In a new study in mice, a scientific collaboration centred at Brown University lays out in unprecedented detail a neurological signalling breakdown in Angelman syndrome, a disorder that affects thousands of children each year, characterised by developmental delay, seizures, and other problems. With the new understanding, the team demonstrated how a synthesised, peptide-like compound called CN2097 works to restore neural functions impaired by the disease.
‘I think we are really beginning to understand what’s going wrong. That’s what’s very exciting,’ said John Marshall, professor of medical science in the Department of Molecular Pharmacology, Physiology, and Biotechnology and the senior author of the study. However Marshall did caution that it is too early to predict how soon a clinical therapy might arise from the results.
In mice and people, Angelman syndrome arises from flaws in a gene called Ube3A. When it functions properly, the gene limits the amount of a protein called Arc in the brain. Left unchecked by the disease, Arc impairs the development of synapses in the hippocampus. Those neural connections may be essential for proper learning and memory function.
In the new study, Marshall and his colleagues report a series of experiments that show how the abundance of Arc creates such negative effects and how Arc might possibly be defeated and its ill-effects repaired in the lab.
Essentially, Arc interferes with the operation of a synaptic protein called PSD-95, that is required for the actions of a growth factor, known as brain-derived neurotrophic factor (BDNF). This growth factor is released at synaptic contacts and initiates a sequence of molecular interactions necessary for the strengthening of neuronal connections or synapses. In mice with the flawed Ube3A gene, the signals sent by BDNF for memory formation are disrupted.
Although the researchers were surprised by the details they discovered about how Arc hinders the signalling process, they didn’t come to the insight with complete naivete.
In other work, Marshall had been studying CN2097, designed by co-author Mark Spaller of Dartmouth College (Spaller synthesised it during earlier tenures at Wayne State University and Brown). The compound, which binds to PSD-95 was predicted to protect neurons under conditions of stroke and in disease states such as multiple sclerosis. With co-senior author Dennis Goebel of Wayne State, Marshall and Spaller found this to be the case. During the course of those studies the Marshall group learned that CN2097 enhanced the action of brain-derived neurotrophic factor (BDNF) which is known to be critically involved in long-term potentiation (LTP), a phenomenon believed by many neuroscientists to underlie learning.
Then, when University of North Carolina professor and former Brown postdoc Ben Philpot, now a leading expert on Angelman syndrome, returned to campus in 2008 to speak about Angelman syndrome, he showed how LTP is notably lacking in mice with the condition. After discussions with Philpot, Marshall and his group decided to test whether CN2097 might restore LTP in Angelman mice.
Early on, Marshall said, the team figured the defect in LTP in Angelman mice effect had to do with BDNF signalling.
‘We started studying BDNF signalling in the Angelman syndrome mouse and discovered the signalling was defective, so that really was the breakthrough,’ he said. ‘It was completely unexpected. It’s a new way of thinking about this disease.’
That led to the set of experiments now reported, in which the group found that CN2097 essentially protects PSD-95 from interference by Arc, helping to restore BDNF signaling and the formation of stronger synapses. In electrophysiological tests on hippocampal tissue of healthy and Angelman mice, the compound made obtaining LTP significantly easier, although observing LTP in Angelman mice is still more difficult than in normal mice, Marshall said. Brown University

A genetic mutation that alters the kinetics of an ion channel in red blood cells has been identified as the cause behind a hereditary anaemia.
The research team was led by Frederick Sachs, PhD, SUNY Distinguished Professor in the UB Department of Physiology and Biophysics, who discovered in the 1980s that some ion channels are mechano-sensitive, that is, they convert mechanical stress into electrical or biochemical signals.
The findings of the new study are significant, Sachs says, because it is the first time defects in a mechano-sensitive ion channel have been implicated as the cause of a disease.
‘We found that the mutations in the gene that codes for the ion channel called PIEZO1 causes the channel to stay open too long, causing an ion leak in red cells,’ explains Sachs. ‘Calcium and sodium enter, and potassium leaves, and that affects the ability of the red cell to regulate its volume. The cells become dehydrated and can break open, releasing their haemoglobin into the blood, and causing symptoms, such as the shortness of breath seen in anaemic patients.’
The anaemia that results from the mutations in PIEZO1 is called familial xerocytosis, a mild to moderate form of anaemia. The ion channel, PIEZO1, is about 10 nanometers across, and it increases its dimensions significantly upon opening; that change in dimensions is what is responsible for its mechanical sensitivity.
Mechano-sensitive ion channels are likely to play a role in many diseases, since all cells are mechanically sensitive. Sachs and his colleagues have worked on activation of these channels in Duchenne muscular dystrophy, which is caused by errors in a gene coding for a fibrous protein that reinforces the cell membrane. The increased stress caused by this loss of reinforcement causes the channels to open and the leak of calcium is likely what causes the muscles to atrophy, Sachs explains. University at Buffalo

In a new study, researchers reveal how a key player in cell growth, immunity and the inflammatory response can be transformed into a primary contributor to tumour growth.
Scientists call this Jekyll-and-Hyde molecule NF-kappa B. In healthy cells, it is a powerful ‘first responder,’ a vital part of the body’s immune and inflammatory responses. It spends most of its life in the cell’s cytoplasm, quietly awaiting orders. But when extracellular signals – of a viral or bacterial invasion, for example – set off chemical alarms, the cell unchains this warhorse, allowing it to go into the nucleus where it spurs a flurry of defensive activity, including the transcription of genes that trigger inflammation, promote cell proliferation and undermine cell death.
Researchers have known for years that a hyperactive form of NF-kappa B that gets into the nucleus and stays there is associated with various cancers. But they didn’t know what was keeping it active in the nucleus.
‘Normally in the cell NF-kappa B is in the cytosol, it’s not in the nucleus, and it’s not activated,’ said University of Illinois medical biochemistry professor Lin-Feng Chen, who led the new study. ‘You have to stimulate normal cells to see NF-kappa B in the nucleus. But in cancer cells without any stimulation you can see this nuclear form of NF-kappa B. The cell just won’t die because of this. That is why NF-kappa B is so important in cancer.’
In the new study, Chen’s group found that another molecule known to help regulate gene expression, called BRD4, recognises a specific amino acid on a subunit of the NF-kappa B protein complex after the amino acid has been marked with a specific tag, called an acetyl group. This ‘acetylation’ allows the BRD4 to bind to NF-kappa B, activating it and preventing its degradation in cancer cells.
Previous studies had shown that BRD4’s recognition of the acetylated subunit increased NF-kappa B activation, but this recognition had not been linked to cancer.
BRD4 belongs to a class of molecules that can recognise chemical markers on other proteins and interact with them to spur the marked proteins to perform new tasks. Chemical ‘readers’ such as BRD4 are important players in the field of epigenetics, which focuses on how specific genes are regulated.
‘In epigenetics, there are writers, there are readers and there are erasers,’ Chen said. The writers make modifications to proteins after they are formed, without changing the underlying sequence of the gene that codes for them. These modifications (such as acetylation) signal other molecules (the readers) to engage with the marked proteins in various ways, allowing the proteins to fulfill new roles in the life of the cell. Epigenetic erasers remove the marks when they are no longer of use.
Such protein modifications ‘have been shown to be critically involved in transcription regulation and cancer development,’ the researchers report.
To test whether BRD4 was contributing to the sustained presence of NF-kappa B in the nucleus of cancer cells, Chen and his colleagues exposed lung cancer cells in cell culture and in immune-deficient mice to JQ1, a drug that interferes with BRD4 activity. Exposure to JQ1 blocked the interaction of BRD4 and NF-kappa B, blocked the expression of genes regulated by NF-kappa B, reduced proliferation of lung cancer cells and suppressed the ability of lung cancer cells to induce tumors in immune-deficient mice, the researchers found.
The researchers also discovered that depletion of BRD4 or the treatment of cells with JQ1 induced the degradation of the NF-kappa B subunit recognized by BRD4.
Chen said that BRD4 likely prevents other molecules from recognising the hyperactive NF-kappa B in the nucleus and marking it for degradation.
‘This is an example of how epigenetic regulators and NF-kappa B may one day be targeted for the treatment of cancer,’ he said. University of Illinois at Urbana Champaign

Foetal alcohol syndrome is the leading preventable cause of developmental disorders in developed countries. And foetal alcohol spectrum disorder (FASD), a range of alcohol-related birth defects that includes foetal alcohol syndrome, is thought to affect as many as 1 in 100 children born in the United States.

Any amount of alcohol consumed by the mother during pregnancy poses a risk of FASD, a condition that can include the distinct pattern of facial features and growth retardation associated with foetal alcohol syndrome as well as intellectual disabilities, speech and language delays, and poor social skills. But drinking can have radically different outcomes for different women and their babies. While twin studies have suggested a genetic component to susceptibility to FASD, researchers have had little success identifying who is at greatest risk or what genes are at play.

Research from Harvard Medical School and Veterans Affairs Boston Healthcare System sheds new light on this question, identifying for the first time a signalling pathway that might determine genetic susceptibility for the development of FASD.

‘Our work points to candidate genes for FASD susceptibility and identifies a path for the rational development of drugs that prevent ethanol neurotoxicity,’ said Michael Charness, chief of staff at VA Boston Healthcare System and HMS professor of neurology. ‘And importantly, identifying those mothers whose foetuses are most at risk could help providers better target intensive efforts at reducing drinking during pregnancy.’

The discovery also solves a riddle that had intrigued Charness and other researchers for nearly two decades. In 1996, Charness and colleagues discovered that alcohol disrupted the work of a human protein critical to foetal neural development—a major clue to the biological processes of FASD. The protein, L1, projects through the surface of a cell to help it adhere to its neighbours. When Charness and his team introduced the protein to a culture of mouse fibroblasts cells, L1 increased cell adhesion. Tellingly, the effect was erased in the presence of ethanol (beverage alcohol).
Charness and his team went on to develop multiple cell lines from that first culture, and that’s where they encountered the riddle: In some of those lines, alcohol disrupted L1’s adhesive effect, while in others it did not.

‘How could it be possible that a cell that expresses L1 is completely sensitive to alcohol, and others that express it are completely insensitive?’ asked Charness, who is also faculty associate dean for veterans hospital programs at HMS and assistant dean at Boston University School of Medicine.

Clearly, something else was affecting the protein’s sensitivity to alcohol — but what? Studies of twins provided one clue: Identical twins are more likely than fraternal twins to have the same diagnosis, positive or negative, for FASD. ‘That concordance suggests that there are modifying genes, susceptibility genes, that predispose to this condition,’ Charness said.

In the current study, Charness’ team and collaborators at the University of North Carolina School of Medicine in Chapel Hill conducted cell culture experiments to identify specific molecular events that contribute to the alcohol sensitivity of L1 adhesion molecules. They focused on what was happening to the L1 molecule inside a cell that could affect an event outside the cell such as disruption by alcohol.

‘We found that phosphorylation events that begin inside the cell can render the external portion of the L1 adhesion molecule more vulnerable to inhibition by alcohol,’ said Xiaowei Dou, HMS instructor in neurology in the Charness Lab and first author on the new study. ‘Phosphorylation was controlled by the enzyme ERK2, and occurred at a specific location on the internal portion of the L1molecule.’

Phosphorylation plays a significant role in a wide range of cellular processes. By adding a phosphate group to a protein or other molecule, phosphorylation turns many protein enzymes on and off, and thereby alters their function and activity.

The researchers also found that variations in ERK2 activity correlated with differences in L1 sensitivity to alcohol that they observed across cell lines and among different strains of mice. ‘Dou showed that he could take these cells that had been insensitive to alcohol for 13-14 years, and make them sensitive by ramping up the activity of this kinase’ Charness said.

These variations suggest that genes for ERK2 and the signalling molecules that regulate ERK2 activity might influence genetic susceptibility to FASD. Moreover, their identification of a specific locus that regulates the alcohol sensitivity of L1 might facilitate the rational design of drugs that block alcohol neurotoxicity.

‘The only thing this modification blocked was alcohol’s ability to inhibit L1,’ Charness said. ‘If you’re looking for a drug, ideally you’re looking for it to block the effects of the toxin without interfering with the target molecule of the toxin.’

The findings will also help guide an international consortium in its search for genes linked to families with fetal alcohol spectrum disorders. Harvard Medical School

An international team of scientists led by the University of Leicester has found new evidence that links faster ‘biological’ ageing to the risk of developing several age-related diseases – including heart disease, multiple sclerosis and various cancers.
The study involved scientists in 14 centres across 8 countries, working as part of the ENGAGE Consortium.
The project studied a feature of chromosomes called telomeres. Telomeres sit on the end of our chromosomes – the strands of DNA stored in the nucleus of cells. The telomeres shorten each time a cell divides to make new cells, until they reach a critical short length and the cells enter an inactive state and then die. Therefore telomeres shorten as an individual gets older. But, individuals are born with different telomere lengths and the rate at which they subsequently shorten can also vary. The speed with which telomeres wear down is a measure of ‘biological ageing’.

Professor Nilesh Samani, British Heart Foundation Professor of Cardiology at the University of Leicester and Director of the National Institute for Health Research (NIHR) Leicester Cardiovascular Biomedical Research Unit, who led the project said: ‘Although heart disease and cancers are more common as one gets older, not everyone gets them – and some people get them at an earlier age. It has been suspected that the occurrence of these diseases may in part be related to some people ‘biologically’ ageing more quickly than others.’

The research team measured telomere lengths in over 48,000 individuals and looked at their DNA and identified seven genetic variants that were associated with telomere length. They then asked the question whether these genetic variants also affected risk of various diseases. As DNA cannot be changed by lifestyle or environmental factors, an association of these genetic variants which affect telomere length with a disease also would suggest a causal link between telomere length and that disease.

The scientists found that the variants were indeed linked to risk of several types of cancers including colorectal cancer as well as diseases like multiple sclerosis and celiac disease. Most interestingly, the authors found that in aggregate the seven variants also associated with risk of coronary artery disease which can lead to heart attacks.

Professor Samani added: ‘These are really exciting findings. We had previous evidence that shorter telomere lengths are associated with increased risk of coronary artery disease but were not sure whether this association was causal or not. This research strongly suggests that biological ageing plays an important role in causing coronary artery disease, the commonest cause of death in the world. This provides a novel way of looking at the disease and at least partly explains why some patients develop it early and others don’t develop it at all even if they carry other risk factors.’

Dr Veryan Codd, Senior Research Associate at the University of Leicester who co-ordinated the study and carried out the majority of the telomere length measurements said: ‘The findings open of the possibility that manipulating telomere length could have health benefits. While there is a long way to go before any clinical application, there are data in experimental models where lengthening telomere length has been shown to retard and in some situations reverse age-related changes in several organs.’ University of Leicester