CRISPR Past and Present: Gene Editing Technology Changes Life
As a physicist proposed in the 1980s, along with the Human Genome Project, "the 21st century is the century of life sciences." In 2012, two scientists, Jennifer Doudna and Emmanuelle Charpentier, researched and developed CRISPR-Cas. Gene editing technology was born and won the 2020 Nobel Prize in Chemistry, becoming a milestone in the history of life sciences and marking the arrival of a new era in the field of life sciences.
CRISPR (Clustered regularly interspaced palindromic repeats) is an adaptive immune mechanism that exists in the immune system of archaea and bacteria and is used to fight against foreign invading plasmids and phages. Scientists have used the working principles of CRISPR, along with new computer and fluorescence imaging techniques, to develop new technologies for CRISPR gene editing. As a symbol of life on earth and a carrier of genetic information, DNA has always been extremely attractive and arousing curiosity to humans due to the conservation and editability of its sequence (aka genome or gene). Genome editing or changes are even more challenging for scientists. Since the birth of CRISPR technology, CRISPR toolbox has played a huge role in research in the biomedical field, such as agricultural plant trait changes, disease diagnosis, etc.
CRISPR Principle
CRISPR is a repetitive segment of DNA sequence, which contains a direct repeat sequence of 21-37 bp and a non-repeating spacer sequence (spacer) in between. Related genes adjacent to CRISPR, also called Cas (CRISPR-associated) genes, encode Cas proteins. In archaea and bacteria, CRISPR and Cas form the CRISPR/Cas system, which work together to resist foreign invading phages or plasmid transduction. The current CRISPR/Cas system is divided into two major categories based on the composition of the Cas protein, six types and more than 30 subtypes. Among them, Cas9 and Cas12a belong to Class 2 and are used in gene editing and gene screening.
CRISPR can guide and recognize specific sequences of target DNA through its own generated RNA (crRNA), which is cut by the Cas protein with DNA shearing enzyme activity and generates DNA breaks. This DNA shearing process is the basis for its application in the genome. The main principle of editing, and therefore, CRISPR/Cas is called "gene scissors". Based on the ability of eukaryotic cells to efficiently repair broken DNA, DNA sequences can be modified or changed as needed. Cas proteins use RNA-DNA base pairing to recognize DNA. Taking Cas12a as an example, the same protein can locate diverse DNA sequences by simply replacing crRNA. In addition, by changing the amino acids in the active site of Cas12a, various desired DNA nicks (nicks obtained by cutting single-stranded DNA) can be achieved. In this way, the CRISPR/Cas system can achieve the down-regulation or up-regulation of specific genes through the inhibition or activation of RNA transcription, which can be used for disease diagnosis or biological research.
CRISPR’s Past and Future
In the past ten years since the birth of CRISPR, the application of CRISPR-Cas technology has mainly focused on knocking out target genes in genes or gene regulatory elements. As a result, a number of technology platforms have been successfully built to achieve rapid manufacturing of gene-knocked-out animals. models, as well as perform genetic screens and multiplex gene editing. In addition to conventional CRISPR-Cas-induced gene knockout, base editing can generate precise point mutations at specific sites. In addition, CRISPR technology has become a genetic engineering tool in the hands of scientists and is widely used in biological function research, understanding of gene interactions, early diagnosis of diseases, as well as combating human diseases and genetically engineered crop production.
By 2024, as CRISPR further penetrates into the fields of medicine, agriculture and climate, there will be opportunities to comprehensively and rapidly improve human health and make the world a better place. In the next ten years, gene editing will further expand in research and application fields, further promote each other with advanced technologies such as machine learning, live cell imaging, and gene sequencing, and expand and optimize the CRISPR toolbox , to address various challenges and continue to play a broad role in basic and applied research. In terms of medical clinical applications, the U.S. FDA has approved multiple CRISPR-based clinical trials in recent years, and more gene therapy clinical trials targeting blood system diseases are ongoing or about to begin.
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7. https://worldscience.cn/c/2023-05-28/642569.shtml