Wyniki wyszukiwania - Biblioteka Nauki

1

Synaptic metalloproteinases in plasticity and epileptogenesis

100%

Wilczynski G. M.

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nr 3

2

The high resolution morphological study of MMP-9 and its mRNA in the rat hippocampus

67%

Konopacki F. A. , Wilczynski G. M. , Lasiecka Z. , Kaczmarek L.

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tom 65

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nr 3

3

Activity-dependent rearrangement of the neuronal cell nucleus

67%

Szczepankiewicz A. A. , Walczak A. , Parobczak K. , Wilczynski G. M.

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nr Suppl.1

EN

It is now firmly established that long-lasting synaptic plasticity involves dramatic changes in gene expression occurring under the influence of specific signaling pathways and transcription factors. Numerous studies have shown that DNA and histone epigenetic modifications play key roles in neuronal plasticity. Recent studies in non-neuronal cells, indicated the existence of epigenetic mechanism of yet another class, related to the nuclei structural remodeling and very poorly understood in neurons. Therefore, we decided to study the ultrastructure of the cell nuclei in the hippocampal dentate gyrus granule neurons upon seizures induced by kainic acid, an analog of glutamate. Under these conditions the granular neurons instead of degradation, undergo an intensive plasticity phenomena. We found that seizures led to rapid and dramatic enlargement and striking reorganization of internal component-structures of interchromatin granule clusters (IGCs) in granular cell’s nucleus. Moreover, unlike IGCs of control animals, the reorganized IGCs contained activated RNA polymerase II CTD phosphoepitopes. These observations may suggest involvement of IGC in activity-dependent transcription events in neurons.

4

The role of adhesion protein CD44 in the shape changes of astrocytes

59%

Konopka A. , Swiech L. , Jaworski J. , Wilczynski G. M. , Dzwonek J.

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nr Suppl.1

EN

CD44 is a widely distributed type I transmembrane glycoprotein and functions as the major hyaluronan receptor on most cell types. CD44 through interaction with actin cytoskeleton affects the transmission of signals from the outside to the inside of the cell in many tissues and organs. Primary cultures of astrocyte are diverse in their morphology and many factors can influence on it. In vivo astrocyte also are able to change their shape in response to various stimuli. The appearance of reactive astrocytes in vivo with thicker and longer processes and increased cellular content of glial fibrillary acidic protein (GFAP) has been observed in the CNS after various types of injury caused by physical, chemical, and pathological trauma. Furthermore, it has been showed that CD44 expression increases after brain injury. In our study we investigated the influence of knock down of CD44 by specific shRNA and CD44 overexpression on the astrocytes shape changes. Our results indicate that knock down of CD44 in astrocytes results in more regular and flat shape. In contrast the overexpression of CD44 promotes more irregular, radial-like shape of astrocyte. Our data support the hypothesis that CD44 plays role in morphological changes of astrocyte and give the opportunity to investigate its role in pathological processes such as brain injury.

5

Role of posttranslational modifications of tubulin in neuronal function

59%

Kasprzak A. A. , Kliszcz B. , Szkop M. , Wloga D. , Wilczynski G. M.

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nr Suppl.1

EN

The axon is a slender projection of a neuron that conducts electrical impulses to synapses in muscles or other neurons. A number of cellular components such as mitochondria and vesicles are transported along the axon by microtubule-based molecular motors (kinesins and dyneins). The most important factors controlling the axonal transport are the structure and function of the motors involved and the condition of the rails (the microtubule, MT). In the last decade, a compelling evidence has been provided that MTs contain marks (posttranslational modifications, PTMs) that indicate what kind of activity should take place in a given MT segment. These cues are read and interpreted by molecular motors, MAPS and other proteins. Kinesin-1, the major motor that transports cargoes along MTs is a homodimer with a pair of MT-binding sites on each end of the molecule. In some conditions, kinesin-1, besides interacting with MT using its N-terminal motor domains, can also bind another MT by its tail site producing sliding of one MT relative to another. This type of pair sliding can be used to sort MTs in the same way it occurs in the mitotic spindle and also act as an efficient way to move large amounts of tubulin, in the form of short MTs. Both activities have been observed in Drosophila cultured neurons. The effects of PTMs on the interaction of the motor domain with MT are to some extent characterized, but the effects of PTMs in the cargo-MT on the MT pair sliding have never been examined. Currently, we are exploring the impact of two well-known PTMs (detyrosination and polyglutamylation) and one recently reported (polyamination) on MT-MT sliding. To that end, we have developed an assay in which the sliding is observed in vitro and quantified by kymographic analysis. Surprisingly, the velocity of the sliding was highly variable along the track indicating that its efficiency may be sensitive to many cellular and developmental mechanisms. FINANCIAL SUPPORT: Supported in part by NCN Grant 2014/13/B/NZ1/03995.