Expression and role of sulfoglucuronyl (HNK-1) carbohydrate and its binding protein SBP-1 in developing rat cerebral cortex

Developmental expression of sulfoglucuronyl carbohydrate (SGC) and its bind ing protein, SBP-1 was studied in the rat cerebral cortex to understand the ir function. Between embryonic day (ED) 14-19, SBP-1 was strongly expressed in neurons of the ventricular zone and migrating neurons throughout the co rtex. SBP-1 declined at birth and by postnatal day (PD) 3 only the latest a rriving neurons in the most superficial segment of the cortical plate expre ssed SBP-1. Between ED 14-16, SGC was expressed in a thin row of glial cell s near the ventricles and on their radial processes. Between ED 16-PD 3, SG C was not in neuronal cell soma, but was in neuronal plasma membranes and p rocesses surrounding the neuronal perikarya. The expression of SGC declined similar to SBP-1 and both of them disappeared by PD 7. The expression of S BP-1 and SGC was chronologically coordinated with neuronal migration. SBP-1 was specifically expressed in immature neuronal nuclei and plasma membrane s. SBP-1 and SGC were colocalized and were available for interaction with e ach other on neuronal cell membranes and processes. This was confirmed with isolated neurons in culture. As in vivo, the expression of SBP-1 in neuron s declined with time in culture. The dissociated cortical neurons when plat ed on SBP-1 as a substratum produced extensive neuritic outgrowth. HNK-1, a nti-SBP-1 antibodies and sulfoglucuronyl glycolipid, SGGL specifically and severely reduced neurite outgrowth. SBP-1-SGC interactions provide a potent ial mechanism for guidance and cell signaling, in the processes of neuronal migration and terminal differentiation. (C) 2000 Wiley-Liss, Inc.