Development and Initial Characterization of Xenomitochondrial Mice

Abstract

Xenomitochondrial mice harboring trans-species mitochondria on a Mus musculus domesticus (MD) nuclear background were produced. We created xenomitochondrial ES cell cybrids by fusing Mus spretus (MS), Mus caroli (MC), Mus dunni (Mdu), or Mus pahari (MP) mitochondrial donor cytoplasts and rhodamine 6-G treated CC9.3.1 or PC4 ES cells. The selected donor backgrounds reflected increasing evolutionary divergence from MD mice and the resultant mitochondrial-nuclear mismatch targeted a graded respiratory chain defect. Homoplasmic (MS, MC, Mdu, and MP) and heteroplasmic (MC) cell lines were injected into MD ova, and liveborn chimeric mice were obtained (MS/MD 18 of 87, MC/MD 6 of 46, Mdu/MD 31 of 140, and MP/MD l of 9 founder chimeras, respectively). Seven MS/MD, 1 MC/MD, and 11 Mdu/MD chimeric founder females were mated with wild-type MD males, and 18 of 19 (95%) were fertile. Of fertile females, only one chimeric MS/MD (1% coat color chimerism) and four chimeric Mdu/MD females (80-90% coat color chimerism) produced homoplasmic offspring with low efficiency (7 of 135; 5%). Four male and three female offspring were homoplasmic for the introduced mitochondrial backgrounds. Three male and one female offspring proved viable. Generation of mouse lines using additional female ES cell lineages is underway. We hypothesize that these mice, when crossbred with neurodegenerative-disease mouse models, will show accelerated age-related neuronal loss, because of their suboptimal capacity for oxidative phosphorylation and putatively increased oxidative stress.

Microinjection of Cytoplasm or Mitochondria Derived from Somatic Cells Affects Parthenogenetic Development of Murine Oocytes1

“…While nuclear transfer technology has been employed since the mid-1990s to either clone or modify the genetic composition of mammals, a parallel genetic mechanism involves mitochondrial genetics using recently described techniques for mitochondrial transfer into embryos [11,23,27,28]. Development of cloned animals by nuclear transfer resulted in conflicting consequences when retrospective studies on mitochondrial transmission were reported [16,23,27].…”

Animal models of human mitochondrial DNA mutations

“…Ease of manipulation of mouse embryos and genetics made the mouse an obvious choice for development of xenomitochondrial models of mitochondrial dysfunction. Injection of female M. m domesticus cybrid ES cells harboring mitochondria derived from an evolutionarily divergent murine species, M. terricolor , into blastocysts led to the creation of chimeric founder xenomitochondrial mice [78–80]. Xenomitochondrial mice were produced by injection of 129S6/SvEvTac (129S6) ES cells harboring M. terricolor mtDNA into host C57BL/6NTac blastocysts, followed by breeding chimeric females to C57BL/6NTac males (B6NTac(129S6)-mt M. terricolor /Capt; line D7).…”

“…Xenomitochondrial mice were produced by injection of 129S6/SvEvTac (129S6) ES cells harboring M. terricolor mtDNA into host C57BL/6NTac blastocysts, followed by breeding chimeric females to C57BL/6NTac males (B6NTac(129S6)-mt M. terricolor /Capt; line D7). This resulted in a maternal lineage of homoplasmic xenomitochondrial mice (designated “D7”) derived from cybrid ES cells, which was used in preliminary phenotypic characterization [28, 80]. …”

The mitochondrial genome sequence of Mus terricolor: Comparison with Mus musculus domesticus and implications for xenomitochondrial mouse modeling

“…However, progress is limited by the lack of mitochondrial DNA sequence information available for species other than the Mus musculus group and Rattus norvegicus. Therefore, to facilitate future studies, the mitochondrial genome of the Asian mouse species M. terricolor was sequenced; the mtDNA source used to create the first xenomitochondrial mice (McKenzie et al, 2004;Trounce et al, 2004).…”

“…m. domesticus is the common inbred laboratory mouse of western European origin. It belongs to the Mus musculus species group that is comprised of the five subspecies M. domesticus, M. musculus, M. castaneus, M. molossinus and M. bactrianus (see Trounce et al, 2004). Interestingly, the mtDNA of these classic laboratory models is nearly identical and is believed to originate from a common M. m. domesticus maternal ancestor (Yonekawa et al, 1981;Ferris et al, 1982;Goios et al, 2007).…”