Phosphorylation of the transcription factor Sp4 is reduced by NMDA receptor signaling

We show that the neuronal transcription factor Sp4, which regulates the developmental patterning of dendrites, is dephosphorylated at S770 in response to NMDA receptor signaling in cerebellar granule neurons and cortical neurons. Dephosphorylation required the activity of the PP1/PP2A phosphatase. A point mutation at S770 to a phosphomimetic aspartic acid residue impaired Sp4-dependent pruning of cerebellar granule neuron primary dendrites.