My question is, will OT-1 heterozygous mice express mostly only OT-1 T cells like the OT-1 homozygous does, or they also express TCRs other than OT-1, like a WT animal does? What would be the mechanism behind it?
Thanks in advance!
Phenotypically, these mice are the same as their homozygous siblings. Progression through T cell development only needs a single effective TCRbeta chair rearrangement in order to proceed. Once that occurs, the other alleles do not rearrange. So, T cell precursors from TCR transgenic mice have a head-start...not needing to recombine either of the endogenous TCR loci. Because of this, you have to be careful to ensure your mice (especially your breeders) are typed. If a WT finds its way into a breeding cage, you can have nonTg progeny in a few short months, and you will not know where they originated (having culled the older breeders).
If your mice are WT at the RAG locus, then the older the mice, the higher the likelihood that there will be T cells that express both the OTI TCR as well as an endogenously-derived TCR...especially extrathymic development. Good Luck.
Yes, any TCR Tg mouse without the RAG genes intact can/will have some endogenous "leakage". It's not specific to OTI.
Oops...Any TCR Tg mouse WITH intact RAG genes can/will have some endogenous "leaky" TCR recombination. Hope I didn't confuse...
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