Growth factor

The growth factors, also called trophic factors, are a group of substances, most of them of a protein nature, which together with hormones and neurotransmitters play an important role in role in intercellular communication. The main function of growth factors is external control of the cell cycle by abandoning cell quiescence (G0) and entering the cell into G1 phase. The increase in cell size is stimulated by increasing protein synthesis.

History

Rita Levi-Montalcini was the discoverer of the first known growth factor, NGF (neuronal growth factor), for which she was awarded the Nobel Prize in Medicine in 1986.

Features

The function of growth factors is not only to stimulate cell proliferation by regulating the cell cycle by initiating mitosis, but also to maintain cell survival, stimulate cell migration, cell differentiation and even apoptosis.

The function of growth factors is regulated by different mechanisms that control gene activation such as:

1. The transcription and translation of the growth factor gene.
2. The signal emission modulation by the receiver.
3. Control of cellular response by molecules with action opposed to initial response.
4. Extracellular control due to the availability of the growth factor that is trapped in the extracellular matrix.

Through studies with cellular crops it was discovered that growth factors are transported by serum. They are produced by large number of cells and the requirements are very variable between different cells. In order for cells to proliferate in a crop, the existence of serum is necessary that provides growth factors and adhesive molecules such as fibronectin, vitronectin and nutritional such as lipoproteins, transferrin, as well as nutrients: amino acids, ions, energy molecules.

Mechanism of action

Growth factors are synthesized by a large number of cells, such as cellular mediators against various stimuli, such as injury. They do not act as enzymes, but as intercellular cell membrane signs. Its mechanism of action begins to join a specific cell receiver that activates a second messenger in which a kinase tyrosine protein intervenes and triggering a signal transduction to the interior of the cell. Due to this mechanism, the action of the factors in the place of the lesion continues even if they have disappeared the same as the medium, since they have activated the system of second messengers or sequentially a staircase of molecules.

Growth factors act in various ways on cells:

• Autocrino: The cell itself that produces the growth factor is self-stimulated by it, after being secreted and joining with its specific receptors.
• Paracrino: The cell produces growth factors that bind to adjacent cell receptors.
• Endocrine: The growth factor is produced by certain body cells that act on other distant cells, usually transported by the blood, such as hormones.
• Yuxtacrino: Some growth factors remain attached to the membrane of the cells that have synthesized them, from where they can activate the receptors of other adjacent cells.

Relation of growth factors and cancer:

Genetic alterations in growth factors are frequently associated with cancer through various mechanisms such as:

- Mutation of the genes that code for growth factors, transforming into a [[oncogene]], which increases growth factor activity.

- Amplification of genes that encode membrane (or cytoplasmic) receptors for a given growth factor.

Types of growth factors

• Adrenomedulin (AM)
• Angiopoyetin (Ang)
• Self-crine motility factor
• Bone morphogenetic protein s (BMP)
• Family of ciliar neurotrophic factor
  • ciliar neurotrophic factor (CNTF)
  • Leukemia inhibitor factor (LIF)
  • Interleucina-6 (IL-6)
• Colony stimulant factor
  • Macrophago colony stimulant factor (M-CSF)
  • granulocyte colony stimulant factor (G-CSF)
  • A stimulating factor of granulocyte and macrophages colonies (GM-CSF)
• Epidermal Growth Factor (EGF)
• Efrín
  • Efrín A1
  • Efrín A2
  • Efrín A3
  • Efrín A4
  • Efrín A5
  • Ephrin B1
  • Efrín B2
  • Ephrin B3
• Eritropoyetin (EPO)
• Fibroblast growth factor (FGF)
  • Fibroblast growth factor 1 (FGF1)
  • Fibroblast growth factor 2 (FGF2)
  • Fibroblast growth factor 3 (FGF3)
  • Fibroblast growth factor 4 (FGF4)
  • Fibroblast growth factor 5 (FGF5)
  • Fibroblast growth factor 6 (FGF6)
  • Fibroblast growth factor 7 (FGF7)
  • Fibroblast growth factor 8 (FGF8)
  • Fibroblast growth factor 9 (FGF9)
  • Fibroblast growth factor 10 (FGF10)
  • Fibroblast growth factor 11 (FGF11)
  • Fibroblast growth factor 12 (FGF12)
  • Fibroblast growth factor 13 (FGF13)
  • Fibroblast growth factor 14 (FGF14)
  • Fibroblast growth factor 15 (FGF15)
  • Fibroblast growth factor 16 (FGF16)
  • Fibroblast growth factor 17 (FGF17)
  • Fibroblast growth factor 18 (FGF18)
  • Fibroblast growth factor 19 (FGF19)
  • Fibroblast growth factor 20 (FGF20)
  • Fibroblast growth factor 21 (FGF21)
  • Fibroblast growth factor 22 (FGF22)
  • Fibroblast growth factor 23 (FGF23)
• Fetal bovine somatotropin (FBS)
• GDNF ligand family
  • Neurotrophic factor derived from the glial cell line (GDNF)
  • Neurturin
  • Persefin
  • Artemin
• Growth Difference Factor 9 (GDF9)
• Hepatocyte Growth Factor (HGF)
• Growth factor derived from hepatoma (HDGF)
• Insulin
• Growth factor similar to insulin s
  • Type 1 Insulin Growth Factor (IGF-1)
  • Type 2 Insulin Growth Factor (IGF-2)
• Interleucines
  • IL-1 - Cofactor for IL-3 and IL-6. Activate T cells.
  • IL-2 - T cell growth factor. Stimulates IL-1 synthesis. Activate B cells and NK cells.
  • IL-3: stimulates the production of all non-lymphoid cells.
  • IL-4: growth factor for activated B cells, T cells at rest and mast cells.
  • IL-5: Induces the differentiation of active B cells and eosinophiles.
  • IL-6 - Stimulates the synthesis of Ig. Plasma cell growth factor.
  • IL-7 - Pre-B cell growth factor.
• Keratinocyte Growth Factor (KGF)
• Migration Stimulant Factor (MSF)
• Macrophagus stimulant protein (MSP), also known as protein similar to the hepatocyte growth factor (HGFLP)
• Miostatin (GDF-8)
• Neuregulin s
  • Neuregulin 1 (NRG1)
  • Neuregulin 2 (NRG2)
  • Neuregulin 3 (NRG3)
  • Neuregulin 4 (NRG4)
• Neurotropines
  • neurotrophic factor derived from the brain (BDNF)
  • Nervous growth factor (NGF)
  • Neurotropine-3 (NT-3)
  • Neurotropine-4 (NT-4)
• Placement growth factor (PGF)
• Modelled Growth Factor (PDGF)
• Renalase (RNLS): antiapopotic survival factor
• T cell growth factor (TCGF)
• Trombopoyetin (TPO)
• Transformative growth factor
  • Alpha transformative growth factor (TGF-α)
  • Beta transformative growth factor (TGF-β)
• Alpha tumor necrosis factor (TNF-α)
• parent cell growth factor (FBC)
• Vascular endothelial growth factor (VEGF)
• Wnt signaling path

Uses

In the last two decades the therapeutic uses of growth factors have been increasing, currently used in the treatment of hematological and oncological diseases like:

• Granulocitopenia
• Myelodysplastic syndromes
• Leukemias
• Aplastic anemia
• Bone marrow transplants

They are also used in cosmetics for skin regeneration or hair loss.