Neuronal-specific Synthesis and Glycosylation of Tenascin-R

Abstract

Tenascin-R (TN-R) is a member of the tenascin family of multidomain matrix glycoproteins that is expressed exclusively in the central nervous system by oligodendrocytes and small neurons during postnatal development and in the adult. TN-R contributes to the regulation of axon extension and regeneration, neurite formation and synaptogenesis, and neuronal growth and migration. TN-R can be modified with three distinct sulfated oligosaccharide structures: HNK-1 (SO(4)-3-GlcUAbeta1,3Galbeta1,4GlcNAc), GalNAc-4-SO(4), and chondroitin sulfate. We have determined that TN-R expressed in dendrite-rich regions of the rat cerebellum, hippocampus, and cerebral cortex is one of the major matrix glycoproteins that bears N-linked carbohydrates terminating with beta1,4-linked GalNAc-4-SO(4). The syntheses of these unique sulfated structures on TN-R are differentially regulated. Levels of HNK-1 on TN-R rise and fall in parallel to the levels of TN-R during postnatal development of the cerebellum. In contrast, levels of GalNAc-4-SO(4) are regulated independently from those of TN-R, rising late in cerebellar development and continuing into adulthood. As a result, the pattern of TN-R modification with distinct sulfated carbohydrate structures changes dramatically over the course of postnatal cerebellar development in the rat. Because TN-R interacts with a number of different matrix components and, depending on the circumstances, can either activate or inhibit neurite outgrowth, the highly regulated addition of these unique sulfated structures may modulate the adhesive properties of TN-R over the course of development and during synapse maintenance. In addition, the 160-kDa form of TN-R is particularly enriched for terminal GalNAc-4-SO(4) later in development and in the adult, suggesting additional levels of regulation.

Microarray-Based Identification of Tenascin C and Tenascin XB, Genes Possibly Involved in Tumorigenesis Associated with Neurofibromatosis Type 1

“…TNR was not expressed by MPNSTs or plexiform and dermal neurofibromas, in agreement with previous reports. Tenascin-R is expressed exclusively in the central nervous system, where it is mainly secreted by oligodendrocytes (39). TNN expression was not significantly different between dermal/plexiform neurofibromas and MPNSTs.…”

Meet the Tenascins: Multifunctional and Mysterious

“…lum, suggesting a mechanism by which the modulatory functions of tenascin-R might change during the life of an organism (38).…”

Chondroitin Sulfate Proteoglycan Tenascin-R Regulates Glutamate Uptake by Adult Brain Astrocytes

“…3B). Because TNR is known to be a CSPG (21,22), and chondroitinase ABC digestion of protein immunoprecipitated with anti-TNR antibody yielded detectable ⌬Di-4S and ⌬Di-6S glycosaminoglycan disaccharides (data not shown), TNR was included in the candidate list of CSPGs that have covalently linked sulfated glycosaminoglycans. TNR was of particular interest because the distribution patterns of other conventional lecticans overlapped little with that of the DACS (see below).…”