CRISPR study reduces cholesterol in mice without "editing" DNA
Rather than hacking away with genetic scissors, recent work has instead used CRISPR to temporarily turn certain genes on and off through epigenetic modulation. In that vein, the new study developed a CRISPR-Cas9 repressor system that can silence a gene called Pcsk9, which regulates cholesterol levels. The Duke researchers managed to package this system and deliver it into the livers of adult mice.
"We previously used these same types of tools to turn genes on and off in cultured cells, and we wanted to see if we could also deliver them to animal models with an approach that is relevant for gene therapy," says Charles Gersbach, lead researcher on the study. "We wanted to change the genes in a way that would have a therapeutic outcome, and Pcsk9 is a useful proof-of-concept given its role regulating cholesterol levels, which in turn affect health issues like heart disease."
The researchers started with a Cas9 enzyme taken from the bacteria species Staphylococcus aureus, and to keep it from making cuts to the target DNA, they created a "dead" version dubbed dCas9. This was bundled with a KRAB protein that silences gene expression, and the combination was then packaged inside adeno-associated viral (AAV) vectors – viruses that are engineered to carry the active ingredients to the right DNA target.
In their tests, the Duke researchers delivered the system to adult mice, where it activated in their livers. Compared to a control group that had simple saline injections, the Pcsk9 genes in the test mice were successfully repressed and the animals' cholesterol levels dropped as a result. Better yet, the effects of a single treatment lasted six months.
RNA-guided transcriptional silencing in vivo with S. aureus CRISPR-Cas9 repressors (open, DOI: 10.1038/s41467-018-04048-4) (DX)
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CRISPR Used to Epigenetically Treat Diseases in Mice
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CRISPR gene modulation has been used to disrupt chronic inflammation:
[Robby] Bowles' team is using the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeat) system — new technology of modifying human genetics — to stop cell death and keep the cells from producing molecules that damage tissue and result in chronic pain. But it doesn't do this by editing or replacing genes, which is what CRISPR tools are typically used for. Instead, it modulates the way genes turn on and off in order to protect cells from inflammation and thus breaking down tissue.
"So they won't respond to inflammation. It disrupts this chronic inflammation pattern that leads to tissue degeneration and pain," Bowles says. "We're not changing what is in your genetic code. We're altering what is expressed. Normally, cells do this themselves, but we are taking engineering control over these cells to tell them what to turn on and turn off."
Now that researchers know they can do this, doctors will be able to modify the genes via an injection directly to the affected area and delay the degeneration of tissue. In the case of back pain, a patient may get a discectomy to remove part of a herniated disc to relieve the pain, but tissue near the spinal cord may continue to breakdown, leading to future pain. This method could stave off additional surgeries by stopping the tissue damage. "The hope is that this stops degeneration in its tracks, and the patient could avoid any future surgeries," Bowles says. "But it's patient to patient. Some might still need surgery, but it could delay it."
Found at ScienceDaily.
CRISPR-Based Epigenome Editing of Cytokine Receptors for the Promotion of Cell Survival and Tissue Deposition in Inflammatory Environments (DOI: 10.1089/ten.tea.2016.0441) (DX) (supplementary data)
Instead of using CRISPR/Cas9 for gene editing, Salk Institute researchers have used gene-activating CRISPR/Cas9 to regulate gene activity in mice:
A new twist on gene editing makes the CRISPR/Cas9 molecular scissors act as a highlighter for the genetic instruction book. Such highlighting helps turn on specific genes. Using the new tool, researchers treated mouse versions of type 1 diabetes, kidney injury and Duchenne muscular dystrophy [open, DOI: 10.1016/j.cell.2017.10.025] [DX], the team reports December 7 in Cell. The new method may make some types of gene therapy easier and could be a boon for researchers hoping to control gene activity in animals, scientists say.
CRISPR/Cas9 is a two-part molecular scissors. A short, guide RNA leads the DNA-cutting enzyme Cas9 to specific places in the genetic instructions that scientists want to slice. Snipping DNA is the first step to making or fixing mutations. But researchers quickly realized the editing system could be even more versatile.
In the roughly five years since CRISPR/Cas9 was first wielded, researchers have modified the tool to make a variety of changes to DNA (SN: 9/3/16, p. 22). Many of those modifications involve breaking the Cas9 scissors so they cannot cut DNA anymore. Strapping other molecules to this "dead Cas9" allows scientists to alter genes or change the genes' activities.
Gene-activating CRISPR/Cas9, known as CRISPRa, could be used to turn on dormant genes for treating a variety of diseases. For instance, doctors might be able to turn on alternate copies of genes to compensate for missing proteins or to reinvigorate genes that grow sluggish with age. So far, researchers have mostly turned on genes with CRISPRa in cells growing in lab dishes, says Charles Gersbach, a biomedical engineer at Duke University not involved in the new study.
Also at GenomeWeb and New Atlas.
(Score: 2) by realDonaldTrump on Tuesday May 01 2018, @06:00AM (1 child)
Some of these articles, it's like English is not their first language. Hard to understand. But I think they're saying it works on the bad cholesterol, the LDL. My bad cholesterol is a little high. It's not high. But it's almost high. I don't know why, I don’t think anybody knows. My doctors put me on some pills. But my bad cholesterol keeps going up. It's not a problem. But if it keeps going up, maybe, probably, it could become a problem. Dr. Jackson says I could live to 200 years old. Amazing genes. But maybe I could go even longer with the artificial ones.
Very disappointed at what the Dems did to Dr. Jackson. I never drink, I've never touched alcohol. But if a guy can drink a lot and still do good work, that's fine. And Dr. Jackson does good work. And he would have done great work for our vets, for our VA. He's a great guy, abused by a bunch of politicians that aren't thinking nicely about our country. Not nicely at all. I'll find another guy. Or a lady. Someone great, believe me. Need to privatize!!
(Score: 3, Interesting) by arslan on Tuesday May 01 2018, @11:47PM
I LDL really the source of bad stuff happening in the body though? Wasn't a theory out somewhere that high LDL is a reaction to something else bad happening in the body and supressing LDL, though beneficial for the direct symptoms caused by it is just turning a blind eye to the source which bad symptoms will still manifest eventually in the body?
Note, INAMD.