The let-7 family of microRNAs

Trends Cell Biol. 2008 Oct;18(10):505-16. doi: 10.1016/j.tcb.2008.07.007. Epub 2008 Sep 4.


The first two known microRNAs (miRNAs), lin-4 and let-7, were originally discovered in the nematode Caenorhabditis elegans and control the timing of stem-cell division and differentiation. let-7 was subsequently found as the first known human miRNA. let-7 and its family members are highly conserved across species in sequence and function, and misregulation of let-7 leads to a less differentiated cellular state and the development of cell-based diseases such as cancer. Although much research has been devoted to let-7 target prediction and to understanding its biological role, research into what regulates let-7 has only just begun. Here, we review let-7-family conservation and the recent advances in understanding how let-7-expression is regulated at the transcriptional and post-transcriptional levels across species. A greater understanding of what controls let-7 expression might enable the development of treatments to fight or prevent many cancers.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Animals
  • Base Sequence
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism
  • Gene Expression Regulation / genetics
  • Humans
  • MicroRNAs / chemistry
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Molecular Sequence Data


  • MicroRNAs
  • let-7 microRNA, C elegans
  • mirnlet7 microRNA, human