scholarly journals Annexin A4 trimers are recruited by high membrane curvatures in giant plasma membrane vesicles

Soft Matter ◽  
2021 ◽  
Author(s):  
Christoffer Dam Florentsen ◽  
Alexander Kamp-Sonne ◽  
Guillermo Moreno-Pescador ◽  
Weria Pezeshkian ◽  
Ali Asghar Hakami Zanjani ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Protein Structure ◽  
Membrane Vesicles ◽  
Membrane Repair ◽  
Plasma Membrane Vesicles ◽  
Curvature Sensing ◽  
Annexin A4 ◽  
P Protein ◽  
Plasma Membrane Repair

Protein structure and curvature sensing for annexin A4 trimers are coupled. These findings may provide new insight for the mechanisms underlying plasma membrane repair.

scholarly journals Annexin A4 trimers are recruited by high membrane curvatures in Giant Plasma Membrane Vesicles

2020 ◽  
Author(s):  
Christoffer Florentsen ◽  
Alexander Kamp-Sonne ◽  
Guillermo Moreno-Pescador ◽  
Weria Pezeshkian ◽  
Ali Asghar Hakami Zanjani ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Vesicles ◽  
Membrane Curvature ◽  
Biological Functions ◽  
Membrane Repair ◽  
Plasma Membrane Vesicles ◽  
Curvature Sensing ◽  
Curved Structures ◽  
Annexin A4 ◽  
Membrane Budding

AbstractThe plasma membrane of eukaryotic cells consists of a crowded environment comprised of a high diversity of proteins in a complex lipid matrix. The lateral organization of membrane proteins in the plasma membrane (PM) is closely correlated with biological functions such as endocytosis, membrane budding and other processes which involve protein mediated shaping of the membrane into highly curved structures. Annexin A4 (ANXA4) is a prominent player in a number of biological functions including plasma membrane repair. Its binding to membranes is activated by Ca2+ influx and it is therefore rapidly recruited to the cell surface near rupture sites where Ca2+ influx takes place. However, the free edges near rupture sites can easily bend into complex curvatures and hence may accelerate recruitment of curvature sensing proteins to facilitate rapid membrane repair. To analyze the curvature sensing behavior of curvature inducing proteins in crowded membranes, we quantifify the affinity of ANXA4 monomers and trimers for high membrane curvatures by extracting membrane nanotubes from giant plasma membrane vesicles (GPMVs). ANXA4 is found to be a sensor of negative membrane curvatures. Multiscale simulations furthermore predicted that ANXA4 trimers generate membrane curvature upon binding and have an affinity for highly curved membrane regions only within a well defined membrane curvature window. Our results indicate that curvature sensing and mobility of ANXA4 depend on the trimer structure of ANXA4 which could provide new biophysical insight into the role of ANXA4 in membrane repair and other biological processes.

Annexins Bend Wound Edges during Plasma Membrane Repair

2020 ◽  
Vol 27 (22) ◽  
pp. 3600-3610 ◽  
Author(s):  
Adam Cohen Simonsen ◽  
Theresa Louise Boye ◽  
Jesper Nylandsted
Keyword(s):  
Plasma Membrane ◽  
Cancer Cells ◽  
Membrane Curvature ◽  
Eukaryotic Cells ◽  
Repair System ◽  
Membrane Repair ◽  
Membrane Injury ◽  
Anionic Phospholipids ◽  
Annexin A4 ◽  
Plasma Membrane Repair

The plasma membrane of eukaryotic cells defines the boundary to the extracellular environment and, thus provides essential protection from the surroundings. Consequently, disruptions to the cell membrane triggered by excessive mechanical or biochemical stresses pose fatal threats to cells, which they need to cope with to survive. Eukaryotic cells cope with these threats by activating their plasma membrane repair system, which is shared by other cellular functions, and includes mechanisms to remove damaged membrane by internalization (endocytosis), shedding, reorganization of cytoskeleton and membrane fusion events to reseal the membrane. Members of the annexin protein family, which are characterized by their Ca2+-dependent binding to anionic phospholipids, are important regulators of plasma membrane repair. Recent studies based on cellular and biophysical membrane models show that they have more distinct functions in the repair response than previously assumed by regulating membrane curvature and excision of damaged membrane. In cells, plasma membrane injury and flux of Ca2+ ions into the cytoplasm trigger recruitment of annexins including annexin A4 and A6 to the membrane wound edges. Here, they induce curvature and constriction force, which help pull the wound edges together for eventual fusion. Cancer cells are dependent on efficient plasma membrane repair to counteract frequent stress-induced membrane injuries, which opens novel avenues to target cancer cells through their membrane repair system. Here, we discuss mechanisms of single cell wound healing implicating annexin proteins and membrane curvature.

scholarly journals Interdisciplinary Synergy to Reveal Mechanisms of Annexin-Mediated Plasma Membrane Shaping and Repair

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 1029 ◽  
Author(s):  
Poul Martin Bendix ◽  
Adam Cohen Simonsen ◽  
Christoffer D. Florentsen ◽  
Swantje Christin Häger ◽  
Anna Mularski ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Biology ◽  
Membrane Damage ◽  
Membrane Integrity ◽  
Interdisciplinary Approach ◽  
Membrane Repair ◽  
Cell Membrane Integrity ◽  
Curvature Sensing ◽  
Plasma Membrane Repair ◽  
Curved Membranes

The plasma membrane surrounds every single cell and essentially shapes cell life by separating the interior from the external environment. Thus, maintenance of cell membrane integrity is essential to prevent death caused by disruption of the plasma membrane. To counteract plasma membrane injuries, eukaryotic cells have developed efficient repair tools that depend on Ca2+- and phospholipid-binding annexin proteins. Upon membrane damage, annexin family members are activated by a Ca2+ influx, enabling them to quickly bind at the damaged membrane and facilitate wound healing. Our recent studies, based on interdisciplinary research synergy across molecular cell biology, experimental membrane physics, and computational simulations show that annexins have additional biophysical functions in the repair response besides enabling membrane fusion. Annexins possess different membrane-shaping properties, allowing for a tailored response that involves rapid bending, constriction, and fusion of membrane edges for resealing. Moreover, some annexins have high affinity for highly curved membranes that appear at free edges near rupture sites, a property that might accelerate their recruitment for rapid repair. Here, we discuss the mechanisms of annexin-mediated membrane shaping and curvature sensing in the light of our interdisciplinary approach to study plasma membrane repair.

Calcium efflux of plasma membrane vesicles exposed to ELF magnetic fields-test of a nuclear magnetic resonance interaction model

2012 ◽  
Vol 33 (7) ◽  
pp. 535-542 ◽  
Author(s):  
Wenjun J. Sun ◽  
Mehri Kaviani Mogadam ◽  
Marianne Sommarin ◽  
Henrietta Nittby ◽  
Leif G. Salford ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Plasma Membrane ◽  
Magnetic Resonance ◽  
Magnetic Fields ◽  
Interaction Model ◽  
Membrane Vesicles ◽  
Resonance Interaction ◽  
Calcium Efflux ◽  
Plasma Membrane Vesicles ◽  
Nuclear Magnetic
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