Muscle insulin-like growth factor-I modulates murine craniofacial bone growth

Area of Science:

• Endocrinology
• Developmental Biology
• Orthodontics

Background:

• Insulin-like Growth Factor I (IGF-I) is crucial for muscle and bone development, mediating growth hormone (GH) actions.
• Limited research explores the interplay between muscle and bone development influenced by IGF-I in vivo during post-natal growth.

Purpose of the Study:

• To investigate the effects of muscle-specific IGF-I overexpression on craniofacial skeleton development during post-natal growth.
• To determine if post-natal modulation of IGF-I in specific muscles impacts mandibular structures.

Main Methods:

• Utilized mice with muscle-specific IGF-I overexpression (mIgf1+/+) and wild-type littermates.
• Employed virus-mediated expression of IGF-I targeting the masseter muscle.
• Analyzed craniofacial bone growth, mandibular morphology, and condylar cartilage thickness.

Main Results:

• Muscle-specific IGF-I overexpression led to accelerated craniofacial bone growth.
• Increased IGF-I in the masseter muscle altered mandibular base plane angle and increased width.
• Enhanced IGF-I in muscle accelerated mandibular condyle cartilage thickness, dependent on IGF-I receptor activity.

Conclusions:

• Muscle-derived IGF-I indirectly influences craniofacial growth via IGF-I-dependent muscle hypertrophy.
• These findings highlight the role of muscle IGF-I in skeletal development and have potential clinical implications for craniofacial disorders.