Advertisements
Feeds:
Posts
Comments

Posts Tagged ‘neuropsychiatry’


Brain Biobank and studies of disease structure correlates

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

Unveiling Psychiatric Diseases

Researchers create neuropsychiatric cellular biobank

Image: iStock/mstroz
Image: iStock/mstroz
Researchers from Harvard Medical School and Massachusetts General Hospital have completed the first stage of an important collaboration aimed at understanding the intricate variables of neuropsychiatric disease—something that currently eludes clinicians and scientists.

The research team, led by Isaac Kohane at HMS and Roy Perlis at Mass General, has created a neuropsychiatric cellular biobank—one of the largest in the world.

It contains induced pluripotent stem cells, or iPSCs, derived from skin cells taken from 100 people with neuropsychiatric diseases such as schizophrenia, bipolar disorder and major depression, and from 50 people without neuropsychiatric illness.

In addition, a detailed profile of each patient, obtained from hours of in-person assessment as well as from electronic medical records, is matched to each cell sample.

As a result, the scientific community can now for the first time access cells representing a broad swath of neuropsychiatric illness. This enables researchers to correlate molecular data with clinical information in areas such as variability of drug reactions between patients. The ultimate goal is to help treat, with greater precision, conditions that often elude effective management.

The cell collection and generation was led by investigators at Mass General, who in collaboration with Kohane and his team are working to characterize the cell lines at a molecular level. The cell repository, funded by the National Institutes of Health, is housed at Rutgers University.

“This biobank, in its current form, is only the beginning,” said Perlis, director of the MGH Psychiatry Center for Experimental Drugs and Diagnostics and HMS associate professor of psychiatry. “By next year we’ll have cells from a total of four hundred patients, with additional clinical detail and additional cell types that we will share with investigators.”

A current major limitation to understanding brain diseases is the inability to access brain biopsies on living patients. As a result, researchers typically study blood cells from patients or examine post-mortem tissue. This is in stark contrast with diseases such as cancer, for which there are many existing repositories of highly characterized cells from patients.

The new biobank offers a way to push beyond this limitation.

 

A Big Step Forward

While the biobank is already a boon to the scientific community, researchers at MGH and the HMS Department of Biomedical Informatics will be adding additional layers of molecular data to all of the cell samples. This information will include whole genome sequencing and transcriptomic and epigenetic profiling of brain cells made from the stem cell lines.

Collaborators in the HMS Department of Neurobiology, led by Michael Greenberg, department chair and Nathan Marsh Pusey Professor of Neurobiology,  will also work to examine characteristics of other types of neurons derived from these stem cells.

“This can potentially alter the entire way we look at and diagnose many neuropsychiatric conditions,” said Perlis.

One example may be to understand how the cellular responses to medication correspond to the patient’s documented responses, comparing in vitro with in vivo. “This would be a big step forward in bringing precision medicine to psychiatry,” Perlis said.

“It’s important to recall that in the field of genomics, we didn’t find interesting connections to disease until we had large enough samples to really investigate these complex conditions,” said Kohane, chair of the HMS Department of Biomedical Informatics.

“Our hypothesis is that here we will require far fewer patients,” he said. “By measuring the molecular functioning of the cells of each patient rather than only their genetic risk, and combining that all that’s known of these people in terms of treatment response and cognitive function, we will discover a great deal of valuable information about these conditions.”

Added Perlis, “In the early days of genetics, there were frequent false positives because we were studying so few people. We’re hoping to avoid the same problem in making cellular models, by ensuring that we have a sufficient number of cell lines to be confident in reporting differences between patient groups.”

The generation of stem cell lines and characterization of patients and brain cell lines is funded jointly by the the National Institute of Mental Health, the National Human Genome Research Institute and a grant from the Centers of Excellence in Genomic Science program.

 

On C.T.E. and Athletes, Science Remains in Its Infancy

Se Hoon ChoiYoung Hye KimMatthias Hebisch, et al.

http://www.nature.com/articles/nature13800.epdf

Alzheimer’s disease is the most common form of dementia, characterized by two pathological hallmarks: amyloid-β plaques and neurofibrillary tangles1. The amyloid hypothesis of Alzheimer’s disease posits that the excessive accumulation of amyloid-β peptide leads to neurofibrillary tangles composed of aggregated hyperphosphorylated tau2, 3. However, to date, no single disease model has serially linked these two pathological events using human neuronal cells. Mouse models with familial Alzheimer’s disease (FAD) mutations exhibit amyloid-β-induced synaptic and memory deficits but they do not fully recapitulate other key pathological events of Alzheimer’s disease, including distinct neurofibrillary tangle pathology4, 5. Human neurons derived from Alzheimer’s disease patients have shown elevated levels of toxic amyloid-β species and phosphorylated tau but did not demonstrate amyloid-β plaques or neurofibrillary tangles6, 7, 8, 9, 10, 11. Here we report that FAD mutations in β-amyloid precursor protein and presenilin 1 are able to induce robust extracellular deposition of amyloid-β, including amyloid-β plaques, in a human neural stem-cell-derived three-dimensional (3D) culture system. More importantly, the 3D-differentiated neuronal cells expressing FAD mutations exhibited high levels of detergent-resistant, silver-positive aggregates of phosphorylated tau in the soma and neurites, as well as filamentous tau, as detected by immunoelectron microscopy. Inhibition of amyloid-β generation with β- or γ-secretase inhibitors not only decreased amyloid-β pathology, but also attenuated tauopathy. We also found that glycogen synthase kinase 3 (GSK3) regulated amyloid-β-mediated tau phosphorylation. We have successfully recapitulated amyloid-β and tau pathology in a single 3D human neural cell culture system. Our unique strategy for recapitulating Alzheimer’s disease pathology in a 3D neural cell culture model should also serve to facilitate the development of more precise human neural cell models of other neurodegenerative disorders.

 

 

Figure 2: Robust increases of extracellular amyloid-β deposits in 3D-differentiated hNPCs with FAD mutations.close

Robust increases of extracellular amyloid-[bgr] deposits in 3D-differentiated hNPCs with FAD mutations.

a, Thin-layer 3D culture protocol. HC, histochemistry; IF, immunofluorescence; IHC, immunohistochemistry. b, Amyloid-β deposits in 6-week differentiated control and FAD ReN cells in 3D Matrigel (green, GFP; blue, 3D6; scale bar, …

 

Stem Cell-Based Spinal Cord Repair Enables Robust Corticospinal Regeneration

 

Novel use of EPR spectroscopy to study in vivo protein structure

http://www.news-medical.net/whitepaper/20160315/Novel-use-of-EPR-spectroscopy-to-study-in-vivo-protein-structure.aspx

α-synuclein

α-synuclein is a protein found abundantly throughout the brain. It is present mainly at the neuron ends where it is thought to play a role in ensuring the supply of synaptic vesicles in presynaptic terminals, which are required for the release of neurotransmitters to relay signals between neurons. It is critical for normal brain function.

However, α-synuclein is also the primary protein component of the cerebral amyloid deposits characteristic of Parkinson’s disease and its precursor is found in the amyloid plaques of Alzheimer’s disease. Although α-synuclein is present in all areas of the brain, these disease-state amyloid plaques only arise in distinct areas.

Alpha-synuclein protein. May play role in Parkinson’s and Alzheimer’s disease.  © molekuul.be / Shutterstock.com

Imaging of isolated samples of α-synuclein in vitro indicate that it does not have the precise 3D folded structure usually associated with proteins. It is therefore classed as an intrinsically disordered protein. However, it was not known whether the protein also lacked a precise structure in vivo.

There have been reports that it can form helical tetramers. Since the 3D structure of a biological protein is usually precisely matched to the specific function it performs, knowing the structure of α-synuclein within a living cell will help elucidate its role and may also improve understanding of the disease states with which it is associated.

If α-synuclein remains disordered in vivo, it may be possible for the protein to achieve different structures, and have different properties, depending on its surroundings.

Techniques for determining protein structure

It has long been known that elucidating the structure of a protein at an atomic level is fundamental for understanding its normal function and behavior. Furthermore, such knowledge can also facilitate the development of targeted drug treatments. Unfortunately, observing the atomic structure of a protein in vivo is not straightforward.

X-ray diffraction is the technique usually adopted for visualizing structures at atomic resolution, but this requires crystals of the molecule to be produced and this cannot be done without separating the molecules of interest from their natural environment. Such processes can modify the protein from its usual state and, particularly with complex structures, such effects are difficult to predict.

The development of nuclear magnetic resonance (NMR) spectroscopy improved the situation by making it possible for molecules to be analyzed under in vivo conditions, i.e. same pH, temperature and ionic concentration.

More recently, increases in the sensitivity of NMR and the use of isotope labelling have enabled determinations of the atomic level structure and dynamics of proteins to be determined within living cells1. NMR has been used to determine the structure of a bacterial protein within living cells2 but it is difficult to achieve sufficient quantities of the required protein within mammalian cells and to keep the cells alive for NMR imaging to be conducted.

Electron paramagnetic resonance (EPR) spectroscopy for determining protein structure

Recently, researchers have managed to overcome these obstacles by using in-cell NMR and electron paramagnetic resonance (EPR) spectroscopy. EPR spectroscopy is a technique that is similar to NMR spectroscopy in that it is based on the measurement and interpretation of the energy differences between excited and relaxed molecular states.

In EPR spectroscopy it is electrons that are excited, whereas in NMR signals are created through the spinning of atomic nuclei. EPR was developed to measure radicals and metal complexes, but has also been utilized to study the dynamic organization of lipids in biological membranes3.

EPR has now been used for the first time in protein structure investigations and has provided atomic-resolution information on the structure of α-synuclein in living mammalians4,5.

Bacterial forms of the α-synuclein protein labelled with 15N isotopes were introduced into five types of mammalian cell using electroporation. Concentrations of α-synuclein close to those found in vivo were achieved and the 15N isotopes allowed the protein to be clearly defined from other cellular components by NMR. The conformation of the protein was then determined using electron paramagnetic resonance (EPR).

The results showed that within living mammalian cells α-synuclein remains as a disordered and highly dynamic monomer. Different intracellular environments did not induce major conformational changes.

Summary

The novel use of EPR spectroscopy has resolved the mystery surrounding the in vivo conformation of α-synuclein. It showed that α-synuclein maintains its disordered monomeric form under physiological cell conditions. It has been demonstrated for the first time that even in crowded intracellular environments α-synuclein does not form oligomers, showing that intrinsic structural disorder can be sustained within mammalian cells.

References

  1. Freedberg DI and Selenko P. Live cell NMR Annu. Rev. Biophys. 2014;43:171–192.
  2. Sakakibara D, et al. Protein structure determination in living cells by in-cell NMR spectroscopy. Nature 2009;458:102–105.
  3. Yashroy RC. Magnetic resonance studies of dynamic organisation of lipids in chloroplast membranes. Journal of Biosciences 1990;15(4):281.
  4. Alderson TA and Bax AD. Parkinson’s Disease. Disorder in the court. Nature 2016; doi:10.1038/nature16871.
  5. Theillet FX, et al. Structural disorder of monomeric α-synuclein persists in mammalian cells. Nature 2016; doi:10.1038/nature16531.

 

Advertisements

Read Full Post »


To understand what happens in the brain to cause mental illness

Larry H Bernstein, MD, FCAP, Curator

Leaders in Pharmaceutical Intelligence

Series E. 2; 5.10

https://bbrfoundation.org/research/basic-research

Fernando Sampaio Goes, M.D., a 2008 NARSAD Young Investigator at Johns Hopkins School of Medicine, and his colleagues took an alternative approach to the ongoing genome-wide association studies (GWAS) that hunt for these factors by scouring the complete genomes of tens of thousands of individuals. The team––which included 2005 Young InvestigatorDimitrios Avramopoulos, M.D., Ph.D.; 2000 Young Investigator, 2008 Independent Investigator, and BBRF Scientific Council member James B. Potash, M.D., M.P.H.; and 2004 Young Investigator Peter P. Zandi, Ph.D.––conceived the study to detect rare genetic variations that GWAS are not designed to find.

Rather than scanning entire genomes for depression-associated variations, Goes’s team narrowed its search to a set of genes in which they already suspected alterations might contribute to depression: those that encode proteins found at or near the junctions between neurons, where cell-to-cell communication takes place. Based on previous surveys of these synaptic proteins, the scientists chose 1,742 genes to include in their analysis.

They compared the protein-coding sequences of that set of genes in 259 people with major depression to the same set in 334 unaffected individuals. To increase the chance of finding relevant genetic factors, all the patients with depression were selected based on the criterion of early-onset, recurrent depression, which is suspected by some to be a more heritable form of the illness. (An important component of depression causation is environmental, and reflects the particular life circumstances of those affected, who may or may not be naturally resilient when faced with stress and other environmental factors.)

The team’s analysis pointed to two sets of genes in which variations were linked with major depression. One includes genes that control the growth of dendritic spines (tiny knob-like protrusions from a neuron’s surface that receive inputs from other neurons). Other research has suggested that the size, density, and shape of these structures may be involved in mood disorders and other mental illnesses. The second gene set includes genes linked with the entry of calcium into neurons, which regulates a variety of processes, including the release of message-propagating neurotransmitters. Variations within this gene set have also been linked to autism and epilepsy.

Researchers have identified unique characteristics of emotional processing in young people with post-traumatic stress disorder (PTSD), showing for the first time how that processing might be disrupted at different ages.

Publishing their findings online August 5th in Neuropsychopharmacology, were 2012 NARSAD Young Investigator grantee Ryan J. Herringa, M.D., Ph.D., of the University of Wisconsin School of Medicine and Public Health and Richard C. Wolf, a Ph.D. candidate at the university. Together they  looked at brain activity during an emotion-related task in children aged 8 to 18, both with and without PTSD. The children with PTSD had experienced trauma such as sexual abuse, the death of a loved one, a physical accident, or witnessing violence.

The children viewed emotionally “threatening” and “neutral” pictures. During this task, the researchers used imaging to measure activity in brain regions associated in PTSD with an increased fear response and sense of threat. These regions include the amygdala, important for processing emotions; the dorsal anterior cingulate cortex (dACC), which helps to gauge threat levels; and the medial portion of the prefrontal cortex (PFC), crucial for dialing back fear responses and putting perceived threats in context.

The researchers found higher threat-related dACC activity in youths with PTSD, as well as weaker connections between the amygdala and mPFC. The findings suggest these brain regions contribute to the difficulty young people with PTSD have in assessing perceptions of threat.  The study also found that amygdala-PFC connections followed a different developmental path for youths with PTSD. Whereas those connections were stronger at older ages in those without PTSD, the same connections grew weaker for children with PTSD as they aged. This may reflect a progressive weakening in the ability of the PFC to reduce fear.

In research reported June 17th in the journal Neuron, scientists have shown that a protein called CPEB3 is critical for the stabilization and storage of long-term memories in mice. Three-timeNARSAD Distinguished Investigator and BBRF Scientific Council member Eric Kandel, M.D., led the research. Also on the team is 2013 NARSAD Young Investigator Pierre Trifilieff, Ph.D.

CPEB3 is a “prion-like” protein. Prions––infectious, misshapen proteins best known for the devastation they cause––clump together and lead to brain damage in people and animals with mad cow disease and related conditions. Similar protein-clumping mechanisms may also contribute to neurodegenerative diseases including Alzheimer’sParkinson’s, and amyotrophic lateral sclerosis. (Curiously, certain proteins with prion-like properties have an important role in the healthy brain.)

The new finding extends previous work showing that prion-like proteins are vital for the stabilization of long-term term memory in sea slugs and fruit flies. Although further work is needed to understand whether the same mechanism is at work in humans, humans do produce a protein similar to the mouse protein CPEB3.

Memories are stored in the connections between neurons, and proteins play a role in the long-term storage of the information. But since proteins degrade over time, scientists had wondered how a memory can persist long after a new experience triggers neurons to make memory-specific proteins. Prion-like proteins, which are self-perpetuating because they can convert normal proteins to their own misshapen form, appear to be the answer.

Genetic studies have recently yielded large numbers of “hits” for genes that subtly increase or decrease risk for disorders, including for schizophrenia. However, there have been no hits for major depression, perhaps because the studies are not yet large enough or because depression is less heritable. Estimates put the heritability of major depression at around 50%, with the remaining contribution coming from environmental and experiential causes.

However, a new approach has paid off: a study published online July 15th at the journal Natureidentifies two genomic regions that harbor genes that increase risk of major depression. A multinational collaboration employed a strategy of narrowing the pool of subjects to women in China with the most severe and stubborn form of depression, with the hope that a more homogenous population would yield results.

In an accompanying News and Views, 2014 Lieber Prizewinner for Outstanding Achievement in Schizophrenia Research,Patrick Sullivan, M.D., of the University of North Carolina, writes, “This first identification of replicable, significant genome-wide associations for MDD is exceptional.”

Qi Xu, Ph.D., of Peking Union Medical College and Jun Wang, Ph.D., of BGI-Shenzhen, who led the China components of the study, along with Foundation Scientific Council Member Kenneth Kendler, M.D., of Virginia Commonwealth University and 2007 NARSAD Distinguished Investigator Grantee Jonathan Flint, M.D., of the University of Oxford in the United Kingdom focused exclusively on women with severe, recurrent depression (an average of more than five episodes), building a sample of 5,303 cases and 5,337 controls. The results were replicated in a separate group of 3,231 Chinese women with major depression and 3,186 mixed male/female controls.

“I think this paper is groundbreaking because it really demonstrates that we can make progress in reducing genetic heterogeneity by paying attention to key clinical indicators,” said three-time NARSAD Grantee, Francis McMahon, M.D., of the National Institute of Mental Health (NIMH), who was not an author on the paper.

A team based at the University of Edinburgh analyzed data from thousands of Scottish adults to see whether they had genetic mutations either linked with obesity or major depressive disorder. They tested for relationships between those genetic profiles, the presence of depression or other psychological distress, and body mass index, a measure used to determine obesity. A genetic predisposition for obesity more strongly predicted actual obesity among those adults who were also depressed.

The findings were reported June 30th in Translational Psychiatry by a team including 2008NARSAD Distinguished Investigator Grantee David J. Porteous, Ph.D., and 2010 Independent Investigator Andrew M. McIntosh, Ph.D.

The study results show people becoming obese in part because of their depression, rather than becoming depressed because they are already obese. The experience of depression may drive disordered eating habits. It may also trigger chemical responses in the body (such as the release of the stress hormone cortisol) that promote weight gain, the researchers hypothesize.

The team also found some degree of association between a genetic profile linked to obesity and current psychological distress, even among individuals who were not obese. Obesity-linked genes also more closely predicted actual obesity among people experiencing distress even if they were not diagnosed with depression. This indicates that psychological strain, and not just depression per se, contributes to obesity.

Read Full Post »