Induction factors

Inducing factors are substances that act on a group of responding target cells and are released from a signaling center. This group includes growth factors, cytokines and hormones. They consist of glycoproteins, polypeptides and peptides.

Superfamily TGF-β
The family of transforming growth factors β was discovered in virus-transformed cells. TGF-β inhibit cell division and stimulate the secretion of extracellular matrix components. TGF-β is involved in the specification of body axes, the formation of mesoderm, cartilage and bone.

Superfamily FGF
The family of fibroblast growth factors includes more than 10 members important for both embryonic and postnatal periods of life. A group of factors was discovered in 1974. The factors work in close association with the extracellular matrix and binding to heparan sulfate is necessary for their function. It transmits a signal via the MAP-kinase pathway, stimulates the growth of limbs, contributes to the regionalization of the brain and to the specification of the dorsoventral arrangement.

Family Hedgehog
This group got its name from fruit fly larvae with a recessive allele of the hh (spiny belly) gene. A special member of the family is the Sonic Hedgehog gene, which is responsible for the dorsoventral arrangement of the neural tube and the anteroposterior arrangement of the limbs. The Indian Hedgehog gene is important in skeletal development.

Family Wnt
Wnt is a water-insoluble single-chain polypeptide. Its signaling pathway contains two sites of repression. Wnt has an important function in kidney development and myotome formation.

System Delta-Notch
The components of the system are the ligand' (Delta) and the receptor' (Notch). Both are built into the cell membrane and their interaction is possible only in close cell contact. The Delta-Notch system is important for neurogenesis and somitogenesis.

Other factors
Mezi další indukční faktory patří:
 * family LIF - maintains mouse germ cell pluripotency and induces human kidney development,
 * insulin family - growth regulation,
 * neurotrophins - necessary for the survival of neurons.

Related articles

 * Growth factor
 * Cytokines
 * Cell signaling
 * Transduction of signals in cells