Brief introduction about Sirna

  • Small interfering RNA (siRNA) is sometimes called short interfering RNA (short interfering RNA) or silencing RNA. It is a double-stranded RNA with a length of 20 to 25 nucleotides. There are many in biology Different uses. It is currently known that siRNA is mainly involved in the phenomenon of RNA interference (RNAi), which regulates gene expression in a specific manner. In addition, it also participates in some reaction pathways related to RNAi, such as antiviral mechanisms or changes in chromatin structure. However, the reaction pathways of these complex mechanisms are currently unclear.



    Small interfering RNA (siRNA), sometimes called short interfering RNA or silencing RNA, is a type of double-stranded RNA molecule that is 20-25 base pairs in length, similar to miRNA, and operates within the RNA interference (RNAi) pathway. It interferes with post-transcriptionally degraded mRNA of specific genes expressing complementary nucleotide sequences, thereby preventing translation.

    siRNA is cleaved by RNase III (such as Dicer) into double-stranded RNA (double strand RNA, dsRNA) in the cell into 21-25bp double-stranded RNA. dsRNA can be exogenous, such as viral RNA replication intermediates or artificially introduced dsRNA; it can also be endogenous, such as dsRNA formed by single-stranded RNA in cells under the action of RNA-dependent RNA polymerase.



    siRNA was first discovered by the team of David Baulcombe in the United Kingdom. It is part of the phenomenon of post-transcriptional gene silencing (PTGS) in plants. The results of the study were published in Science. In 2001, Thomas Tuschl's team discovered that synthetic siRNA can induce RNAi in mammals. The results were published in Science. This discovery led to the use of controllable RNAi for biomedical research and drug development.



    siRNA has a well-defined structure: a short (usually 20 to 24 bp) double-stranded RNA (dsRNA) with a phosphorylated 5'end and a hydroxylated 3'end with two overhanging nucleotides. The siRNA produced by the Dicer enzyme is composed of long dsRNA and small hairpin RNA. siRNA can also be introduced into cells by transfection. Since in principle any gene can be knocked down by synthetic siRNA with complementary sequences, siRNA is an important tool for verifying gene function and drug targeting in the post-genomic era.

    siRNA is usually a 21-nucleotide double-stranded RNA (dsRNA). The two strands are 2 nucleotides beyond the other end of the RNA, as shown in the figure below:

    Each strand has a 5'phosphate end and a 3'hydroxyl end. This structure is processed by an enzyme called dicer, which can cut long double-stranded RNA or small hairpin RNA (small hairpin RNA) into siRNA. In addition, siRNA can also be introduced into cells through a variety of different transfection techniques, and produce specific knockdown effects on specific genes. Therefore, the complementarity of appropriately tailored siRNA can be used to calibrate genes with known sequences. This phenomenon makes siRNA an important tool for studying gene function and drug targets.


    siRNA mechanism

    1. Long dsRNA (which can come from hairpins, complementary RNA and RNA-dependent RNA polymerase) is cleaved by an endoribonuclease called Dicer. Dicer cleaves long dsRNA to form short interfering RNA or siRNA; this allows the molecule to form an RNA-induced silencing complex (RISC).
    2. Once siRNA enters the cell, it will be integrated into other proteins to form RISC.
    3. Once the siRNA is part of the RISC complex, the siRNA is unfolded to form a single-stranded siRNA.
    4. The thermodynamically unstable chain due to its base pairing at the 5'end was selected as part of the RISC complex.
    5. The single-stranded siRNA that is part of the RISC complex can now scan and find complementary mRNA
    6. Once the single-stranded siRNA (part of the RISC complex) binds to its target mRNA, it induces mRNA cleavage.
    7. Now the mRNA is cut and recognized as abnormal by the cell. This leads to degradation of mRNA, and in turn does not translate mRNA into amino acids and then into protein. This silences the gene encoding the mRNA.

    siRNA is also similar to miRNA, however, miRNA is derived from a shorter stem-loop RNA product, which usually silences genes by inhibiting translation, and has a wider specificity of action, while siRNA usually works by cutting mRNA before translation, and has 100% complementarity, so the target specificity is very strict.


    About us

    BOC RNA is a sub-brand of BOC Sciences, which mainly focuses on RNA technology and its broad prospects in disease treatment.

    We provide comprehensive RNA related products and services, including jnk sirna, antibody sirna conjugate, sirna reagent, sirna therapeutics and mRNA vaccines, covering all development processes of RNA drugs.

    We will make every effort to help simplify and accelerate your drug discovery and disease treatment research efforts.