Neurochemical Research

, Volume 35, Issue 12, pp 1867–1874

In Search of a Solution to the Sphinx-Like Riddle of GM1

OVERVIEW

DOI: 10.1007/s11064-010-0286-0

Cite this article as:
Ledeen, R.W. & Wu, G. Neurochem Res (2010) 35: 1867. doi:10.1007/s11064-010-0286-0

Abstract

Among the many glycoconjugates contributing to the sugar code, gangliosides have drawn special attention owing to their predominance as the major sialoglycoconjugate category within the nervous system. However, their occurrence, albeit at lower levels, appears ubiquitous in vertebrate cells and even some invertebrate tissues. Now that over 100 gangliosides have been structurally characterized, their diverse physiological functions constitute a remaining enigma. This has been especially true of GM1, for which a surprising array of functions has already been revealed. Our current research has focused on two areas of GM1 function: (a) signaling induced in neural and immune cells by cross-linking of GM1 in the plasma membrane that leads to activation of TRPC5 (transient receptor potiential, canonical form 5) channels, a process important in neuritogenesis and autoimmune suppression; (b) activation by GM1 of a sodium-calcium exchanger (NCX) in the inner membrane of the nuclear envelope (NE) with resulting modulation of nuclear and cellular calcium. The latter has a role in maintaining neuronal viability, loss of which renders neurons vulnerable to Ca2+ overload. Pathological manifestations in mutant mice and their cultured neurons lacking GM1 have shown dramatic rescue with a membrane permeable derivative of GM1 that enters the nucleus and restores NCX activity. Nuclear function of GM1 is related to the presence of neuraminidase in the NE, an enzyme that generates GM1 through hydrolysis of GD1a. A different isoform of this enzyme was found in each of the two membranes of the NE.

Keywords

GM1GangliosideNeuraminidaseCalcium regulationCross-linking of GM1TRPC5 channelsGM1 in the nuclear envelopeSodium-calcium exchanger

Abbreviations

CtxB

B subunit of cholera toxin

ER

Endoplasmic reticulum

Gal-1

Galectin-1

IP

Intraperitoneal

N’ase

Neuraminidase

NCX

Sodium-calcium exchanger

NE

Nuclear envelope

Teff

Effector T cell

Treg

Regulatory T cell

TRPC5

Transient receptor potential, isoform 5 of canonical subgroup

Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  1. 1.Department of Neurology and NeurosciencesNew Jersey Medical School, UMDNJNewarkUSA