What are chemokines?
Chemokines are a group of cytokines with small molecular weight whose main action is the recruitment of leukocyte subsets under homeostatic and pathological conditions. Their name is derived from their ability to induce directed chemotaxis in nearby responsive cells; they are chemotactic cytokines.
Trough interacting with chemokine receptors that are expressed on the cell surface as 7-transmembrane proteins coupled with G-protein for signaling transduction, chemokines can induce firm adhesion of targeted cells to the endothelium and direct the movement of targeted cells to their destination according to the concentration gradient of a given chemokine.
What is the function of chemokines?
Generally, chemokines are divided into two sections by function.
1. Homeostatic. They are constitutively produced in certain tissues and are responsible for basal leukocyte migration.
These include CCL14, CCL19, CCL20, CCL21, CCL25, CCL27, CXCL12 and CXCL13. This classification is not strict; for example, CCL20 can act also as pro-inflammatory chemokine.
2. Inflammatory. They are formed under pathological conditions (on pro-inflammatory stimuli, such as IL-1, TNF-alpha, LPS, or viruses) and actively participate in the inflammatory response attracting immune cells to the site of inflammation.
Examples are CXCL-8, CCL2, CCL3, CCL4, CCL5, CCL11, CXCL10 , etc.
The big family of chemokines
Reading here, you may wonder how big the chemokine family it is. The latest data indicates that the chemokine family consists of 50 endogenous chemokine ligands in humans and mice based on different behavior and structural characteristics and includes four families, involving CC chemokines, CXC chemokines, C chemokines and CX3C chemokines.
CUSABIO almost has all of chemokines, and all of them have biologic activity and high purity. Additionally, they are in stock. Once your experiment requires them, we'll post them as soon as possible. Here are several SDS-PAGE images of hot chemokines for your reference.
As mentioned above, the major role of chemokines is to act as a chemoattractant to guide the migration of cells. Cells that are attracted by chemokines follow a signal of increasing chemokine concentration towards the source of the chemokine. Currently, about the mechanism of chemokines is illustrated by one signaling pathway.
Through interacting with chemokine receptors that are expressed on the cell surface as 7-transmembrane proteins coupled with G-protein to transmit cell signals following ligand binding. Activation of G proteins, by chemokine receptors, causes the subsequent activation of an enzyme known as phospholipase C (PLC). PLC cleaves a molecule called phosphatidylinositol (4,5)-bisphosphate (PIP2) into two second messenger molecules known as Inositol triphosphate (IP3) and diacylglycerol (DAG) that trigger intracellular signaling events; DAG activates another enzyme called protein kinase C (PKC), and IP3 triggers the release of calcium from intracellular stores. These events promote many signaling cascades (such as the MAP kinase pathway) that generate responses like chemotaxis, degranulation, release of superoxide anions and changes in the avidity of cell adhesion molecules called integrins within the cell harbouring the chemokine receptor. You can click here to see the entire picture of signaling pathway.