Growth factor
Encyclopedia
A growth factor is a naturally occurring substance capable of stimulating cellular growth, proliferation and cellular differentiation
. Usually it is a protein
or a steroid
hormone
. Growth factors are important for regulating a variety of cellular processes.
Growth factors typically act as signaling molecules between cells. Examples are cytokine
s and hormone
s that bind to specific receptors
on the surface of their target cells
.
They often promote cell differentiation and maturation, which varies between growth factors. For example, bone morphogenic proteins
stimulate bone cell differentiation, while fibroblast growth factor
s and vascular endothelial growth factor
s stimulate blood vessel differentiation (angiogenesis
).
. Historically, cytokines were associated with hematopoietic (blood forming) cells and immune system
cells (e.g., lymphocytes and tissue cells from spleen
, thymus
, and lymph node
s). For the circulatory system
and bone marrow
in which cells can occur in a liquid suspension and not bound up in solid tissue
, it makes sense for them to communicate by soluble, circulating protein molecule
s. However, as different lines of research converged, it became clear that some of the same signaling proteins the hematopoietic and immune system
s used were also being used by all sorts of other cells and tissues, during development and in the mature organism.
While growth factor implies a positive effect on cell division, cytokine is a neutral term with respect to whether a molecule affects proliferation. While some cytokines can be growth factors, such as G-CSF and GM-CSF, others have an inhibitory effect on cell growth or proliferation. Some cytokines, such as Fas ligand
, are used as "death" signals; they cause target cells to undergo programmed cell death or apoptosis
.
arily related proteins. There are many families, which are listed below:
Stimulates cell cycle from G0 phase to G1 phase
and oncologic
diseases and cardiovascular diseases like:
Cellular differentiation
In developmental biology, cellular differentiation is the process by which a less specialized cell becomes a more specialized cell type. Differentiation occurs numerous times during the development of a multicellular organism as the organism changes from a simple zygote to a complex system of...
. Usually it is a protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
or a steroid
Steroid
A steroid is a type of organic compound that contains a characteristic arrangement of four cycloalkane rings that are joined to each other. Examples of steroids include the dietary fat cholesterol, the sex hormones estradiol and testosterone, and the anti-inflammatory drug dexamethasone.The core...
hormone
Hormone
A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...
. Growth factors are important for regulating a variety of cellular processes.
Growth factors typically act as signaling molecules between cells. Examples are cytokine
Cytokine
Cytokines are small cell-signaling protein molecules that are secreted by the glial cells of the nervous system and by numerous cells of the immune system and are a category of signaling molecules used extensively in intercellular communication...
s and hormone
Hormone
A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...
s that bind to specific receptors
Receptor (biochemistry)
In biochemistry, a receptor is a molecule found on the surface of a cell, which receives specific chemical signals from neighbouring cells or the wider environment within an organism...
on the surface of their target cells
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
.
They often promote cell differentiation and maturation, which varies between growth factors. For example, bone morphogenic proteins
Bone morphogenetic protein
Bone morphogenetic proteins are a group of growth factors also known as cytokines and as metabologens . Originally discovered by their ability to induce the formation of bone and cartilage, BMPs are now considered to constitute a group of pivotal morphogenetic signals, orchestrating tissue...
stimulate bone cell differentiation, while fibroblast growth factor
Fibroblast growth factor
Fibroblast growth factors, or FGFs, are a family of growth factors involved in angiogenesis, wound healing, and embryonic development. The FGFs are heparin-binding proteins and interactions with cell-surface associated heparan sulfate proteoglycans have been shown to be essential for FGF signal...
s and vascular endothelial growth factor
Vascular endothelial growth factor
Vascular endothelial growth factor is a signal protein produced by cells that stimulates vasculogenesis and angiogenesis. It is part of the system that restores the oxygen supply to tissues when blood circulation is inadequate....
s stimulate blood vessel differentiation (angiogenesis
Angiogenesis
Angiogenesis is the physiological process involving the growth of new blood vessels from pre-existing vessels. Though there has been some debate over terminology, vasculogenesis is the term used for spontaneous blood-vessel formation, and intussusception is the term for the formation of new blood...
).
Growth factors versus cytokines
Growth factor is sometimes used interchangeably among scientists with the term cytokineCytokine
Cytokines are small cell-signaling protein molecules that are secreted by the glial cells of the nervous system and by numerous cells of the immune system and are a category of signaling molecules used extensively in intercellular communication...
. Historically, cytokines were associated with hematopoietic (blood forming) cells and immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
cells (e.g., lymphocytes and tissue cells from spleen
Spleen
The spleen is an organ found in virtually all vertebrate animals with important roles in regard to red blood cells and the immune system. In humans, it is located in the left upper quadrant of the abdomen. It removes old red blood cells and holds a reserve of blood in case of hemorrhagic shock...
, thymus
Thymus
The thymus is a specialized organ of the immune system. The thymus produces and "educates" T-lymphocytes , which are critical cells of the adaptive immune system....
, and lymph node
Lymph node
A lymph node is a small ball or an oval-shaped organ of the immune system, distributed widely throughout the body including the armpit and stomach/gut and linked by lymphatic vessels. Lymph nodes are garrisons of B, T, and other immune cells. Lymph nodes are found all through the body, and act as...
s). For the circulatory system
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
and bone marrow
Bone marrow
Bone marrow is the flexible tissue found in the interior of bones. In humans, bone marrow in large bones produces new blood cells. On average, bone marrow constitutes 4% of the total body mass of humans; in adults weighing 65 kg , bone marrow accounts for approximately 2.6 kg...
in which cells can occur in a liquid suspension and not bound up in solid tissue
Tissue (biology)
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
, it makes sense for them to communicate by soluble, circulating protein molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
s. However, as different lines of research converged, it became clear that some of the same signaling proteins the hematopoietic and immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
s used were also being used by all sorts of other cells and tissues, during development and in the mature organism.
While growth factor implies a positive effect on cell division, cytokine is a neutral term with respect to whether a molecule affects proliferation. While some cytokines can be growth factors, such as G-CSF and GM-CSF, others have an inhibitory effect on cell growth or proliferation. Some cytokines, such as Fas ligand
FAS ligand
Fas ligand is a type-II transmembrane protein that belongs to the tumor necrosis factor family. Its binding with its receptor induces apoptosis. Fas ligand/receptor interactions play an important role in the regulation of the immune system and the progression of cancer.- Structure :Fas ligand or...
, are used as "death" signals; they cause target cells to undergo programmed cell death or apoptosis
Apoptosis
Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...
.
Classes of growth factors
Individual growth factor proteins tend to occur as members of larger families of structurally and evolutionEvolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
arily related proteins. There are many families, which are listed below:
- AdrenomedullinAdrenomedullinAdrenomedullin is a peptide associated with pheochromocytoma- a tumour arising from adrenal medulla. It was discovered in 1993.Adrenomedullin is a ubiquitously expressed peptide initially isolated from phaechromyctoma in 1993...
(AM) - AngiopoietinAngiopoietinThe angiopoietins are protein growth factors that promote angiogenesis, the formation of blood vessels from pre-existing blood vessels. There are now four identified angiopoietins:...
(Ang) - Autocrine motility factor
- Bone morphogenetic proteinBone morphogenetic proteinBone morphogenetic proteins are a group of growth factors also known as cytokines and as metabologens . Originally discovered by their ability to induce the formation of bone and cartilage, BMPs are now considered to constitute a group of pivotal morphogenetic signals, orchestrating tissue...
s (BMPs) - Brain-derived neurotrophic factorBrain-derived neurotrophic factorBrain-derived neurotrophic factor, also known as BDNF, is a protein that, in humans, is encoded by the BDNF gene. BDNF is a member of the "neurotrophin" family of growth factors, which are related to the canonical "Nerve Growth Factor", NGF...
(BDNF) - Epidermal growth factorEpidermal growth factorEpidermal growth factor or EGF is a growth factor that plays an important role in the regulation of cell growth, proliferation, and differentiation by binding to its receptor EGFR...
(EGF) - ErythropoietinErythropoietinErythropoietin, or its alternatives erythropoetin or erthropoyetin or EPO, is a glycoprotein hormone that controls erythropoiesis, or red blood cell production...
(EPO) - Fibroblast growth factorFibroblast growth factorFibroblast growth factors, or FGFs, are a family of growth factors involved in angiogenesis, wound healing, and embryonic development. The FGFs are heparin-binding proteins and interactions with cell-surface associated heparan sulfate proteoglycans have been shown to be essential for FGF signal...
(FGF) - Glial cell line-derived neurotrophic factorGlial cell line-derived neurotrophic factorGlial cell-derived neurotrophic factor, also known as GDNF is a protein that, in humans, is encoded by the GDNF gene.GDNF is a small protein that potently promotes the survival of many types of neurons.-Function:...
(GDNF) - Granulocyte colony-stimulating factorGranulocyte colony-stimulating factorGranulocyte colony-stimulating factor is a colony-stimulating factor hormone. G-CSF is also known as colony-stimulating factor 3 ....
(G-CSF) - Granulocyte macrophage colony-stimulating factor (GM-CSF)
- Growth differentiation factor-9Growth differentiation factor-9Growth/differentiation factor 9 is a protein that in humans is encoded by the GDF9 gene.GDF9 plays an important role in the development of primary follicles in the ovary...
(GDF9) - Hepatocyte growth factorHepatocyte growth factorHepatocyte growth factor/scatter factor is a paracrine cellular growth, motility and morphogenic factor. It is secreted by mesenchymal cells and targets and acts primarily upon epithelial cells and endothelial cells, but also acts on haemopoietic progenitor cells...
(HGF) - Hepatoma-derived growth factor (HDGF)
- Insulin-like growth factorInsulin-like growth factorThe insulin-like growth factors are proteins with high sequence similarity to insulin. IGFs are part of a complex system that cells use to communicate with their physiologic environment...
(IGF) - Migration-stimulating factor
- MyostatinMyostatinMyostatin is a secreted TGF beta protein family member that inhibits muscle differentiation and growth. Myostatin is produced primarily in skeletal muscle cells, circulates in the blood and acts on muscle tissue, by binding a cell-bound receptor called the activin type II receptor...
(GDF-8) - Nerve growth factorNerve growth factorNerve growth factor is a small secreted protein that is important for the growth, maintenance, and survival of certain target neurons . It also functions as a signaling molecule. It is perhaps the prototypical growth factor, in that it is one of the first to be described...
(NGF) and other neurotrophins - Platelet-derived growth factorPlatelet-derived growth factorIn molecular biology, platelet-derived growth factor is one of the numerous growth factors, or proteins that regulate cell growth and division. In particular, it plays a significant role in blood vessel formation , the growth of blood vessels from already-existing blood vessel tissue. Uncontrolled...
(PDGF) - ThrombopoietinThrombopoietinThrombopoietin also known as megakaryocyte growth and development factor is a protein that in humans is encoded by the THPO gene....
(TPO) - Transforming growth factor alpha(TGF-α)
- Transforming growth factor beta(TGF-β)
- Tumor necrosis factor-alpha(TNF-α)
- Vascular endothelial growth factorVascular endothelial growth factorVascular endothelial growth factor is a signal protein produced by cells that stimulates vasculogenesis and angiogenesis. It is part of the system that restores the oxygen supply to tissues when blood circulation is inadequate....
(VEGF) - Wnt Signaling PathwayWnt signaling pathwayThe Wnt signaling pathway is a network of proteins best known for their roles in embryogenesis and cancer, but also involved in normal physiological processes in adult animals.-Discovery:...
- placental growth factorPlacental growth factorPlacental growth factor is a protein that in humans is encoded by the PGF gene.Placental growth factor is a member of the VEGF sub-family - a key molecule in angiogenesis and vasculogenesis, in particular during embryogenesis. The main source of PGF during pregnancy is the placental trophoblast...
(PlGF) - [(Foetal Bovine Somatotrophin)] (FBS)
- IL-1- Cofactor for IL-3 and IL-6. Activates T cells.
- IL-2- T-cell growth factor. Stimulates IL-1 synthesis. Activates B-cells and NK cells.
- IL-3- Stimulates production of all non-lymphoid cells.
- IL-4- Growth factor for activated B cells, resting T cells, and mast cells.
- IL-5- Induces differentiation of activated B cells and eosinophils.
- IL-6- Stimulates Ig synthesis. Growth factor for plasma cells.
- IL-7- Growth factor for pre-B cells.
Stimulates cell cycle from G0 phase to G1 phase
Uses in medicine
For the last two decades, growth factors have been increasingly used in the treatment of hematologicHematology
Hematology, also spelled haematology , is the branch of biology physiology, internal medicine, pathology, clinical laboratory work, and pediatrics that is concerned with the study of blood, the blood-forming organs, and blood diseases...
and oncologic
Oncology
Oncology is a branch of medicine that deals with cancer...
diseases and cardiovascular diseases like:
- neutropeniaNeutropeniaNeutropenia, from Latin prefix neutro- and Greek suffix -πενία , is a granulocyte disorder characterized by an abnormally low number of neutrophils, the most important type of white blood cell...
- myelodysplastic syndromeMyelodysplastic syndromeThe myelodysplastic syndromes are a diverse collection of hematological medical conditions that involve ineffective production of the myeloid class of blood cells....
(MDS) - leukemiaLeukemiaLeukemia or leukaemia is a type of cancer of the blood or bone marrow characterized by an abnormal increase of immature white blood cells called "blasts". Leukemia is a broad term covering a spectrum of diseases...
s - aplastic anaemia
- bone marrowBone marrowBone marrow is the flexible tissue found in the interior of bones. In humans, bone marrow in large bones produces new blood cells. On average, bone marrow constitutes 4% of the total body mass of humans; in adults weighing 65 kg , bone marrow accounts for approximately 2.6 kg...
transplantation - angiogenesisAngiogenesisAngiogenesis is the physiological process involving the growth of new blood vessels from pre-existing vessels. Though there has been some debate over terminology, vasculogenesis is the term used for spontaneous blood-vessel formation, and intussusception is the term for the formation of new blood...
for cardiovascular diseases
See also
- Wound healing#Overview of involved growth factors
- Signal transductionSignal transductionSignal transduction occurs when an extracellular signaling molecule activates a cell surface receptor. In turn, this receptor alters intracellular molecules creating a response...
- Receptor (biochemistry)Receptor (biochemistry)In biochemistry, a receptor is a molecule found on the surface of a cell, which receives specific chemical signals from neighbouring cells or the wider environment within an organism...
- CytokineCytokineCytokines are small cell-signaling protein molecules that are secreted by the glial cells of the nervous system and by numerous cells of the immune system and are a category of signaling molecules used extensively in intercellular communication...
- AngiogenesisAngiogenesisAngiogenesis is the physiological process involving the growth of new blood vessels from pre-existing vessels. Though there has been some debate over terminology, vasculogenesis is the term used for spontaneous blood-vessel formation, and intussusception is the term for the formation of new blood...
- Human Genome OrganisationHuman Genome OrganisationThe Human Genome Organisation is an organization involved in the Human Genome Project, a project about mapping the human genome. HUGO was established in 1989 as an international organization, primarily to foster collaboration between genome scientists around the world...
- Growth factor receptorGrowth factor receptorA growth factor receptor is a receptor which binds to growth factor.These receptors may use the JAK/STAT, MAP kinase, and PI3 kinase pathways....
- MitogenMitogenA mitogen is a chemical substance that encourages a cell to commence cell division, triggering mitosis. A mitogen is usually some form of a protein.Mitogenesis is the induction of mitosis, typically via a mitogen....