On the role of membrane anisotropy in the beading transition of undulated tubular membrane structures

Iglič, Aleš; Babnik, Blaž; Gimsa, Ulrike; Kralj‐Iglič, Veronika

doi:10.1088/0305-4470/38/40/004

Cited by 50 publications

(73 citation statements)

References 31 publications

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“…55,56 While it was previously acknowledged that membrane composition and shape are interdependent, 34,57−59 the orientational ordering model provides a unified explanation of the above feature, and has been reviewed extensively elsewhere. 37,45,60,61 Figure 5 presents some of these nanostructures, with buds and nanovesicles of the erythrocyte membrane and nanotubules observed in urothelial cancer cells. Dilatations of the nanotubules are often present.…”

Section: Deviatoric Elasticity May Stabilize Anisotropic Nanostructuresmentioning

confidence: 99%

Stability of membranous nanostructures: a possible key mechanism in cancer progression

Kralj‐Iglič¹

2012

IJN

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Abstract:Membranous nanostructures, such as nanovesicles and nanotubules, are an important pool of biological membranes. Recent results indicate that they constitute cell-cell communication systems and that cancer development is influenced by these systems. Nanovesicles that are pinched off from cancer cells can move within the circulation and interact with distant cells. It has been suggested and indicated by experimental evidence that nanovesicles can induce metastases from the primary tumor in this way. Therefore, it is of importance to understand better the mechanisms of membrane budding and vesiculation. Here, a theoretical description is presented concerning consistently related lateral membrane composition, orientational ordering of membrane constituents, and a stable shape of nanovesicles and nanotubules. It is shown that the character of stable nanostructures reflects the composition of the membrane and the intrinsic shape of its constituents. An extension of the fluid mosaic model of biological membranes is suggested by taking into account curvature-mediated orientational ordering of the membrane constituents on strongly anisotropically curved regions. Based on experimental data for artificial membranes, a possible antimetastatic effect of plasma constituents via mediation of attractive interaction between membranous structures is suggested. This mediated attractive interaction hypothetically suppresses nanovesiculation by causing adhesion of buds to the mother membrane and preventing them from being pinched off from the membrane.

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Section: Deviatoric Elasticity May Stabilize Anisotropic Nanostructuresmentioning

confidence: 99%

Stability of membranous nanostructures: a possible key mechanism in cancer progression

Kralj‐Iglič¹

2012

IJN

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“…44,45 Membrane area, enclosed volume, and average mean curvature were kept constant during minimization. The system of differential equations was solved numerically, as described by Iglič et al 45 …”

Section: Determination Of Theoretical Shapesmentioning

confidence: 99%

“…45 It was assumed that the vesicle has no internal structure and that its shape was determined by the properties of the membrane. The membrane free energy was derived using the energies of individual membrane constituents and for simplicity, it was assumed that all constituents were equal.…”

mentioning

confidence: 99%

Nanoparticles isolated from blood: a reflection of vesiculability of blood cells during the isolation process

Šuštar¹,

Bedina-Zavec²,

Stukelj³

et al. 2011

IJN

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Background: Shedding of nanoparticles from the cell membrane is a common process in all cells. These nanoparticles are present in body fluids and can be harvested by isolation. To collect circulating nanoparticles from blood, a standard procedure consisting of repeated centrifugation and washing is applied to the blood samples. Nanoparticles can also be shed from blood cells during the isolation process, so it is unclear whether nanoparticles found in the isolated material are present in blood at sampling or if are they created from the blood cells during the isolation process. We addressed this question by determination of the morphology and identity of nanoparticles harvested from blood. Methods: The isolates were visualized by scanning electron microscopy, analyzed by flow cytometry, and nanoparticle shapes were determined theoretically. Results: The average size of nanoparticles was about 300 nm, and numerous residual blood cells were found in the isolates. The shapes of nanoparticles corresponded to the theoretical shapes obtained by minimization of the membrane free energy, indicating that these nanoparticles can be identified as vesicles. The concentration and size of nanoparticles in blood isolates was sensitive to the temperature during isolation. We demonstrated that at lower temperatures, the nanoparticle concentration was higher, while the nanoparticles were on average smaller. Conclusion:These results indicate that a large pool of nanoparticles is produced after blood sampling. The shapes of deformed blood cells found in the isolates indicate how fragmentation of blood cells may take place. The results show that the contents of isolates reflect the properties of blood cells and their interaction with the surrounding solution (rather than representing only nanoparticles present in blood at sampling) which differ in different diseases and may therefore present a relevant clinical parameter.

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“…According to the theory of isotropic membrane elasticity, 45,46 the cell tubular membrane protrusion cannot be stabilized by isotropic membrane components alone, 43 but requires the accumulation of anisotropic membrane nanodomains. 6,8,10,47,48 Previous theoretical studies provide insight into the stability of the tubular membrane protrusion following the disassembly of the inner rod cytoskeleton, 4 or into the stability of actin-free filopodia.…”

Section: Discussionmentioning

confidence: 99%

“…The difference between the membrane curvature and the membrane intrinsic (spontaneous) curvature determines the energy cost for bending the membrane away from its favorable curvature. 43 The intrinsic (spontaneous) curvatures of the membrane nanodomain depend on the relative density of cholesterol molecules in the outer lipid layer, as follows: …”

Section: The Model Of Icn Stability and Theoretical Predictionsmentioning

confidence: 99%

The role of cholesterol-sphingomyelin membrane nanodomains in the stability of intercellular membrane nanotubes

Lokar

Kabaso²,

Resnik³

et al. 2012

IJN

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Intercellular membrane nanotubes (ICNs) are highly curved tubular structures that connect neighboring cells. The stability of these structures depends on the inner cytoskeleton and the cell membrane composition. Yet, due to the difficulty in the extraction of ICNs, the cell membrane composition remains elusive. In the present study, a raft marker, ostreolysin, revealed the enrichment of cholesterol-sphingomyelin membrane nanodomains along ICNs in a T24 (malignant) urothelial cancer cell line. Cholesterol depletion, due to the addition of methyl-β-cyclodextrin, caused the dispersion of cholesterol-sphingomyelin membrane nanodomains and the retraction of ICNs. The depletion of cholesterol also led to cytoskeleton reorganization and to formation of actin stress fibers. Live cell imaging data revealed the possible functional coupling between the change from polygonal to spherical shape, cell separation, and the disconnection of ICNs. The ICN was modeled as an axisymmetric tubular structure, enabling us to investigate the effects of cholesterol content on the ICN curvature. The removal of cholesterol was predicted to reduce the positive spontaneous curvature of the remaining membrane components, increasing their curvature mismatch with the tube curvature. The mechanisms by which the increased curvature mismatch could contribute to the disconnection of ICNs are discussed.

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On the role of membrane anisotropy in the beading transition of undulated tubular membrane structures

Cited by 50 publications

References 31 publications

Stability of membranous nanostructures: a possible key mechanism in cancer progression

Stability of membranous nanostructures: a possible key mechanism in cancer progression

Nanoparticles isolated from blood: a reflection of vesiculability of blood cells during the isolation process

The role of cholesterol-sphingomyelin membrane nanodomains in the stability of intercellular membrane nanotubes

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