Transforming growth factor (, or TGF) is used to describe two classes of
polypeptide
Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty ...
growth factor
A growth factor is a naturally occurring substance capable of stimulating cell proliferation, wound healing, and occasionally cellular differentiation. Usually it is a secreted protein or a steroid hormone. Growth factors are important for ...
s,
TGFα and
TGFβ.
The name "Transforming Growth Factor" is somewhat arbitrary, since the two classes of TGFs are not structurally or genetically related to one another, and they act through different
receptor
Receptor may refer to:
* Sensory receptor, in physiology, any neurite structure that, on receiving environmental stimuli, produces an informative nerve impulse
*Receptor (biochemistry), in biochemistry, a protein molecule that receives and respond ...
mechanisms. Furthermore, they do not always induce cellular transformation, and are not the only growth factors that induce cellular transformation.
Types
*
TGFα is upregulated in some human
cancer
Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...
s. It is produced in
macrophage
Macrophages (; abbreviated MPhi, φ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that ...
s,
brain
The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...
cells, and
keratinocyte
Keratinocytes are the primary type of cell found in the epidermis, the outermost layer of the skin. In humans, they constitute 90% of epidermal skin cells. Basal cells in the basal layer (''stratum basale'') of the skin are sometimes referre ...
s, and induces
epithelial
Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial ( mesothelial) tissues line the outer surfaces of man ...
development. It belongs to the
EGF family.
*
TGFβ exists in three known subtypes in humans, TGFβ1, TGFβ2, and TGFβ3. These are upregulated in
Marfan's syndrome and some human cancers, and play crucial roles in
tissue regeneration,
cell differentiation
Cellular differentiation is the process in which a stem cell changes from one type to a differentiated one. Usually, the cell changes to a more specialized type. Differentiation happens multiple times during the development of a multicellular ...
,
embryonic development
In developmental biology, animal embryonic development, also known as animal embryogenesis, is the developmental stage of an animal embryo. Embryonic development starts with the fertilization of an egg cell (ovum) by a sperm, sperm cell (spermat ...
, and regulation of the
immune system
The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as Tumor immunology, cancer cells, Parasitic worm, parasitic ...
. Isoforms of transforming growth factor-beta (TGF-β1) are also thought to be involved in the pathogenesis of
pre-eclampsia
Pre-eclampsia is a multi-system disorder specific to pregnancy, characterized by the new onset of hypertension, high blood pressure and often a significant amount of proteinuria, protein in the urine or by the new onset of high blood pressure a ...
. They belong to the
transforming growth factor beta family
The transforming growth factor beta (TGF-β) superfamily is a Protein superfamily, large group of structurally related cell regulatory proteins that was named after its first member, TGF beta 1, TGF-β1, originally described in 1983. They interac ...
.
TGFβ receptors are single pass
serine/threonine kinase receptors.
Function
These proteins were originally characterized by their capacity to induce
oncogenic transformation in a specific
cell culture
Cell culture or tissue culture is the process by which cell (biology), cells are grown under controlled conditions, generally outside of their natural environment. After cells of interest have been Cell isolation, isolated from living tissue, ...
system, rat kidney fibroblasts. Application of the transforming growth factors to normal
rat
Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include '' Neotoma'' (pack rats), '' Bandicota'' (bandicoo ...
kidney
In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...
fibroblasts
A fibroblast is a type of biological cell typically with a spindle shape that synthesizes the extracellular matrix and collagen, produces the structural framework ( stroma) for animal tissues, and plays a critical role in wound healing. Fibrobla ...
induces the cultured cells to proliferate and overgrow, no longer subject to the normal inhibition caused by contact between cells.
See also
*
Bone morphogenetic protein
Bone morphogenetic proteins (BMPs) are a group of growth factors also known as cytokines and as metabologens. Professor Marshall Urist and Professor Hari Reddi discovered their ability to induce the formation of bone and cartilage, BMPs are now ...
*
TGF beta signaling pathway
The transforming growth factor beta (TGFβ) signaling pathway is involved in many cellular processes in both the adult organism and the developing embryo including cell growth, cell differentiation, cell migration, apoptosis, cellular homeostasis a ...
*
Tubuloglomerular feedback
References
External links
Tumor growth factor (TGF) citations*
*
{{TGFβ receptor superfamily modulators
Growth factors
Signal transduction