PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Synthetic circuit allows dialing gene expression up or down in human cells

Ability to tune gene activity will permit refined research for drug resistance, cancer

Synthetic circuit allows dialing gene expression up or down in human cells
2013-02-12
(Press-News.org) HOUSTON - Scientists who built a synthetic gene circuit that allowed for the precise tuning of a gene's expression in yeast have now refined this new research tool to work in human cells, according to research published online in Nature Communications.

"Using this circuit, you can turn a gene from completely off to completely on and anywhere between those two extremes in each cell at once. It's a nice tool if you want to know what happens at intermediate levels of gene expression. There has been no such system so far, but now it is available for mammalian cell research," said senior author Gábor Balázsi, Ph.D., associate professor in The University of Texas MD Anderson Cancer Center Department of Systems Biology.

Present options for altering gene expression in human cells are blunt instruments by comparison. Knocking out a gene eliminates its expression completely. Inhibiting it with RNA interference dials it partially down and can affect other genes. Inserting a gene expression vector into cells overexpresses the gene, but it's usually uncontrolled. Commercially available versions can switch a gene on or off, but cannot precisely dial between these extremes.

"For cancer research, the system will allow scientists to test the boundaries of a gene known to confer resistance to a drug in cancer cells by dialing its expression to different levels and treating the cells with the drug," said first author Dmitry Nevozhay, M.D. Ph.D., instructor in Systems Biology.

"Likewise, such a system would allow personalized gene therapy, by precisely tuning the therapeutic gene level expression depending on disease progression and the patient's need," Nevozhay said.

In microbial or yeast biology research scientists have started to understand and manipulate gene function quantitatively, almost like we understand electronic circuits, Balázsi said. "This makes research in those areas more amenable to engineering and mathematical characterization, - but that's not true for human cells, and part of the problem is that tools that tune gene expression have been lacking."

A step-by-step guide for others to build mammalian synthetic gene circuits

By refining their circuit to work in a human breast cancer cell line, the team demonstrated that their approach can be used in mammalian cells while offering a step-by-step guide that other researchers could follow to build other synthetic circuits for use with other genes.

"With all of our steps reported, if someone wants to build another type of gene expression switch, or oscillator, they could build the circuit in fast-growing yeast cells, where it can be engineered and optimized quickly and reliably," Balázsi said. "Once you know it works in yeast, you know the steps to make it function in human cells. This process is similar to extensive testing of NASA's space operations on Earth before actually carrying them out in space."

Synthetic biologists apply engineering principles to design and build new biological systems for predefined purposes.

In yeast, Balázsi and colleagues synthesized a gene circuit designed to control the level of gene expression precisely using the tetracycline repressor.

They made the promoter for the repressor identical to the promoter for the reporter gene yEGFP encoding the green fluorescent protein. This caused a negative feedback loop, creating a linear dependence of the yEGFP level on the tetracycline analog in the growth medium.

Tunable control of gene expression in mammalian cells

The researchers modified the synthetic network, which initially did not work at all in human cells. A computational model suggested a strategy to optimize the network for mammalian cells.

Several modifications improving transcription, translation and intracellular localization of the regulator protein were added to the synthetic network one at a time. Each one bolstered the network's output in human cells, until it finally achieved a linear dose response of gene expression to the tetracycline analog doxycycline.

Among the additions made to the circuit: Addition of an intron (non-coding DNA), which when inserted into genes can increase their expression in mammalian cells. Codon optimization in the repressor and reporter genes. Introduction of a nuclear-localization sequence, to take the circuit into the cell nucleus, where it can influence gene expression. Addition of the Kozak sequence, which improves gene expression in mammalian cells by enhancing translation. Promoter optimization, which maximizes the gap between full and basal expression.

Finally, they used the same circuit to control expression of an additional red fluorescence protein gene called mCherry as proof of concept for regulating other genes.

His synthetic gene circuit research won Balázsi a National Institutes of Health New Innovator Award in 2009, one of only 54 such grants made nationally that year to fund bold ideas with the potential to quickly translate research into improved human health.

"This research is not possible without the New Innovator Award," Balázsi said. "It allows you to explore off the beaten path. We aren't looking directly at the next obvious step towards curing cancer or discovering new molecular interactions.

"Yet, we believe steps that don't seem obvious today are crucial for tomorrow's therapies. We've outlined a set of engineering steps that will help us better understand and control gene expression to improve cancer treatment or develop new approaches to gene therapy," he said. "Traditional funding mechanisms would not have done it."

INFORMATION:

He also received an MD Anderson seed grant to launch his research.

Co-authors with Balázsi and Nevozhay is Tomasz Zal, Ph.D., of MD Anderson's Departments of Immunology and of Molecular and Cellular Oncology.

Research was funded by the NIH Director's New Innovator Award (1DP2 OD006481-01), a grant from the National Cancer Institute (R01 CA137059) and an MD Anderson Institutional Research Grant.

[Attachments] See images for this press release:
Synthetic circuit allows dialing gene expression up or down in human cells

ELSE PRESS RELEASES FROM THIS DATE:

Scientists create automated 'time machine' to reconstruct ancient languages

2013-02-12
Ancient languages hold a treasure trove of information about the culture, politics and commerce of millennia past. Yet, reconstructing them to reveal clues into human history can require decades of painstaking work. Now, scientists at the University of California, Berkeley, have created an automated "time machine," of sorts, that will greatly accelerate and improve the process of reconstructing hundreds of ancestral languages. In a compelling example of how "big data" and machine learning are beginning to make a significant impact on all facets of knowledge, researchers ...

Refocusing important on and off the court, says recent study.

2013-02-12
Toronto – If an employee's performance drops in one area, does that mean they're slacking off? It could mean that they've simply shifted and refocused their efforts on a different set of tasks -- a positive sign of adaptability that should be considered in performance evaluations, says a study lead by a researcher at the University of Toronto's Rotman School of Management. The study, published in Human Performance, draws on statistics from professional basketball players for its data and conclusions. Researchers assessed data on more than 700 members of the NBA to ...

Consumers have few negative reactions to the results of genetic testing for cancer mutations

2013-02-12
A 23andMe study of consumers' reactions to genetic testing found that even when the tests revealed high-risk mutations in individuals, those individuals had few negative reactions to the news. Instead of inducing serious anxiety, the test results prompted people to take positive steps, including follow-up visits with a doctor and discussions with family members who could also be at risk. The study, titled "Dealing with the unexpected: Consumer responses to direct-access BRCA mutation testing" published today as part of the launch of PeerJ, a new peer reviewed open access ...

Scientists advance the art of magic with a study of Penn and Teller's 'cups and balls' illusion

2013-02-12
Cognitive brain researchers have studied a magic trick filmed in magician duo Penn & Teller's theater in Las Vegas, to illuminate the neuroscience of illusion. Their results advance our understanding of how observers can be misdirected and will aid magicians as they work to improve their art. The research team was led by Dr. Stephen Macknik, Director of the Laboratory of Behavioral Neurophysiology at Barrow Neurological Institute, in collaboration with fellow Barrow researchers Hector Rieiro and Dr. Susana Martinez-Conde, Director of the Laboratory of Visual Neuroscience. ...

Identification of abnormal protein may help diagnose, treat ALS and frontotemporal dementia

Identification of abnormal protein may help diagnose, treat ALS and frontotemporal dementia
2013-02-12
Amyotrophic lateral sclerosis (ALS), or Lou Gehrig's disease, and frontotemporal dementia (FTD) are devastating neurodegenerative diseases with no effective treatment. Researchers are beginning to recognize ALS and FTD as part of a spectrum disorder with overlapping symptoms. Now investigators reporting online February 12 in the Cell Press journal Neuron have discovered an abnormal protein that first forms as a result of genetic abnormalities and later builds up in the brains of many patients with either disease. "In identifying the novel protein that abnormally accumulates ...

Neuroprosthesis gives rats the ability to 'touch' infrared light

2013-02-12
Researchers have given rats the ability to "touch" infrared light, normally invisible to them, by fitting them with an infrared detector wired to microscopic electrodes implanted in the part of the mammalian brain that processes tactile information. The achievement represents the first time a brain-machine interface has augmented a sense in adult animals, said Duke University neurobiologist Miguel Nicolelis, who led the research team. The experiment also demonstrated for the first time that a novel sensory input could be processed by a cortical region specialized in ...

A new 'virtual moderator' helps reach consensus in troubled negotiations

2013-02-12
A group of researchers have designed a new fuzzy ontology-based system to help people in disagreement reach consensus. This system, which acts as a virtual moderator, is a step forward in the field on Artificial Intelligence. This tool can be useful in making everyday decisions –such as choosing a wine in a restaurant–, but it can also be helpful in complex negotiations between countries fighting for their interests in the European Union framework. Fuzzy ontologies represent the relationships among basic concepts. This new system uses ontology to help in the decision-making ...

Low-arsenic rice discovered in Bangladesh could have major health benefits

2013-02-12
Amsterdam, NL, 12 February 2013 – Millions of people worldwide are regularly exposed to arsenic through drinking water and eating rice grown in soil and water containing high amounts of arsenic. Long-term exposure can lead to the development of different types of cancer as well as serious cardiovascular, neurological, and other health problems. Scientists have now identified aromatic rice from Bangladesh that has far lower arsenic concentrations than found in non-aromatic rice. The other important benefit is that it contains higher amounts of selenium and zinc. The discovery ...

Young children may go above and beyond when helping adults

2013-02-12
WASHINGTON – Even very young children understand that adults don't always know best. When it comes to helping, 3-year-olds may ignore an adult's specific request for an unhelpful item and go out of their way to bring something more useful, according to new research published by the American Psychological Association. Youngsters may also attempt to warn adults who are doing something counterproductive, such as reaching for an empty box of crayons to draw a picture or putting on a wet sweatshirt when they say they are cold, according to the article published online in ...

Mainz scientists confirm original tetrahedral model of the molecular structure of water

2013-02-12
Researchers at Johannes Gutenberg University Mainz (JGU) have confirmed the original model of the molecular structure of water and have thus made it possible to resolve a long-standing scientific controversy about the structure of liquid water. The tetrahedral model was first postulated nearly 100 years ago and it assumes that every water molecule forms a so-called hydrogen bond with four adjacent molecules. This concept was almost toppled in 2004 when an international research group announced that it had experimentally established that water molecules form bonds only with ...

LAST 30 PRESS RELEASES:

Sensing sickness

Cost to build multifamily housing in California more than twice as high as in Texas

Program takes aim at drinking, unsafe sex, and sexual assault on college campuses

Inability to pay for healthcare reaches record high in U.S.

Science ‘storytelling’ urgently needed amid climate and biodiversity crisis

KAIST Develops Retinal Therapy to Restore Lost Vision​

Adipocyte-hepatocyte signaling mechanism uncovered in endoplasmic reticulum stress response

Mammals were adapting from life in the trees to living on the ground before dinosaur-killing asteroid

Low LDL cholesterol levels linked to reduced risk of dementia

Thickening of the eye’s retina associated with greater risk and severity of postoperative delirium in older patients

Almost one in ten people surveyed report having been harmed by the NHS in the last three years

Enhancing light control with complex frequency excitations

New research finds novel drug target for acute myeloid leukemia, bringing hope for cancer patients

New insight into factors associated with a common disease among dogs and humans

Illuminating single atoms for sustainable propylene production

New study finds Rocky Mountain snow contamination

Study examines lactation in critically ill patients

UVA Engineering Dean Jennifer West earns AIMBE’s 2025 Pierre Galletti Award

Doubling down on metasurfaces

New Cedars-Sinai study shows how specialized diet can improve gut disorders

Making moves and hitting the breaks: Owl journeys surprise researchers in western Montana

PKU Scientists simulate the origin and evolution of the North Atlantic Oscillation

ICRAFT breakthrough: Unlocking A20’s dual role in cancer immunotherapy

How VR technology is changing the game for Alzheimer’s disease

A borrowed bacterial gene allowed some marine diatoms to live on a seaweed diet

Balance between two competing nerve proteins deters symptoms of autism in mice

Use of antifungals in agriculture may increase resistance in an infectious yeast

Awareness grows of cancer risk from alcohol consumption, survey finds

The experts that can outsmart optical illusions

Pregnancy may reduce long COVID risk

[Press-News.org] Synthetic circuit allows dialing gene expression up or down in human cells
Ability to tune gene activity will permit refined research for drug resistance, cancer