Mitochondrial network structure controls cell-to-cell mtDNA variability generated by cell divisions.

Area of Science:

• Cell Biology
• Genetics
• Computational Biology

Background:

• Mitochondria are dynamic organelles with essential mitochondrial DNA (mtDNA).
• Mitochondrial physical structures vary, influencing mtDNA population genetics between cell divisions.
• The precise role of mitochondrial structure in mtDNA inheritance during cell division is not fully understood.

Purpose of the Study:

• To quantify how mitochondrial network structure influences the inheritance of mtDNA copy number and mutant load.
• To assess the limitations of moment-based approximations in describing heteroplasmy variance.
• To explore how network organization can modulate mtDNA inheritance patterns.

Main Methods:

• Statistical and computational modeling of mtDNA distribution within mitochondrial networks.
• Analysis of mtDNA content inside and outside the reticulated network.
• Evaluation of moment-based approximations for heteroplasmy variance.

Main Results:

• Biased mtDNA inclusion in the network can create a genetic bottleneck, increasing heteroplasmy variance.
• Controlled distribution of mitochondrial mass and mtDNA can reduce heteroplasmy variance below binomial expectations.
• Network structure can generate heteroplasmy variance while maintaining sub-binomial copy number inheritance.

Conclusions:

• Mitochondrial network structure is a key determinant of mtDNA inheritance patterns.
• Computational models can predict how network organization affects mtDNA copy number and mutant load.
• Understanding these mechanisms reconciles experimental observations and highlights the adaptability of mtDNA inheritance.