Background: Dock4, a guanine nucleotide exchange factor for Rac1, is associated with neuropsychiatric diseases. Results: Dock4 regulates neurite differentiation in neuroblastoma cells and hippocampal neurons. Conclusion: Dock4 is an important regulator during neural differentiation. Significance: This study contributes to a better understanding of the molecular and cellular events during neural differentiation and may provide new insights into the molecular pathophysiology of neuropsychiatric diseases.

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Neurite outgrowth is crucial during neuronal development and regeneration, and strategies that aim at promoting neuritogenesis are beneficial for reconstructing synaptic connections after neuronal degeneration and injury. Using a bivalent analogue strategy as a successful approach, the current study identifies a series of novel dimeric securinine analogues as potent neurite outgrowth enhancers. Compounds 13, 14, 17-19, and 21-23, with different lengths of carbon chain of N,N-dialkyl substituting diacid amide linker between two securinine molecules at C-15 position, exhibited notable positive effects on both neuronal differentiation and neurite extension of neuronal cells. Compound 14, one of the most active compounds, was used as a representative compound for mechanistic studies. Its action on neurite outgrowth was through phosphorylation/activation of multiple signaling molecules including Ca/calmodulin-dependent protein kinase II (CaMKII), extracellular signal-regulated kinase (ERK) and Akt. These findings collectively identify a new group of beneficial compounds for neuritogenesis, and may provide insights on drug discovery of neural repair and regeneration.