Long noncoding RNA MALAT1; A novel and potential therapeutic target for Alzheimer’s disease

Abstract Background Alzheimer disease (AD) is the most common form of dementia, characterized pathologically by amyloid plaques and neurofibrillary tangles. Despite considerable advances in the knowledge of AD pathogenesis, we know little about preventing or delaying the ongoing neurodegenerative process, indicating that there remain critical gaps in our understanding of disease mechanisms and opportunities for new treatment approaches. Long noncoding RNAs (lncRNAs) are larger than 200 nucleotides, structurally resemble mRNAs but do not encode proteins. LncRNAs participate in regulation of several physiological and pathophysiological processes by modulating gene expression and have been documented in several neurodegenerative diseases. Among them, metastasis associated lung adenocarcinoma transcript 1 (MALAT1) is a highly abundant and evolutionary conserved lncRNA and regulates a subset of genes involved in synaptic plasticity, cognitive function and memory. Method To test the hypothesis that lncRNA MALAT1 plays an important role in AD pathology, we quantified expression levels of lncRNA MALAT1 in the brains of age‐matched AD patients and cognitively normal controls (Non‐AD) by QRT‐PCR and RNAScope in situ hybridization assays, respectively. We further examined the lncRNA MALAT1 expressions and AD‐related neuropathology in the brains of 5XFAD transgenic mouse model of AD and their WT littermates using dual RNAScope/Immunofluorescence technique. Result We observed reduced expressions of lncRNA MALAT1 in the hippocampus of AD brains compared to the non‐AD control brains. Next, we found marked reduced expression of lncRNA MALAT1 in the brain of 5xFAD mice compared to non‐transgenic mice. Interestingly, decreased expression levels of lncRNA MALAT1 are correlated with AD‐related neuropathology and memory deficits in 5xFAD mice. Conclusion These findings provided compelling evidence that AD is associated with altered expression of lncRNA MALAT1 which may influence several pathways related to neural damage and memory deficits in AD. Because expression patterns, interacting proteins, pathways, and biological functions of lncRNA MALAT1 are remain largely unexplored in AD, understanding how lncRNA MALAT1 regulates AD‐related neuropathology may allow development of effective therapies for this incurable disease.