An allergen is a type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise be harmless to the body. Such reactions are called allergies.
Microfilaments, also called actin filaments, are protein filaments in the cytoplasm of eukaryotic cells that form part of the cytoskeleton. They are primarily composed of polymers of actin, but are modified by and interact with numerous other proteins in the cell. Microfilaments are usually about 7 nm in diameter and made up of two strands of actin. Microfilament functions include cytokinesis, amoeboid movement, cell motility, changes in cell shape, endocytosis and exocytosis, cell contractility, and mechanical stability. Microfilaments are flexible and relatively strong, resisting buckling by multi-piconewton compressive forces and filament fracture by nanonewton tensile forces. In inducing cell motility, one end of the actin filament elongates while the other end contracts, presumably by myosin II molecular motors. Additionally, they function as part of actomyosin-driven contractile molecular motors, wherein the thin filaments serve as tensile platforms for myosin's ATP-dependent pulling action in muscle contraction and pseudopod advancement. Microfilaments have a tough, flexible framework which helps the cell in movement.
Allergic rhinitis, of which the seasonal type is called hay fever, is a type of inflammation in the nose that occurs when the immune system overreacts to allergens in the air. Signs and symptoms include a runny or stuffy nose, sneezing, red, itchy, and watery eyes, and swelling around the eyes. The fluid from the nose is usually clear. Symptom onset is often within minutes following allergen exposure, and can affect sleep and the ability to work or study. Some people may develop symptoms only during specific times of the year, often as a result of pollen exposure. Many people with allergic rhinitis also have asthma, allergic conjunctivitis, or atopic dermatitis.
A myofibril is a basic rod-like organelle of a muscle cell. Skeletal muscles are composed of long, tubular cells known as muscle fibers, and these cells contain many chains of myofibrils. Each myofibril has a diameter of 1–2 micrometres. They are created during embryonic development in a process known as myogenesis.
Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of over 100 μM; its mass is roughly 42 kDa, with a diameter of 4 to 7 nm.
Phalloidin belongs to a class of toxins called phallotoxins, which are found in the death cap mushroom (Amanita phalloides). It is a rigid bicyclic heptapeptide that is lethal after a few days when injected into the bloodstream. The major symptom of phalloidin poisoning is acute hunger due to the destruction of liver cells. It functions by binding and stabilizing filamentous actin (F-actin) and effectively prevents the depolymerization of actin fibers. Due to its tight and selective binding to F-actin, derivatives of phalloidin containing fluorescent tags are used widely in microscopy to visualize F-actin in biomedical research.
Oral allergy syndrome (OAS) or pollen-food allergy is a type of food allergy classified by a cluster of allergic reactions in the mouth and throat in response to eating certain fruits, nuts, and vegetables that typically develops in adults with hay fever.
ADF/cofilin is a family of actin-binding proteins associated with the rapid depolymerization of actin microfilaments that give actin its characteristic dynamic instability. This dynamic instability is central to actin's role in muscle contraction, cell motility and transcription regulation.
Cytochalasins are fungal metabolites that have the ability to bind to actin filaments and block polymerization and the elongation of actin. As a result of the inhibition of actin polymerization, cytochalasins can change cellular morphology, inhibit cellular processes such as cell division, and even cause cells to undergo apoptosis. Cytochalasins have the ability to permeate cell membranes, prevent cellular translocation and cause cells to enucleate. Cytochalasins can also have an effect on other aspects of biological processes unrelated to actin polymerization. For example, cytochalasin A and cytochalasin B can also inhibit the transport of monosaccharides across the cell membrane, cytochalasin H has been found to regulate plant growth, cytochalasin D inhibits protein synthesis and cytochalasin E prevents angiogenesis.
In molecular biology, treadmilling is a phenomenon observed within protein filaments of the cytoskeletons of many cells, especially in actin filaments and microtubules. It occurs when one end of a filament grows in length while the other end shrinks, resulting in a section of filament seemingly "moving" across a stratum or the cytosol. This is due to the constant removal of the protein subunits from these filaments at one end of the filament, while protein subunits are constantly added at the other end. Treadmilling was discovered by Wegner, who defined the thermodynamic and kinetic constraints. Wegner recognized that: “The equilibrium constant (K) for association of a monomer with a polymer is the same at both ends, since the addition of a monomer to each end leads to the same polymer.”; a simple reversible polymer can’t treadmill; ATP hydrolysis is required. GTP is hydrolyzed for microtubule treadmilling.
Expansins are a family of closely related nonenzymatic proteins found in the plant cell wall, with important roles in plant cell growth, fruit softening, abscission, emergence of root hairs, pollen tube invasion of the stigma and style, meristem function, and other developmental processes where cell wall loosening occurs. Expansins were originally discovered as mediators of acid growth, which refers to the widespread characteristic of growing plant cell walls to expand faster at low (acidic) pH than at neutral pH. Expansins are thus linked to auxin action. They are also linked to cell enlargement and cell wall changes induced by other plant hormones such as gibberellin, cytokinin, ethylene and brassinosteroids.
Profilin-1 is a protein that in humans is encoded by the PFN1 gene.
Vasodilator-stimulated phosphoprotein is a protein that in humans is encoded by the VASP gene.
Profilin-2 is a protein that in humans is encoded by the PFN2 gene.
Toll-like receptor 11 (TLR11) is a protein that in mice and rats is encoded by the gene TLR11, whereas in humans it is represented by a pseudogene. TLR11 belongs to the toll-like receptor (TLR) family and the interleukin-1 receptor/toll-like receptor superfamily. In mice, TLR11 has been shown to recognise (bacterial) flagellin and (eukaryotic) profilin present on certain microbes, it helps propagate a host immune response. TLR11 plays a fundamental role in both the innate and adaptive immune responses, through the activation of Tumor necrosis factor-alpha, the Interleukin 12 (IL-12) response, and Interferon-gamma (IFN-gamma) secretion. TLR11 mounts an immune response to multiple microbes, including Toxoplasma gondii, Salmonella species, and uropathogenic E. coli, and likely many other species due to the highly conserved nature of flagellin and profilin.
The Actin assembly-inducing protein (ActA) is a protein encoded and used by Listeria monocytogenes to propel itself through a mammalian host cell. ActA is a bacterial surface protein comprising a membrane-spanning region. In a mammalian cell the bacterial ActA interacts with the Arp2/3 complex and actin monomers to induce actin polymerization on the bacterial surface generating an actin comet tail. The gene encoding ActA is named actA or prtB.
Actin remodeling is the biochemical process that allows for the dynamic alterations of cellular organization. The remodeling of actin filaments occurs in a cyclic pattern on cell surfaces and exists as a fundamental aspect to cellular life. During the remodeling process, actin monomers polymerize in response to signaling cascades that stem from environmental cues. The cell's signaling pathways cause actin to affect intracellular organization of the cytoskeleton and often consequently, the cell membrane. Again triggered by environmental conditions, actin filaments break back down into monomers and the cycle is completed. Actin-binding proteins (ABPs) aid in the transformation of actin filaments throughout the actin remodeling process. These proteins account for the diverse structure and changes in shape of Eukaryotic cells. Despite its complexity, actin remodeling may result in complete cytoskeletal reorganization in under a minute.
mDia1 is a member of the protein family called the formins and is a Rho effector. It is the mouse version of the diaphanous homolog 1 of Drosophila. mDia1 localizes to cells' mitotic spindle and midbody, plays a role in stress fiber and filopodia formation, phagocytosis, activation of serum response factor, formation of adherens junctions, and it can act as a transcription factor. mDia1 accelerates actin nucleation and elongation by interacting with barbed ends of actin filaments. The gene encoding mDia1 is located on Chromosome 18 of Mus musculus and named Diap1.
In molecular biology, the cyclase-associated protein family (CAP) is a family of highly conserved actin-binding proteins present in a wide range of organisms including yeast, flies, plants, and mammals. CAPs are multifunctional proteins that contain several structural domains. CAP is involved in species-specific signalling pathways. In Drosophila, CAP functions in Hedgehog-mediated eye development and in establishing oocyte polarity. In Dictyostelium discoideum, CAP is involved in microfilament reorganisation near the plasma membrane in a PIP2-regulated manner and is required to perpetuate the cAMP relay signal to organise fruitbody formation. In plants, CAP is involved in plant signalling pathways required for co-ordinated organ expansion. In yeast, CAP is involved in adenylate cyclase activation, as well as in vesicle trafficking and endocytosis. In both yeast and mammals, CAPs appear to be involved in recycling G-actin monomers from ADF/cofilins for subsequent rounds of filament assembly. In mammals, there are two different CAPs that share 64% amino acid identity.
Ursula Wiedermann is an Austrian medical scientist who has made significant contributions in the field of allergies and of cancer immunotherapy. She is currently Professor of Vaccinology at the Medical University of Vienna. Wiedermann's work in the field of B cell peptide vaccines led to the creation of HER-Vaxx, an immunotherapy for the treatment of HER-2-positive cancers. This vaccine is currently being taken into mid-stage clinical development in gastric cancer by the biotech company Imugene, where Wiedermann is Chief Scientific Officer.
