ABSTRACT
Mechano-growth factor (MGF) is a product of a unique muscle-specific splice variant of the insulin-like growth factor I gene. Potential use of MGF to improve regenerative capability of skeletal muscle as well as to prevent neuronal damage has been widely discussed. Human MGF was expressed in Saccharomyces cerevisiae, but the yield of the recombinant protein was low due to its rapid degradation. The proteinase B was identified as the enzyme responsible for MGF processing. A yeast strain with Deltaprb1 deletion was created resulting in a fivefold increase of MGF yield that reached 50 mg/l. The biological activity of recombinant MGF was verified in a proliferation assay employing human postnatal myoblasts.
Subject(s)
Insulin-Like Growth Factor I/biosynthesis , Insulin-Like Growth Factor I/genetics , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae/genetics , Serine Endopeptidases/metabolism , Gene Deletion , Humans , Recombinant Proteins/biosynthesis , Recombinant Proteins/genetics , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae Proteins/genetics , Serine Endopeptidases/geneticsABSTRACT
MGF is a product of a unique muscle-specific splice variant of IGF1 gene (insulin-like growth factor). Its peculiar feature is a specific E-peptide, a 16 a.a. strand at the C-terminus. MGF increases cellular proliferation and inhibits terminal differentiation of myoblasts necessary for the secondary myotube formation. Previous analysis of physiological effects of MGF was performed using indirect methods such as RT-PCR based examination of the transcript contents in normal tissues, adenovirus-mediated DNA delivery and synthetic E-domain administration. Here, we describe isolation and purification of recombinant MGF thus allowing for the first time the possibility of direct examining MGF effects. The recombinant MGF of directly examining--was expressed in Escherichia coli as inclusion bodies (about 100-200mg/l), purified and refolded. Biological activity of refolded MGF was analyzed in vitro in proliferation assays with normal human myoblasts. As a result of our work, it has become possible to generate a standard MGF control with characterized activity and a ready-to use MGF test-system neither of which have been previously described. Our data open opportunities for the future works on MGF characterization and to the development of a powerful and highly specific therapeutic agent potentially applicable for muscle growth up-regulation, post-trauma muscle repair, age and hereditary myodystrophy mitigation and in sport medicine.
