What is PRI-miRNA?

MicroRNAs (miRNAs) are small, regulatory RNAs that are expressed in animals and plants and affect the translation or stability of target mRNAs. The 17-24 nt, single-stranded (ss) miRNAs are derived from longer, primary transcripts termed “pri-miRNAs” [1].

How is PRI-miRNA made?

The microRNA (miRNA) genes are transcribed by RNA polymerase II (Pol II), which results in the production of a pri-miRNA. Drosha, along with DiGeorge syndrome critical region gene-8 (DGCR-8; Pasha in flies), mediates the initial processing step (primary processing) that produces a ~ 65 nucleotide (nt) pre-miRNA.

How long is PRI-miRNA?

The pri-miRNAs, which can be more than 1000 nt in length, contain an RNA hairpin in which one of the two strands includes the mature miRNA [1]. The hairpin, which typically comprises 60-120 nt, is cleaved from the pri-miRNA in the nucleus by the double-strand-specific ribonuclease, Drosha [1].

What is the function of DGCR8?

Within the microprocessor complex, DGCR8 function as a molecular anchor necessary for the recognition of pri-miRNA at dsRNA-ssRNA junction and directs DROSHA to cleave 11 bp away form the junction to release hairpin-shaped pre-miRNAs that are subsequently cut by the cytoplasmic DICER to generate mature miRNAs (PubMed: …

Where is PRI miRNA made?

cytoplasm
MicroRNA Nuclear Export Subsequent pre-miRNA (and possibly mirtron) processing occurs in the cytoplasm. Pre-miRNA assembles into a complex with the nucleocytoplasmic transporter factor Exportin-5 and RanGTP, which prevents nuclear degradation and facilitates translocation into the cytoplasm [101-105].

What is Drosha and Pasha?

Drosha is a type III RNase, which plays a critical role in miRNA biogenesis. Drosha and its double-stranded RNA-binding partner protein Pasha/DGCR8 likely recognize and cleave miRNA precursor RNAs or pri-miRNA hairpins cotranscriptionally.

What is the role of the microprocessor complex in miRNA biogenesis?

Located in the cell nucleus, the microprocessor complex cleaves primary miRNA (pri-miRNA), typically at least 1000 nucleotides long, into precursor miRNA (pre-miRNA). Its two subunits have been determined as necessary and sufficient for the mediation of the development of miRNAs from the pri-miRNAs.

How many miRNAs are there?

There are now over 2000 miRNAs that have been discovered in humans and it is believed that they collectively regulate one third of the genes in the genome. miRNAs have been linked to many human diseases and are being pursued as clinical diagnostics and as therapeutic targets.