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Biosynthesis and regulation of expression of the HNK‐1 epitope on myelin‐associated glycoprotein in a transfected cell model system
Author(s) -
Pedraza L.,
Spagnol G.,
Latov N.,
Salzer James L.
Publication year - 1995
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.490400603
Subject(s) - epitope , transfection , myelin associated glycoprotein , biology , glycoprotein , linear epitope , cell culture , microbiology and biotechnology , antibody , myelin , central nervous system , immunology , genetics , neuroscience
The HNK‐1 antibody recognizes a carbohydrate epitope expressed by many cell adhesion molecules in the nervous system that has been proposed to be an important adhesive determinant. This epitope is particularly prominent on the myelin‐associated glycoprotein (MAG) and is related to the antigenic target in an autoimmune mediated demyelinating neuropathy. Elucidation of the mechanisms underlying the biosynthesis and regulation of expression of the HNK‐1 epitope is therefore likely to have important functional and clinical implications. In order to investigate its biosynthesis and the regulation of its expression, we have expressed both human and rat MAG in several different cell lines by retroviral infection. These studies indicate that the cellular milieu determines whether the HNK‐1 epitope is expressed on the MAG polypeptide and provide an explanation for the significant variation in HNK‐1 levels that has been noted in different species. Using a transfected human neuroblastoma line, we have determined that this epitope is present on the fourth and/or fifth immunoglobulin‐like domain of rat MAG and that it is added intracellularly, probably in the trans Golgi. Finally we have found that expression of the HNK‐1 epitope is increased by activation of different second messenger systems, providing direct evidence that its expression can be regulated independently from that of the MAG polypeptide.© 1995 Wiley‐Liss, Inc.