ADAMTS2 promotes radial migration by activating TGF-β signaling in the developing neocortex.

The mammalian neocortex is formed by sequential radial migration of newborn excitatory neurons. Migrating neurons undergo a multipolar-to-bipolar transition at the subplate (SP) layer, where extracellular matrix (ECM) components are abundantly expressed. Here, we investigate the role of the ECM at the SP layer.

Phosphacan acts as a repulsive cue in murine and rat cerebellar granule cells in a TAG-1/GD3 rafts-dependent manner.

Phosphacan, a chondroitin sulfate proteoglycan, is a repulsive cue of cerebellar granule cells. This study aims to explore the molecular mechanism. The glycosylphosphatidylinositol-anchored neural adhesion molecule TAG-1 is a binding partner of phosphacan, suggesting that the repulsive effect of phosphacan is possibly because of its interaction with TAG-1.

Histochemical Analysis of Heparan Sulfate 3-O-sulfotransferase Expression in Mouse Brain.

In situ hybridization provides information for understanding the localization of gene expression in various tissues. The relative expression levels of mRNAs in a single cell can be sensitively visualized by this technique. Furthermore, since in situ hybridization is a histological technique, tissue structure is maintained after fixation, and it is possible to accurately identify the cell types.

Glypicans and Heparan Sulfate in Synaptic Development, Neural Plasticity, and Neurological Disorders.

Heparan sulfate proteoglycans (HSPGs) are components of the cell surface and extracellular matrix, which bear long polysaccharides called heparan sulfate (HS) attached to the core proteins. HSPGs interact with a variety of ligand proteins through the HS chains, and mutations in HSPG-related genes influence many biological processes and cause various diseases. In particular, recent findings from vertebrate and invertebrate studies have raised the importance of glycosylphosphatidylinositol-anchored HSPGs, glypicans, as central players in the development and functions of synapses.

The HSPG Glypican Regulates Experience-Dependent Synaptic and Behavioral Plasticity by Modulating the Non-Canonical BMP Pathway.

Under food deprivation conditions, Drosophila larvae exhibit increases in locomotor speed and synaptic bouton numbers at neuromuscular junctions (NMJs). Octopamine, the invertebrate counterpart of noradrenaline, plays critical roles in this process; however, the underlying mechanisms remain unclear. We show here that a glypican (Dlp) negatively regulates type I synaptic bouton formation, postsynaptic expression of GluRIIA, and larval locomotor speed.

Synaptic transmission from subplate neurons controls radial migration of neocortical neurons.

The neocortex exhibits a six-layered structure that is formed by radial migration of excitatory neurons, for which the multipolar-to-bipolar transition of immature migrating multipolar neurons is required. Here, we report that subplate neurons, one of the first neuron types born in the neocortex, manage the multipolar-to-bipolar transition of migrating neurons. By histochemical, imaging, and microarray analyses on the mouse embryonic cortex, we found that subplate neurons extend neurites toward the ventricular side of the subplate and form transient glutamatergic synapses on the multipolar neurons just below the subplate.

Heparan sulfate proteoglycans in Drosophila neuromuscular development.

Heparan sulfate proteoglycans (HSPGs) are glycoconjugates bearing heparan sulfate (HS) chains covalently attached to core proteins, which are ubiquitously distributed on the cell surface and in the extracellular matrix. HSPGs interact with a number of molecules mainly through HS chains, which play critical roles in diverse physiological and disease processes. Among these, recent vertebrate studies showed that HSPGs are closely involved in synapse development and function.

The Strip-Hippo Pathway Regulates Synaptic Terminal Formation by Modulating Actin Organization at the Drosophila Neuromuscular Synapses.

Synapse formation requires the precise coordination of axon elongation, cytoskeletal stability, and diverse modes of cell signaling. The underlying mechanisms of this interplay, however, remain unclear. Here, we demonstrate that Strip, a component of the striatin-interacting phosphatase and kinase (STRIPAK) complex that regulates these processes, is required to ensure the proper development of synaptic boutons at the Drosophila neuromuscular junction.

Proteoglycans and neuronal migration in the cerebral cortex during development and disease.

Chondroitin sulfate proteoglycans and heparan sulfate proteoglycans are major constituents of the extracellular matrix and the cell surface in the brain. Proteoglycans bind with many proteins including growth factors, chemokines, axon guidance molecules, and cell adhesion molecules through both the glycosaminoglycan and the core protein portions. The functions of proteoglycans are flexibly regulated due to the structural variability of glycosaminoglycans, which are generated by multiple glycosaminoglycan synthesis and modifying enzymes.

Histochemical analysis of heparan sulfate 3-O-sulfotransferase expression in mouse brain.

In situ hybridization provides information for understanding the localization of gene expression in various tissues. The relative expression levels of mRNAs in a single cell can be sensitively visualized by this technique. Furthermore, since in situ hybridization is a histological technique, tissue structure is maintained after fixation, and it is possible to accurately identify cell types.

Structural and biochemical characterization of O-mannose-linked human natural killer-1 glycan expressed on phosphacan in developing mouse brains.

The human natural killer-1 (HNK-1) carbohydrate comprising a sulfated trisaccharide (HSO3-3GlcAβ1-3Galβ1-4GlcNAc-) is expressed on N-linked and O-mannose-linked glycans in the nervous system and involved in learning and memory functions. Although whole/core glycan structures and carrier glycoproteins for the N-linked HNK-1 epitope have been studied, carrier glycoproteins and the biosynthetic pathway of the O-mannose-linked HNK-1 epitope have not been fully characterized. Here, using mass spectrometric analyses, we identified the major carrier glycoprotein of the O-linked HNK-1 as phosphacan in developing mouse brains and determined the major O-glycan structures having the terminal HNK-1 epitope from partially purified phosphacan.

Perlecan regulates bidirectional Wnt signaling at the Drosophila neuromuscular junction.

Heparan sulfate proteoglycans (HSPGs) play pivotal roles in the regulation of Wnt signaling activity in several tissues. At the Drosophila melanogaster neuromuscular junction (NMJ), Wnt/Wingless (Wg) regulates the formation of both pre- and postsynaptic structures; however, the mechanism balancing such bidirectional signaling remains elusive. In this paper, we demonstrate that mutations in the gene of a secreted HSPG, perlecan/trol, resulted in diverse postsynaptic defects and overproduction of synaptic boutons at NMJ.

In vivo manipulation of heparan sulfate structure and its effect on Drosophila development.

Heparan sulfate proteoglycans (HSPGs) participate in a wide range of biological processes through interactions with a number of ligand proteins. The nature of these interactions largely depends on the heparan sulfate (HS) moiety of HSPGs, which undergoes a series of modifications by various HS-modifying enzymes (HSMEs). Although the effects of alterations in a single HSME on physiological processes have started to be studied, it remains elusive how a combination of these molecules control the structure and function of HS.

Structural variation of chondroitin sulfate and its roles in the central nervous system.

Chondroitin sulfate is popular in the field of neuroscience, because the treatment of nervous tissues with chondroitinase ABC, which degrades chondroitin sulfate up to unsaturated disaccharides, causes severe changes in various aspects of neural development and functions. Chondroitinase ABC treatments of developing nervous tissue impair the growth and differentiation of neural progenitor cells, and cause various pathfinding errors of axons. After injury to the adult central nervous system, axon regeneration fails at scar regions expressing large amounts of chondroitin sulfate proteoglycans.

Chondroitin sulfate proteoglycans in neural development and plasticity.

PTPzeta and lectican family members are major chondroitin sulfate proteoglycans (CS-PGs) in the brain, which bind with many proteins via core protein and CS portions. Recent studies revealed that the oversulfated structures in CS constitute high affinity binding sites for various growth factors and axon guidance molecules, and play important roles in the proliferation of neural progenitor cells, neurite extension and neuronal migration. PTPzeta uses pleiotrophin as a ligand.

Oversulfated chondroitin sulfate plays critical roles in the neuronal migration in the cerebral cortex.

Chondroitin sulfate (CS) proteoglycans bind with various proteins through CS chains in a CS structure-dependent manner, in which oversulfated structures, such as iB (IdoA(2-O-sulfate)alpha1-3GalNAc(4-O-sulfate)), D (GlcA(2-O-sulfate)beta1-3GalNAc(6-O-sulfate)), and E (GlcAbeta1-3GalNAc(4,6-O-disulfate)) units constitute the critical functional module. In this study, we examined the expression and function of three CS sulfotransferases in the developing neocortex: uronyl 2-O-sulfotransferase (UST), N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase (4,6-ST) and dermatan 4-O-sulfotransferase-1 (D4-ST), which are responsible for the synthesis of oversulfated structures. The CS chains of the neocortex of mouse embryos contained significant amounts of D and E units that are generated by UST and 4,6-ST, respectively.

Spatiotemporal expression of chondroitin sulfate sulfotransferases in the postnatal developing mouse cerebellum.

Chondroitin sulfate (CS) proteoglycans are major components of the cell surface and the extracellular matrix in the developing brain and bind to various proteins via CS chains in a CS structure-dependent manner. This study demonstrated the expression pattern of three CS sulfotransferase genes, dermatan 4-O-sulfotransferase (D4ST), uronyl 2-O-sulfotransferase (UST), and N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase (GalNAc4S-6ST), in the mouse postnatal cerebellum. These sulfotransferases are responsible for the biosynthesis of oversulfated structures in CS chains such as B, D, and E units, which constitute the binding sites for various heparin-binding proteins.

Receptor type protein tyrosine phosphatase zeta-pleiotrophin signaling controls endocytic trafficking of DNER that regulates neuritogenesis.

Protein tyrosine phosphatase zeta (PTPzeta) is a receptor type protein tyrosine phosphatase that uses pleiotrophin as a ligand. Pleiotrophin inactivates the phosphatase activity of PTPzeta, resulting in the increase of tyrosine phosphorylation levels of its substrates. We studied the functional interaction between PTPzeta and DNER, a Notch-related transmembrane protein highly expressed in cerebellar Purkinje cells.

Reduced expression of MAb6B4 epitopes on chondroitin sulfate proteoglycan aggrecan in perineuronal nets from cerebral cortices of SAMP10 mice: a model for age-dependent neurodegeneration.

The accelerated senescence-prone SAMP10 mouse strain is a model for age-dependent neurodegeneration and is characterized by brain atrophy and deficits in learning and memory. Because perineuronal nets play an important role in the synaptic plasticity of adult brains, we examined the distributions of molecules that constitute perineuronal nets in SAMP10 mouse brain samples and compared them with those in control SAMR1 mouse samples. Proteoglycan-related monoclonal antibody 6B4 (MAb6B4) clearly immunostained perineuronal nets in SAMR1 mice cortices, but the corresponding immunostaining in SAMP10 mice was very faint.

The binding of chondroitin sulfate to pleiotrophin/heparin-binding growth-associated molecule is regulated by chain length and oversulfated structures.

Pleiotrophin is an 18-kDa heparin-binding growth factor, which uses chondroitin sulfate (CS) proteoglycan, PTPzeta as a receptor. It has been suggested that the D-type structure (GlcA(2S)beta1-3GalNAc(6S)) in CS contributes to the high affinity binding between PTPzeta and pleiotrophin. Here, we analyzed the interaction of shark cartilage CS-D with pleiotrophin using a surface plasmon resonance biosensor to reveal the importance of D-type structure.

Developmental change and function of chondroitin sulfate deposited around cerebellar Purkinje cells.

Chondroitin sulfate is a long sulfated polysaccharide with enormous structural heterogeneity that binds with various proteins, such as growth factors, in a structure-dependent manner. In this study, we analyzed the expression of chondroitin sulfate in the postnatally developing cerebellar cortex by using three monoclonal antibodies against chondroitin sulfate, MO-225, 2H6, and CS-56, which recognize different structural domains in this polysaccharide. During the first postnatal week, the patterns of immunohistochemical staining made by these antibodies were quite similar, and the molecular layer, the granule cell layer, and Bergmann glial fibers in the external granular layer were densely stained.

Developmental and regional expression of heparan sulfate sulfotransferase genes in the mouse brain.

Heparan sulfate (HS) binds with various proteins including growth factors, morphogens, and extracellular matrix molecules to regulate their biological functions. These regulatory interactions are considered to be dependent on the structure of HS, which is determined by HS sulfotransferases. To gain insights into the functions of HS sulfotransferases in the development of the nervous system, we examined the expression of these enzymes (3-O-sulfotransferase-1 [3-OST-1], -2, -4; 6-OST-1, -2, -3; and N-deacetylase /N-sulfotransferase-1 [NDST-1], -2, -3) by in situ hybridization and real-time reverse transcription-polymerase chain reaction (RT-PCR).