What is the Difference Between shRNA and siRNA?

The main difference between small interfering RNA (siRNA) and short hairpin RNA (shRNA) lies in their structure, biogenesis, and stability within the cell. Here are the key differences:

1. Structure: SiRNAs are typically double-stranded RNA molecules, 20-25 nucleotides in length. On the other hand, shRNAs are sequences of RNA, about 80 base pairs in length, that include a region of internal hybridization, creating a hairpin structure.
2. Biogenesis: siRNAs are directly delivered to the cytosol as a siRNA duplex. In contrast, shRNAs are synthesized in the nucleus of cells, further processed, and transported to the cytoplasm, where they are incorporated into the RNA-induced silencing complex.
3. Stability: siRNAs are transiently expressed in cells and are degraded within the cell after a period of time. In contrast, shRNAs can be stably integrated through virus-mediated transduction, allowing for longer knockdown of the target mRNA.
4. Delivery: shRNAs can be incorporated into plasmid vectors and integrated into the cell's genome, enabling longer-lasting gene silencing. This stability allows for the potential use of shRNA in gene therapy applications, while siRNA is mainly used for transient gene silencing.
5. Expression Control: shRNAs can be controlled using inducible promoters, allowing for more precise regulation of gene expression. SiRNAs, on the other hand, are typically transfected directly into cells without the option for such control.
6. Gene Silencing: Both siRNAs and shRNAs are used for gene silencing through the RNA interference (RNAi) pathway, but shRNAs may cause fewer off-target effects compared to siRNAs.

Comparative Table: shRNA vs siRNA

Here is a table comparing the differences between shRNA and siRNA:

Please note that these are general differences, and specific characteristics and applications may vary depending on the experimental system and design.