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The MAPT gene encodes Tau protein, a member of the large family of microtubule-associated proteins. Tau forms large insoluble aggregates that are toxic to neurons in several neurological disorders, and neurofibrillary Tau tangles represent a key pathological hallmark of Alzheimer's disease (AD) and other tauopathies. Lowering Tau expression levels constitutes a potential treatment for AD but the mechanisms that regulate Tau expression at the transcriptional or translational level are not well understood. Natural antisense transcripts (NATs) are a particular class of long non-coding RNAs (lncRNAs) that can regulate expression of their overlapping protein-coding genes at the epigenetic, transcriptional, or translational level. We and others identified a long non-coding RNA associated with the MAPT gene, named MAPT antisense 1 (MAPT-AS1). We confirmed that MAPT-AS1 is expressed in neurons in human post mortem brain tissue. To study the role of MAPT-AS1 on MAPT expression regulation, we modulated the expression of this lncRNA in human neuroblastoma cell lines and in human induced pluripotent stem cell (iPSC) derived neurons. In contrast to previous reports, we observed no changes on MAPT mRNA or Tau protein levels upon modulation of MAPT-AS1 levels in these cellular models. Our data suggest that MAPT-AS1 does not regulate Tau expression levels in human neurons in vitro. Thus, MAPT-AS1 does not represent a valuable therapeutic target to lower Tau expression in patients affected by tauopathies including AD. [ABSTRACT FROM AUTHOR]

With the ongoing demographic shift towards increasingly elderly populations, it is estimated that approximately 150 million people will live with Alzheimer's disease (AD) by 2050. By then, AD will be one of the most burdensome diseases of this and potentially next centuries. Although its exact etiology remains elusive, both environmental and genetic factors play crucial roles in the mechanisms underlying AD neuropathology. Genome-wide association studies (GWAS) identified genetic variants associated with AD susceptibility in more than 40 different genomic loci. Most of these disease-associated variants reside in non-coding regions of the genome. In recent years, it has become clear that functionally active transcripts arise from these non-coding loci. One type of non-coding transcript, referred to as long non-coding RNAs (lncRNAs), gained significant attention due to their multiple roles in neurodevelopment, brain homeostasis, aging, and their dysregulation or dysfunction in neurological diseases including in AD. Here, we will summarize the current knowledge regarding genetic variations, expression profiles, as well as potential functions, diagnostic or therapeutic roles of lncRNAs in AD. We postulate that lncRNAs may represent the missing link in AD pathology and that unraveling their role may open avenues to better AD treatments. [ABSTRACT FROM AUTHOR]