Bridging of membrane surfaces by annexin A2

Abstract

The protein-mediated formation of membrane contacts is a crucial event in many cellular processes ranging from the establishment of organelle contacts to the docking of vesicles to a target membrane. Annexins are Ca2+ regulated membrane-binding proteins implicated in providing such membrane contacts; however, the molecular basis of membrane bridging by annexins is not fully understood. We addressed this central question using annexin A2 (AnxA2) that functions in secretory vesicle exocytosis possibly by providing membrane bridges. By quantitatively analyzing membrane contact formation using a novel assay based on quartz crystal microbalance recordings, we show that monomeric AnxA2 can bridge membrane surfaces Ca2+ dependently. However, this activity depends on an oxidative crosslink involving a cysteine residue in the N-terminal domain and thus formation of disulfide-linked dimers. Alkylated AnxA2 in which this cysteine residue has been modified and AnxA2 mutants lacking the N-terminal domain are not capable of bridging membrane surfaces. In contrast, a heterotetrameric complex comprising two membrane binding AnxA2 subunits linked by a S100A10 dimer can provide membrane contacts irrespective of oxidation status. Thus, monomeric AnxA2 only contains one lipid binding site and AnxA2-mediated linking of membrane surfaces under non-oxidative intracellular conditions most likely requires AnxA2-S100 complex formation.

Expression of Annexin A2 Promotes Cancer Progression in Estrogen Receptor Negative Breast Cancers

“…Altered calcium homeostasis has been observed within breast cancer, however, it is currently unclear whether the dysregulation of calcium binding proteins like Annexin A2 are a cause or a consequence of this imbalance [64]. Despite this, it is known that Ca 2+ level within the cell regulates Annexin A2 s affinity for its binding partners and cellular components such as the plasma membrane and the actin cytoskeleton [51,66,67]. Apart from Annexin A2, calcium binding proteins such as the S100 family (several of which were identified in our screen, Table S1) have been thoroughly investigated in the context of cancer, as reviewed by Bresnick et al [68] and these, along with Annexin A2, have the potential to be utilized as prognostic or therapeutic targets in breast cancer [69].…”

“…We thus tested the value of our experimental design by conducting a focused study on Annexin A2-a protein identified in both our migration and invasion experiments. Annexin A2 is a calcium ion regulated membrane binding protein [67] found to play a role in a wide range of cellular processes, from endo-and exo-cytosis to proliferation and apoptosis [51]. One of its best-known functions is its hand in the proteolytic cascade, triggered by the activation of plasmin.…”

Ileal proteomic changes associated with IL-25-mediated resistance against intestinal trematode infections

“…Annexin 2 is a protein that is part of the lipid rafts in the intestinal brush border and is associated with actin filaments mediating in membrane-membrane and membranecytoskeletal interactions influencing actin cytoskeletal remodeling through targeting signaling molecules to membrane domains. As a consequence it plays an important role in membrane trafficking and stabilization of membrane-associated protein complexes with the actin cytoskeleton and has been implicated in the migration of various cell types including epithelial cells and cell matrix interaction [41,49]. Moreover, annexin 2 has been shown to induce clustering of specific plasma membrane phospholipids and play a role in lipid domain formation [41].…”

Ileal proteomic changes associated with IL-25-mediated resistance against intestinal trematode infections

“…Annexin 2 is a protein that is part of the lipid rafts in the intestinal brush border and is associated with actin filaments mediating in membrane-membrane and membrane-cytoskeletal interactions influencing actin cytoskeletal remodeling through targeting signaling molecules to membrane domains. As a consequence, it plays a crucial role in membrane trafficking and stabilization of membrane-associated protein complexes with the actin cytoskeleton and has been involved in the migration of several types of cells, such as epithelial cells and cell matrix interaction [41,[49][50][51]. Moreover, annexin 2 induces clustering of specific plasma membrane phospholipids and is involved in lipid domain formation [41].…”