The Notch co-repressor protein NKAP is highly expressed in adult mouse subventricular zone neural progenitor cells

• The NKAP protein is expressed in neurogenic cells of the adult mammalian brain.
• NKAP is highly expressed in transit amplifying cells and neuroblasts.
• NKAP expression levels are downregulated during differentiation.

In the adult mammalian brain niches for neural stem cells are maintained, which enable a steady-state neurogenesis. This process is tightly regulated by multiple niche factors, including Notch and NF-κB signaling. The NF-κB-activating-protein (NKAP) has previously been shown to act as Notch co-repressor component by binding CIR and recruiting HDAC3 in T-cell development and furthermore to regulate NF-κB-dependent transcription. Here, we provide first evidence for the expression of NKAP in neurogenic cells of the adult mammalian brain. NKAP is highly expressed in Mash1+ transit amplifying cells and PSA-NCAM+ migrating neuroblasts throughout the subventricular zone (SVZ) and the rostral migratory stream (RMS), as well as in the hippocampus. We further show that NKAP expression levels are downregulated during the course of the RMS. Eventually, most differentiated cells in the olfactory bulb (OB) and the corpus callosum only display low levels of NKAP expression. Finally, large subsets of mature neurons in the OB, the hippocampus and the thalamus express NKAP at high levels, suggesting an additional role of NKAP outside of SVZ progenitor cells.