Insulin‐Like Growth Factor I Regulation and Its Actions in Skeletal Muscle

Abstract

The insulin‐like growth factor (IGF) pathway is essential for promoting growth and survival of virtually all tissues. It bears high homology to its related protein insulin, and as such, there is an interplay between these molecules with regard to their anabolic and metabolic functions. Skeletal muscle produces a significant proportion of IGF‐1, and is highly responsive to its actions, including increased muscle mass and improved regenerative capacity. In this overview, the regulation of IGF‐1 production, stability, and activity in skeletal muscle will be described. Second, the physiological significance of the forms of IGF‐1 produced will be discussed. Last, the interaction of IGF‐1 with other pathways will be addressed. © 2019 American Physiological Society. Compr Physiol 9:413‐438, 2019.

Characterization of a novel alternatively-spliced 5′ exon in the human insulin-like growth factor I (IGF-I) gene, expressed in liver and some cancers

“…Alternative splicing of the IGF-I gene has been recognized for many years, with, in mammals, the 6 exons of this complex gene differentially spliced at both the 5' and 3' ends, resulting in at least 6 different mRNAs and IGF-I precursors, all including the mature IGF-I sequence [1][2][3]6]. At the 5' end of the gene, two exons have been identified, exons 1 and 2 ( Fig.…”

“…In mammals this gene comprises at least 6 exons, with the sequence encoding mature IGF-I included in exons 3 and 4. Alternative splicing allows these two exons to be combined with various combinations of the others, leading to production of at least 6 different IGF-I precursors [1][2][3] all of which include the sequence of mature IGF-I, which is generally strongly conserved [4][5][6]. At the 5' end the alternative splicing leads to production of mRNAs and IGF-I precursors with differing leader/signal sequences while at the 3' end varying amino acid (aa) sequences are produced, which can be processed to a number of peptides with potential biological actions [2][3][4][5].…”

DHEAS and Human Development: An Evolutionary Perspective

“…IGF-1 (Insulin-like Growth Factor 1), as the name suggests, is closely related to insulin. Like insulin, IGF-1 plays a role in glucose regulation (92), and both hormones impact mitochondrial function, protecting against oxidative damage while promoting oxidative capacity (93). However, IGF-1 is most directly associated with protein metabolism, including cell proliferation and differentiation (72) as well as protein synthesis (92).…”

“…Like insulin, IGF-1 plays a role in glucose regulation (92), and both hormones impact mitochondrial function, protecting against oxidative damage while promoting oxidative capacity (93). However, IGF-1 is most directly associated with protein metabolism, including cell proliferation and differentiation (72) as well as protein synthesis (92). At an organismal level, variation in circulating IGF-1 levels has been related to differences in protein consumption across the life cycle, including during infancy (94), childhood (59), and adulthood (48,49).…”

Insulin-like growth factor-1 improves postoperative cognitive dysfunction following splenectomy in aged rats

“…Insulin-like growth factor I (IGF-I) serves critical roles in regulating body growth and metabolism and affects multiple cerebral functions (12). IGF-I promotes brain development, neuronal excitability, myelin sheath production, angiogenesis, synaptogenesis and neuronal survival, growth and differentiation (13).…”