Galectin is a group of animal lectins, which have common properties, that is, specific for beta galactoside, not dependent on metal ion, and different from C-type lectins (Akimoto et al. 1998). Galectin-1 has been found in human tissues as well and is non-covalent homodimer of a subunit of about 14 kDa. We isolated galectin-1 from human placenta and showed, based on our immunological and sequence analysis, that human galectin-1 has quite similar amino acid sequence to chick 14- and 16-kDa galectins. The human galectin-1 has some regions homologous to those in the C-terminal half of CBP35 and 33-kDa galectin.

In this study, light microscopic localization of galectin-1 was observed in the human nervous tissue. In the cerebellum, galectin-1 was found in the neurons that were present between the molecular and granular layers (Fig. 1a). In the peripheral nervous system, galectin-1 existed in parasympathetic ganglions. Also seen in the ganglion cells of the myenteric plexus, which exists between the inner circular and the outer longitudinal layers of the smooth muscle in the muscularis externa of the digestive tract, and in those of the submucosal plexus, which exists in the submucosa of the digestive tract (Fig. 1b). Galectin-1 was also localized in the ganglion cells of the pancreas, that form one of the intramural ganglion (Fig. 1c). In the peripheral nerve fiber bundles, the galectin existed in both axon and Schwann cell (Fig. 1d).

Galectin-1 is involved in the growth and/or guidance of a subpopulation of axons in the olfactory system during development (Key and Puche 1997). In this study galectin-1 is shown to exist in the cytoplasm and nucleus of the neuron. We speculate that the galectin-1 has an important role in the neuron, such as transportation of glycoproteins in the cytoplasm and nucleus, signal transduction, etc.

[Collaborated with Dr. Kasai's lab (Dept. Biol. Chem. Fac. Pharm. Sci. Teikyo Univ.)]

(Reference)
Akimoto Y, Imai Y, Hirabayashi J, Kasai K, Hirano H: Histochemistry and cytochemistry of endogenous animal lectins. Progress in Histochemistry and Cytochemistry 33 (1) 1-92, 1998.

Key B, Puche AC: Role of Galectin-1 in the olfactory nervous system. Trends in Glycosciences and Glycotechnology 9 (45) 41-45, 1997.

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