HuR’s interaction with lincBRN1a and lincBRN1b is implicated in neuronal stem cells differentiation

INTRODUCTION: LncRNAs play crucial roles in cellular processes but their regulatory effects in the adult brain and neural stem cells (NSCs) remain to be entirely characterized. Interestingly, it has been shown that genetic ablation of specific lncRNAs can cause strong modifications in mouse brain’s development. RESULTS: Here, we demonstrate that 10 lncRNAs (LincENC1, FABL, lincp21, HAUNT, PERIL, lincBRN1a, lincBRN1b, HOTTIP, TUG1 and FENDRR) are deregulated during murine NSCs differentiation. By RNA immunoprecipitation assay we show that they interact with the RNA binding protein ELAVL1/HuR. Furthermore, we characterize the function of two of the deregulated lncRNAs, lincBRN1a and lincBRN1b, during NSCs’ differentiation. Their inhibition leads to the induction of differentiation, with a concomitant decrease in stemness and increase in neuronal markers, indicating that they exert key functions in neuronal cells differentiation. The treatment with actinomycin D, a transcriptional inhibitor, allowed to evaluate the half-life of these RNA molecules, and we found that HuR’s inhibition lead to a modification in their decay rates both in neural stem cells and in differentiated ones. We also identify the human homologs of the mentioned 10 lncRNAs and we report their deregulation during human iPSCs differentiation into neurons. Figure 1: Expression analysis of lncRNAs in NSCs and during differentiation (d1, d3, d8). DISCUSSION & CONCLUSIONS: Our results show that these lncRNAs play a role in neural stem cells biology influencing their differentiation capabilities, as the alteration of their levels may have an effect on this process. Moreover, we report that the inhibition of HuR’s interaction with the analyzed lncRNAs leads to neural differentiation, suggesting a complementary role for the lncRNAs and the RNA-binding protein (HuR) in this process. The study of their expression in human iPSCs differentiation into neurons suggest that our results could also be applied to human neuronal development. ACKNOWLEDGEMENTS: The authors are deeply grateful to Professor Alfredo Gorio (University of Milan, Italy) for his scientific support and unswerving encouragement to the work. Moreover, authors acknowledge the economic support by FAIP (Federazione Associazioni Italiane Paratetraplegici), “Neurogel-en-March” Foundation (France) to AG, Fondazione “Romeo and Enrica Invernizzi” to AMDG, Fondazione Regionale per la Ricerca Biomedica (FRRB) (Regione Lombardia, TRANS_ALS, project nr. 2015-0023, to AG, AMDG and CC). Federica Rey would like to acknowledge and thank the Fondazione Fratelli Confalonieri for financial support during her PhD.