BioQuakes

AP Biology class blog for discussing current research in Biology

Category: Student Post (Page 2 of 37)

CRISPR/CAS9: Potential to destroy malaria?

CRISPR. Sounds more like a new brand of potato chip than something potentially revolutionary (Bold new flavor. Bold new crunch. CRISPR.). Nevertheless, this tool used for easy gene editing and slicing is tearing up the science world because it could be the key to combatting disorders and diseases.

Recent research indicates that CRISPR/Cas9 based genome editing tools could aid in the fight against malaria, one of the “big three” diseases that has long affected and continues to affect humans worldwide. How is CRISPR/Cas9 able to do this?

CRISPRs (Clustered Regularly Interspaced Short Palindromic Repeats) originally are how bacteria protect themselves from foreign viruses. CRISPRs contain DNA from viruses that have attacked the bacteria, and so when a similar virus attacks, the bacteria knows that this virus and his DNA are bad. Essentially, CRISPRs allow bacteria to build up immunity. When foreign DNA is detected, the Cas9 enzyme is guided by the CRISPR and is able to cut the desired DNA. Scientists have come up with a way to engineer and manipulate the CRISP/CAS9 system into other organisms (such as mosquitoes) so that we can successfully edit genome sequences and genes to produce desired results. We take advantage by specifying which genes the Cas9 should cut/replace, and then it does just that. Therefore, the CRISPR/Cas9 system allows us new genome editing potential like none before.

Made by Viktoria Anselm.

How does this apply to mosquitoes and malaria? Scientists experimented with genetically modified malaria-transmitting mosquitoes (Anopheles gambiae), altering the fibrinogen-related protein 1 (FREP1) gene on them. This gene essentially codes for a protein that makes mosquitoes a vector for malaria. The scientists used the CRISPR/Cas9 to inactivate this gene.

The results produced mosquitoes with significantly less transmission of malaria to both human and rodent cells. However, these mosquitoes have “reduced fitness”: a significantly lower blood-feeding propensity, egg hatching rate, a retarded larval development, and reduced longevity after a blood meal. Essentially this means that these mosquitoes have a low chance of affecting populations of mosquitoes in the wild without being “pushed” by scientists, where scientists are “forcing DNA to inherit particular sets of genes.” This is called a gene drive. With a strong push for a couple of years, there is potential for worldwide mosquito populations to be significantly changed in 10-15 years.

Photo taken by JJ Harrison

I chose to write about this new research and potential breakthrough because it really means something to me, as I have lived in and visited countries threatened by malaria. I had to take preventative pills every morning, and I would have to sleep in a restrictive mosquito net. All that made me wonder about and feel for a kid in the same country who didn’t have those things and how he or she would manage without those barriers to malaria. Having said that, I really do believe this is a worthwhile option we should explore, and I think it can make a difference for the world.

What do you think? Do you think it is realistic for theses mosquitoes to change the entire mosquito population and effectively help reduce malaria transmission? Will CRISPR/Cas9 work as we hoped? Or is it too good to be true?

CRISPR Cas9, too good to be true?

After its peak in popularity following its reveal as a possible “genetic modifier” in 2013, the CRISPR Cas-9 enzyme system has been the center of debate within the biology community. Thought to be the solution to all genetic and hereditary diseases by simply “cutting out” the fault gene, new research and studies have shown that a majority of people (65 to 79 percent) have antibodies that would fight cas-9 proteins.

“The study analyzed blood for antibodies to two bacteria from which Cas9 is derived: Streptococcus pyogenes and Staphylococcus aureus. The researchers’ concern stemmed from the fact that these bacteria frequently cause infections in humans, and so antibodies to them may be in our blood” states bigthink.com

While the overall effects are unclear, the study concludes that the result would be “significant toxicity” and an unsafe use of the gene editing tool.

What do you think? Is the current risk of using Cas-9 worth the reward?

Click here, here, and here for more information.

Cas9, photo by J LEVIN W

 

Potential cure to ALS, the disease that inspired the ice bucket challenge!

You all remember the ALS ice bucket challenge, that took social media by storm, in which people dumped ice water on their heads in order to raise money and awareness to ALS, a neurodegenerative disease that progressively destroys the motor neurons and eventually leads to death.

 

There is currently no cure to this horrible disease. However new genetic technology (CRISPR) may change all that.

In short, CRISPR is a new form of gene editing that allows scientists to change an organism’s DNA.

Scientists discovered that ALS is caused by a mutation in the C9orf72 gene. ALS is often caused by a significant repeat of a segment of DNA that becomes toxic. So, using CRISPR, scientists deducted which genes either protect against or cause these toxic DNA segments. This process was extremely effective and scientists found about 200 genes that affect ALS. For example, scientists found a gene that codes for a protein called Tmx2 that when removed from mice neurons caused the mice to survive whereas not removing them killed them. This means that scientists are beginning to figure out how to cure ALS.

Discoveries such as these are revolutionary as we can now find specific causes for previously fatal, cureless diseases  such as this. In addition, using this technology we can target these specific genes and save lives.

However, whenever we discuss gene editing we must ethically consider when does this become too far? Where is the line between helping to cure people and helping to destroy society by designing babies?

To answer my own question, I think it is crucial that we take any step possible to help find cures in situations such as this. That being said, there are clear limits that must be respected. The line is definitely hazy. Let me know in the comments your thoughts about gene editing!

But for now, let’s enjoy this scientific win and hope that ALS can be officially cured. Good job ice bucket challenge for bringing attention to a serious issue that may now actually be cured.

Original Article: https://www.sciencedaily.com/releases/2018/03/180305111517.htm

Cas9: A Clue Into Making Gene Editing Safer

CRISPR is a revolutionary system that edits the DNA of living organisms with ease. The gene-editing technology offers scientists insight into genetic diseases and is widely used in biotech and agriculture, as well as to treat cancer and viral infections. But the CRISPR system and its mechanisms are not yet fully understood. However, researchers at the Ohio State University have reported that they have figured out the mechanism of how the CRISPR system figures out where and when to cut the DNA strands. This is particularly revolutionary as it provides insight into preventing gene-cutting errors.

Cas9 is an enzyme that is used by the system to target and cut out or insert specific genes. In the second of two paper published in the Journal of the American Chemical Society, the team invalidates the widely-held belief that the enzyme cuts DNA evenly. Professor of chemistry and biochemistry Zucai Suo explains that instead of cutting both sides of the DNA double-helix to the same length, Cas9  actually trims each side to uneven lengths. Ohio State doctoral student Austin Raper and his co-authors determined that the two different parts of the “Cas9 molecule communicate with each other to set the location and timing of a cut”. The first part of the molecule sets forth to cut its respective DNA strand and changes shape and signals to the second part to cut its respective second strand.

Crystal Structure of Cas9 Enzyme

Suo says that he hopes their work allows for scientists to minimize and eventually eliminate gene-editing errors. CRISPR rarely target unintended genes, but gene-editing errors can have very serious consequences. For example, if the system accidentally cut a tumor suppressor gene from a person’s DNA, they would be much more likely to develop cancer. As Raper says, it is important to understand CRISPR and the Cas9 enzyme mechanisms in order to allow CRISPR to advance to its full potential.

 

Source: https://news.osu.edu/news/2018/02/28/cas9-2cuts/

Deleting Genes to Stop Malaria

A new discovery has highlighted the positive effects that the revolutionary new gene editing tool, CRISPR-Cas9, can have. Scientists at the Johns Hopkins Bloomberg School of Public Health’s Malaria Research Institute have discovered that the deletion of a single gene from the Anopheles Gambiae mosquito, called the FREP1 gene, yields promising results in the eradication of the malaria disease.

 

Image result for mosquito gene editing

Gene Editing

The FREP1 gene has been associated with being a malaria “host factor” gene because it helps the parasite live in the gut of the mosquitoes.  However, the scientists, using the CRISPR-Cas9 gene editing procedures, have been able to delete the FREP1 gene from the mosquitoes and have seen significant decreases in the spread of malaria. Without the host factor gene, the parasite has difficulty surviving in the mosquito, which decreases the spread of the disease to other organisms.

 

The deletion of the FREP1 gene had other effects in addition to the resistance of the malaria parasites. In the mosquitoes where the gene was deleted, many showed no signs of sporozoite-stage parasites in their salivary glands, which can spread to humans through mosquito bites. George Dimopoulos, PhD, professor in the Bloomberg School’s Department of Molecular Microbiology and Immunology, commented on the study, saying that “if you could successfully replace ordinary, wild-type mosquitoes with these modified mosquitoes, it’s likely that there would be a significant impact on malaria transmission”.

Inside Out

CRISPR is a revolutionary tool used for editing the human genome. It allows for the altering of  any given DNA sequence and ability to modify any one specific genes’ function. Its applicability consists of correcting genetic defects, treating and preventing the spread of diseases, and improving crops. However, it also raises some ethical concerns, that of which mainly is the idea that practicing CRISPR technology could be considered as playing the role of “God”.

CRISPR was adapted from the natural defense mechanisms of bacteria, which use CRISPR-derived RNA and Cas proteins, to prevent attacks by viruses and other intruding organisms. They do so by chopping up and destroying the DNA of the virus. When these components are derived and applied to more complex, organisms, it allows for the manipulation of genes.

Disregarding its ethical concerns, CRISPR can provide substantial support to a previously uncharted area of medicine; the diagnosing and treating of genetic disorders, which was previously thought to be that if one had a genetic disorder it would be incurable.  Clinical trials are set to take place both in Europe and in North America, where patients with rare genetic disorders will give cellular samples in an attempt to alter their genome, implant them back into the individual, and hopefully cure the genetic abnormality.

With CRSPR taking such progressive strides in the past year, it is not outrageous to predict what its usage could end up providing society with.  With the ability to edit the human genome there are endless possibilities in which science could evolve this area of study to benefit the human race.  CRISPR can even be used to boost the expected intelligence of an embryo.  Who knows, thirty years from now we could be watching the news and hear of the first ever “superhuman”, a genetically modified human that has been hand-coded for optimality in all human functions.

Hello, CRISPR and Goodbye, Malaria

Everybody hates mosquitoes. Not only are they annoying pests that bite us during the summertime, but they are also transmitters of the parasite that spreads malaria–Plasmodium.  However, scientists believe that they have found a way to wipe out malaria for future generations. By using CRISPR in order to alter the fibrinogen-related protein 1 (FREP1), Plasmodium can be stopped from spreading amongst human beings.  The alteration stops the plasmodium from reaching the mosquitoes’ salvatory glands, effectively halting transmission into the human bloodstream.

However, although CRISPR is a lot less drastic than simply wiping out the mosquito population, it does come with minor setbacks.  The alteration made to the FREP1 gene causes the fertility of the mosquito as well as the egg-hatching rate to drop.  These effects cause the reproduction rates of the altered mosquitoes to be significantly lower than that of other mosquitoes.  If the modified mosquitoes are not able to reproduce, then the genetic modifications are unlikely to have any real effect on the transmission of malaria since they are not being passed on generationally.

The solution? Alter the female mosquitoes.  Only female mosquitoes transmit malaria, so scientists have realized that altering the genetic code of female mosquitoes might be the way to solve the problem with reproduction.  This way, the mosquitoes are able to maintain the genetic resistance to Plasmodium whilst avoiding the dramatic drop in reproduction.

Even though the alteration of mosquitoes’ genetics is definitely a scientific feat, there are no certainties when it comes to this attempt to stop malaria. Nobody is positive about whether or not CRISPR is the solution, but it is definitely a huge step in the right direction.

A New Addition to Gene Altering Technology

Today, there is new technology that allows genes to be edited. This is called CRISPR. CRISPR can fix genetic defects that lead to disease, improve food nutrition, and even resurrect extinct species. A research team in Japan created a new technology in addition to CRISPR that can change a single DNA base in the human genome. This is called Microhomology-Assisted eXcision or MhAX. The team called this new technique “absolute precision” in their article published in the Nature Communications journal.

MhAX originated when a group of researched wanted to have a better understanding on single nucleotide polymorphisms (SNP), which are single DNA mutations that can contribute to hereditary disease. In order to discover that these SNPS cause disease, researchers need to compare two genetically matched “twin cells.” However, twin cells are difficult to make because twin cells are not completely identical-they have a single different SNP. MhAX gives a new way to make twin cells.

The research teams used an extensive process to make the edits. First, the SNP modification and fluorescent reporter gene is inputed into the cell. This allows for researchers to see which cells are changed. The researchers then created another same DNA sequence, called microhomology, that was stationed on each side of the fluorescent gene. This allowed for sites where CRISPR can enter and trim the DNA. In order to leave only the SNP in, the research team used microhomology-mediated end system (MMEJ), a repair system that can remove the fluorescent gene. This technique, according to the team of researches, is precise and they are hopeful that it will be used to gain a better understanding of disease mechanisms which could potentially lead to gene therapies.

MhAX is very interesting because it is an additional technique to CRISPR that can help alter genes. It is very fascinating to read about the future of genetics and the new technology being created that can changes genes connected to diseases and improve the lives of people. For more information on MhAX, click here and here. Based on this research, how do you think this technology will be used in the future?

 

 

 

The Future of CRISPR

CRISPR is starting to become more and more of a reality as Harvard professor David Liu continues to work on it. Liu was the person who originally developed CRISPR first base editor which allowed for single letter changes in the genetic code. Liu has come up with two new features to CRISPR-Cas9.

The first is called cellular detective or CAMERA(CRISPR-mediated analog multievent recording apparatus systems). What this function does is it finds the genetic problem that is responsible for the disease someone is experiencing. Cas9 will record all the cell data and piece info together, which overall will provide more information about cancer, stem cells, aging, and overall disease.

Photo Source

The second finding is referred to as sharp scissors which is a CRISPR enzyme. Sharp scissors are way more precise and accurate than the old enzyme making is much safer. The scissors depend on specific DNA to find the region where it is supposed to cut or edit. CRISPR is progressing and as more research is being done could be used on humans in the future.

 

CRISPRainbow

The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)and CRISPR-associated protein 9 complex has become one of the biggest technological advances in science. This genome editing technology has taken multiple advances toward closer research into studies of embryonic development to cancer. CRISPRainbow, a modification to CRISPR where the Cas9 is mutated, allows researchers to label up to seven different genomic locations in live cells.
CRISPR has been used for editing genomes, however, research specialist Hanhui Ma and his team has used it to label DNA and track the movement of DNA in live cells. With this new research, we can find the precise genomic location in order to understand the movement of chromosomes. This is important because the genes that create our biological make-up and control our health do so by their location in the 3-D space.
Currently, with CRISPR, we can only label three genomic locations at a time in each cell. It has extremely challenged scientists to label more sites because it would require cells to be mixed in formaldehyde, which would kill them, making it impossible to observe the chromosome’s structure when stimulated by a response.
The new Cas9 mutation causes the nuclease to deactivate, so it only binds to DNA and doesn’t cut the genome. Then, the CRISPRainbow is docked into location by the guide RNA which can be programmed technologically. Research specialist, Hanhui Ma was able to figure out a way to implement computational coloring. Each guide RNA would include one of the three primary fluorescent proteins: red, green or blue which then can be observed in real time under a microscope. Pretty cool, right? Well, guess what? It doesn’t stop here. Ma decided to go even further in his research and attach a second fluorescent protein to the guide RNA. Ma could then combine the three primary colors to generate three additional labels: cyan, magenta, and yellow. From the primary colors, he was able to achieve white as the seventh color.
CRISPRainbow can track the challenging and dynamic movement of genomes that may lead to biological consequences. Research Scientist, Hanhui Ma, states “With this technology, we can visualize different chromosome loci at different points in time.” We can observe the structural changes in chromosomes overtime with help us understand their relation to health and disease. So why do you think they called is CRISPRainbow? What kind of diseases can we track with this new technology? What more can CRISPRainbow do in the near future?

CRISPR used to treat diabetes, kidney disease, muscular dystrophy

Scientists have now created a new method of using CRISPR genome editing, which would allow them to activate genetics without breaking the DNA. It could potentially be a major improvement in using gene editing techniques to treat human diseases. Currently, most of the CRISPR systems work by creating DSBs or Double strand Breaks in regions of the genome targeted for editing. Many scientists and researchers have opposed creating breaks in the DNA of living humans. So the Salk group tried their new method to treat diseases such as diabetes, kidney disease, and muscular dystrophy in the mouse models.

CRISPR has proved to be a powerful tool for gene therapy, but there are still many concerns regarding some mutations generated by the DSBs though the Salk group is able to get around that concern. Originally, Cas9 enzyme couples with guide RNA to create DSBs. But just recently, researchers have used a dead form of dcas9 to stop the cutting of DNA. DCas9 would couple with transcriptional activation domains, that turn on targeted genes. But it is still difficult to be used in clinical applications.

Salk group team combined dcas9 with bunch of activator switches to uncover a combination that would work even when the proteins are not fused with one another. These components all work together to influence endogenous genes. It would influence genetic activities without having to change the DNA sequence.

In order to prove the usefulness of this method, scientists used mouse models of acute kidney disease, type 1 diabetes, and a form of muscular dystrophy. They engineered their new CRISPR system to boost the expression of an endogenous gene that would reverse the symptoms of the disease. In all three cases, they reversed disease symptoms.

To understand more, click here.

 

Photo credit: Martyn Fletcher

 

CRISPR Cas-9 is the New Key to Curing Parkinson’s Disease

A new screening tool for Parkinson’s Disease was just discovered by a team of researchers at the University of Central Florida. They did this by using cutting edge gene-editing technology, CRISPR Cas-9, which allows scientists to detect levels of alpha-synuclein, a brain protein associated with Parkinson’s.

What is alpha-synuclein?

This protein can be found in our brain, it is something all humans have. When someone develops Parkinson’s, the levels of this protein become abnormal. This protein can become dangerous to neurons and kill them. This person would gradually loose brain cells, affecting their motor functions.

What is CRISPR Cas-9?

CRISPR Cas-9, Clustered Regularly Interspaced Short Palindromic Repeats, is a gene-editing system that enables scientists to edit DNA while preserving the cell. Instead of extracting all of the proteins from a cell and measuring them, CRISPR Cas-9 allows us to edit one gene.

How is used?

The specific gene the team wanted to edit was the alpha-synuclein. The CRISPR Cas-9 helped them edit the gene and add a luminescent tag, made up of similar proteins that make fireflies glow, in order to track how much of this protein is produced in a brain cell. When the brain cell produces alpha-synuclein, it glows, making it easier to visualize once the cell is in a diseased state. Furthermore, scientists can treat these cells with different medications, whether or not they glow will tell if the medications tested are successful.

The Future:

Engineered cells and light detection are a great duo for the future of researchers. Light detection on these engineered cells is helpful for high throughput screening where multiple drugs can be tested at the same time. This research can potentially lower the number of Parkinson’s cases per year. Currently, 60,000 new cases are reported per year in just the United States! Could these numbers drop in the future? Can CRISPR help find a cure to other diseases as well? Reading this article opened my mind to the endless possibilities CRISPR unlocked, I am excited to see where else it could take science.

 

 

 

CRISPR: Back at it Again

Researchers at the Gladstone Institutes made scientific history by turning skin cells of rats into stem cells by activating a certain gene in those cells using CRISPR technology. CRISPR technology is a tool used for editing genomes through making it easy for researchers to modify gene function and easily alter DNA sequences. CRISPR stands for “clusters of regularly interspaced short palindromic repeats” and it has been a popular topic of discussion and research in the science world.

Gladstone senior investigator, Sheng Ding and his team shaped their research aiming to answer the question; “can you reprogram a cell just by unlocking a specific location of the genome?” which they answered yes at the end. They decided to test on specific stem cells that can be turned into any cell type in the body, Pluripotent cells. Ding built upon a different senior investigators discovery, Shinya Yamanaka, who found he could make stem cells out of skin cells by treating skin cells with four key proteins called transcription factors. Here Yamanaka learned that the transcription factors could change which genes are expressed in the cell, turn off genes associated with skin cells, and turn on genes associated with stem cells and he called these skin turned to stem cells Induced Pluripotent Stem Cells (iPSC).

So Sheng Ding was inspired by Yamanaka’s investigation and decided to follow the same process but treat skin cells with CRISPR  instead of transcription factors. They targeted genes Sox2 and Oct4, only expressed in stem cells, which can turn on stem cell genes and turn off those associated with different cell types. With CRISPR, Ding and his team discovered they could reprogram cells activating Sox2 or Oct4. This proved to be more efficient than previous study, as using the CRISPR technology to target a specific location on the genome immediately triggered a natural chain reaction reprogramming the entire cell into an iPSC.

This was surprising and groundbreaking for this research group as they answered their guided question but came out with more. They still want to understand how the CRISPR technology was able to trigger a change within a whole cell efficiently and immediately compared to any other tested process. This study expanded knowledge on CRISPR and its many functions, and creates more questions on why and how it can do what it does. CRISPR technology continues to confuse scientists by manipulating genes in new, different, and unpredictable ways so the next question is, what does it have up its sleeve next???

Original Article 

CRISPR-cas9: Coming to a Human Near You

CRISPR

What is CRISPR?

As the world becomes more technologically developed, CRISPR is a new and upcoming technique to genetically edit genes. Being able to alter DNA sequences and revise gene roles, scientists now have the ability to correct defects, prevent diseases/mutations and improve genes overall.  As time goes on, scientists now feel that they are ready to genetically alter humans.

This image represents what CRISPR is capable of. The two wrenches represent that CRISPR edits the DNA strands and creates new and improved DNA.

How does CRISPR work?

CRISPRs are specialized stretches of DNA recognized by the protein Cas9. Cas9 is an enzyme that acts like a pair of molecular scissors, capable of cutting strands of DNA. Without that enzyme, CRISPR would not be successful.

CRISPR stands for “clusters of regularly interspaced short palindromic repeats.” It is a specialized region of DNA with two obvious characteristics

  1. the presence of nucleotide repeats and spacers.
  2. Repeated sequences of nucleotides — the building blocks of DNA — are distributed throughout a CRISPR region.

Spacers are bits of DNA that are interspersed among these repeated sequences.

***According to livescience.com, there is a built-in safety apparatus, which guarantees that Cas9 will not cut anywhere in a genome. Short DNA sequences become tags and stay adjacent to the target DNA sequence. If the Cas9 complex doesn’t see a short DNA sequence next to its target DNA sequence, it won’t cut.***

Is this really safe for humans?

Not too long ago, a study by Columbia University Medical Center was published in May, in the journal Nature Methods, about this “revolutionary” CRISPR gene-editing technique. It claimed that CRISPR caused unwanted and dangerous mutations and left the medical community baffled. The paper questioned how effective gene-editing technology is and called for a reassessment of the technique’s safety. However, this publication has to do with how CRISPR was first tested: 3 mice and very controversial results. Editage.com stated that “two of the three study subjects, the CRISPR-edited mice, happened to be more closely related and thus shared more mutations. Therefore, the paper claimed that “the premise of the old study was incorrect.”



If you have the choice, will you use CRISPR to design your children? Comment!

Hacking Evolution to Stop Malaria?

Kevin Esvelt is a biochemist, at MIT Media Lab, his approach to dealing with disease is instead of waiting for a disease to infect you, eradicate it completely. His hope is that on animals, such as mosquitos. he could use the CRISPR technology to block the gene. He believes that “we should be able to build organisms that are programmed to be immune to every virus known to infect them“.  By using the CRISPR/Cas9 gene editing and gene drive he, and his team, would be able to block that gene from appearing in the next generation.

C

 

https://commons.wikimedia.org/wiki/Category:CRISPR#/media/File:15_Hegasy_Cas9_DNA_Tool_Wiki_E_CCBYSA.png

 

Although, eradicating horrible diseases such as Ebola and Malaria sounds extremely beneficial; there is some draw back. Malaria, for example, is spread across many nations; therefor, scientist would need permission to genetically alter a species from each nation; but before this can be agreed upon test communities would need to be set up. Esvelt would want to test the CRISPR technology in small, localized areas before moving on to an entire species. Esvelt is confident that with a disease as deadly as Malaria, nations would be able to reach an agreement to go with gene editing. Esvelt hopes that by using CRISPR technology he would be able to create organisms, like mosquitos, in the case of Malaria, that are programmed to be immune to Malaria. If this were to happen these deadly disease would not be able to spread. Hence, Esvelt’s key belief of not waiting for the disease infect you, but rather eradicate it completely,

 

 

CRISPR The End of ALS?

ALS, amyotrophic lateral sclerosis, is a nervous system disease that weakens muscles and impacts physical functions. ALS is diagnosed in less than 20,000 people a year but there is currently no cure. Amyotrophic lateral sclerosis is caused by protein clumps in the brain which make voluntary movements progressively harder. The protein clumps destroy neurons in the brain through toxins. Scientist are yet to figure out how the toxins do this. A group of researches then decided to use CRISPR-Cas9 to get a better understanding of what is actually happening. During their research they realized that when a gene was affected it protected the neurons. It was already known that a gene called C9orf72 caused for unnatural repeating in certain parts of DNA and is the cause for the build up of proteins in ALS. The research group isolated certain genes by knocking out others. During this process they realized that when the gene Tmx2 is inactive it hindered cell deaths in mouse neurons. “If you have a small molecule that could somehow impede the function of Tmx2, there might be a therapeutic window there” said co-author Micheal Haney. Michael Bassik, Ph.D., assistant professor of genetics at Stanford and other reaserchers plan to do more studies on Tmx2 to get more detailed and accurate information. They also plan on doing CRISPR screens to find other possible causes for ALS and work on cures for other neurodegenerative disorders.

Other researchers are trying to use CRISPR-Cas9 to find a cure to ALS. Researchers are beginning to focus on editing RNA in hopes to cure a form ALS and other neurodegenerative diseases.This technique has produced mixed results. Research at the University of California, Riverside, has made progress in developing a molecule which can target EphA, this is a “gene that’s known to govern the onset and progression of neurodegenerative diseases”.

You can read more here.

New Enzyme Reducing Off-Target DNA Editing

A new enzyme named xCas9 allows researchers to target more sites in the genome than with traditional CRISPR-Cas9 editing, while also reducing off-target effects. The technique was reported earlier this year (February 28) by a biologist David Liu and his colleagues.

CRISPR-Cas9 has become the gene-editing tool of choice in many labs due to the effectiveness and convenience. But CRISPR-Cas9 has limitations like the necessity of targeting a particular sequence called a PAM near the gene to be modified, which limits researchers’ ability to make specific genetic changes.

“Relief from the PAM restriction is quite important,” Albert Jeltsch of the University of Stuttgart in Germany. “Some of these elements are quite small, and then the restriction can be quite relevant.”

Liu and his colleagues used a laboratory technique to evolve an enzyme that could recognize a broader range of PAM sequences, enabling more sites in the genome to be targeted. It just so happens that xCas9 also turned out to be more specific to the targeted sites, with fewer off-target effects. xCas9 will allow gene therapy to have higher success rates.

Transporting Organs from Pigs to People!

The shortage of human organs for transplants is one of the biggest problems facing the medical field, about 22 people die on waitlists for organs die every day in the United States. But there is a newfound hope! A recent discovery using CRISPR-cas9 gene editing may address this challenge.

Scientists have been dreaming about transplanting organs from pigs into people for years, a process called xenotransplantation, but they have been held back by threatening viruses in the pigs DNA called PERVs. PERVs are present throughout the pig genome and would infect a person who receives a pigs heart, lung, kidney, etc. This infection could be fatal and may cause a human epidemic. Scary right? However, scientists at well-known laboratories had a breakthrough this past summer using CRISPR-cas9 and created healthy pigs with no traces of PERV genes!

It was, in fact, the two early developers of that gene-editing technology, Harvard University’s George Church, and Luhan Yang, who first believed CRISPR’s guide RNA and a DNA-slicing enzyme could make precise, genome-wide changes to pig cells. Their results showed that CRISPR could “knock out” PERV genes at all 62 sites in the pig genome. However, there were some flaws in their experiments, they used a line of “immortal” pig kidney cells, which were chosen for their ability to survive in the dish. Earlier the team had tried to use genetically “normal” pig cells, but once the cells were edited they failed to grow normally. Yang says, “CRISPR’s hacking job of the DNA may have prompted them to stop dividing or self-destruct.” But when they exposed the cells to a “chemical cocktail” making them “immortal,” the growth of PERV free cells in the dish rose to 100%.  The next step was to actually produce piglets. The researchers inserted DNA containing the nuclei of the edited cells into the eggs taken from the ovaries of pigs in a slaughterhouse. They allowed each egg to develop into an embryo and implanted it in the uterus of a surrogate mother. Boom, healthy, PERV-free piglets!

https://commons.wikimedia.org/wiki/File:Cute_Piglet.jpg

After this huge finding, Church and Yang co-founded a company called eGenesis which focuses on the engineering of transplant organs and projects in laboratories around the world exploded. Currently, a transplant surgeon at the University of Maryland is gearing up to swap a pig heart into the chest of a baboon! However, obstacles still remain in regard to humans; the rejection of the organs once in humans, the physiological incompatibility, how to insert genes that will prevent toxic interactions with human blood, and (what I believe is most important) the ethical question.

 

 

 

 

CRISPR/Cas9: Is it really the cure?

There are many benefits to the CRISPR/Cas9 defense system. But, do the pros outweigh the cons?

CRISPR is a molecule that can be programmed to target a specific sequence in a genome. It guides an enzyme, such as Cas9, to chop the code like scissors. There have been many studies and tests done using the defense. The most important advantages of CRISPR/Cas9 over other genome editing systems are its simplicity and efficiency. Since it can be applied directly in the embryo, CRISPR/Cas9 reduces the time required to change certain genes compared to other systems.

However, many attempts to use this mechanism have failed. Using the mechanism is not as easy as it sounds. A Cas9 repair is not always precise. On ZMEScience, one HIV patient tried the process. But, the HIV cells were only made stronger. Researchers equipped T-cells to hurt the virus with the enzyme Cas9. T cells are a type of lymphocyte that play a central role in cell-mediated immunity. T cells equipped with Cas9 were seen to successfully hurt the HIV genome, and make it unable to properly reproduce. This project led by Chen Liang from McGill University in Montreal, Canada seemed to work fine. But, the team noticed that two weeks later T cells were producing copies of virus particles that had escaped the CRISPR attack. The area around Cas9 only developed more mutations, aka it made the HIV stronger. It is also impossible to direct the Cas9 exactly where one wants it to go. So in essence, it is a risky gamble.

Although there are hopes for this technique to be more refined and successful in the future, for now, its uses are limited.

For more information click here.

CRISPR, A Cure to Heart Disease?

Photo Source page: Flickr.com

     While CRISPR‘s full potential in the department of gene editing is still being researched, scientists have just successfully discovered CRISPR’s ability to correct a defective gene that causes a certain type of heart disease. Though scientists are unclear as to the type of gene corrected in order to cause this change, this discovery was made for the first time in the United States, by an experiment done on live human embryos. However the new information yielded from this experiment is extremely beneficial as it shows CRISPR’s potential in correcting genetic errors that cause disease, as well as in human embryos meant for pregnancy.

Another reason for which this study particularly stands out in its importance, is because it is much different from the other developments scientists have made in CRISPR’s abilities. Studies have been conducted worldwide using CRISPR to edit of somatic cell’s gnomes, however, this only affects individual people. This study (also done by researchers in China), has been done by editing germ line cells, which result in changes that are passed down through every following generation.

However since the changes made to cells do affect all generations that follow, scientists are unsure of the exact effects of this new technique. Although it seems that this technology will be very beneficial in stopping harmful genetic diseases, it can also be used for changing DNA to genetically determine the eye colors, height or even mental and physical abilities and intelligence. This new phenomenon is own as “designer babies”, and for many reasons, this is not something that the United States is trying to use CRISPR’s abilities for. For this reason, United States has recently created more severe guidelines regarding gene editing technology, as well as enforcing CRISPR’s use on embryos only for prevention of harmful genetic diseases, when other treatments were not successful – as a last resort – formed by the National Academies of Sciences, Engineering and Medicine.

In the study done, scientists edited out a mutant copy of MYBPC3, using CRISPR. MYBPC3 is a gene that encodes a protein that creates well maintained and structured heart muscles. Hypertrophic cardiomyopathy, known as HCM, are caused by mutations in that gene, and cause spontaneous cardiac arrest. This occurs in even the youngest and healthiest of athletes, affecting 1 in 500 humans.

In this study, the mother was carrying the normal version of a gene, while the father had the mutant gene. Using CRISPR, the scientists were able fix the mutant version, by cutting and replacing the DNA. Directly after they placed the fertilized egg in a petri dish, while introducing the genome editing parts at the same time. The results of this process proved to be very effective, as 75% of the embryos showed no mutant genome. Without the use of CRISPR when egg fertilization occurred, the chances of mutation would have been present in 50%!

From these results the researchers came to the conclusion that they have realized the potential for mosaicism. Mosaicism is when only some of the cells are edited and the rest are not affected, which results in some normal cells, as well as some mutant cells. The scientists have also gathered the effects of off-targets. Off targets are the CRISPR edited genes that appear to look like mutant genes, but are actually not. Within this study, one egg fertilized from 58 showed mosaicism, and there was no detection of effects from off-targets. Theseare very impressive results, due to the fact that both of these possible situations can cause limitations in effectiveness and safety.

Though researchers need to do over this experiment many times in order to soliditfy the effectiveness of this study for the future, if they want to use this on eggs intended for pregnancy, as the eggs fertilized in the study were not meant for pregnancy… However, the results have yielded nothing but good news for the future of CRISPR technology (besides, the risk in advancements in “designer babies”, which couldchange the future of conceiving, forever…). This article was extremely interesting for me to read, as I am very interested in studying Biology in the future, or even pursuing a track to medicine. Perhaps, I may get the chance to even experiment with CRISPR at some time in my life, as it becomes a growing presence throughout the science world!

Primary Source Article: U.S. researchershave used gene editing to combat heart disease in human embryos

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