Author:
Castillo Juan,Ammendrup-Johnsen Ina,Codina Marta,Navarro Isabel,Gutiérrez Joaquim
Abstract
In this study, primary cultures of trout skeletal muscle cells were used to investigate the main signal transduction pathways of insulin and IGF-I receptors in rainbow trout muscle. At different stages of in vitro development (myoblasts on day 1, myocytes on day 4, and fully developed myotubes on day 11), we detected in these cells the presence of immunoreactivity against ERK 1/2 MAPK and Akt/PKB proteins, components of the MAPK and the phosphatidylinositol 3-kinase-Akt pathways, respectively, two of the main intracellular transduction pathways for insulin and IGF-I receptors. Both insulin and IGF-I activated both pathways, although the latter provoked higher immunoreactivity of phosphorylated MAPKs and Akt proteins. At every stage, increases in total MAPK immunoreactivity levels were observed when cells were stimulated with IGF-I or insulin, while total Akt immunoreactivity levels changed little under stimulation of peptides. Total Akt and total MAPK levels increased as skeletal muscle cells differentiated in culture. Moreover, when cells were incubated with IGF-I or insulin, MAPK-P immunoreactivity levels showed greater increases over the basal levels on days 1 and 4, with no effect observed on day 11. Although Akt-P immunoreactivity displayed improved responses on days 1 and 4 as well, a stimulatory effect was still observed on day 11. In addition, the present study demonstrates that purified trout insulin receptors possess higher phosphorylative activity per unit of receptor than IGF-I receptors. In conclusion, these results indicate that trout skeletal muscle culture is a suitable model to study the insulin and IGF-I signal transduction molecules and that there is a different regulation of MAPK and Akt pathways depending on the developmental stage of the muscle cells.
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology
Reference53 articles.
1. Human skeletal muscle cell differentiation is associated with changes in myogenic markers and enhanced insulin-mediated MAPK and PKB phosphorylation
2. Altomare DA, Lyons GE, Mitsuuchi Y, Cheng JQ, and Testa JR.Akt2 mRNA is highly expressed in embryonic brown fat and the AKT2 kinase is activated by insulin.Oncogene16: 2407–2411, 1988.
3. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding
4. Butler AA, Yakar S, Gewolb IH, Karas M, Okubo Y, and LeRoith D.Insulin-like growth factor-I receptor signal transduction: at the interface between physiology and cell biology.Comp Biochem Physiol B121: 19–26, 1988.
5. Induction of Akt-2 Correlates with Differentiation in Sol8 Muscle Cells
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