aggrecan is expressed by embryonic brain glia and regulates astrocyte development pdf

Aggrecan Is Expressed By Embryonic Brain Glia And Regulates Astrocyte Development Pdf

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Metrics details. Traumatic brain injury TBI is one of the leading causes of fatality and disability worldwide. Despite its high prevalence, effective treatment strategies for TBI are limited.

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Extracellular matrix of the central nervous system: from neglect to challenge

The basic concept, that specialized extracellular matrices rich in hyaluronan, chondroitin sulfate proteoglycans aggrecan, versican, neurocan, brevican, phosphacan , link proteins and tenascins Tn-R, Tn-C can regulate cellular migration and axonal growth and thus, actively participate in the development and maturation of the nervous system, has in recent years gained rapidly expanding experimental support. The swift assembly and remodeling of these matrices have been associated with axonal guidance functions in the periphery and with the structural stabilization of myelinated fiber tracts and synaptic contacts in the maturating central nervous system. Particular interest has been focused on the putative role of chondroitin sulfate proteoglycans in suppressing central nervous system regeneration after lesions. The axon growth inhibitory properties of several of these chondroitin sulfate proteoglycans in vitro, and the partial recovery of structural plasticity in lesioned animals treated with chondroitin sulfate degrading enzymes in vivo have significantly contributed to the increased awareness of this long time neglected structure. It was not until that the existence of an extracellular matrix ECM in the central nervous system CNS was generally acknowledged Tani and Ametani In the following, we will focus on the structure, expression and putative functions of this major matrix components that form this extraordinary extracellular meshwork. Not discussed in this review are less abundant, but nonetheless functionally important macromolecules of the nervous system, such as reelin, agrin and thrombospondins.

Extracellular matrix of the central nervous system: from neglect to challenge

Synapses are specialized structures that mediate rapid and efficient signal transmission between neurons and are surrounded by glial cells. Astrocytes develop an intimate association with synapses in the central nervous system CNS and contribute to the regulation of ion and neurotransmitter concentrations. Together with neurons, they shape intercellular space to provide a stable milieu for neuronal activity. Extracellular matrix ECM components are synthesized by both neurons and astrocytes and play an important role in the formation, maintenance, and function of synapses in the CNS. The components of the ECM have been detected near glial processes, which abut onto the CNS synaptic unit, where they are part of the specialized macromolecular assemblies, termed perineuronal nets PNNs.

Research of the past 25 years has shown that astrocytes do more than participating and building up the blood-brain barrier and detoxify the active synapse by reuptake of neurotransmitters and ions. Indeed, astrocytes express neurotransmitter receptors and, as a consequence, respond to stimuli. Within the tripartite synapse, the astrocytes owe more and more importance. Besides the functional aspects the differentiation of astrocytes has gained a more intensive focus. Specific differentiation of neural stem cells toward the astroglial lineage is performed as a multi-step process. Astrocytes and oligodendrocytes develop from a multipotent stem cell that prior to this has produced primarily neuronal precursor cells.

Glial cells in the central nervous system CNS contribute to formation of the extracellular matrix, which provides adhesive sites, signaling molecules, and a diffusion barrier to enhance efficient neurotransmission and axon potential propagation. In the normal adult CNS, the extracellular matrix ECM is relatively stable except in selected regions characterized by dynamic remodeling. However, after trauma such as a spinal cord injury or cortical contusion, the lesion epicenter becomes a focus of acute neuroinflammation. An advantage of this response is to limit the invasion of damaging cells and diffusion of toxic molecules into the spared tissue regions, but this occurs at the cost of inhibiting migration of endogenous repair cells and preventing axonal regrowth. This article highlights structural and functional features of the normal adult CNS ECM and then focuses on the reactions of glial cells and changes in the perilesion border that occur following spinal cord or contusive brain injury. Current research strategies directed at modifying the inhibitory perilesion microenvironment without eliminating the protective functions of glial cell activation are discussed.

Sugar glues for broken neurons

Neurons and glial cells in the central nervous system are tightly associated to each other, maintaining physiological homeostasis of the human body. In addition to the cell-cell interaction, the CNS is also composed of elaborated and complicated extracellular matrixes ECMs. Neural ECMs are radically different from those of other tissues. The interstitial ECMs are mainly composed of a loose meshwork of hyaluronan, sulfated proteoglycans, and tenascins 1 , 2.

Proteoglycans in brain development

Biochem J 15 July ; 14 : — The a disintegrin-like and metalloproteinase with thrombospondin type-1 motifs ADAMTS family of metzincins are complex secreted proteins that have diverse functions during development. The hyalectanases ADAMTS1, 4, 5, 8, 9, 15 and 20 are a subset of this family that have enzymatic activity against hyalectan proteoglycans, the processing of which has important implications during development.

Astrocytes as a source for extracellular matrix molecules and cytokines

Он был крупнее, чем ожидал Беккер. Волосатая грудь начиналась сразу под тройным подбородком и выпячивалась ничуть не меньше, чем живот необъятного размера, на котором едва сходился пояс купального халата с фирменным знаком отеля. Беккер старался придать своему лицу как можно более угрожающее выражение. - Ваше имя. Красное лицо немца исказилось от страха.

Экран монитора был погашен, но она понимала, что он не заперт: по краям экрана было видно свечение. Криптографы редко запирали свои компьютеры, разве что покидая Третий узел на ночь. Обычно они лишь уменьшали их яркость; кодекс чести гарантировал, что никто в их отсутствие к терминалу не прикоснется. К черту кодекс чести, - сказала она.  - Посмотрим, чем ты тут занимаешься. Окинув быстрым взглядом находящееся за стеклом помещение шифровалки, Сьюзан включила кнопку яркости.

Стратмор виновато улыбнулся. - Сегодня утром Дэвид рассказал мне о ваших планах. Он сказал, что ты будешь очень расстроена, если поездку придется отложить. Сьюзан растерялась. - Вы говорили с Дэвидом сегодня утром. - Разумеется.


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2 comments

Ben G.

Proteoglycans PGs regulate diverse functions in the central nervous system CNS by interacting with a number of growth factors, matrix proteins, and cell surface molecules.

REPLY

Seth V.

Proteoglycans, as part of the extracellular or cell-surface milieu of most tissues and organ systems, play important roles in morphogenesis by modulating cell-matrix or cell-cell interactions, cell adhesiveness, or by binding and presenting growth and differentiation factors.

REPLY

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