, ranging from lipid metabolism/transport to the exchange of metabolites and ions (i.e., Ca ), and general organellar biogenesis. The functional crosstalk between juxtaposed membranes at MCSs relies on a defined composite of proteins and lipids that populate these microdomains in a dynamic fashion. This is particularly important in the nervous system, where alterations in the composition of MCSs have been shown to affect their functions and have been implicated in the pathogenesis of neurodegenerative diseases. In this review, we focus on the MCSs that are formed by the tethering of the endoplasmic reticulum (ER) to the mitochondria, the ER to the endo-lysosomes and the mitochondria to the lysosomes. We highlight how glycosphingolipids that are aberrantly processed/degraded and accumulate ectopically in intracellular membranes and the PM change the topology of MCSs, disrupting signaling pathways that lead to neuronal demise and neurodegeneration. In particular, we focus on neurodegenerative lysosomal storage diseases linked to altered glycosphingolipid catabolism.
Topics: Humans; Glycosphingolipids; Neurodegenerative Diseases; Intracellular Membranes; Endoplasmic Reticulum; Mitochondria
PubMed: 37014126
DOI: 10.1002/2211-5463.13605 -
Archives of Biochemistry and Biophysics Apr 2024G-protein-coupled receptors (GPCRs) are the largest family of membrane proteins, regulate a plethora of physiological responses and are the therapeutic target for 30-40%... (Review)
Review
G-protein-coupled receptors (GPCRs) are the largest family of membrane proteins, regulate a plethora of physiological responses and are the therapeutic target for 30-40% of clinically-prescribed drugs. They are integral membrane proteins deeply embedded in the plasma membrane where they activate intracellular signalling via coupling to G-proteins and β-arrestin. GPCRs are in intimate association with the bilayer lipids and that lipid environment regulates the signalling functions of GPCRs. This complex lipid 'landscape' is both heterogeneous and dynamic. GPCR function is modulated by bulk membrane properties including membrane fluidity, microdomains, curvature, thickness and asymmetry but GPCRs are also regulated by specific lipid:GPCR binding, including cholesterol and anionic lipids. Understanding the molecular mechanisms whereby GPCR signalling is regulated by lipids is a very active area of research currently. A major advance in membrane protein research in recent years was the application of poly(styrene-co-maleic acid) (SMA) copolymers. These spontaneously generate SMA lipid particles (SMALPs) encapsulating membrane protein in a nano-scale disc of cell membrane, thereby removing the historical need for detergent and preserving lipid:GPCR interaction. The focus of this review is how GPCR-SMALPs are increasing our understanding of GPCR structure and function at the molecular level. Furthermore, an increasing number of 'second generation' SMA-like copolymers have been reported recently. These are reviewed from the context of increasing our understanding of GPCR molecular mechanisms. Moreover, their potential as a novel platform for downstream biophysical and structural analyses is assessed and looking ahead, the translational application of SMA-like copolymers to GPCR drug discovery programmes in the future is considered.
Topics: Cell Membrane; Lipids; Membrane Proteins; Receptors, G-Protein-Coupled
PubMed: 38395122
DOI: 10.1016/j.abb.2024.109946 -
Microbial Cell Factories Sep 2023Saccharomyces cerevisiae has been used in the biosynthesis of acid products such as organic acids owing to its acid tolerance. Improving the acid tolerance of S....
BACKGROUND
Saccharomyces cerevisiae has been used in the biosynthesis of acid products such as organic acids owing to its acid tolerance. Improving the acid tolerance of S. cerevisiae is beneficial for expanding its application range. Our previous study isolated the TAMC strain that was tolerant to a pH 2.3 through adaptive laboratory evolution; however, its mechanism underlying tolerance to low pH environment remains unclear.
RESULTS
In this study, through visual observation and order analysis of plasma membrane and membrane microdomains, we revealed that the membrane microdomains of TAMC strain play an indispensable role in acid tolerance. Transcriptomic analysis showed an increase in the expression of genes related to key components of membrane microdomains in TAMC strain. Furthermore, an obvious reduction was observed in the acid tolerance of the strain with sterol C-24 methyltransferase encoding gene ERG6 knockout for inhibiting membrane microdomain formation. Finally, colocalization analysis of H-ATPase PMA1 and plasma membrane protein PMP1 showed that disruption of membrane microdomains could inhibit the formation of the H-ATPase complex.
CONCLUSIONS
Membrane microdomains could provide a platform for forming H-ATPase complexes to facilitate intracellular H homeostasis, and thereby improve cell acid resistance. This study proposed a novel acid tolerance mechanism, providing a new direction for the rational engineering of acid-tolerant strains.
Topics: Saccharomyces cerevisiae; Cell Membrane; Gene Expression Profiling; Gene Knockout Techniques; Membrane Microdomains
PubMed: 37700284
DOI: 10.1186/s12934-023-02195-y