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Gene Expression & Silencing

Sigma-Aldrich® Advanced Genomics is the leading provider of gene editing and silencing technologies including CRISPR, Cas9, synthetic guide RNA (sgRNA), and Zinc Finger Nuclease (ZFN).

Modulating gene expression is one of the most powerful techniques employed by researchers investigating the complex genetic networks governing biological processes. In particular, gene modulation experiments are used extensively to identify therapeutics effective in combatting diseases ranging from cancer to developmental and neurodegenerative disorders.  

Numerous technologies exist for the effective regulation of gene expression in cells and tissues. RNAi (RNA interference) is a natural biological mechanism wherein siRNA (short interfering RNA) duplexes induce potent, targeted inhibition of gene expression. SigmaAldrich® Advanced Genomics has been a leader in developing commercial RNAi products for researchers. 

More recently, the development of CRISPR inhibition (CRISPRi) and CRISPR activation (CRISPRa) gives researchers a powerful new set of tools that allows for almost unlimited gene regulation options. Utilizing the unparalleled portfolio of CRISPR products from SigmaAldrich® Advanced Genomics, researchers are able to accurately and efficiently knock-down, knock-out, activate or overexpress virtually any gene.

Related Technical Articles

  • We offer advanced design and quality synthesis for predesigned siRNA and siRNA libraries using the Rosetta siRNA Design Algorithm to reduce off-target effects and increase RNAi performance. The algorithm utilizes Position-Specific Scoring Matrices (PSSM) and knowledge of the siRNA seed region to predict the most effective and specific siRNA sequences for a target gene of interest.
  • One approach to the analysis of gene expression is to measure the concentration of mRNA of a gene. There are several challenges to such analyses, such as the differences in half life between different transcripts, the temporal patterns of transcription and the lack of correlation between mRNA and protein.
  • A series of vectors to enable a successful implementation of your RNAi experiments.
  • Enzyme Explorer Product Application Index for Superoxide Dismutase offered by us online. Superoxide Dismutase (SOD) catalyzes the reduction of superoxide anions to hydrogen peroxide.
  • Firefly luciferase is a widely used bioluminescent reporter for studying gene regulation and function. It is a very sensitive genetic reporter due to the absence of endogenous luciferase activity in mammalian cells or tissues.
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Diagram showing the mechanistic flow of shRNA and siRNA mediated gene silencing in cells.

Diagram showing the mechanistic flow of shRNA and siRNA mediated gene silencing in cells.

RNAi - Gene Modulation to Illuminate Genetic Pathways

Functional genomics screens are an integral part of discovery research, allowing you to unravel the mechanisms that belie biological systems, pathways, and diseases. Effective interrogation of these complex molecular interaction networks can be accomplished using shRNA libraries to deliver reliable, efficient, and long-term knockdown.

Sigma-Aldrich® Advanced Genomics is the exclusive provider of the TRC1.5 and TRC2 collections from The RNAi Consortium (TRC). These lentivirus-based shRNA libraries deliver unparalleled coverage and are available in multiple formats that include whole-genome, individual RNAi clones/vectors, and gene family sets.

CRISPRi and CRISPRa - Powerful Gene Inhibition and Activation

CRISPRi (CRISPR interference) and CRISPRa (CRISPR activation) deliver highly efficient silencing and activation of genes, respectively, without altering the underlying DNA sequence. When employed in large scale LOF (loss-of-function) and GOF (gain-of-function) screens, researchers are able to identify unique, yet functionally related, gene pathways that are often missed with other methods.


Schematic diagrams of CRISPRa with the Synergystic Activation Mediator complex (SAM) and CRISPRi using the KRAB domain.

Sigma-Aldrich® Advanced Genomics offers a complete suite of optimized CRISPRi and CRISPRa libraries for gene knockdown and overexpression experiments. Pooled CRISPRi and SAM CRISPRa lentiviral libraries are available off-the-shelf or customized to your specific needs.

Wondering if CRISPR is right for your project? Connect with a Sigma-Aldrich® Advanced Genomics Expert.


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