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Production of homoplasmic xenomitochondrial mice
Matthew McKenzie1, Ian A Trounce, Carolyn A Cassar
1Genomic Disorders Research Centre, Department of Medicine, St. Vincent's Hospital, University of Melbourne, Melbourne, Victoria 3065, Australia.
Abstract:
The unique features of mtDNA, together with the lack of a wide range of mouse cell mtDNA mutants, have hampered the creation of mtDNA mutant mice. To overcome these barriers mitochondrial defects were created by introducing mitochondria from different mouse species into Mus musculus domesticus (Mm) mtDNA-less (rho(0)) L cells. Introduction of the closely related Mus spretus (Ms) or the more divergent Mus dunni (Md) mitochondria resulted in xenocybrids exhibiting grossly normal respiratory function, but mild metabolic deficiencies, with 2- and 2.5-fold increases in lactate production compared with controls. The transfer of this model from in vitro to in vivo studies was achieved by introducing Ms and Md mitochondria into rhodamine-6G-treated Mm mouse embryonic stem (ES) cells. The resultant xenocybrid ES cells remained pluripotent, and live-born chimerae were produced from both Ms and Md xenocybrid ES cells. Founder chimeric females (G(0)) were mated with successful germ-line transmission of Ms or Md mtDNA to homoplasmic G(1) offspring. These xenocybrid models represent the first viable transmitochondrial mice with homoplasmic replacement of endogenous mtDNA and confirm the feasibility of producing mitochondrial defects in mice by using a xenomitochondrial approach.
Insights
Researchers created the first viable transmitochondrial mice by introducing foreign mitochondria into mouse cells. This xenomitochondrial approach enables the study of mitochondrial defects and their genetic transmission in vivo.
Area of Science:
- Mitochondrial biology
- Genetics
- Animal models
Background:
- Creating mouse models with mitochondrial DNA (mtDNA) mutations is challenging due to mtDNA's unique features and limited mutant availability.
- Existing methods for studying mtDNA defects in mice are insufficient.
Purpose of the Study:
- To develop a novel method for creating mice with specific mitochondrial defects.
- To establish viable transmitochondrial mice with homoplasmic replacement of endogenous mtDNA.
Main Methods:
- Mitochondria from different mouse species (Mus spretus and Mus dunni) were introduced into Mus musculus domesticus (Mm) mtDNA-less (rho(0)) L cells to create in vitro xenocybrids.
- These xenocybrid cells were then introduced into mouse embryonic stem (ES) cells for in vivo studies.
- Chimeric mice were generated, and germ-line transmission of the introduced mtDNA was confirmed.
Main Results:
- In vitro xenocybrids showed normal respiratory function but mild metabolic deficiencies, including increased lactate production.
- Live-born chimeric mice were successfully produced from xenocybrid ES cells.
- Germ-line transmission of foreign mtDNA to homoplasmic offspring was achieved, creating the first transmitochondrial mice.
Conclusions:
- The xenomitochondrial approach is feasible for creating viable transmitochondrial mice with homoplasmic mtDNA replacement.
- This new model system allows for in vivo investigation of mitochondrial defects and their inheritance.
- The study overcomes previous limitations in generating mouse models for mitochondrial research.
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