ADCY9, a crucial member of the adenylate cyclase family, exerts neuroprotective and analgesic effects in the nervous system by modulating the activity of the cAMP/AMPK signaling pathway. However, the role of the ADCY9 gene in neural regeneration remains unreported. In this study, we utilized Dugesia japonica, a highly regenerative planarian species, as a model to systematically examine the spatiotemporal expression pattern of the ADCY9 gene during planarian brain regeneration and investigate its regulatory function in this process. The results demonstrated that the downregulation of ADCY9 resulted in abnormal brain regeneration in planarians, characterized by partial loss of the nerve cord, reduced numbers of collateral branches, and significant inhibition of the regeneration and differentiation of multiple neuron types. RNA sequencing revealed that the downregulation of ADCY9 led to 499 differentially expressed genes, with KEGG enrichment pathway analysis indicating significant associations with neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease. Double RNAi experiments demonstrated that simultaneous knockdown of ADCY9 and Mitofusin-1 significantly restored neural regeneration. Collectively, ADCY9 might promote the comprehensive reconstruction of neural structure by hierarchically regulating the regeneration intensity through negative regulation of the downstream inhibitory factor Mitofusin-1. This study discloses the function of ADCY9 in planarian neural regeneration, providing a theoretical foundation for its application in investigating neural regeneration mechanisms and neurodegenerative disease pathogenesis in higher vertebrates.

Neural stem cells (NSCs) are self-renewing, multipotent cells of the central nervous system (CNS) that can differentiate into a range of specialized cell types, including neurons, astrocytes, and oligodendrocytes (OLs). Due to their remarkable ability to self-renew and differentiate, NSCs hold immense potential for the treatment of neurodegenerative diseases (NDDs). However, clinical translation remains hindered by challenges such as expansion difficulties and phenotypic drift. This review synthesizes evidence on the divergent effects of microgravity on NSC biology. While real spaceflight has been shown to enhance NSC proliferation, it paradoxically reduces neurosphere volume. Microgravity simulations yield contrasting results: rotating wall vessel (RWV) systems promote neuron and astrocyte generation, whereas rotating cell culture systems (RCCSs) inhibit differentiation despite the use of pro-differentiation media. These phenotypic variations critically depend on experimental conditions, cell sources, and observation time. Future research should focus on elucidating cross-pathway interactions and optimizing culture parameters to enable clinical-scale NSC applications.

Regeneration and repair of the injured central nervous system is a major focus in biological research, yet many key questions remain unanswered, making it essential to explore the mechanisms underlying neural regeneration. Dorsal switch protein 1 (DSP1) plays critical roles in embryonic development and immune regulation in multiple invertebrates including Drosophila , whereas its vertebrate ortholog HMGB1 participates in diverse biological processes; however, its function in central nervous system regeneration has not been reported. In this study, we found that DSP1 was widely expressed in the intact planarian, predominantly in parenchyma, retropharyngeal and cephalic ganglia. Knockdown of DSP1 promoted blastema growth at one dpa, without affecting the stem cell population. Silencing of DSP1 accelerated brain regeneration and significantly increased the number of daughter cells derived from stem cells, accompanied by downregulated expression of calcineurin subunit B ( CnB ), a Wnt signaling pathway gene. Notably, simultaneous knockdown of DSP1 and CnB promoted blastema regeneration. These findings suggest DSP1 is associated with CnB to regulate neural regeneration in planarian. These findings provide a theoretical basis for understanding the DSP1/CnB signaling axis in regulating neural regeneration in mammals, and have important implications for the development of drugs targeting neuronal regeneration.