(AGENPARL) – gio 21 dicembre 2023 Source: Tokyo Institute of Technology
Immediate release: December 21, 2023
Headline: The Evolutionary Timeline of Diminished Boric Acid and Urea
Transportation in Aquaporin 10
Body: (Tokyo, December 21) *Aquaporin (Aqp) 10 water channels in humans
allow the free passage of water, glycerol, urea, and boric acid across
cells. However, Aqp10.2b in pufferfishes allows only the passage of water
and glycerol and not urea and boric acid. Researchers from the Tokyo
Institute of Technology sought to understand the evolutionary timeline that
resulted in the variable substrate selection mechanisms among Aqp10s. Their
results indicate that Aqp10.2 in ray-finned fishes may have reduced or lost
urea and boric acid permeabilities through evolution.*
Aquaporins (Aqps) are proteins that form water channels in the membranes of
living cells, including those of bacteria, fungi, animals, and plants.
These channels facilitate water transportation across cells more rapidly
than diffusion through the membrane phospholipid bilayer.
Aqp10 belongs to the aquaglyceroporin subfamily of water channels. These
proteins facilitate many of our body’s physiological processes, including
gut function, liver and fat cell metabolism, and skin elasticity. Water and
solutes, such as glycerol, urea, and boric acid, get transported through
human Aqp10 depending on concentration gradients across the membrane.
Sarcopterygians, which include coelacanths, lungfish, and tetrapods (such
as amphibians, reptiles, birds, and mammals), are known to have a single
gene that codes for Aqp10. In contrast, actinopterygians, such as
ray-finned fishes, have paralogs, or near-identical copies, of the *aqp10*
gene, such as *aqp10.1* and *aqp10.2*. Interestingly, the ray-finned
Japanese pufferfish has paralog called *aqp10.2b *that shows permeability
to water and glycerol but not to urea and boric acid.
To understand how these functional differences between solute
permeabilities in Aqp10 in humans and pufferfish may have evolved, a team
of researchers from the School of Life Science and Technology, Tokyo
Institute of Technology (Tokyo Tech), Department of Advanced Bioscience,
Faculty of Agriculture, Kindai University, Department of Integrative
Biology at Michigan State University, Aquamarine Fukushima AMF, and
Department of Physiology and Biomedical Engineering at the Mayo Clinic
College of Medicine and Science analyzed Aqp10s in different species. The study
was published in *Genome Biology and Evolution *on December 01, 2023
.
When asked about their study, Dr. Ayumi Nagashima, who is an Assistant
Professor in the Department of Life Science and Technology at Tokyo Tech
and the lead scientist of the study, explains, “Evolutionary adaptations in
solute selectivity could present a promising model for analyzing solute
permeability evolution in aquaglyceroporins. In this study, to elucidate
the evolutionary history of Aqp10 solute selectivity, we analyzed and
compared the permeability and evolutionary relationships of Aqp10s in eight
bony vertebrate species.”
The research team found that similar to the tetrapod and lobe-finned fish
Aqp10s, Aqp10.1 in ray-finned fishes also transport water, glycerol, urea,
and boric acid. On the other hand, while Aqp10.2 in ray-finned fishes
transport water and glycerol, they restrict urea and boric acid passage
much more than Aqp10 and Aqp10.1.
These intriguing results indicate that water, glycerol, urea, and boric
acid permeabilities are plesiomorphic features of Aqp10 water channels in
all tetrapods and lobe-finned fish. However, the Aqp10.2 found in
ray-finned fish may have reduced or lost urea and boric acid permeability
during evolution.
In this regard, Dr. Nagashima remarks, “Our study showed that the Aqp10.2
of ray-finned fishes allows only limited or no urea or boric acid transport
across it. These activities were likely systematically reduced and
subsequently lost through evolution in the common ancestor of these fishes.
This research is expected to shed light on the elucidation of the substrate
selection mechanism of aquaglyceroporins, which contributes to nutrient
transport and other processes in the future.”
In summary, this study highlights that water, glycerol, urea, and boric
acid transport activities are plesiomorphic activities of Aqp10
characteristic of the ancestral type common to the studied species.
Consequently, the results suggest that Aqp10.2 in actinopterygians evolved
to diminish the transport activity of urea and boric acid.
Infographic: https://tokyotech.box.com/s/pp12cejq7a237pw7b2qzppva5s1z3bmk
*About Tokyo Institute of Technology *
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leading university for science and technology in Japan. Tokyo Tech
researchers excel in fields ranging from materials science to biology,
computer science, and physics. Founded in 1881, Tokyo Tech hosts over
10,000 undergraduate and graduate students per year, who develop into
scientific leaders and some of the most sought-after engineers in industry.
Embodying the Japanese philosophy of “monotsukuri,” meaning “technical
ingenuity and innovation,” the Tokyo Tech community strives to contribute
to society through high-impact research. https://www.titech.ac.jp/english/
*Contact: *Emiko Kawaguchi, Public Relations Department, Tokyo Institute