The researchers found that a protein complex called the DROSHA microprocessor complex plays a key role in this process. The DROSHA microprocessor complex is responsible for processing long primary microRNAs (pri-miRNAs) into shorter precursor miRNAs (pre-miRNAs). These pre-miRNAs are then further processed into mature miRNAs, which can then bind to and regulate gene expression.
The researchers found that the DROSHA microprocessor complex contains a protein called DGCR8, which is responsible for recognizing and binding to the pri-miRNAs. DGCR8 then recruits the DROSHA enzyme, which cleaves the pri-miRNAs into pre-miRNAs.
The researchers also found that the DROSHA microprocessor complex interacts with a protein called Exportin-5, which is responsible for exporting the pre-miRNAs from the nucleus to the cytoplasm. This process is essential for the miRNAs to be able to bind to and regulate gene expression.
The findings of this study provide new insights into the mechanisms by which gene-regulating small RNAs are processed and sorted by cellular machinery. This information could lead to the development of new therapies for diseases that are caused by the misregulation of miRNAs.
The study is published in the journal Nature Structural & Molecular Biology.
