Proinsulin C-Peptide Enhances Cell Survival and Protects against Simvastatin-Induced Myotoxicity in L6 Rat Myoblasts

• Published in: International journal of molecular sciences Vol. 20; no. 7; p. 1654
• Main Authors: Essid, Sumia Mohamed, Bevington, Alan, Brunskill, Nigel J
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 03.04.2019; MDPI
• Subjects: AKT protein; Amino acids; Animals; Apoptosis; C-Peptide - pharmacology; Caspase 3 - metabolism; Catabolism; Cell Death - drug effects; Cell Line; Cell Shape - drug effects; Cell Survival - drug effects; Diabetes; Diabetes mellitus; Enzyme Activation - drug effects; Extracellular Signal-Regulated MAP Kinases - metabolism; Glucose; Homeostasis; Hyperglycemia; Insulin; Morphology; Muscle, Skeletal - pathology; Muscles; Muscular Diseases - chemically induced; Muscular Diseases - metabolism; Muscular Diseases - pathology; Musculoskeletal system; Myoblasts; Myoblasts - drug effects; Myoblasts - metabolism; Myoblasts - pathology; Myopathy; myotoxicity; Oxidative stress; Peptides; Pertussis; Pertussis toxin; Phosphorylation; Pretreatment; proinsulin C-peptide; Protein biosynthesis; Protein synthesis; Proteins; Proto-Oncogene Proteins c-akt - metabolism; Rats; Reactive Oxygen Species - metabolism; Signal Transduction - drug effects; Simvastatin; Simvastatin - adverse effects; Skeletal muscle; Type 1 diabetes; Whooping cough; myotoxicity; simvastatin; proinsulin C-peptide; Type 1 diabetes
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms20071654

The repair capacity of progenitor skeletal muscle satellite cells (SC) in Type 1 diabetes mellitus (T1DM) is decreased. This is associated with the loss of skeletal muscle function. In T1DM, the deficiency of C-peptide along with insulin is associated with an impairment of skeletal muscle functions such as growth, and repair, and is thought to be an important contributor to increased morbidity and mortality. Recently, cholesterol-lowering drugs (statins) have also been reported to increase the risk of skeletal muscle dysfunction. We hypothesised that C-peptide activates key signaling pathways in myoblasts, thus promoting cell survival and protecting against simvastatin-induced myotoxicity. This was tested by investigating the effects of C-peptide on the L6 rat myoblast cell line under serum-starved conditions. Results: C-peptide at concentrations as low as 0.03 nM exerted stimulatory effects on intracellular signaling pathways-MAP kinase (ERK1/2) and Akt. When apoptosis was induced by simvastatin, 3 nM C-peptide potently suppressed the apoptotic effect through a pertussis toxin-sensitive pathway. Simvastatin strongly impaired Akt signaling and stimulated the reactive oxygen species (ROS) production; suggesting that Akt signaling and oxidative stress are important factors in statin-induced apoptosis in L6 myoblasts. The findings indicate that C-peptide exerts an important protective effect against death signaling in myoblasts. Therefore, in T1DM, the deficiency of C-peptide may contribute to myopathy by rendering myoblast-like progenitor cells (involved in muscle regeneration) more susceptible to the toxic effects of insults such as simvastatin.