Role of MicroRNA Let-7 in Modulating Multifactorial Aspect of Neurodegenerative Diseases: an Overview.

The multifactorial aspect of neurodegenerative diseases has posed challenges in terms of understanding various mechanistic cues behind these ailments. The fact that single microRNA (miRNA) molecules can regulate multiple genes and associated pathways makes these molecules interesting for studies within the area of age-associated neurodegenerative diseases. miRNAs are endogenous, evolutionarily conserved, 20-23 nucleotide non-coding RNAs, which were first discovered in Caenorhabditis elegans. They play a key role in gene regulation and are known to be deregulated in many disease conditions. Steady regulations of miRNAs are required for normal biological processes. One of the crucial miRNA molecules let-7 is highly conserved and is known to be required for development and viability. It acts as a regulator for oncogenes and insulin-PI3K-mTOR pathway genes. Upregulation of let-7 impairs glucose homeostasis and results in degeneration of neurons, while its downregulation leads to cancer. Maturation of let-7 in cancer subjects is inhibited by lin-28, an RNA-binding protein inhibitor. This highlights the importance of let-7 miRNAs in various diseases and developmental processes. This article provides an overview on the functions of let-7 and its probable association with various neurodegenerative diseases.