Shape of the membrane neck around a hole during plasma membrane repair.

Plasma membrane damage and rupture occurs frequently in cells, and holes must be sealed rapidly to ensure homeostasis and cell survival. The membrane repair machinery is known to involve recruitment of curvature-inducing annexin proteins, but the connection between membrane remodeling and hole closure is poorly described. The induction of curvature by repair proteins leads to the possible formation of a membrane neck around the hole as a key intermediate structure before sealing.

Lens Nucleation and Droplet Budding in a Membrane Model for Lipid Droplet Biogenesis.

Lipid droplet biogenesis comprises the emergence of cytosolic lipid droplets with a typical diameter 0.1-5 μm via synthesis of fat in the endoplasmatic reticulum, the formation of membrane-embedded lenses, and the eventual budding of lenses into solution as droplets. Lipid droplets in cells are increasingly being viewed as highly dynamic organelles with multiple functions in cell physiology.

Human myelin protein P2: from crystallography to time-lapse membrane imaging and neuropathy-associated variants.

Peripheral myelin protein 2 (P2) is a fatty acid-binding protein expressed in vertebrate peripheral nervous system myelin, as well as in human astrocytes. Suggested functions of P2 include membrane stacking and lipid transport. Mutations in the PMP2 gene, encoding P2, are associated with Charcot-Marie-Tooth disease (CMT).

Annexins A1 and A2 Accumulate and Are Immobilized at Cross-Linked Membrane-Membrane Interfaces.

Rapid membrane repair is required to ensure cell survival after rupture of the plasma membrane. The annexin family of proteins is involved in plasma membrane repair (PMR) and is activated by the influx of Ca from the extracellular medium at the site of injury. Annexins A1 and A2 (ANXA1 and ANXA2, respectively) are structurally similar and bind to negatively charged phosphatidylserine (PS) to induce membrane cross-linking and to promote fusion, which are both essential processes that occur during membrane repair.

Timescale of hole closure during plasma membrane repair estimated by calcium imaging and numerical modeling.

Plasma membrane repair is essential for eukaryotic cell life and is triggered by the influx of calcium through membrane wounds. Repair consists of sequential steps, with closure of the membrane hole being the key event that allows the cell to recover, thus identifying the kinetics of hole closure as important for clarifying repair mechanisms and as a quantitative handle on repair efficiency. We implement calcium imaging in MCF7 breast carcinoma cells subject to laser damage, coupled with a model describing the spatio-temporal calcium distribution.

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

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 Ca- and phospholipid-binding annexin proteins.

Membrane rolling induced by bacterial toxins.

Membrane curvature effects are important in numerous cellular processes and many membrane interacting proteins induce spontaneous curvature upon membrane binding. Shiga and cholera toxins both belong to the AB5 family of toxins and consist of a toxic A subunit and a membrane-binding pentameric B subunit. Shiga and cholera toxins induce tubular membrane invaginations in cells and GUVs due to curvature effects and the toxins are known from MD simulations to induce curvature.