Question

Discuss in detail how mitogen Epidermal growth factor (EGF) influences the cell cycle

Answer 1

Mitogens are the  stimulators of  cell division, stops intracellular negative controls that block progress through the cell cycle.

The G1 checkpoint is controlled most directly by mitogens after that  cell cycle progression does not need mitogens to continue. Mitogens can be either endogenous or exogenous factors. Growth factors can act as mitogens and the well known among them are vascular endothelial growth fatctor, platelet derived growth factor, epidermal growth factor.

The transition from G0 to G1 is controlled by growth factors for:

• skin cells (epidermal growth factor, EGF)
• nerve cells (nerve growth factor, NGF)
• connective tissue or mesenchymal cells (fibroblast growth factor, FGF)
• thrombus-forming cells that line blood vessels (platelet- derived growth factor, PDGF)

Epidermal growth factor (EGF) is a protein that signals cells to undergo mitotic cell division and differentiation. The EGF receptor is a transmembrane protein. Within the cytoplasmic domain of the receptor there is a region, near the membrane, that functions as a kinase. There is also a stretch of 230 amino acids, near the end of the protein, which is associated with regulation of endocytosis. When the EGF receptor binds to the EGF ligand, individual receptor proteins move within the plane of the membrane and interact to form dimers. The kinase domains phosphorylate tyrosine amino acids on the cytoplasmic tail of the adjacent receptor and may be involved in phosphorylation of other, nearby proteins.