Oxidative stress is involved in age-dependent spermatogenic damage of Immp2l mutant mice

Area of Science:

• Reproductive biology
• Mitochondrial biology
• Oxidative stress research

Background:

• Mitochondrial reactive oxygen species (ROS) are linked to spermatogenic damage.
• Direct in vivo evidence demonstrating this link has been limited.
• A mouse model with an inner mitochondrial membrane peptidase 2-like (Immp2l) gene mutation was previously generated.

Purpose of the Study:

• To confirm age-dependent spermatogenic damage in a new cohort of Immp2l mutant mice.
• To investigate the role of mitochondrial ROS in age-dependent spermatogenic impairment in vivo.
• To explore the molecular mechanisms underlying ROS-mediated damage in testes.

Main Methods:

• Generation and characterization of Immp2l mutant mice.
• Assessment of age-dependent spermatogenic damage and testicular oxidative stress markers (protein carbonyl content).
• Analysis of antioxidant enzyme expression (superoxide dismutases, catalase, glutathione peroxidase 4) and apoptosis in testes.
• Measurement of mitochondrial DNA (mtDNA) mutation rates in germ cells.

Main Results:

• Mutant mice exhibited age-dependent spermatogenic damage starting at 10.5 months.
• Elevated protein carbonyl content in testes of older mutants indicated increased oxidative stress.
• Reduced expression of cytosolic glutathione peroxidase 4 was observed in 13-month-old mutants.
• Increased apoptosis was noted in testicular cells of mutant mice with impaired spermatogenesis.
• Mitochondrial DNA mutation rates remained unchanged, ruling out mtDNA mutations as a primary cause.

Conclusions:

• Increased mitochondrial ROS are a key factor driving age-dependent spermatogenic impairment.
• The Immp2l mutation leads to mitochondrial dysfunction and subsequent oxidative stress in testes.
• This study provides direct in vivo evidence for the role of mitochondrial ROS in male reproductive damage.