Lack of lacto/neolacto-glycolipids enhances the formation of glycolipid-enriched microdomains, facilitating B cell activation

Akira Togayachi, Yuko Kozono, Yuzuru Ikehara, Hiromi Ito, Nami Suzuki, Yuki Tsunoda, Sumie Abe, Takashi Sato, Kyoko Nakamura, Minoru Suzuki, Hatsumi M. Goda, Makoto Ito, Takashi Kudo, Satoru Takahashi, Hisashi Narimatsu

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28 Citations (Scopus)

Abstract

In a previous study, we demonstrated that β1,3-N- acetylglucosaminyltransferase 5 (B3gnt5) is a lactotriaosylceramide (Lc 3Cer) synthase that synthesizes a precursor structure for lacto/neolacto-series glycosphingolipids (GSLs) in in vitro experiments. Here, we generated B3gnt5-deficient (B3gnt5-/-) mice to investigate the in vivo biological functions of lacto/neolacto-series GSLs. In biochemical analyses, lacto/neolacto-series GSLs were confirmed to be absent and no Lc 3Cer synthase activity was detected in the tissues of these mice. These results demonstrate that β3GnT5 is the sole enzyme synthesizing Lc3Cer in vivo. Ganglioside GM1, known as a glycosphingolipid- enriched microdomain (GEM) marker, was found to be upregulated in B3gnt5 -/- B cells by flow cytometry and fluorescence microscopy. However, no difference in the amount of GM1 was observed by TLC-immunoblotting analysis. The GEM-stained puncta on the surface of B3gnt5-/- resting B cells were brighter and larger than those of WT cells. These results suggest that structural alteration of GEM occurs in B3gnt5-/- B cells. We next examined whether BCR signaling-related proteins, such as BCR, CD19, and the signaling molecule Lyn, had moved into or out of the GEM fraction. In B3gnt5-/- B cells, thesemolecules were enriched in the GEM fraction or adjacent fraction. Moreover, B3gnt5-/- B cells were more sensitive to the induction of intracellular phosphorylation signals on BCR stimulation and proliferated more vigorously than WT B cells. Together, these results suggest that lacto/neolacto-series GSLs play an important role in clustering of GEMs and tether-specific proteins, such as BCR, CD19, and related signaling molecules to the GEMs.

Original languageEnglish
Pages (from-to)11900-11905
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume107
Issue number26
DOIs
Publication statusPublished - Jun 29 2010

All Science Journal Classification (ASJC) codes

  • General

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    Togayachi, A., Kozono, Y., Ikehara, Y., Ito, H., Suzuki, N., Tsunoda, Y., Abe, S., Sato, T., Nakamura, K., Suzuki, M., Goda, H. M., Ito, M., Kudo, T., Takahashi, S., & Narimatsu, H. (2010). Lack of lacto/neolacto-glycolipids enhances the formation of glycolipid-enriched microdomains, facilitating B cell activation. Proceedings of the National Academy of Sciences of the United States of America, 107(26), 11900-11905. https://doi.org/10.1073/pnas.0914298107