Combining In Vivo 2-Photon Imaging with Photoactivatable Fluorescent Labeling Shows Low Rates of Mitochondrial...

Area of Science:

• Mitochondrial biology
• Skeletal muscle physiology
• Aging research

Background:

• Mitochondrial dynamics, including fusion and fission, are crucial cellular processes.
• Traditional assessments rely on indirect methods like protein markers or isolated models.
• In vivo visualization techniques offer new insights into mitochondrial dynamics.

Purpose of the Study:

• To directly measure mitochondrial dynamics in vivo within skeletal muscle.
• To compare mitochondrial dynamics in young versus old mice.
• To contrast in vivo findings with ex vivo and in vitro models.

Main Methods:

• Utilized multiphoton microscopy to image mitochondrial dynamics in vivo in mouse tibialis anterior muscle.
• Employed mitochondrial matrix-targeted photo-activatable GFP for visualization.
• Compared in vivo data with measurements from isolated single muscle fibers and C2C12 myotubes.

Main Results:

• In vivo mitochondrial dynamics occur at slower rates than previously estimated.
• C2C12 myoblasts exhibited the fastest rates of dynamic events across all models.
• Mitochondrial dynamics were reduced in older mice compared to younger mice.
• Acute exercise increased mitochondrial dynamic rates in aged skeletal muscle.

Conclusions:

• Direct in vivo measurement of mitochondrial dynamics in skeletal muscle is feasible.
• This advanced technique offers a powerful approach for studying mitochondrial function in muscle.
• Findings highlight age-related decline in mitochondrial dynamics, with potential for exercise intervention.