Abolishing Trp53-dependent apoptosis does not benefit spinal muscular atrophy model mice

Spinal muscular atrophy (SMA) is the most common genetic motoneuron degenerative disorder, but the mechanism(s) of motoneuron death is unclear. Previously, a direct interaction between tumor-suppressive TP53 protein and the SMA determinant gene product, survival motor neuron protein, was identified and therefore it has been suggested that a mechanism of TP53-dependent apoptosis plays an important role in motoneuron degeneration in SMA. We used our SMA model mice, generated by a combination of knockout and transgenic techniques, to decipher the role of TP53 protein in the motoneuron degeneration in SMA. We detected a significant increase of Trp53 expression in the spinal cord of SMA-like mice compared to their normal littermates. After crossing SMA-like mice with Trp53 knockout mice, the progeny Trp53-deficient SMA-like mice did not show milder disease severity or longer lifespan compared to SMA littermates with wild-type Trp53 genes. Our studies provide in vivo evidence indicating that Trp53-dependent apoptosis does not play a crucial role in motoneuron degeneration in SMA-like mice.