International Laboratory for Brain Extracellular Matrix Research
The International Laboratory for Brain Extracellular Matrix Research was founded at the Nizhniy Novgorod State University named after N. I. Lobachevsky at the end of 2010 as a structural subdivision responsible for the implementation of the project "Brain extracellular matrix as the determinant of intercellular communications and the target of therapy".
Grant Agreement No.: 11.G34.31.0012
Host institution of higher learning:
State educational institution of higher professional education "Nizhniy Novgorod State University named after N. I. Lobachevsky"
Scientific research area:
To create a modern neurobiological laboratory and a state-of-the-art neurobiological research infrastructure in Nizhniy Novgorod required to conduct world-class scientific research in neurobiology.
Key project objectives:
1. To conduct fundamental research and publish its results in authoritative national and international journals;
2. To integrate the new laboratory into the European brain research consortia;
3. To engage undergraduate and graduate students in scientific research activities implemented as part of the project with the view to train highly skilled professionals specializing in neurological biotechnologies.
Anticipated project outputs:
1. The project will help establish a world-class state-of-the-art scientific research center in Nizhniy Novgorod specializing in brain science;
2. The project will help uncover molecular mechanisms responsible for the impact produced by the extracellular matrix molecules on elastic properties of the brain's neuron-glial grid in healthy patients and in patients with brain pathologies, including epileptogenesis.
Leading scientist's full name: Dityatev, Alexander Eduardovich
Academic degree and title:
Candidate of biological sciences, professor
Professor at the University of Magdeburg, head of the Department of molecular neuroplasticity at the German Center for Neurodegenerative Conditions
Field of scientific interests:
Neurobiology: synapses and cellular adhesion and extracellular matrix molecules
- Recipient of a German Science Foundation scholarship for independent research in 2004-2007;
- A recipient of 13 research grants;
- Has more than 100 invitations to deliver lectures in 19 countries of the world.
1. The project team has conducted experiments studying epileptogenesis caused by disintegration of extracellular matrix (ECM) using two enzymes: hyaluronidase and heparanase. The scientists investigated the mechanisms of spontaneous and evoked calcium activity of the neuron-glial grid of primary hippocampus culture. They discovered that epileptiform activity caused by disintegration of extracellular matrix (ECM) resembles the kind of activity caused by the blockage of L-type calcium channels and can be blocked by the agonist of gamkergic transmission. The methods they developed and the pharmacological data they received have commercial promise in the development of medications that work to protect or restore ECM (hyaluronic acid and heparan sulphates) in patients with epilepsy and other neurodegenerative and neuro-circulatory conditions and traumas associated with ECM disorders.
2. The scientists developed techniques and methods of visualizing synaptic plasticity and associated changes in ECM. They created a series of viral vectors to visualize synaptic plasticity and to investigate the role of the LGI1 (leucine-richgliomainactivated 1) ECM molecule in epileptogenesis. The methods they developed and the pharmacological data they received have promise for commercial application of this series of viral vectors to visualize synaptic plasticity and, particularly, to study the role of ECM molecules at various scientific research laboratories. The scientists discovered that ECM surrounding the synapses on the neurons' dendrites have a fine structure. They used super-high resolution STORM-microscopy (stochastic optical reconstruction microscopy) method combined with secondary antibodies marked with pairs of fluorophores, such as AlexaFluor405-AlexaFluor647 and Cy3-AlexaFluor647.
3. The scientists conducted quantitative modeling of synaptic dynamics using a mathematical model of four-component synapse. They found out how ECM influences neuron signalization and investigated the effect produced by extrasynaptic control over neuronal signalization on effectiveness of synaptic transmission by activating astrocytes. Based on existing experimental data, the scientists proposed and investigated a phenomenological model of astrocytic control over activity of the neuronal network. Analysis of the model showed that astrocytes could effectively regulate the frequency of generation of electric signals depending on activity of the neuronal network. Interestingly, similarly to the previously researched ECM impact, activation of an astrocyte may lead to bistability in neuronal network dynamics.
4. The scientists researched the role of ECM molecules in regulation of synaptic plasticity. They discovered that disintegration of heparan sulphates diminishes the long-term potentiation by employing a mechanism that depends on the L-type calcium channels. They found out that chondroitin sulphate proteoglycans affect excitation and synaptic transmission of CA1 field pyramid neurons. They also realized that one of the mechanisms reducing long-term potentiation following exposure to ABC chondroitinase is a reduction of the NMDA/AMPA currents ratio in СА1 pyramid neurons while membranous excitability remains intact. This also causes a long-term depression of disynaptic inhibition potentials.
5. The scientists analyzed the behavior characteristic of the model of schizophrenia brought about by NMDA receptors being blocked by the MK801 antagonist. An immunocytochemical analysis identified abnormalities in the ECM structure in some areas of the brain that correlate with modified behavior of mice that is evaluated based on the "open field", "learned fear reflex", and "Maurice labyrinth" tests, which indicates that ECM plays a certain role in the pathogenesis of schizophrenia.
Project results in 2013
1. The scientists analyzed presynaptic plasticity following a heparanase treatment. The new data obtained using two-photon microscopy demonstrate a decreased intracellular calcium concentration in dendrites and dendritic spines during the evocation of long-term potentiation following exposure to heparanase. The scientists presume that removal of heparan sulphates affects restoration processes following Са2+ dependent inactivation of calcium channels.
2. The scientists analyzed epileptogenic mechanisms of heparanase activity in vitro and tested them in vivo. The discovered increased frequency and amplitude of excitation currents following exposure to heparanase. Thus, the scientists assume that removal of heparan sulphates slows down the activity of L-type calcium channels, which starts increasing synaptic expression of AMPA subtype glutamate receptors, changes the excitation/inhibition ratio, and, as a consequence, affects epileptoform activity.
3. The scientists analyzed epileptogenic mechanisms of hyaluronidase activity in vitro and tested them in vivo. They discovered transformation of calcium oscillations in neurons and astrocytes in very long periods of increased calcium concentration. These changes preceded the formation of super-long packet of neurons' electric discharges.
4. The scientists improved the mathematical model of inhibiting and exciting neuron-glial-ECM interactions during periods of network activity. They designed a mathematical model of astrocytic control over inhibiting and exciting signal pathways of neuronal network. They established that an astrocyte can coordinate both exciting and inhibiting entryways which makes it possible, for example, to prevent excessive excitation of neurons.
5. The scientists researched the mechanisms responsible for plasticity changes following ECM disintegration brought about by ABC chondroitinase. They established that ABC chondroitinase affects excitability of pyramidal cells in hippocampus by modulating SK channels. The scientists obtained (using two-photon microscopy) images of second order dendrites taken every 20 minutes over a period of two hours of incubation with ABC chondroitinase. In addition, they obtained electronic-microscopic images for reconstruction of synapses and neuroglia following ECM disintegration caused by ABC chondroitinase.
6. The scientists developed a new paradigm for analysis of oscillation-dependent synaptic plasticity. The demonstrated that by using short packets of impulses and providing sufficient stimulation one can bring about network activity oscillations of up to 200-300 ms following afferent stimulation and long-term potentiation whose level depends on the extent of network oscillations. Mice whose AE3-/- gene was knocked out demonstrated stronger oscillations, a higher level of long-term potentiation, and improved learning ability.