These DAT-PF-tTA mice express tetracycline responsive transactivator (tTA) in dopamine neurons from the mouse Slc6a3 (solute carrier family 6 (neurotransmitter transporter, dopamine), member 3; also called DAT) promoter. A downstream “PF” (tetO-tTA) positive feedback amplification cassette enhances tTA expression, but itself has no transcription activity due to an upstream "stop". Homozygotes have little or no endogenous SLC6A3/DAT expression and show growth retardation.
When these tTA mice are crossed with tetO-human α-synuclein A53T mutant animals (see Stock No. 012442), double mutant DASYN53 mice develop features of Parkinson’s disease. These animals do not have detectable transgenic α-synuclein protein expression at 1 week after birth, later than endogenous DAT expression (E15–E17), suggesting that the transgene amplification through “PF” may increase gradually. This pattern of expression can help avoid complications in phenotype interpretation due to early developmental effects. At 6 weeks, the DASYN53 mice have transgenic α-synuclein expression in more than 95% of dopamine neurons in the midbrain. The DASYN53 mice showed profound early-onset mitochondria abnormalities, characterized by macroautophagy marker-positive cytoplasmic inclusions containing mainly mitochondrial remnants, which precede the degeneration of dopamine neurons.
