1. A new technology developed at MIT and the Broad Institute that can rapidly start or halt the expression of any gene of interest simply by shining light on the cells.
The work is based on a technique known as optogenetics, which uses proteins that change their function in response to light. In this case, the researchers adapted the light-sensitive proteins to either stimulate or suppress the expression of a specific target gene almost immediately after the light comes on.
“Cells have very dynamic gene expression happening on a fairly short timescale, but so far the methods that are used to perturb gene expression don’t even get close to those dynamics. To understand the functional impact of those gene-expression changes better, we have to be able to match the naturally occurring dynamics as closely as possible,” says Silvana Konermann, an MIT graduate student in brain and cognitive sciences.
The ability to precisely control the timing and duration of gene expression should make it much easier to figure out the roles of particular genes, especially those involved in learning and memory. The new system can also be used to study epigenetic modifications — chemical alterations of the proteins that surround DNA — which are also believed to play an important role in learning and memory.
2. CRISPR genome editing is being made more effective and accurate
Earlier this year, MIT researchers developed a way to easily and efficiently edit the genomes of living cells. Now, the researchers have discovered key factors that influence the accuracy of the system, an important step toward making it safer for potential use in humans, says Feng Zhang, leader of the research team.
With this technology, scientists can deliver or disrupt multiple genes at once, raising the possibility of treating human disease by targeting malfunctioning genes. To help with that process, Zhang’s team, led by graduate students Patrick Hsu and David Scott, has now created a computer model that can identify the best genetic sequences to target a given gene.
The genome-editing system, known as CRISPR, exploits a protein-RNA complex that bacteria use to defend themselves from infection. The complex includes short RNA sequences bound to an enzyme called Cas9, which slices DNA. These RNA sequences are designed to target specific locations in the genome; when they encounter a match, Cas9 cuts the DNA.
This approach can be used either to disrupt the function of a gene or to replace it with a new one. To replace the gene, the researchers must also add a DNA template for the new gene, which would be copied into the genome after the DNA is cut.
This technique offers a much faster and more efficient way to create transgenic mice, which are often used to study human disease. Current methods for creating such mice require adding small pieces of DNA to mouse embryonic cells. However, the process is inefficient and time-consuming.
With CRISPR, many genes are edited at once, and the entire process can be done in three weeks, says Zhang, who is a core member of the Broad Institute and MIT’s McGovern Institute for Brain Research. The system can also be used to create genetically modified cell lines for lab experiments much more efficiently.
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Nature - DNA targeting specificity of RNA-guided Cas9 nucleases
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The work is based on a technique known as optogenetics, which uses proteins that change their function in response to light. In this case, the researchers adapted the light-sensitive proteins to either stimulate or suppress the expression of a specific target gene almost immediately after the light comes on.
“Cells have very dynamic gene expression happening on a fairly short timescale, but so far the methods that are used to perturb gene expression don’t even get close to those dynamics. To understand the functional impact of those gene-expression changes better, we have to be able to match the naturally occurring dynamics as closely as possible,” says Silvana Konermann, an MIT graduate student in brain and cognitive sciences.
The ability to precisely control the timing and duration of gene expression should make it much easier to figure out the roles of particular genes, especially those involved in learning and memory. The new system can also be used to study epigenetic modifications — chemical alterations of the proteins that surround DNA — which are also believed to play an important role in learning and memory.
2. CRISPR genome editing is being made more effective and accurate
Earlier this year, MIT researchers developed a way to easily and efficiently edit the genomes of living cells. Now, the researchers have discovered key factors that influence the accuracy of the system, an important step toward making it safer for potential use in humans, says Feng Zhang, leader of the research team.
With this technology, scientists can deliver or disrupt multiple genes at once, raising the possibility of treating human disease by targeting malfunctioning genes. To help with that process, Zhang’s team, led by graduate students Patrick Hsu and David Scott, has now created a computer model that can identify the best genetic sequences to target a given gene.
The genome-editing system, known as CRISPR, exploits a protein-RNA complex that bacteria use to defend themselves from infection. The complex includes short RNA sequences bound to an enzyme called Cas9, which slices DNA. These RNA sequences are designed to target specific locations in the genome; when they encounter a match, Cas9 cuts the DNA.
This approach can be used either to disrupt the function of a gene or to replace it with a new one. To replace the gene, the researchers must also add a DNA template for the new gene, which would be copied into the genome after the DNA is cut.
This technique offers a much faster and more efficient way to create transgenic mice, which are often used to study human disease. Current methods for creating such mice require adding small pieces of DNA to mouse embryonic cells. However, the process is inefficient and time-consuming.
With CRISPR, many genes are edited at once, and the entire process can be done in three weeks, says Zhang, who is a core member of the Broad Institute and MIT’s McGovern Institute for Brain Research. The system can also be used to create genetically modified cell lines for lab experiments much more efficiently.
Nature - DNA targeting specificity of RNA-guided Cas9 nucleases
Read more »
