Heart drug may help treat ALS

ALS, also known as Lou Gehrig's disease, destroys the nerve cells that control muscles. This leads to loss of mobility, difficulty breathing and swallowing and eventually death. Riluzole, the sole medication approved to treat the disease, has only marginal benefits in patients.

But in a new study conducted in cell cultures and in mice, scientists showed that when they reduced the activity of an enzyme or limited cells' ability to make copies of the enzyme, the disease's destruction of nerve cells stopped. The enzyme maintains the proper balance of sodium and potassium in cells.

"We blocked the enzyme with digoxin," said senior author Azad Bonni, MD, PhD. "This had a very strong effect, preventing the death of nerve cells that are normally killed in a cell culture model of ALS."

The findings appear online Oct. 26 in Nature Neuroscience.

The results stemmed from Bonni's studies of brain cells' stress responses in a mouse model of ALS. The mice have a mutated version of a gene that causes an inherited form of the disease and develop many of the same symptoms seen in humans with ALS, including paralysis and death.

Efforts to monitor the activity of a stress response protein in the mice unexpectedly led the scientists to another protein: sodium-potassium ATPase. This enzyme ejects charged sodium particles from cells and takes in charged potassium particles, allowing cells to maintain an electrical charge across their outer membranes.

Maintenance of this charge is essential for the normal function of cells. The particular sodium-potassium ATPase highlighted by Bonni's studies is found in nervous system cells called astrocytes. In the ALS mice, levels of the enzyme are higher than normal in astrocytes.

Bonni's group found that the increase in sodium-potassium ATPase led the astrocytes to release harmful factors called inflammatory cytokines, which may kill motor neurons.

Recent studies have suggested that astrocytes may be crucial contributors to neurodegenerative disorders such as ALS, and Alzheimer's, Huntington's and Parkinson's diseases. For example, placing astrocytes from ALS mice in culture dishes with healthy motor neurons causes the neurons to degenerate and die.

"Even though the neurons are normal, there's something going on in the astrocytes that is harming the neurons," said Bonni, the Edison Professor of Neurobiology and head of the Department of Anatomy and Neurobiology.

How this happens isn't clear, but Bonni's results suggest the sodium-potassium ATPase plays a key role. When he conducted the same experiment but blocked the enzyme in ALS astrocytes using digoxin, the normal motor nerve cells survived. Digoxin blocks the ability of sodium-potassium ATPase to eject sodium and bring in potassium.

In mice with the mutation for inherited ALS, those with only one copy of the gene for sodium-potassium ATPase survived an average of 20 days longer than those with two copies of the gene. When one copy of the gene is gone, cells make less of the enzyme.

"The mice with only one copy of the sodium-potassium ATPase gene live longer and are more mobile," Bonni said. "They're not normal, but they can walk around and have more motor neurons in their spinal cords."

Many important questions remain about whether and how inhibitors of the sodium-potassium ATPase enzyme might be used to slow progressive paralysis in ALS, but Bonni said the findings offer an exciting starting point for further studies.

repost from http://www.sciencedaily.com/releases/2014/10/141026195413.htm

How Much Do You Know About Enzyme

WHAT are enzymes?

Enzymes are macromolecular biological catalysts, which are responsible for thousands of metabolic processes that sustain life. Enzymes are also highly selective catalysts, greatly accelerating both the rate and specificity of metabolic reactions, from the digestion of food to the synthesis of DNA. Most enzymes are proteins, although some catalytic RNA molecules have been identified. It exists in the form of specific three-dimensional structure, and may employ organic and inorganic cofactors to assist in catalysis.

HOW do they work?

Enzymes act by converting starting molecules into different molecules. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates sufficient for life. Enzymes are selective for their substrates and speed up only a few reactions from among many possibilities. The set of enzymes made in a cell determines which metabolic pathways occur in that cell, tissue and organ.

Like all catalysts, enzymes increase the rate of a reaction by lowering its activation energy. Most enzyme reaction rates are millions of times faster than those of comparable un-catalyzed reactions. Just as all catalysts, enzymes will not be consumed by the reactions they catalyze, nor will they alter the equilibrium of these reactions. However, enzymes do differ from most other catalysts for they are highly specific for their substrates.

WHAT function do they have?

Enzymes serve a wide variety of functions inside living organisms.

l  They are indispensable for signal transduction and cell regulation, often via kinases and phosphatases.

l  They also generate movement, with myosin hydrolyzing ATP to generate muscle contraction and also moving cargo around the cell as part of the cytoskeleton.

l  An important function of enzymes is in the digestive systems of animals. Enzymes such as amylases and proteases break down large molecules into smaller ones, so they can be absorbed by the intestines.

l  Enzymes are also involved in more exotic functions, such as luciferase generating light in fireflies. Viruses can also contain enzymes for infecting cells.

About us

Creative Biogene is a US-based manufacturer and provider of genomics and proteomics products and services for academic and governmental research institutes, pharmaceutical and biotechnology industry. The company offers a range of enzymes such as restriction enzyme, polymerases, nucleases, ligases, and reverse transcriptase, nuclease, phosphatase and kinase to perform the most commonly performed nucleic acid modifications. To become the premier provider of innovative technologies, products, unique tools and services for research discoveries and product development in the areas of biological and biomedical research. Emphasis will be placed on the manufacture and distribution of genomics and proteomics based biological research reagent products of the highest possible quality, which include nucleic acid, protein and antibody based research reagent products and services.

 http://www.creative-biogene.com/

A New Role of Enzyme as DNA Protector was Found

A New Role of Enzyme As DNA Protector Was Found

Embryonic Stem Cells in Trial for Diabetes

Embryonic Stem Cells in Trial for Diabetes

Finding the switch: Researchers create roadmap for gene expression

In a new study, researchers from North Carolina State University, UNC-Chapel Hill and other institutions have taken the first steps toward creating a roadmap that may help scientists narrow down the genetic cause of numerous diseases. Their work also sheds new light on how heredity and environment can affect gene expression.

Pinpointing the genetic causes of common diseases is not easy, as multiple genes may be involved with a disease. Moreover, disease-causing variants in DNA often do not act directly, but by activating nearby genes. To add to the complexity, genetic activation is not like a simple on/off switch on a light, but behaves more like a "dimmer switch" -- some people may have a particular gene turned all the way up, while others have it only turned halfway on, completely off, or somewhere in between. And different factors, like DNA or the environment, play a role in the dimmer switch's setting.

According to Fred Wright, NC State professor of statistics and biological sciences, director of NC State's Bioinformatics Center and co-first author of the study, "Everyone has the same set of genes. It's difficult to determine which genes are heritable, or controlled by your DNA, versus those that may be affected by the environment. Teasing out the difference between heredity and environment is key to narrowing the field when you're looking for a genetic relationship to a particular disease."

Wright, with co-first author Patrick Sullivan, Distinguished Professor of Genetics and Psychiatry at UNC-Chapel Hill and director of the Center for Psychiatric Genomics, and national and international colleagues, analyzed blood sample data from 2,752 adult twins (both identical and fraternal) from the Netherlands Twin Register and an additional 1,895 participants from the Netherlands Study of Depression and Anxiety. For all 20,000 individual genes, they determined whether those genes were heritable -- controlled by the DNA "dimmer switch" -- or largely affected by environment.

"Identical twins have identical DNA," Wright explains, "so if a gene is heritable, its expression will be more similar in identical twins than in fraternal twins. This process allowed us to create a database of heritable genes, which we could then compare with genes that have been implicated in disease risk. We saw that heritable genes are more likely to be associated with disease -- something that can help other researchers determine which genes to focus on in future studies."

The study appears online April 13 in Nature Genetics.

"This is by far the largest twin study of gene expression ever published, enabling us to make a roadmap of genes versus environment," Sullivan says, adding that the study measured relationships with disease more precisely than had been previously possible, and uncovered important connections to recent human evolution and genetic influence in disease.

The Netherlands Twin Register has followed twin pairs for over 25 years and in collaboration with the longitudinal Netherlands Study of Depression and Anxiety established a resource for genetic and expression studies. Professor Dorret Boomsma, who started the twin register, says, "in addition to the fundamental insights into genetic regulation and disease, the results provide valuable information on causal pathways. The study shows that the twin design remains a key tool for genetic discovery."

---

Story Source:

The above story is based on materials provided by North Carolina State University. The original article was written by Tracey Peake. Note: Materials may be edited for content and length.

All the cell's a stage: One protein directs epigenetic players

Date:

October 10, 2014

Source:

University of North Carolina School of Medicine

Summary:

One gene-regulating protein called Bre1 must be maintained in the proper amount for other epigenetic players to do their jobs properly, researchers have found. It’s a key coordinator in the sort of cellular scenes that can turn a healthy cell into a cancer cell.

Every single human cell contains every single human gene. But depending on the cell, only some of these genes need to be expressed or "turned on." For instance, a heart cell has all the genes needed for, say, proper kidney function. But that heart cell won't express those genes. In a heart cell, those genes are "turned off." When one of these "wrong" genes is turned on by mistake, the result can be rampant cell growth -- cancer.

How this happens used to be the stuff of science fiction. Now, scientists know that there are tiny proteins -- epigenetic proteins -- that sit atop the genetic code inside cells. These proteins are responsible for turning on or off the genes.

Now, UNC researchers discovered that one gene-regulating protein called Bre1 must be maintained in the proper amount for other epigenetic players to do their jobs properly. It's a key coordinator in the sort of cellular scenes that can turn a healthy cell into a cancer cell.

Setting the Scene

Within each cell of the body is an ongoing and intricate performance with genes playing some of the leading roles. As with all performances, the actors do not act alone, but instead, rely on support from behind the scenes. This supporting staff provides the script and cues for what the genes are supposed to say and do -- how genes are accessed and used. Important members of the support staff are histones -- the proteins that package genes inside cells and allow them to be used for various cellular functions that keep us healthy; they allow the plot to unfold perfectly.

Unfortunately, sometimes cues are missed or lines are forgotten and the show doesn't go as planned. This causes the actors to speak when they should be quiet or stay quiet when they should speak. And if one of these actor genes happens to be essential for, say, cell growth, then the result can be disastrous. The actors take the story in an unintended direction.

All this supporting staff is part of epigenetics -- epi meaning on or above -- a field that focuses on the environment and the players that allow our genes to act.

"I think epigenetics is a new frontier of cancer research," says Brian Strahl, Ph.D., a professor of biochemistry and biophysics in the UNC School of Medicine. "We can now sequence the entire genome of a cancer cell, and what we're finding is that many cancers have mutations in the epigenetic machinery. We're not just finding this in cancer cell lines in the lab but in cancer patients."

The director's cut

Strahl, who's a member of the UNC Lineberger Comprehensive Cancer Center, said major questions surround how histones wrap up the DNA into chromatin -- a structure that allows or denies access to the genetic information inside our cells.

This is what Strahl studies. His goal is to figure out precisely how histones contribute to basic biological functions and, in turn, contribute to cancers and other diseases. Adding a twist to this idea, however, is the fact that not every histone is the same. "We've already learned that the histone proteins found at the sites of genes can be chemically modified with a variety of small chemical "tags" that either promote or further prevent access to our genetic information -- our DNA. And this access or denial ultimately affects genes so they are either activated or not."

These chemical tags come from a variety of sources -- mainly the food we eat, the chemicals in the environment that gets inside us through our skin and lungs, for example, and the various biological chemicals that simply make us tick. Proper nutrients, for instance, allow for the formation of chemical tags to direct the histones to activate genes in the proper ways. Nasty environmental stuff, such as cigarette smoke, can mess up the epigenetic machinery.

Yet, these chemical tags are not ultimately in charge of the genes. Another layer of proteins above the histones are responsible for putting on the chemical tags.

"Something has to ensure that these chemical tags on histones are regulated properly, to ensure that the tags are only present on the right genes at the right time," Strahl said. Strahl and graduate student Glenn Wozniak focused on one of the proteins that add these chemical tags -- a protein called Bre1, which keeps one tag -- ubiquitin -- in check. In a sense, Bre1 hires ubiquitin; it allows ubiquitin to do its job.

Ubiquitin is known to help a histone open up the cell's chromatin to expose genes for activation. When ubiquitin is finished, it is removed from the histones, and the genes become inactivated.

If this process goes awry -- if the genes are allowed to remain active indefinitely -- then normal cells can turn into cancer cells. And the entire cellular performance collapses.

The Goldilocks effect

Until now, how this happened was unclear. Through a series of experiments, Strahl and Wozniak found that, like the chemical tags themselves, a precise amount of Bre1 must be maintained to ensure that just the right amount of ubiquitin is added to histones.

"We found that if there's too little Bre1, then the gene doesn't turn on," Strahl said. "If there's too much, the gene doesn't shut off. We call it the Goldilocks effect."

Wozniak added, "We also found that when Bre1 is not needed or when it doesn't perform its function, it's removed as a control mechanism. There won't be as much ubiquitin on histones because Bre1 is not there."

Strahl and Wozniak's finding illuminates what had been an epigenetic mystery. Scientific literature on Bre1 had been mixed.

"Some studies indicated that Bre1 had a role as a tumor suppressor," Strahl said. "Other studies showed that it's a cancer promoter. So there's been conflicting evidence about all of this. Now we know. If there's too little Bre1, the gene won't turn on." This could turn off the genes that protect the cell from cancer. "If there's too much," Strahl said. "Then the genes might not turn off." This could also trigger cancer development.

"When you think about it, Bre1 could be a really good target for a cancer drug," Strahl said. "Cancer cells divide rapidly. A lot of chemotherapies involve creating DNA damage within all rapidly dividing cells. But if you just target the Bre1 protein and maybe shut it off, you could have very bad outcomes specifically for rapidly dividing cancer cells. They wouldn't be able to transcribe genes anymore."

Shooting the messenger: small RNA as a target for antibiotics

By S.E. Gould | October 12, 2014 |  

The views expressed are those of the author and are not necessarily those of Scientific American.

Email  Print

---

All living cells contain DNA; the code for producing every protein needed by the cell. As DNA is important it needs to be kept safe. Plants and animals keep their DNA tightly twisted and organised inside a double-membrane bound nucleus while bacteria keep their DNA coiled up in a big circle, with the occasional loop floating around separately. With smaller cells, bacteria don’t have the space for large membrane-bound organelles, and they can also tolerate a bit of genetic damage slightly more than large multicellular structures.

To act as an intermediate between DNA and proteins cells also contain RNA – which is a more flexible and shorter lived molecule in the same family as DNA. If the DNA is a library with all cellular information neatly filed then RNA is a messy folder full of notes that can be scattered around the cell to wherever they are most needed. RNA has lots of jobs; it is a vital part of protein production and can also be used to regulate and control cellular processes.

Although bacterial DNA is not locked up in a nucleus, it is still useful for bacteria to be able to make and distribute copies of it. Small pieces of RNA, imaginatively called small-RNA (sRNA) can be used to control the production of proteins and other pieces of RNA. These little lines of code require little energy to produce and can regulate their targets in a coordinated manner, and because of this they are often used to help the bacteria respond quickly to changing circumstances.

A single strand of RNA. "ARNm-Rasmol" by Corentin Le Reun - Own work. Licensed under Public domain via Wikimedia Commons.

Recent studies have shown that when bacteria are exposed to antibiotics they produce more sRNA. Many of the cellular processes targeted by antibiotics (including damage to the cell wall and protein production) are normally controlled by sRNA so the sudden flurry of production may be the bacteria attempting to minimise damage or activate antibiotic resistance pathways. sRNA is also important for active antibacterial resistance such as the production of protein pumps that forcibly remove the antibiotic from the cell.

More interestingly, it was found that blocking the production of sRNA leaves the cell more vulnerable to antibiotic attack. While preventing sRNA production may not be a viable antibiotic therapy by itself the targeted blocking of specific small RNA pieces could be used as an adjuvant – a therapy added along with the antibiotic to make it more powerful. As antibiotic resistance starts to spread, the need for therapies to increase the power of the antibiotics currently in circulation will always be useful, and sRNA is a fascinating little molecule to study.

sRNA and antibiotics: a summary. Image from the reference.

—

Reference: Lalaouna D, Eyraud A, Chabelskaya S, Felden B, Massé E (2014) Regulatory RNAs Involved in Bacterial Antibiotic Resistance. PLoS Pathog 10(8): e1004299. doi:10.1371/journal.ppat.1004299

About the Author: A biochemist with a love of microbiology, the Lab Rat enjoys exploring, reading about and writing about bacteria. Having finally managed to tear herself away from university, she now works for a small company in Cambridge where she turns data into manageable words and awesome graphs. Follow on Twitter @labratting.