[Skip to Content](https://www.sigmaaldrich.com#main-content) [](https://www.sigmaaldrich.com/US/en) Products Cart0 USEN Products [Login / Register](https://www.sigmaaldrich.com/oidc-sign-in) [Order Lookup](https://www.sigmaaldrich.com/US/en/order-lookup) [Quick Order](https://www.sigmaaldrich.com/US/en/quick-order) Cart0 [Home](https://www.sigmaaldrich.com/US/en)[Applications](https://www.sigmaaldrich.com/US/en/applications)[Genomics](https://www.sigmaaldrich.com/US/en/applications/genomics)Gene Expression & Silencing # Gene Expression & Silencing  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](https://www.sigmaaldrich.com/US/en/products/molecular-biology-and-functional-genomics/gene-editing-and-functional-genomics/rnai-libraries) 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](https://www.sigmaaldrich.com/US/en/products/molecular-biology-and-functional-genomics/gene-editing-and-functional-genomics/crispr-gene-editing) from SigmaAldrich® Advanced Genomics, researchers are able to accurately and efficiently knock-down, knock-out, activate or overexpress virtually any gene. * * * ## Related Products Slide 1 of 12 1 of 3 [ \ Sigma-Aldrich \ DCAS9P300 \ Sigma CRISPR dCas9-p300 Activator Expression Plasmid](https://www.sigmaaldrich.com/US/en/product/sigma/dcas9p300) Quick View [ \ Sigma-Aldrich \ CAS9P \ Cas9 plasmid](https://www.sigmaaldrich.com/US/en/product/sigma/cas9p) Quick View [ \ Sigma-Aldrich \ CAS9D10AP \ CRISPR Cas9-D10A Nickase Plasmid](https://www.sigmaaldrich.com/US/en/product/sigma/cas9d10ap) Quick View [ \ Sigma-Aldrich \ CAS9MRNA \ Cas9 mRNA](https://www.sigmaaldrich.com/US/en/product/sigma/cas9mrna) Quick View [ \ Sigma-Aldrich \ CAS9D10AMRNA \ CRISPR Cas9-D10A Nickase mRNA](https://www.sigmaaldrich.com/US/en/product/sigma/cas9d10amrna) Quick View [ \ Sigma-Aldrich \ CRISPR01 \ CRISPR Human EMX1 Positive Control](https://www.sigmaaldrich.com/US/en/product/sigma/crispr01) Quick View [ \ Sigma-Aldrich \ CAS9RFPP \ CMV-CAS9-2A-RFP Plasmid](https://www.sigmaaldrich.com/US/en/product/sigma/cas9rfpp) Quick View [ \ Sigma-Aldrich \ T1706 \ *Trans*IT-CRISPR®](https://www.sigmaaldrich.com/US/en/product/sigma/t1706) Quick View [ \ Sigma-Aldrich \ SNC10 \ mirPremier® microRNA Isolation Kit](https://www.sigmaaldrich.com/US/en/product/sigma/snc10) Quick View [ \ Sigma-Aldrich \ SNC50 \ mirPremier® microRNA Isolation Kit](https://www.sigmaaldrich.com/US/en/product/sigma/snc50) Quick View [ \ Sigma-Aldrich \ S1452 \ MISSION® siRNA Transfection Reagent](https://www.sigmaaldrich.com/US/en/product/sigma/s1452) Quick View [ \ Roche \ XTG360-RO \ X-tremeGENE™ 360 Transfection Reagent](https://www.sigmaaldrich.com/US/en/product/roche/xtg360ro) Quick View * * * ## Featured Categories [](https://www.sigmaaldrich.com/US/en/products/chemistry-and-biochemicals/biochemicals/agarose) [Agarose: Properties and Research Applications](https://www.sigmaaldrich.com/US/en/products/chemistry-and-biochemicals/biochemicals/agarose) Agarose bioreagents cater to cell culture and molecular biology applications, offering ready-to-pour agarose gels for RNA/DNA electrophoresis. [Shop Products](https://www.sigmaaldrich.com/US/en/products/chemistry-and-biochemicals/biochemicals/agarose) * * * Overview Related Articles & Protocols Support  Diagram showing the mechanistic flow of shRNA and siRNA mediated gene silencing in cells. ## [](https://www.sigmaaldrich.com)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. - [Explore shRNA CLONES & LIBRARIES](https://www.sigmaaldrich.com/US/en/product/sigma/shrna?context=product) ## [](https://www.sigmaaldrich.com)CRISPRi and CRISPRa - Powerful Gene Inhibition and Activation [CRISPRi (CRISPR interference)](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/genomics/advanced-gene-editing/crispri-crispra-pooled-lentiviral-screening) and [CRISPRa (CRISPR activation)](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/genomics/advanced-gene-editing/crispri-crispra-pooled-lentiviral-screening) 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. [](https://www.sigmaaldrich.com/documents-search) [Looking for More Specific Information?](https://www.sigmaaldrich.com/documents-search) Visit our document search for data sheets, certificates and technical documentation. [Find Documents](https://www.sigmaaldrich.com/documents-search)  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](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/genomics/advanced-gene-editing/crispri-crispra-pooled-lentiviral-screening) and [CRISPRa](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/genomics/advanced-gene-editing/crispri-crispra-pooled-lentiviral-screening) 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. - [CRISPRi Whole Genome and Non-Coding Libraries](https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/marketing/global/documents/284/436/crispri-genome-non-coding-libraries-fl7521en-ms.pdf) - [CRISPRa Whole Genome SAM Libraries](https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/marketing/global/documents/293/308/crispra-sam-library-flyer-fl1927en-ms.pdf) Wondering if CRISPR is right for your project? [Connect with a Sigma-Aldrich® Advanced Genomics Expert](https://www.sigmaaldrich.com/US/en/services/crispr-request-form).  ## Related Articles - [Predesigned siRNA](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/genomics/gene-expression-and-silencing/mission-predesigned-sirna) Rosetta siRNA Design Algorithm optimizes siRNA sequences for reduced off-target effects and increased RNAi performance. - [Reverse Transcription](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/genomics/gene-expression-and-silencing/reverse-transcription) Challenges in gene expression analysis include mRNA stability, temporal transcription patterns, and mRNA-protein correlation, impacting accuracy. - [Vector Maps](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/genomics/gene-expression-and-silencing/vector-map) A series of vectors to enable a successful implementation of your RNAi experiments. - [Superoxide Dismutase](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/research-and-disease-areas/cell-signaling/superoxide-dismutase) Enzyme Explorer Product Application Index for Superoxide Dismutase offered by us online. Superoxide Dismutase (SOD) catalyzes the reduction of superoxide anions to hydrogen peroxide. - [Bioluminescent Firefly Luciferase Assays](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/cell-culture-and-cell-culture-analysis/imaging-analysis-and-live-cell-imaging/firefly-luciferase-assays) Firefly luciferase is a sensitive reporter for gene studies due to its absence in mammalian cells or tissues. - [See All (53)](https://www.sigmaaldrich.com/US/en/search/facet-search?focus=sitecontent&term=facet-search) ## Related Protocols - [Spinoculation Protocol](https://www.sigmaaldrich.com/US/en/technical-documents/protocol/genomics/gene-expression-and-silencing/spinoculation-protocol) Protocol for lentiviral transduction of suspension cells using MISSION TRC shRNA Lentiviral Particles for long-term silencing. - [FACS Titration of Lentivirus Protocol](https://www.sigmaaldrich.com/US/en/technical-documents/protocol/genomics/gene-expression-and-silencing/facs-titration-of-lentivirus) FACS sorts cells based on light scattering and fluorescence for objective cell analysis. - [MystiCq® MicroRNA® Quantitation System](https://www.sigmaaldrich.com/US/en/technical-documents/protocol/genomics/gene-expression-and-silencing/mysticq-microrna-analysis) Method for purification, reverse transcription and quantitative PCR for MicroRNAs using Mysticq reagents - [Antibiotic Optimization for Cell Transduction](https://www.sigmaaldrich.com/US/en/technical-documents/protocol/genomics/gene-expression-and-silencing/cytotoxicity-profile) Determine optimal antibiotic concentration for stable cell lines, ensuring efficient selection in transduced cells. - [Preparation of the Lentiviral Transduction Particles Using Packaging Plasmid Mix](https://www.sigmaaldrich.com/US/en/technical-documents/protocol/genomics/gene-expression-and-silencing/lentiviral-packaging) Preparation of the Lentiviral Transduction Particles Using Packaging Plasmid Mix - [See All (18)](https://www.sigmaaldrich.com/US/en/search/facet-search?focus=sitecontent&term=facet-search) ### Find More Articles and Protocols Enter Keywords Search ## How Can We Help In case of any questions, please submit a [customer support request](https://www.sigmaaldrich.com/US/en/support/customer-support) or talk to our customer service team: Email [custserv@sial.com](mailto:custserv@sial.com) or call +1 (800) 244-1173 ## Additional Support - [Chromatogram Search](https://www.sigmaaldrich.com/chromatogram-search) Use the Chromatogram Search to identify unknown compounds in your sample. - [Calculators & Apps](https://www.sigmaaldrich.com/US/en/support/calculators-and-apps) Web Toolbox - science research tools and resources for analytical chemistry, life science, chemical synthesis and materials science. - [Customer Support Request](https://www.sigmaaldrich.com/US/en/support/customer-support) Customer support including help with orders, products, accounts, and website technical issues. - [FAQ](https://maestro.my.site.com/knowledgeportal/s/) Explore our Frequently Asked Questions for answers to commonly asked questions about our products and services. * * * __Featured Articles__ [3D Printable Inks: Energy & Environmental Apps](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/materials-science-and-engineering/3d-printing/3d-printable-inks-for-energy-and-environmental-applications) Additive manufacturing combined with nanomaterial-based inks enhances material properties, particularly in energy and environmental applications. [Predesigned siRNA](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/genomics/gene-expression-and-silencing/mission-predesigned-sirna) Rosetta siRNA Design Algorithm optimizes siRNA sequences for reduced off-target effects and increased RNAi performance. [Vector Maps](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/genomics/gene-expression-and-silencing/vector-map) A series of vectors to enable a successful implementation of your RNAi experiments. [Superoxide Dismutase](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/research-and-disease-areas/cell-signaling/superoxide-dismutase) Enzyme Explorer Product Application Index for Superoxide Dismutase offered by us online. Superoxide Dismutase (SOD) catalyzes the reduction of superoxide anions to hydrogen peroxide. * * * ## Related Resources - [Vector Maps](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/genomics/gene-expression-and-silencing/vector-map) A series of vectors to enable a successful implementation of your RNAi experiments. - [General shRNA FAQs](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/genomics/gene-expression-and-silencing/general-shrna-faqs) We answers your frequently asked questions about shRNA, the TRC. MISSION and more. Top __Sign In To Continue__ To continue reading please sign in or create an account. Sign In__Don't Have An Account?__Register An unknown error has occured. - English - EN - Español - ES [Learn More](https://www.sigmaaldrich.com)