91Ó°¿â

The mechanistic understanding of bacterial immune systems recognized by this year's Nobel Prize in Chemistry has engendered an explosion of creative uses for the technology. There are far too many to cover them all, but here are snapshots of interesting papers.

Some approaches are clearly translational, while others solve problems in basic research. Either way, the first thing any CRISPR scientist will tell you about their field is that basic research can have applications no one would have predicted.

These approaches are not all ready for clinical or industrial use, and some may never go that far. Researchers are still learning how to prevent unintended side effects of CRISPR editing.

(clockwise from top): Innovative Genomics Institute; GerryShaw/Wikimedia; Umberto Salvagnin/Wikimedia; Geralt/Pixabay

Basic biology in cultured cells

Some of the cleverest CRISPR applications start out as publications answering a design question: "Would this work?" Researchers have adapted the basic template of an RNA-guided protein effector in myriad ways. RNA-directed targeting has been used …

• As a molecular recorder that logs in a living cell.
• To edit DNA only in cells illuminated with blue light, through .
• To knock out in a cancer cell line one by one, finding drivers of drug resistance.
• To alter genome architecture by bringing two DNA regions together, forming reversible loops in the chromatin using .
• To in DNA without introducing a double-stranded cut, using a cytidine deamidase, or similar enzyme, targeted using dCas9. Such editors can convert C to G, G to A, T to C or A to G.
• As a potential antiviral that many related viruses.
• To rewrite epigenetic modifications; researchers have used fusion proteins made of catalytically inactive Cas9 fused to , s and other enzymes to find out what happens when epigenetic marks on specific sequences change.
• To screen for enhancer regions and other using a panel of guide RNAs directed to regions outside of the coding region of a growth-essential gene.
• To find synthetic lethal genetic interactions, which exist when a cell can survive without either of two genes but having both removed.
• To manipulate gene expression; researchers can either by blocking RNA polymerase from binding, or by recruiting transcriptional activators to DNA.
• With guide RNA constructs that can take two conformations, to run or coincidence-detecting Cas12 and Cas9 systems.

(clockwise from top) Diego Delso/Wikimedia; Rama/Wikimedia; Sanjay Acharya/Wikimedia; PublicDomain Pictures/pixabay.

In model organisms in the lab

• To generate more realistic, genetically diverse tumors in .
• To knock a gene into only certain tissues in a mouse by expressing Cas9 globally, but delivering sgRNAs only to .
• To diminish the population of sub-subtypes of T cells that contribute to diseases like encephalitis by disrupting a that is normally dispensable but required to survive in some microenvironments.
• To generate Cas9 systems that are cell type–specific because of endogenous microRNAs blocking or enabling expression of a or an .  
• To understand the biology of organisms that have never before been used as genetic model organisms, such as , , snail and .

(clockwise from left): Nottmpictures/pixabay; K Wol/pixabay; Alicja/pixabay; ngari.norway/Wikimedia.

In agriculture and environmental management

To power gene drives that can propagate a new allele through populations more rapidly than it usually would be transmitted through general reproduction — for example, to render malaria-carrying mosquitoes the malaria parasite.

• To understand how crops important to human health and perhaps use that information to breed or engineer more nutritious varieties.
• To breed dairy cattle , eliminating the need for painful de-horning of calves.
• To study microbes that could be used to produce biofuels, but are compared to E. coli and various pathogens.  
• To develop more s through microbiome engineering.

Centers for Disease Control and Prevention; Needpix; Ed Uthman/flickr; Alice Pien/Wikimedia.

In clinical settings

• To that detect genes from SARS-COV-2, the virus that causes COVID-19, or other pathogens.
• To excise from cellular reservoirs using CRISPR/Cas9 targeting the long tandem repeats in the HIV genome.
• To generate for transplant onto patients with a blistering skin .
• To expand the pool of potential donors to HIV-positive patients by editing CCR5, the viral receptor, in an otherwise matched donor prior to transplant.
• To within cells that might govern the toxicity of antibody/drug conjugates used to deliver targeted chemotherapy — and could help predict which patients will benefit and which will experience more harmful side effects.
• As a target in  bacteria with CRISPR systems, for new antibiotics that work by sensitizing certain strains to phages: for example, targeting only or bacteria.
• To screen for new or inhibitors of G-protein–coupled receptors, including — by coexpressing a variety of G proteins and GPCRs — for only certain receptor/signal protein pairs. 
• To alter methylation patterns in cultured neurons derived from induced pluripotent stem cells, of the gene FMR1 that is associated with fragile X syndrome. 
• To deliver gene therapy for sickle cell anemia and the related disease beta-thalassemia, genetic disorders that affect the hemoglobin protein; patients received a bone marrow transplant with CRISPR/Cas9-edited bone marrow cells modified to of fetal hemoglobin.

Did we miss an application of CRISPR technology that's important to you? Let us know by emailing asbmbtoday@asbmb.org, and we'll consider adding it to the list.