Thymosins are small proteins present in many animal tissues. They are named thymosins because they were originally isolated from the

thymus The thymus (: thymuses or thymi) is a specialized primary lymphoid organ of the immune system. Within the thymus, T cells mature. T cells are critical to the adaptive immune system, where the body adapts to specific foreign invaders. The thymus ...

, but most are now known to be present in many other tissues. Thymosins have diverse biological activities, and two in particular, thymosins α₁ and β₄, have potentially important uses in medicine, some of which have already progressed from the laboratory to the clinic. In relation to diseases, thymosins have been categorized as

biological response modifiers Biological response modifiers (BRMs) are substances that modify immune responses. They can be endogenous (produced naturally within the body) or exogenous (as pharmaceutical drugs), and they can either enhance an immune response or suppress it. ...

. Thymosins are important for proper T-cell development and differentiation.

Discovery

The discovery of thymosins in the mid 1960s emerged from investigations of the role of the

in development of the vertebrate

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 ...

. Begun by

Allan L. Goldstein Allan L. Goldstein is emeritus professor in the Department of Biochemistry and Molecular Medicine at the George Washington University School of Medicine. He chaired the department from 1978 until March 2009 and was awarded emeritus status in 20 ...

in the Laboratory of Abraham White at the

Albert Einstein College of Medicine The Albert Einstein College of Medicine is a Private university, private medical school in New York City. Founded in 1953, Einstein is an independent degree-granting institution within the Montefiore Einstein Health System. Einstein hosts Doc ...

in New York, the work continued at

University of Texas Medical Branch The University of Texas Medical Branch (UTMB) is a Public university, public Academic health science centre, academic health science center in Galveston, Texas, United States. It is part of the University of Texas System. UTMB includes the olde ...

in Galveston and at The George Washington University School of Medicine and Health Sciences in Washington D.C. The supposition that the role of the thymus might involve a

hormone A hormone (from the Ancient Greek, Greek participle , "setting in motion") is a class of cell signaling, signaling molecules in multicellular organisms that are sent to distant organs or tissues by complex biological processes to regulate physio ...

-like mechanism led to the isolation from thymus tissue of a biologically active preparation. Known as "Thymosin Fraction 5", this was able to restore some aspects of immune function in animals lacking thymus gland. Fraction 5 was found to contain over 40 small

peptides 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 Dalton (unit), Da or more are called proteins. Chains of fewer t ...

(molecular weights ranging from 1000 to 15,000 Da.), which were named "thymosins" and classified as α, β and γ thymosins on the basis of their behaviour in an electric field. Although found together in Fraction 5, they are now known to be structurally and genetically unrelated. Thymosin β₁ was found to be

ubiquitin Ubiquitin is a small (8.6 kDa) regulatory protein found in most tissues of eukaryotic organisms, i.e., it is found ''ubiquitously''. It was discovered in 1975 by Gideon Goldstein and further characterized throughout the late 1970s and 19 ...

(truncated by two C-terminal glycine residues). When individual thymosins were isolated from Fraction 5 and characterized, they were found to have extremely varied and important biological properties. However they are not truly thymic hormones in that they are not restricted in occurrence to thymus and several are widely distributed throughout many different tissues.

Doping in sports

Thymosin beta-4 Thymosin beta-4 is a protein that in humans is encoded by the ''TMSB4X'' gene. Recommended INN (International Nonproprietary Name) for thymosin beta-4 is 'timbetasin', as published by the World Health Organization (WHO). The protein consists (in ...

was allegedly used by some players in various Australian football codes and is under investigation by the Australian Sports Anti-Doping Authority for anti-doping violations.

Thymosin as a hair loss treatment

The process of hair growth utilizes many cellular and molecular mechanisms common to angiogenesis and wound healing. While studying the influence of thymosin beta-4 (Tβ4) on wound healing, Philp et al. accidentally found that hair grew more rapidly around the edges of wounds. In due course, they showed that Tβ4 induced rapid hair growth on the dorsal skin of healthy mice.

References

;Notes ;Sources *Koh, B. (2013). Cronulla Sharks and thymosin beta-4 ... is it doping? Retrieved from http://theconversation.edu.au/cronulla-sharks-and-thymosin-beta-4-is-it-doping-12694

External links

* {{Hormones Hormones of the thymus gland Hormones of the immune system

Discovery

Doping in sports

Thymosin as a hair loss treatment

See also

References

External links