Imbalance of neural cell adhesion molecule and polysialyltransferase alleles causes defective brain connectivity

• Published in: Brain (London, England : 1878) Vol. 132; no. 10; pp. 2831 - 2838
• Main Authors: Hildebrandt, Herbert, Mühlenhoff, Martina, Oltmann-Norden, Imke, Röckle, Iris, Burkhardt, Hannelore, Weinhold, Birgit, Gerardy-Schahn, Rita
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.10.2009
• Subjects: Alleles; Animals; axon tract development; Axons - pathology; Biological and medical sciences; Blotting, Western; Brain - pathology; Development. Senescence. Regeneration. Transplantation; Fundamental and applied biological sciences. Psychology; Medical sciences; Mice; Mice, Inbred C57BL; Mice, Knockout; Nerve Fibers - pathology; neural cell adhesion molecule; Neural Cell Adhesion Molecules - genetics; Neural Pathways - pathology; Neurology; polysialic acid; Regression Analysis; Reverse Transcriptase Polymerase Chain Reaction; schizophrenia; Sialic Acids - metabolism; Sialyltransferases - genetics; Vertebrates: nervous system and sense organs; polysialic acid; brain pathology; axon tract development; schizophrenia; neural cell adhesion molecule; Psychosis; Anatomic pathology; Nervous system diseases; Neural cell adhesion molecule; Central nervous system; Schizophrenia; Axon; Encephalon
• ISSN: 0006-8950; 1460-2156
• DOI: 10.1093/brain/awp117

The neural cell adhesion molecule (NCAM) and its post-translational modification polysialic acid (polySia) are broadly implicated in neural development. Mice lacking the polysialyltransferases ST8SiaII and ST8SiaIV are devoid of polySia, and show severe malformation of major brain axon tracts. Here, we demonstrate how allelic variation of three interacting gene products (NCAM, ST8SiaII and ST8SiaIV) translates into various degrees of anterior commissure, corpus callosum and internal capsule hypoplasia. Loss of ST8SiaII alone caused mild, but distinct defects and the severity of the pathological phenotype found in mice lacking both polysialyltransferases could be stepwise attenuated by reducing NCAM expression. Analysis of mice with overall nine selected combinations of mutant NCAM and polysialyltransferase alleles revealed that the extent of the fibre tract deficiencies was not linked to the total amount of polySia or NCAM, but correlated strictly with the level of NCAM erroneously devoid of polySia during brain development. The defects implemented by the gain of polySia-free NCAM were reminiscent to abnormalities found in patients with schizophrenia. Since variations in NCAM1 and ST8SIA2 have been implicated in schizophrenia, these findings provide a mechanism how genetic interference with the complex coordination of NCAM polysialylation may lead to a neurodevelopmental predisposition to schizophrenia.