Cis-regulation vs Trans-regulation (in gene expression):
| Feature | Cis-regulation | Trans-regulation |
|---|---|---|
| Location | Regulator is on the same DNA molecule, near the target gene | Regulator is on a different molecule, often a diffusible factor (like a protein or RNA) |
| Examples | Promoters, enhancers, silencers (DNA elements) | Transcription factors, miRNAs, long non-coding RNAs |
❓ So, is miRNA cis or trans?
✅ miRNAs (microRNAs) are trans-regulators.
They are transcribed from their own genes and act on other target mRNAs, usually by base-pairing with complementary sequences in the 3' UTR.
Since they do not regulate genes at their own locus, but instead move to regulate other transcripts, they clearly function in trans.