Antisense oligonucleotide-mediated redirection of Igf1 alternative polyadenylation

Area of Science:

• Molecular Biology
• Genetics
• Exercise Physiology

Background:

• Insulin-like growth factor-1 (IGF-1) is crucial for muscle growth and function, making it a therapeutic target for muscle wasting disorders.
• Alternative polyadenylation (APA) of the Igf1 gene generates 3'UTR isoforms affecting mRNA stability and translation efficiency.
• Shorter Igf1 3'UTRs are associated with increased mRNA stability and protein translation efficiency.

Purpose of the Study:

• To investigate the impact of exercise on Igf1 3'UTR isoforms in wild-type (WT) and mdx mice.
• To develop and test a strategy for redirecting Igf1 APA to enhance IGF-1 protein expression in vitro.
• To explore the therapeutic potential of modulating Igf1 APA for muscle disorders.

Main Methods:

• Full-length isoform sequencing of Igf1 transcripts in exercised WT and mdx mice.
• In vitro manipulation of Igf1 APA using antisense oligonucleotides (AONs) in C2C12 myoblasts.
• Analysis of IGF-1 protein levels and AKT phosphorylation following APA redirection.

Main Results:

• Exercise induced a shift in Igf1 APA towards the proximal polyadenylation site exclusively in WT mice (P < 0.05).
• AON-mediated redirection of Igf1 APA in C2C12 cells significantly increased IGF-1 expression and AKT phosphorylation.
• Genes involved in sarcomere organization, muscle development, and calcium homeostasis were enriched.

Conclusions:

• Downhill running exercise alters Igf1 3'UTR usage in WT mice.
• Redirecting Igf1 APA is a viable in vitro strategy to enhance IGF-1 protein expression without altering the gene's coding sequence.
• This APA modulation approach holds promise for therapeutic applications in muscle-related conditions.