Deciphering developmental-aging mechanisms in cell culture: Aberrant ADNP cytoplasmic-nuclear crosstalk and NAP (davunetide) protection

Background: Activity-dependent neuroprotective protein (ADNP) is crucial for chromatin/cytoskeletal functions. ADNP deregulation is linked to neurodevelopmental/neurodegenerative/psychiatric diseases. Mutations in ADNP cause the ADNP syndrome and parallel tauopathy in Alzheimer’. We showed aberrant nuclear-cytoplasmic distribution in ADNP-mutated neuronal-like cells, which was corrected by the ADNP-derived fragment, NAP (Cells, 2022). Here we asked what is the mechanism in which NAP corrects the aberrant distribution. Methods: CRISPR/Cas9 genome-editing established N1E-115 neuroblastoma cell lines that express different green fluorescent protein (GFP) – labeled mutated ADNP proteins. NAP-conjugated to Cy5 was added immediately before confocal live cell imaging. Cells were characterized using quantitative morphology/immunocytochemistry and NAP-ADNP association was modeled in silico. Results: Live cell imaging showed that NAP was not only associated with the cytoplasm but also rapidly seen in the nucleus. Furthermore, reduced microtubule content was observed in the ADNP-mutated cell lines. In turn, reducing microtubules by zinc intoxication mimicked the ADNP mutation phenotype and resulted in aberrant nuclear- cytoplasmic boundaries. This malformation was rapidly corrected by NAP treatment, discovered to interact with an ADNP zinc finger, associated with chromatin regulation (Cells 2023). Conclusions: We showed here nuclear -cytoplasmic impairments characterizing deleterious ADNP mutations, and NAP immediate nuclear localization and correction of mutated ADNP-related deficiencies, through a microtubule-linked mechanism. ADNP mutations are now further linked with changes in nuclear bodies' compaction in mutated cell lines, toward better understanding of fundamental cell development and aging mechanisms, as well protective drug development.