LncRNAs involved in neuronal development seem to play a role in ALS pathology

Introduction: Neuronal proliferation and development processes play a role in ALS, with studies demonstrating how in G93A-SOD1 mice ependymal stem progenitor cells show a higher proliferation and differentiation towards the neuronal lineage. Moreover, human derived neural progenitor cells from ALS patients tend to differentiate to neuronal lineages. LncRNAs play a role in neuronal cell’s development, and the ablation of a panel of 8 lncRNAs causes strong modifications in mouse brain’s development. Recently, we investigated the role of 8 of these lncRNAs (lincENC1, lincBRN1a, lincBRN1b, TUG1, FENDRR, lincp21, HOTTIP and ELDR) in neuronal stem cells’ differentiation, finding a deregulation in their expression during this process. We then decided to study the role of these lncRNAs in ALS pathology. Materials and Methods: The lncRNAs expression was investigated in three different spinal cord (SC) areas (cervical, thoracic and lumbar) and in seven brain areas (prefrontal cortex, motor cortex, hippocampus, mesencephalon, striatum, cerebellum and motor nuclei) of G93A-SOD1 mice, both at a pre-symptomatic stage (8 weeks of age) and at a symptomatic stage (18 weeks of age). Furthermore, 6 human homologues (lincBRN1a, TUG1, lincp21, FENDRR, HOTTIP and ELDR) were identified and their expression was investigated in an in vitro model of the disease (SH-SY5Y cells transfected with the SOD1-G93A gene). Total RNA was extracted using TRIZOL® reagent (Life Technologies) and the lncRNAs’ expression levels were measured by Real Time PCR. Results: The lncRNAs expression profile was deregulated in all analyzed areas except for the mesencephalon, cerebellum and the motor nuclei. Interestingly, there is a specific alteration pattern in the brain compared to the spinal cord. Indeed, lincBRN1a, lincBRN1b and TUG1 resulted specifically deregulated in the more central areas (hippocampus, prefrontal cortex, motor cortex and striatum), whereas HOTTIP, ELDR and ENC presented a spinal cord-specific deregulation. Furthermore, it emerged how one specific lncRNA, lincp21 (already partially characterized as a lncRNAs involved in the p53 oncogene regulation pathway) is deregulated in all the affected areas. At a cellular level, it was possible to identify how all the 6 human homologues analyzed in the human in vitro model were deregulated, supporting their importance in the pathology. Conclusions: These results allowed to highlight new potential targets involved in ALS. Indeed, it was possible to identify an area specific deregulation, allowing the stratification of the lncRNAs between those more implicated in brain areas versus those more implicated in the spinal cord. Furthermore, it was possible to identify one globally deregulated lncRNA, lincp21, which could play a crucial role in the cellular processes involved in the disease. The analysis in an in vitro human model indicates a plausible translation of these results from a murine model into the human ALS pathology.