Okayama University research: Links discovered between plant complex type N-glycans and hay fever

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Okayama University researchers identify plants expressing substantial amounts of a nitrogen-linked polysaccharide, which is linked to allergic responses in mammals, and may provide useful study models for understanding hay fever. The findings are reported in the journal Carbohydrate Research, November 2016.

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the Lewis a type plant N-glycans were commonly expressed in a substantial amount on the glycoproteins produced in these three water plants

Okayama University researchers identify plants expressing substantial amounts of a nitrogen-linked polysaccharide, which is linked to allergic responses in mammals, and may provide useful study models for understanding hay fever. The findings are reported in the journal Carbohydrate Research, November 2016.

Researchers have noted the occurrence of plant complex type N-glycans on cedar pollen allergens, which carry a component called the “Lewis a epitope”. However previous studies found that rather than triggering allergic responses the core structure of plant complex type N-glycans may inhibit them.

One of the main stumbling blocks in studies to understand the immunological significance of Lewis a type plant N-glycans studies has been the lack of means for preparing Lewis a type plant N-glycans in substantial amounts. The demonstration of high levels of plant complex type N-glycans expressed in three sea water plants provides a significant step forward for these studies.

The “epitope” is the part of toxic and foreign substances and other antigens that is recognised to trigger the immune system into action. In certain types of antigen – allergens – the epitope overstimulates the immune system.

In previous work the Okayama researchers reported that many types of seaweed and marine algae express high-mannose type N-glycans, but not plant complex type N-glycans. In this work they identify three water plants that instead have N-glycans bearing β1-2 xylosyl and/or α1-3 fucosyl residues but not high-mannose type.

Megumi Maeda, Yoshinobu Kimura and their colleagues at Okayama University studied the plants Elodea nuttallii, Egeria densa, and Ceratophyllum demersum. Structural investigations identified eight types of N-glycans. “Moreover, the Lewis a type plant N-glycans were commonly expressed in a substantial amount on the glycoproteins produced in these three water plants,” they add in their conclusions.

Land plants are well known to ubiquitously carry plant complex type N-glycans. Seaplants such as seaweed are thought to have evolved from land plants in the cretaceous period. Further genetic studies are underway to understand the why N-glycans expression differs in these plants and to identify any possible physicochemical or biological functions for these glycoproteins.

Publication and Affiliation

Megumi Maeda, Misato Tani, Takeo Yoshiie, Christopher J. Vavricka, Yoshinobu Kimura, Structural features of N-glycans linked to glycoproteins expressed in three kinds of water plants: Predominant occurrence of the plant complex type N-glycans bearing Lewis a epitope. Carbohydrate Research 435 50-57, (2016).

http://dx.doi.org/10.1016/j.carres.2016.09.008

Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science, Okayama University, 1-1-1 Tsushima-Naka, Okayama 700-8530, Japan
Department of Biofunctional Chemistry, Graduate School of Natural Science and Technology, Okayama University, 1-1-1 Tsushima-Naka, Okayama 700-8530, Japan

About Okayama University

Okayama University is one of the largest comprehensive universities in Japan with roots going back to the Medical Training Place sponsored by the Lord of Okayama and established in 1870. Now with 1,300 faculty and 14,000 students, the University offers courses in specialties ranging from medicine and pharmacy to humanities and physical sciences. Okayama University is located in the heart of Japan approximately 3 hours west of Tokyo by Shinkansen.
Website: http://www.okayama-u.ac.jp/index_e.html

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S. Kinoshita
Okayama University
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