Growth factor

"Growth factors" redirects here. For the journal, see Growth Factors (journal).

A growth factor is a naturally occurring substance capable of stimulating cellular growth,[1] proliferation, healing, 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 cytokines and hormones 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 morphogenetic proteins stimulate bone cell differentiation, while fibroblast growth factors and vascular endothelial growth factors IGF stimulate blood vessel differentiation (angiogenesis).

Growth factors versus cytokines

Growth factor is sometimes used interchangeably among scientists with the term cytokine.[2] Historically, cytokines were associated with hematopoietic (blood forming) cells and immune system cells (e.g., lymphocytes and tissue cells from spleen, thymus, and lymph nodes). 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 molecules. However, as different lines of research converged, it became clear that some of the same signaling proteins the hematopoietic and immune systems 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.

The growth factor was first discovered by Rita Levi-Montalcini, which won her a Nobel prize.

Classes of growth factors

Individual growth factor proteins tend to occur as members of larger families of structurally and evolutionarily related proteins. There are many families, some of which are listed below:

This list is incomplete; you can help by expanding it.

Growth factors in platelets

The alpha granules in blood platelets contain growth factors PDGF, IGF-1, EGF, and TGF-β which begin healing of wounds by attracting and activating macrophages, fibroblasts, and endothelial cells.

Uses in medicine

For the last two decades, growth factors have been increasingly used in the treatment of hematologic and oncologic diseases and cardiovascular diseases such as:

See also

References

  1. ↑ "growth factor" at Dorland's Medical Dictionary
  2. ↑ Thomas Yorio; Abbot F. Clark; Martin B. Wax (15 October 2007). Ocular Therapeutics: Eye on New Discoveries. Academic Press. pp. 88–. ISBN 978-0-12-370585-3. Retrieved 28 November 2010.

External links


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