Knockdown and knockout of the Integrated Stress Response (ISR) and ATF4 in cultures of adult mouse dorsal root ganglia

Here we use an in vitro model of axon regeneration to investigate the contributions of ATF4 to the transcriptional injury response of adult mouse sensory neurons of the dorsal root ganglion (DRG). We find that, in contrast to optic axon injury, the upregulation of the pro-regenerative transcription factor ATF3 is not ATF4-dependent, and without that contribution, ATF4 instead limits adult DRG axon regrowth in collaboration with C/EBPgamma.

Knockout or knockdown of ATF4 enhances axon regeneration in this model while regulating a collection of genes strongly overlapping with those regulated by C/EBPgamma. We find that overexpression of ATF4 suppresses axon regeneration in a C/EBPgamma-dependent manner. This effect, however, is not a simple reciprocal of ATF4 knockout, as it is also correlated with suppression of ATF3- and c-Jun-dependent transcription.