MGF receptors, as detected in rabbit mesenchymal stem cells. From Xin J, Wang Y, Wang Z, Lin F. Functional and transcriptomic analysis of the regulation of osteoblasts by mechano-growth factor E peptide. Biotechnology and applied biochemistry. 2014;61(2):193-201, reproduced under the terms of the Creative Commons Attribution License

MGF receptors, as detected in rabbit mesenchymal stem cells. From Xin J, Wang Y, Wang Z, Lin F. Functional and transcriptomic analysis of the regulation of osteoblasts by mechano-growth factor E peptide. Biotechnology and applied biochemistry. 2014;61(2):193-201, reproduced under the terms of the Creative Commons Attribution License

Mechano-growth factor is derived from insulin-like growth factor IGF-11. Natural MGF is produced as a result of differential splicing of mRNA that normally expresses this hormone2. MGF may be detected in sites of tissue damage3. For example, it may induce accelerated growth in injured skeletal muscle tissue4. Therefore, it is regarded as a response to mechanical stress on tissues. However, chemical and thermal stress may also be associated in the expression of MGF5. It may be released in response to the presence of myofibrillar proteins, and may increase the concentrations of cyclic AMP in cultured muscle cells2. The inhibition of adenylyl cyclase was also associated with reduced MGF synthesis, suggesting that this enzyme is involved in MGF regulation5. A group of researchers also reported that the administration of hydrocortisone abolished MGF expression in cultured muscle cells and tissues2. Other forms of mechanical stress may also be associated with MGF expression4. Some researchers assert that treatment with MGF results in improved muscle tissue re-modeling following injury1. Therefore, MGF may be applied in studies and models of tissue repair and regeneration6. The molecular weight of MGF is nearly 2.9kDa, and it is available as a laboratory-grade compoundi. It has a receptor, which is found in locations such as the surfaces of some stem cell types7.

The mechanism by which MGF induces hypertrophy in stressed tissues is not as yet clear1. A 2014 study using murine muscle tissue and cells in culture found that it did not affect a number of markers of differentiation1. Interestingly, the peptide may be associated with differentiation in other tissue types. Rabbit stem cells incubated with up to 75ng/ml MGF exhibited differentiation into bone cells, which was associated with protein kinase B signaling7. However, no significant differences were reported in this study. Other groups have claimed that protein kinase B and its activation is required for similar effects in cardiac cells1. A further study using rat bone progenitor cells indicated that MGF acts to enhance the proliferation, rather than the differentiation, of these cells6. More chronic treatment with MGF, however, may promote differentiation at a later stage of bone tissue development (or regeneration)6.

Hypertrophy and abnormal heart function are detrimental side-effects of myocardial infarction8. Mice that underwent experimental infarctions received chronic MGF treatment for ten weeks8. This resulted in significant improvements in cardiac function, but did not affect hypertrophy, compared to control animals8. It would stand to reason that MGF would be present in the growth plates (sites in bone along which cells proliferate and are distributed to increase the length of said bone) of young animals4. A recent study using infant pigs detected MGF mRNA in these sites4. The peptide, however, does not appear to function to affect proliferation in the growth plates4.

Mechano-growth factor is a truncated form of IGF-1 which may be expressed in vivo in response to a variety of cellular stress. Some studies infer that it functions to enhance the proliferation of cells in response to damage and to induce hypertrophy in growing tissues.

References:

  1. Fornaro M, Hinken AC, Needle S, et al. Mechano-growth factor peptide, the COOH terminus of unprocessed insulin-like growth factor 1, has no apparent effect on myoblasts or primary muscle stem cells. American journal of physiology. Endocrinology and metabolism. 2014;306(2):E150-156.
  2. Kravchenko IV, Furalyov VA, Popov VO. Stimulation of mechano-growth factor expression by myofibrillar proteins in murine myoblasts and myotubes. Molecular and cellular biochemistry. 2012;363(1-2):347-355.
  3. Vassilakos G, Philippou A, Tsakiroglou P, Koutsilieris M. Biological activity of the e domain of the IGF-1Ec as addressed by synthetic peptides. Hormones (Athens, Greece). 2014;13(2):182-196.
  4. Schlegel W, Raimann A, Halbauer D, et al. Insulin-like growth factor I (IGF-1) Ec/Mechano Growth factor--a splice variant of IGF-1 within the growth plate. PloS one. 2013;8(10):e76133.
  5. Kravchenko IV, Furalyov VA, Popov VO. Hyperthermia and acidification stimulate mechano-growth factor synthesis in murine myoblasts and myotubes. Biochemical and biophysical research communications. 2008;375(2):271-274.
  6. Xin J, Wang Y, Wang Z, Lin F. Functional and transcriptomic analysis of the regulation of osteoblasts by mechano-growth factor E peptide. Biotechnology and applied biochemistry. 2014;61(2):193-201.
  7. Tong Y, Feng W, Wu Y, Lv H, Jia Y, Jiang D. Mechano-growth factor accelerates the proliferation and osteogenic differentiation of rabbit mesenchymal stem cells through the PI3K/AKT pathway. BMC biochemistry. 2015;16(1):1.
  8. Shioura K, Pena J, Goldspink P. Administration of a Synthetic Peptide Derived from the E-domain Region of Mechano-Growth Factor Delays Decompensation Following Myocardial Infarction. International journal of cardiovascular research. 2014;3(3):1000169.
  9. MGF Product Page. Blue Sky Peptide. 2016