Alterations in insulin-like growth factor system in spinal muscular atrophy


YEŞBEK KAYMAZ A., Bal S. K. , Bora G., TALİM B., Ozon A., ALİKAŞİFOĞLU A., ...More

MUSCLE & NERVE, 2022 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Publication Date: 2022
  • Doi Number: 10.1002/mus.27715
  • Journal Name: MUSCLE & NERVE
  • Journal Indexes: Science Citation Index Expanded, Scopus, Academic Search Premier, BIOSIS, CINAHL, EMBASE, MEDLINE
  • Keywords: IGFBP, IGF-I, motor neuron, muscle atrophy, spinal muscular atrophy, BINDING PROTEIN-5 IGFBP-5, FACTOR-I, SKELETAL-MUSCLE, IGF, SMA, DIFFERENTIATION, PHENOTYPE, SURVIVAL

Abstract

Introduction/Aims Spinal muscular atrophy (SMA) is an inherited neuromuscular disease caused by survival motor neuron (SMN) protein deficiency. Insulin-like growth factor-I (IGF-I) is a myotrophic and neurotrophic factor that has been reported to be dysregulated in in vivo SMA model systems. However, detailed analyses of the IGF-I system in SMA patients are missing. In this study, we analyzed the components of the IGF-I system in serum and archived skeletal muscle biopsies of SMA patients. Methods Serum IGF-I, IGF binding protein (IGFBP)-3, and IGFBP-5 levels were analyzed in 11 SMA patients and 13 healthy children by immunoradiometric and enzyme-linked immunosorbent assays. The expression of IGF-I, IGF-I receptor, and IGFBP-5 proteins was investigated by immunofluorescence analysis in the archived skeletal muscle biopsies of nine SMA patients, six patients with non-SMA-related neuromuscular disease and atrophic fibers in muscle biopsy, and four controls. Results A significant decrease in IGF-I levels (mean +/- SD: -1.39 +/- 1.46 vs. 0.017 +/- 0.83, p = .02) and increase in IGFBP-5 levels (mean +/- SD: 2358.5 +/- 1617.4 ng/mL vs. 1003.4 +/- 274.3 ng/mL, p = .03) were detected in serum samples of SMA patients compared to healthy controls. Increased expression of IGF-I, IGF-I receptor, and IGFBP-5 was detected in skeletal muscle biopsies of SMA patients and non-SMA neuromuscular diseases, indicating atrophy-specific alterations in the pathway. Discussion Our findings suggested that the components of the IGF-I system are altered in SMA patients at both the systemic and tissue-specific levels.