Expression of IGF-1 isoforms after exercise-induced muscle damage in humans: characterization of the MGF E peptide actions in vitro.
نویسندگان
چکیده
Different insulin-like growth factor-1 (IGF-1) isoforms, namely IGF-1Ea, IGF-1Eb and IGF-1Ec (MGF), have been proposed to have various functions in muscle repair and growth. To gain insight into the potentially differential actions of IGF-1 isoforms in the regulation of muscle regeneration, we assessed the time course of their expressions at both mRNA and protein levels after exercise-induced muscle damage in humans. In addition, we characterized mature IGF-1 and synthetic MGF E peptide signalling in C2C12 myoblast-like cells in vitro. Ten healthy male volunteers were subjected to exercise-induced muscle damage and biopsy samples were taken from the exercised muscles before and 6 h, 2, 5 and 16 days post exercise. Muscle damage was documented by specific functional and biochemical responses post exercise. PCR-based analyses of muscle biopsy samples revealed a rapid and transient up-regulation of MGF mRNA expression which was followed by a prolonged increase of IGF-1Ea and IGF-1Eb mRNA expression (p<0.05). Patterns similar to those for mRNA expression were detected for MGF and IGF-1Ea expression at the protein level. The action of synthetic MGF E peptide differed from that of mature IGF-1 since its proliferative effect on C2C12 myoblast-like cells was not blocked by an anti-IGF-1 receptor neutralizing antibody and it did not phosphorylate Akt. Therefore, we conclude that the differential expression profile of IGF-1 isoforms in vivo and the possible IGF-1R - independent MGF E peptide signalling in skeletal muscle-like cells in vitro support the notion that tissue-specific mRNA expression of MGF isoform produces mature IGF-1 and MGF E peptides which possibly act as distinct mitogens in skeletal muscle regeneration.
منابع مشابه
Insulinlike growth factor-1Ec (MGF) expression in eutopic and ectopic endometrium: characterization of the MGF E-peptide actions in vitro.
The transcription of the insulinlike growth factor 1 (igf-1) gene generates three mRNA isoforms, namely IGF-1Ea, IGF-1Eb and IGF-1Ec (or MGF [mechano growth factor]). Herein, we analyzed the expression of IGF-1 isoforms in eutopic and ectopic endometrium (red lesions and endometriotic cysts) of women with endometriosis, and we characterized the actions of a synthetic MGF E-peptide on KLE cells....
متن کاملCharacterization of a rabbit antihuman mechano growth factor (MGF) polyclonal antibody against the last 24 amino acids of the E domain.
The human insulin-like growth factor-1 (IGF-1) gene gives rise to multiple, heterogeneous mRNA transcripts by alternative splicing, thus producing different IGF-1 isoforms. The mechano growth factor (MGF) is an IGF-1 isoform that was found to be markedly up-regulated in exercised or damaged muscle. The specific E domain of the MGF splice variant may act as an independent growth factor. The aim ...
متن کاملThe role of the insulin-like growth factor 1 (IGF-1) in skeletal muscle physiology.
The human insulin-like growth factor-1 (IGF-1) gene gives rise to multiple, heterogeneous mRNA transcripts through a combination of multiple transcription initiation sites, alternative splicing and different polyadenylation signals. These IGF-1 mRNA transcripts code different isoforms of the precursor peptide of IGF-1 (IGF-1Ea, IGF-1Eb and IGF-1Ec or MGF in human skeletal muscle), which also un...
متن کاملShort-term strength training and the expression of myostatin and IGF-I isoforms in rat muscle and tendon: differential effects of specific contraction types.
In skeletal muscle, an increased expression of insulin like growth factor-I isoforms IGF-IEa and mechano-growth factor (MGF) combined with downregulation of myostatin is thought to be essential for training-induced hypertrophy. However, the specific effects of different contraction types on regulation of these factors in muscle are still unclear, and in tendon the functions of myostatin, IGF-IE...
متن کاملMinireview: Mechano-growth factor: a putative product of IGF-I gene expression involved in tissue repair and regeneration.
The discovery that IGF-I mRNAs encoding isoforms of the pro-IGF-I molecule are differentially regulated in response to mechanical stress in skeletal muscle has been the impetus for a number of studies designed to demonstrate that alternative splicing of IGF-I pre-mRNA involving exons 4, 5, and 6 gives rise to a unique peptide derived from pro-IGF-I that plays a novel role in myoblast proliferat...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- In vivo
دوره 23 4 شماره
صفحات -
تاریخ انتشار 2009