Let-7 Micro RNA Precursor
The Let-7 microRNA precursor was identified from a study of developmental timing in C. elegans, and was later shown to be part of a much larger class of non-coding RNAs termed microRNAs. miR-98 microRNA precursor from human is a let-7 family member. Let-7 miRNAs have now been predicted or experimentally confirmed in a wide range of species (MIPF000002). miRNAs are initially transcribed in long transcripts (up to several hundred nucleotides) called primary miRNAs (pri-miRNAs), which are processed in the nucleus by Drosha and Pasha to hairpin structures of about ~70 nucleotide. These precursors (pre-miRNAs) are exported to the cytoplasm by exportin5, where they are subsequently processed by the enzyme Dicer to a ~22 nucleotide mature miRNA. The involvement of Dicer in miRNA processing demonstrates a relationship with the phenomenon of RNA interference.
Other related articles:
... Let-7 is also a very attractive potential therapeutic that can prevent tumorigenesis and angiogenesis, typically in cancers that underexpress let-7 ... part of which may directly correlates with the reduced expression of let-7, and may be repressed by introduction of let-7 ... Intranasal administration of let-7 has already be found effective in reducing tumor growth in a transgenic mouse model of lung cancer ...