Effects of Active Immunization Against Akirin2 on Muscle Fiber-type Composition in Pigs

Area of Science:

• Muscle physiology
• Immunology

Background:

• Akirin2 plays a role in muscle development and function.
• Understanding factors influencing muscle fiber-type composition is crucial for livestock productivity.

Purpose of the Study:

• To investigate the impact of active immunization against Akirin2 on muscle fiber-type composition in pigs.
• To explore the underlying molecular mechanisms, including signaling pathways involved in this shift.

Main Methods:

• Active immunization of pigs using porcine Akirin2 (pAkirin2).
• Measurement of antibody titers against pAkirin2.
• Analysis of muscle enzyme activities (succinic dehydrogenase, malate dehydrogenase, lactate dehydrogenase) in the longissimus dorsi muscle.
• Quantification of mRNA and protein expression levels for various myosin heavy chain (MyHC) isoforms (MyHC I, MyHC IIa, MyHC IIb, fast-MyHC).
• Assessment of mRNA expression for key signaling molecules including nuclear factors of activated T cells c1 (NFATc1), PPARγ coactivator-1α, myocyte enhancer factor 2C, and modulatory calcineurin interacting protein 1.

Main Results:

• Successful induction of antibodies against pAkirin2 in immunized pigs.
• Demonstrated a shift in muscle enzyme activities, with decreased oxidative enzymes and increased glycolytic enzymes.
• Observed a significant decrease in slow-twitch fiber markers (MyHC I mRNA and protein) and an increase in fast-twitch fiber markers (MyHC IIb mRNA and protein).
• Found decreased mRNA expression of NFATc1, PPARγ coactivator-1α, myocyte enhancer factor 2C, and modulatory calcineurin interacting protein 1.

Conclusions:

• Active immunization against pAkirin2 induces a slow-to-fast muscle fiber-type shift in pigs.
• This fiber-type transition is potentially mediated by the suppression of the calcineurin/NFATc1 signaling pathway.