A Snippet on Micro RNA

A Snippet on Micro RNA - Mr. V. Kuzhandai Velu, MGMCRI, Puducherry

Serum and other body fluid con-tain cell free DNA, RNA and cir-culating Nucleic acids which serve as potential biomarkers. One such biomarker which has gaining interest in recent years is small non-coding (~18 – 24 nts) RNA which is microRNA (miRNA). It was discovered in 1993 by Ambros and colleagues in Caenorhabditis elegans. The important roles of miRNA are regulation of gene expression, cell-cell communication, cell di-vision and apoptosis. Recent data shows that there are about 1789 mature and 1658 pri-miRNA found in humans. 

miRNA transcribed similarly as protein coding gene by RNA polymerase II and RNA poly-merase III. Pri-miRNA tran-scribed in the nucleus and un-dergoes post transcriptional processing in cytosol similar to other RNA. Drosha and Dicer are RNase III enzymes which are involved in both the phas-es. During sequence ~70nt Pri-miRNA converted into 18 – 24~nt matured double strand miRNA.

The other important function of miRNA is in down regula-tion of gene expression, that could be a useful diagnostic and prognostic tool in cancer. It has high stability in serum and plasma and represents as a novel marker. Current stud-ies provide new algorithm for screening and diagnoses.