Experimental perturbations to investigate cardiovascular physiology
Neil Herring, David J. Paterson in Levick's Introduction to Cardiovascular Physiology, 2018
Another way of reducing gene expression without genomic knockout is through interference RNA (RNAi). Small interfering RNA (siRNA) sequences or genomic non-coding microRNA can bind to specific mRNA molecules and prevent translation into protein. Endogenous double-stranded RNA (dsRNA) is cleaved into short interfering dsRNA (siRNA) by an endoribonuclease enzyme (endoribonuclease Dicer). siRNA can be unwound into a guide strand and a passenger strand with the guide strand targeting specific mRNA to the RNA-induced silencing complex (RISC), where the catalytic argonaute 2 cleaves the mRNA and prevents translation, as demonstrated in Figure 20.5. This pathway has been exploited by introducing dsRNA or siRNA to target specific mRNA. This was first achieved in Caenorhabditis elegans by feeding the worm with Escherichia coli carrying the required dsRNA; it led to the award of the 2006 Nobel Prize in Medicine or Physiolog y to Andrew Fire and Craig Mello. Introduction of RNAi can also be achieved with a viral vector delivery system. The challenge with RNAi is to find sequences that produce significant degrees of knockdown in protein expression without having off-target effects on other mRNAs. Scrambled sequences should also be used as a negative control.
Introduction to molecular exercise physiology
Adam P. Sharples, James P. Morton, Henning Wackerhage in Molecular Exercise Physiology, 2022
Finally, additional epigenetic modifications include post-transcriptional modifications to mRNA that can lead to altered protein structure and function. This can occur via small RNA species known as siRNA (small interfering RNA) and miRNAs (micro RNA) (120). Investigations have been conducted in response to both aerobic exercise and resistance exercise and miRNA profiles (121, 122) and miRNA expression can differ between high and low responders to exercise adaptation (123). Work by Timmons’ group was really the first, most comprehensive study in this area, as genetic (genomic), gene expression (transcriptomic) and miRNA (‘miRomic’) profiles were undertaken within the same study. Indeed, they found that a gene network associated with the transcription factors Runx1, Pax3 and Sox9 were associated with adaptation to endurance exercise and that the regulatory miRNA’s post-transcriptionally regulated these transcription factors (124). There are still only a few studies that investigate the role miRNAs have on transcribed mRNA sequences, and therefore the protein structure and function of the corresponding translated proteins, in response to exercise.
Recent Advances In HIV/AIDS
Anne George, K. S. Joshy, Mathew Sebastian, Oluwatobi Samuel Oluwafemi, Sabu Thomas in Holistic Approaches to Infectious Diseases, 2017
Small interfering RNA (siRNA) is small RNA of 18-25 nucleotides (nt) in length that play important role in regulating gene expression. It is incorporated into an RNA-induced silencing complex (RISC) and serves as guides for silencing their corresponding target mRNAs based on complementary base-pairing. The promise of gene silencing has led many researchers to consider siRNA as an anti-viral load tool. However, in long-term settings, many viruses appear to escape from this therapeutical strategy. HIV sets a very good example in evading RNA silencing, by either mutating the siRNA-targeted sequence or by encoding for a partial suppressor of RNAi (RNA interference) (Man et al., 2005).
The emerging role of dipeptidyl-peptidase-4 as a therapeutic target in lung disease
Published in Expert Opinion on Therapeutic Targets, 2020
Hai Zou, Ning Zhu, Shengqing Li
Small interfering RNA (siRNA), are also commonly referred to as short interfering RNA or silencing RNA. siRNA is a type of double-stranded, non-coding RNA molecule similar to micro RNA (miRNA), that operates within the RNA interference (RNAi) pathway. They are designed to impede the expression of targeted genes with complementary nucleotide sequences, by degrading mRNA after transcription, and thus inhibiting translation. Jean et al. are developing novel delivery vehicles to transfer siRNA specific to DPP-4. Moreover, positively charged nucleic acids are challenging to deliver across the cell membrane, and the therapeutic nucleic acids are vulnerable to nucleases. Novel chitosan (CS)-based nanoparticles (NP) were developed to help deliver siRNA to target cells. RT-PCR assays confirmed reduced expression the DPP-4 gene in treated cells [54]. Recent advances in research have shown the potential that DPP-4 holds in treatment of diseases, not least respiratory ones. Furthermore, its biological functions beyond metabolic disorders are slowly emerging and the molecular pathways, interactions and associations are being understood. This paves the way to innovative anti-DPP-4 therapies which are being developed and furthers its use as a drug target. It can be used in a wide spectrum of pharmaceutical approaches and different domains of the protein can be targeted. These strategies also hold the potential to reduce side effects and thus be approved for therapeutic use.
Strategies for targeting undruggable targets
Published in Expert Opinion on Drug Discovery, 2022
Gong Zhang, Juan Zhang, Yuting Gao, Yangfeng Li, Yizhou Li
For undruggable targets, another stunning approach is manipulating at genetic/transcription level rather than protein level. Small interfering RNA (siRNA) down-regulates mRNA and subsequent protein expression[46]. There have been over 50 siRNA-based clinical trials, including attempts to target mutant-specific p53 to treat kidney acute renal failure by I5NP (QPI-1002) and silence c-myc to treat solid tumor or multiple myeloma[47]. CRISPR-Cas technology is also a promising gene-editing strategy for future therapeutics (Figure 1e)[48]. These strategies are still faced with challenges, to name a few, delivery efficiency, rapid degradation, and off-target effect. These limitations might be solved by chemical modification, rational sequence design, and exquisite RNA carrier system. RNA-based therapies could be complementary to the strategies above on the therapeutic entity level to synergistically crack undruggable targets.
Clinical implications of extracellular vesicles in neurodegenerative diseases
Published in Expert Review of Molecular Diagnostics, 2019
Arada Vinaiphat, Siu Kwan Sze
Great examples of the therapeutic potential of exosome-mediated siRNA delivery have been demonstrated in vivo. siRNA, or small interfering RNA, represents as a therapeutic tool by interfering with neurodegenerative disease-associated gene expression. However, due to its large size, siRNA transport across the BBB is mostly restricted. Cooper et al., and colleagues have successfully developed an exosomal siRNA delivery system across the BBB that could potentially reverse dysfunctional brain α-synuclein aggregates [114]. They engineered dendritic cell-derived exosomes to express Rabies virus glycoprotein (RVG), a brain-targeting peptide, onto the N-terminal of exosomal Lamp2b surface membrane protein. Genetically modified exosomes were then loaded with siRNA that target the α-synuclein gene. Peripheral injection of exosomes expressing RVG and loaded with α-synuclein siRNA into transgenic mice exhibiting α-synuclein aggregates induced a reduction in intraneuronal proteinopathy [114,115].
Related Knowledge Centers
- Gene Expression
- Hydroxylation
- Microrna
- Molecule
- Rna
- Rna Interference
- Phosphorylation
- NON-Coding Rna
- Base Pair
- Translation