Research

Galectin-1 is expressed in early-type neural progenitor cells and down-regulates neurogenesis in the adult hippocampus

Yoichi Imaizumi^1,2, Masanori Sakaguchi¹, Tsuyoshi Morishita³, Mamoru Ito⁴, Françoise Poirier⁵, Kazunobu Sawamoto^2,6 and Hideyuki Okano^1*

• * Corresponding author: Hideyuki Okano hidokano@sc.itc.keio.ac.jp

Author Affiliations

¹ Department of Physiology, Keio University School of Medicine, Tokyo, Japan

² Bridgestone Laboratory of Developmental and Regenerative Neurobiology, Keio University School of Medicine, Tokyo, Japan

³ Development Division, Kyowa Hakko Kirin Co., Ltd., Tokyo, Japan

⁴ Central Institute for Experimental Animals, Kanagawa, Japan

⁵ Institut Jacques Monod, UMR CNRS 7592, University Paris Diderot, Paris, France

⁶ Department of Developmental and Regenerative Biology, Nagoya City University Graduate School of Medical Sciences, Aichi, Japan

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Molecular Brain 2011, 4:7 doi:10.1186/1756-6606-4-7

Published: 27 January 2011

Abstract

Background

In the adult mammalian brain, neural stem cells (NSCs) proliferate in the dentate gyrus (DG) of the hippocampus and generate new neurons throughout life. A multimodal protein, Galectin-1, is expressed in neural progenitor cells (NPCs) and implicated in the proliferation of the NPCs in the DG. However, little is known about its detailed expression profile in the NPCs and functions in adult neurogenesis in the DG.

Results

Our immunohistochemical and morphological analysis showed that Galectin-1 was expressed in the type 1 and 2a cells, which are putative NSCs, in the subgranular zone (SGZ) of the adult mouse DG. To study Galectin-1's function in adult hippocampal neurogenesis, we made galectin-1 knock-out mice on the C57BL6 background and characterized the effects on neurogenesis. In the SGZ of the galectin-1 knock-out mice, increased numbers of type 1 cells, DCX-positive immature progenitors, and NeuN-positive newborn neurons were observed. Using triple-labeling immunohistochemistry and morphological analyses, we found that the proliferation of the type-1 cells was increased in the SGZ of the galectin-1 knock-out mice, and we propose that this proliferation is the mechanism for the net increase in the adult neurogenesis in these knock-out mice DG.

Conclusions

Galectin-1 is expressed in the neural stem cells and down-regulates neurogenesis in the adult hippocampus.