scholarly journals Sialic Acids in the Brain: Gangliosides and Polysialic Acid in Nervous System Development, Stability, Disease, and Regeneration

2014 ◽  
Vol 94 (2) ◽  
pp. 461-518 ◽  
Author(s):  
Ronald L. Schnaar ◽  
Rita Gerardy-Schahn ◽  
Herbert Hildebrandt

Every cell in nature carries a rich surface coat of glycans, its glycocalyx, which constitutes the cell's interface with its environment. In eukaryotes, the glycocalyx is composed of glycolipids, glycoproteins, and proteoglycans, the compositions of which vary among different tissues and cell types. Many of the linear and branched glycans on cell surface glycoproteins and glycolipids of vertebrates are terminated with sialic acids, nine-carbon sugars with a carboxylic acid, a glycerol side-chain, and an N-acyl group that, along with their display at the outmost end of cell surface glycans, provide for varied molecular interactions. Among their functions, sialic acids regulate cell-cell interactions, modulate the activities of their glycoprotein and glycolipid scaffolds as well as other cell surface molecules, and are receptors for pathogens and toxins. In the brain, two families of sialoglycans are of particular interest: gangliosides and polysialic acid. Gangliosides, sialylated glycosphingolipids, are the most abundant sialoglycans of nerve cells. Mouse genetic studies and human disorders of ganglioside metabolism implicate gangliosides in axon-myelin interactions, axon stability, axon regeneration, and the modulation of nerve cell excitability. Polysialic acid is a unique homopolymer that reaches >90 sialic acid residues attached to select glycoproteins, especially the neural cell adhesion molecule in the brain. Molecular, cellular, and genetic studies implicate polysialic acid in the control of cell-cell and cell-matrix interactions, intermolecular interactions at cell surfaces, and interactions with other molecules in the cellular environment. Polysialic acid is essential for appropriate brain development, and polymorphisms in the human genes responsible for polysialic acid biosynthesis are associated with psychiatric disorders including schizophrenia, autism, and bipolar disorder. Polysialic acid also appears to play a role in adult brain plasticity, including regeneration. Together, vertebrate brain sialoglycans are key regulatory components that contribute to proper development, maintenance, and health of the nervous system.

2001 ◽  
Vol 204 (2) ◽  
pp. 305-314 ◽  
Author(s):  
A. Nighorn ◽  
P.J. Simpson ◽  
D.B. Morton

Guanylyl cyclases are usually characterized as being either soluble (sGCs) or receptor (rGCs). We have recently cloned a novel guanylyl cyclase, MsGC-I, from the developing nervous system of the hawkmoth Manduca sexta that cannot be classified as either an sGC or an rGC. MsGC-I shows highest sequence identity with receptor guanylyl cyclases throughout its catalytic and dimerization domains, but does not contain the ligand-binding, transmembrane or kinase-like domains characteristic of receptor guanylyl cyclases. In addition, MsGC-I contains a C-terminal extension of 149 amino acid residues. In this paper, we report the expression of MsGC-I in the adult. Northern blots show that it is expressed preferentially in the nervous system, with high levels in the pharate adult brain and antennae. In the antennae, immunohistochemical analyses show that it is expressed in the cell bodies and dendrites, but not axons, of olfactory receptor neurons. In the brain, it is expressed in a variety of sensory neuropils including the antennal and optic lobes. It is also expressed in structures involved in higher-order processing including the mushroom bodies and central complex. This complicated expression pattern suggests that this novel guanylyl cyclase plays an important role in mediating cyclic GMP levels in the nervous system of Manduca sexta.


Author(s):  
Karl Zilles ◽  
Nicola Palomero-Gallagher

The pre- and post-natal development of the human nervous system is briefly described, with special emphasis on the brain, particularly the cerebral and cerebellar cortices. The central nervous system originates from a specialized region of the ectoderm—the neural plate—which develops into the neural tube. The rostral part of the neural tube forms the adult brain, whereas the caudal part (behind the fifth somite) differentiates into the spinal cord. The embryonic brain has three vesicular enlargements: the forebrain, the midbrain, and the hindbrain. The histogenesis of the spinal cord, hindbrain, cerebellum, and cerebral cortex, including myelination, is discussed. The chapter closes with a description of the development of the hemispheric shape and the formation of gyri.


2018 ◽  
Vol 18 (1) ◽  
pp. 115-140
Author(s):  
Fu`ad Arif Noor

Neuroscience, are simply the science devoted to learning Neoron(nerve cells). Nerve cells make up the nervous system, both thecentral nervous system (brain and spinal cord) and the peripheralnerves (31 pairs and 12 pairs of spinal nerve head). A nerve cellitself is not the smallest unit away from the nerve cell, the smallestunit of nerve cells (neurons) are the synapses ie the meeting point oftwo nerve cells move and pass the information (neurotransmitters).At the level of molecular biology, the smallest unit is like genes(genetic studies). Generally, the neuroscientist focused on nervecells in the brain. In the Qur'an sense has a glorious position. It wasevident the word "reasonable" in the Qur'an is mentioned insignificant amounts. The word "reasonable" in the Qur'an is called49 times. All in the form mudhari deed '(a verb that indicates thecurrent and future), but one that is shaped madhi verb (a verb thatindicates the past).Although the Qur'an does not mention the "sense" in its form as' acertain part of the human self '(سفنلا ىف لاقتسم ارهوج), which becamethe source of the birth of any acts rationally, but the Qur'anmentions "reasonable" in its meaning as' activities reasonable use'(لقعتلا ةيلمع), the appeal that invites use of reason as the path to truth(لقعتلا), thinking (ركفتلا), watching (رظنلا), to understand and learn(هقفتلا), take the wisdom and lessons from each incident (رابتعلاا) andetc.


Development ◽  
1996 ◽  
Vol 122 (3) ◽  
pp. 925-936
Author(s):  
M. Tiemeyer ◽  
C.S. Goodman

Interactions between embryonic neural cells generate the specific patterns of connectivity observed in nervous systems. Cell surface carbohydrates have been proposed to function in cellular recognition events guiding such interactions. Carbohydrate-binding proteins (lectins) that recognize specific oligosaccharide ligands in embryonic neural tissue provide a molecular mechanism for carbohydrate-mediated cell-cell interactions in neural development. Therefore, we have screened an embryonic Drosophila melanogaster cDNA library, expressed in COS1 cells, for carbohydrate-binding activity. COS1 cells expressing putative Drosophila lectins were identified and recovered based on their adhesion to immobilized preparations of neutral and zwitterionic glycolipids extracted from Drosophila embryos. We have identified an endogenous lectin expressed during Drosophila embryogenesis. The cloned lectin, designated ‘gliolectin’, possesses a novel protein sequence with a calculated molecular mass of 24,993. When expressed in Drosophila S2 cells, the lectin mediates heterophilic cellular aggregation. In embryos, gliolectin is expressed by a subset of glial cells found at the midline of the developing nervous system. Expression is highest during the formation of the Drosophila embryonic axonal commissures, a process requiring midline glial cell funcion. Immunoprecipitation with a monoclonal antibody against gliolectin yields a protein of Mr=46,600 from Drosophila embryonic membranes, suggesting that post-translational modification of gliolectin is extensive. Epitope- tagged chimericproteins composed of the amino terminal one-half of gliolectin and the Fc region of human IgG bind a small subset of the total glycolipids extracted from Drosophila embryos, demonstrating that the lectin activity of gliolectin can discriminate between oligosaccharide structures. The presence of gliolectin in the developing Drosophila embryonic nervous system further supports a role for cell surface carbohydrates in cell-cell recognition and indicates that the molecular diversity of animal lectins is not yet completely defined.


1988 ◽  
Vol 8 (12) ◽  
pp. 5378-5385 ◽  
Author(s):  
L Saez ◽  
M W Young

The per locus influences biological rhythms in Drosophila melanogaster. In this study, per transcripts and proteins were localized in situ in pupae and adults. Earlier genetic studies have demonstrated that per expression is required in the brain for circadian locomotor activity rhythms and in the thorax for ultradian rhythmicity of the Drosophila courtship song. per RNA and proteins were detected in a restricted group of cells in the eyes and optic lobes of the adult brain and in many cell bodies in the adult and pupal thoracic ganglia. per products were also found in the pupal ring gland complex, a tissue involved in rhythmic aspects of Drosophila development. Abundant expression was seen in gonadal tissue. No biological clock phenotypes have been reported for this tissue in any of the per mutants, per protein mapped to different subcellular locations in different tissues. The protein accumulated in or around nuclei in some cells and appeared to be cytoplasmic in others.


2021 ◽  
Vol 22 (18) ◽  
pp. 10021
Author(s):  
Antoni Parcerisas ◽  
Alba Ortega-Gascó ◽  
Lluís Pujadas ◽  
Eduardo Soriano

Although it has been over 20 years since Neural Cell Adhesion Molecule 2 (NCAM2) was identified as the second member of the NCAM family with a high expression in the nervous system, the knowledge of NCAM2 is still eclipsed by NCAM1. The first studies with NCAM2 focused on the olfactory bulb, where this protein has a key role in axonal projection and axonal/dendritic compartmentalization. In contrast to NCAM1, NCAM2’s functions and partners in the brain during development and adulthood have remained largely unknown until not long ago. Recent studies have revealed the importance of NCAM2 in nervous system development. NCAM2 governs neuronal morphogenesis and axodendritic architecture, and controls important neuron-specific processes such as neuronal differentiation, synaptogenesis and memory formation. In the adult brain, NCAM2 is highly expressed in dendritic spines, and it regulates synaptic plasticity and learning processes. NCAM2’s functions are related to its ability to adapt to the external inputs of the cell and to modify the cytoskeleton accordingly. Different studies show that NCAM2 interacts with proteins involved in cytoskeleton stability and proteins that regulate calcium influx, which could also modify the cytoskeleton. In this review, we examine the evidence that points to NCAM2 as a crucial cytoskeleton regulation protein during brain development and adulthood. This key function of NCAM2 may offer promising new therapeutic approaches for the treatment of neurodevelopmental diseases and neurodegenerative disorders.


Development ◽  
2001 ◽  
Vol 128 (24) ◽  
pp. 4949-4958
Author(s):  
Monika Marx ◽  
Urs Rutishauser ◽  
Martin Bastmeyer

Polysialic acid (PSA), a carbohydrate epitope attached to the neural cell adhesion molecule, serves as a modulator of axonal interactions during vertebrate nervous system development. We have used PSA-specific antibodies and whole-mount immunocytochemistry to describe the spatiotemporal expression pattern of PSA during zebrafish central nervous system development. PSA is transiently expressed on all cell bodies and, except for the posterior commissure, it is not found on axons. Floorplate cells in the spinal cord and hindbrain strongly express PSA throughout development. Enzymatic removal of PSA leads to a defasciculated growth pattern of the posterior commissure and also affects distinct subsets of commissural axons in the hindbrain, which fail to cross the midline. Whereas the disordered growth pattern of hindbrain commissures produced by PSA-removal could be mimicked by injections of soluble PSA, the growth of axons in the posterior commissure was unaffected by such treatment. These results suggest that there are distinct mechanisms for PSA action during axon growth and pathfinding in the developing zebrafish CNS.


Endocrinology ◽  
2010 ◽  
Vol 151 (11) ◽  
pp. 5550-5558 ◽  
Author(s):  
Arturo Hernandez ◽  
Laure Quignodon ◽  
M. Elena Martinez ◽  
Frederic Flamant ◽  
Donald L. St. Germain

The type 3 deiodinase (D3) is an enzyme that inactivates thyroid hormones (TH) and is highly expressed during development and in the central nervous system. D3-deficient (D3KO) mice develop markedly elevated serum T3 level in the perinatal period. In adulthood, circulating T4 and T3 levels are reduced due to functional deficits in the thyroid axis and peripheral tissues (i.e. liver) show evidence of decreased TH action. Given the importance of TH for brain development, we aimed to assess TH action in the brain of D3KO mice at different developmental stages and determine to what extent it correlates with serum TH parameters. We used a transgenic mouse model (FINDT3) that expresses the reporter gene β-galactosidase (β-gal) in the central nervous system as a readout of local TH availability. Together with experiments determining expression levels of TH-regulated genes, our results show that after a state of thyrotoxicosis in early development, most regions of the D3KO brain show evidence of decreased TH action at weaning age. However, later in adulthood and in old age, the brain again manifests a thyrotoxic state, despite reduced serum TH levels. These region-specific changes in brain TH status during the life span of the animal provide novel insight into the important role of the D3 in the developing and adult brain. Our results suggest that, even if serum concentrations of TH are normal or low, impaired D3 activity may result in excessive TH action in multiple brain regions, with potential consequences of altered neural function that may be of clinical relevance to neurological and neuroendocrine disorders.


2019 ◽  
Vol 4 (1) ◽  
pp. 32-52
Author(s):  
Fuad Arif Noor

Neuroscience is simply the science that specifically studies Neurons (nerve cells). These nerve cells make up the nervous system, both the central nervous system (brain and spinal cord) and peripheral nerves (31 pairs of spinal nerves and 12 pairs of head nerves). Nerve cells themselves are no longer the smallest unit of nerve cells, the smallest unit of nerve cells (neurons) in synapses, which are the meeting points of two nerve cells that move and forward information (neurotransmitters). At the level of molecular biology, the smallest units are like genes (genetic studies). Generally, neuroscientists focus on nerve cells in the brain. In the Qur'an, the mind has a noble position. It was proven that the word "reason" in the Qur'an is mentioned in large numbers. The word "reason" in the Qur'an is mentioned 49 times. All of them are in the form of 'muilāri' (a verb that indicates the present and the future), except for the one in the form of 'māḍī (a verb denoting the past). Although the Qur'an does not mention "reason" in its form as "a certain part of humanity" (جوهرا مستقلا فى النفس), which is the source of birth for all rational actions, but the Qur'an refers to "reason" in its meaning as " activities using reason '(عملية التعقل), i.e. calls to use reason as a path to truth (التعقل), think (التفكر), pay attention (النظر), understand and learn (التفقه), take wisdom and lessons from each event (الاعتبار), etc.


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