A Short Note On Gene Regulation And Expression - 2403 Words

BS31006 – Gene Regulation Expression – Dr. Armel Nicolas Genome engineering using the CRISPR-Cas9 system Matei Agavriloaei - 120004682 24/11/2014 ABSTRACT: Modified nucleases have been used for years in order to achieve successful genome editing and are nowadays an almost universally-used method. RNA-guided nucleases (such as Cas9) with easily changeable characteristics have been generated in great numbers especially since the emergence of clustered regularly interspaced short palindromic repeats (CRISPR). This represents the most modern tool that can be used by scientists for genome editing. This technology can bring a broad range of medical benefits and advancements (1). CRISPR-Cas systems: CRISPRs are DNA loci that include†¦show more content†¦Figure 1: Overview of the CRISPR-Cas system – it shows the adaptive immunity with the use of viral DNA (3); Cas genes code for proteins related to CRISPRs. This association is a prokaryotic immune system. CRISPR spacers recognize and cut the foreign DNA material, just as RNAi does in eukaryotic organisms (2). In 2013, this system started being used (and is still widely used today) for adding and changing sequences of targeted genes (4), process also known as genome editing. The genome can be cut any location by guiding properly RNAs into a cell and also delivering Cas9 protein. In theory, it could be possible to build RNA-guided gene drives with the use of CRISPR to alter the genetic code of entire populations (5). CRISPR-RNA (crRNA) and Cas proteins come together and form CRISPR-ribonucleic proteins (crRNPs) for appropriate targeting and cleaving of the foreign nucleic acid (3). Due to the accelerate evolution of the immune system, the CRISPR-Cas systems are highly diverse and have been catalogued into three main types, each of them having a specific Cas protein. Type I and III and related and contain Cas3 nuclease-helicase and Cas10 (a protein with an unknown function) respectively. Type II is phylogenetically different and is represented by the Cas9 nuclease. Type II has three different subunits (A, B and C) and their crRNPs are all known as Cas9 complexes. They are restricted only to bacteria, not being in present in archaea as well (3).