Controlling and Measuring the Interdependence of Local Properties in Biomembranes

D'Onofrio, Terrence G.; Hatzor, Anat; Counterman, Anne E.; Heetderks, Julia J.; Sandel, M. J.; Weiss, Paul S.

doi:10.1021/la026133a

Cited by 25 publications

(32 citation statements)

References 54 publications

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“…In an initial experiment, after obtaining a fluorescence micrograph of the vesicle with the tubulin extension, we observed that the extended region of the membrane exhibited pearling and that the MT had depolymerized (19). Pearling was typically observed only at high 6-AS concentrations, and is consistent with the behavior of a membrane tether after the release of stress (20,21).…”

Section: Resultssupporting

confidence: 56%

A physical model of axonal damage due to oxidative stress

Counterman

D'Onofrio²,

Andrews³

et al. 2006

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

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Oxidative damage is implicated in the pathogenesis of neurodegenerative disorders, including Alzheimer's, Parkinson's, and Huntington's diseases, and in normal aging. Here, we model oxidative stress in neurons using photogenerated radicals in a simplified membrane-encapsulated microtubule system. Using fluorescence and differential interference contrast microscopies, we monitor photochemically induced microtubule breakdown on the supported region of membrane in encapsulating synthetic liposomes as a function of lipid composition and environment. Degradation of vesicle-encapsulated microtubules is caused by attack from free radicals formed upon UV excitation of the lipid-soluble fluorescent probe, 6-(9-anthroyloxy)stearic acid. Probe concentration was typically limited to a regime in which microtubule degradation was slow, and microtubule degradation was monitored by changes in the observed protrusion of the membrane surface. The kinetics of microtubule degradation are influenced by lipid saturation level, fluorescent probe concentration, and the presence of free-radical scavengers. This system is sufficient to reproduce some degenerative morphologies found in vivo.O xidative modifications to proteins in neurons have been implicated in a number of degenerative disorders and have become a controversial topic in elucidating the progression of Parkinson's, Huntington's, and Alzheimer's diseases (1-7). Microtubules (MTs) are key cytoskeletal proteins in nerve cell axons. These protein polymers are responsible for many disparate functions of cells, including structural support and imparting polarity, and they are involved in motility and transport of intracellular cargo (8). Fundamental studies of MTs in vivo are complicated by the presence of the full complement of biomolecules that are required for cell survival. Thus, a substantial effort has been devoted to characterizing MT dynamics in vitro, and these studies have led to increased understanding of issues such as dynamic instability (9) and the involvement of molecular motors in producing motility (10). To mimic the confinement of a bilayer, MT assemblies (asters) have previously been examined in rigid, microfabricated wells (11). The drawback of such studies is that interactions between MTs and components of the elastic lipid membrane are neglected. It is important to be able to isolate and to quantify specific factors that impact the structural integrity of the cytoskeleton, while maintaining a simplified cell-like environment.Toward this aim, we have developed a minimal physical system with which to investigate the effects of oxidative stress on the cytoskeleton. Previous studies have demonstrated that incorporating actin and tubulin into liposomes and inducing these proteins to polymerize results in a morphological change in the liposome; a protrusion of the membrane is observed at one or both ends of the protein polymer (12-15). The asymmetry occurs frequently, when the MT wraps around within the encapsulating liposome (16). Here, we employ the membrane as a...

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Section: Resultssupporting

confidence: 56%

A physical model of axonal damage due to oxidative stress

Counterman

D'Onofrio²,

Andrews³

et al. 2006

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

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“…that the generation and stability of the lipid bilayer tubes in the cellular and artificial multicomponent membrane systems in the absence of elongated inner stiff supporters , e.g. microtubules [23]–[27] or external pulling forces , such as, optical tweezers [28], [29] or motor proteins (kinesin, dynamin) [29], [30], can be explained by the presence of membrane elements (nanodomains) and attached proteins with anisotropic properties. As for example, the membrane attached crescent shaped BAR domain proteins have clearly anisotropic shape and therefore their energy depend on their local orientation or statistically averaged local orientation, depending on the local curvature of the membrane [5], [20], [31].…”

Section: Introductionmentioning

confidence: 99%

On the Role of Anisotropy of Membrane Components in Formation and Stabilization of Tubular Structures in Multicomponent Membranes

et al. 2013

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Influence of isotropic and anisotropic properties of membrane constituents (nanodomains) on formation of tubular membrane structures in two-component vesicle is numerically investigated by minimization of the free energy functional based on the deviatoric-elasticity model of the membrane. It is shown that the lateral redistribution and segregation of membrane components may induce substantial change in membrane curvature resulting in the growth of highly curved tubular structures.

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“…Several methods produce giant liposomes; these methods include “gentle hydration”,7–11 “freeze-and-thaw”,12,13 “solid hydration”,14 “solvent evaporation”,15,16 emulsion-based methods,17 and “electroformation” 1,2,9,18–21. These methods generate giant liposomes of high quality and yield, but they are typically limited to solutions of low ionic strength (≤50 mM monovalent salt)1,3,7–10,16,22 unless specialized lipid formulations8–10 or specific electroformation protocols22,23 are used.…”

Section: Introductionmentioning

confidence: 99%

Films of Agarose Enable Rapid Formation of Giant Liposomes in Solutions of Physiologic Ionic Strength

et al. 2009

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This paper describes a method to form giant liposomes in solutions of physiologic ionic strength, such as phosphate buffered saline (PBS) or 150 mM KCl. Formation of these cell-sized liposomes proceeded from hybrid films of partially dried agarose and lipids. Hydrating the films of agarose and lipids in aqueous salt solutions resulted in swelling and partial dissolution of the hybrid films and in concomitant rapid formation of giant liposomes in high yield. This method did not require the presence of an electric field or specialized lipids; it generated giant liposomes from pure phosphatidylcholine lipids or from lipid mixtures that contained cholesterol or negatively charged lipids. Hybrid films of agarose and lipids even enabled the formation of giant liposomes in PBS from lipid compositions that are typically problematic for liposome formation, such as pure phosphatidylserine, pure phosphatidylglycerol, and asolectin. This paper discusses biophysical aspects of the formation of giant liposomes from hybrid films of agarose and lipids in comparison to established methods and shows that gentle hydration of hybrid films of agarose and lipids is a simple, rapid, and reproducible procedure to generate giant liposomes of various lipid compositions in solutions of physiologic ionic strength without the need for specialized equipment.

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Controlling and Measuring the Interdependence of Local Properties in Biomembranes

Cited by 25 publications

References 54 publications

A physical model of axonal damage due to oxidative stress

A physical model of axonal damage due to oxidative stress

On the Role of Anisotropy of Membrane Components in Formation and Stabilization of Tubular Structures in Multicomponent Membranes

Films of Agarose Enable Rapid Formation of Giant Liposomes in Solutions of Physiologic Ionic Strength

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