micro RNAs (miRNAs)

Introduction

1st discovered in 1993
MicroRNAs are small non-coding RNAs and act as fundamental post-transcriptional modulators of several critical cellular processes
in most cases, miRNAs interact with the 3′ untranslated region (3′ UTR) of target mRNAs to induce mRNA degradation and translational repression ¹⁾
interaction of miRNAs with other regions, including the 5′ UTR, coding sequence, and gene promoters, have also been reported
under certain conditions, miRNAs can also activate translation or regulate transcription
miRNAs have a central role in regulating a number of genes, particularly those genes involved in signaling pathways, and several physiological processes in human cells, including (but not limited to) cellular proliferation, lifespan, metabolism, and cell cycle control
Extracellular vesicles (EVs) can package, release, and transfer miRNAs between cells in a somewhat selective manner where they can be taken up by target cells and then release their contents into the target cells
viruses also create miRNAs and package them into EVs
aberrant expression of miRNAs is associated with many human diseases

miRNA let-7 functions as an essential regulator of the function and differentiation of both innate and adaptive immune cells
- in mammals, let-7 is among the miRNAs with the highest expression level in numerous cell types in different species.
- Let-7 family members are involved in critical physiological processes, such as organ development, growth, tissue regeneration, metabolism, and various types of cancer and are associated with viral infection, dysfunction of liver cells, and immune response ²⁾
expression in liver is increased with metformin and this has a role in reducing hepatic gluconeogenesis

¹⁾

²⁾