THE UNIVERSITY OF OSAKA School of ScienceTHE UNIVERSITY OF OSAKA School of Science https://www.sci.osaka-u.ac.jp/en “Science” covers all natural sciences and contributes to culture and happiness of the human through studies of basic science. Wed, 26 Aug 2026 23:56:05 +0000 ja hourly 1 Warning signs before a granular crystal breaks https://www.sci.osaka-u.ac.jp/en/researchs/11359_1/ https://www.sci.osaka-u.ac.jp/en/researchs/11359_1/#respond Wed, 26 Aug 2026 23:56:05 +0000 https://www.sci.osaka-u.ac.jp/en/?post_type=researchs&p=11359 Theory reveals that vibrations soften and long waves slow down just before an ordered structure begins to yield

Osaka, Japan — Sand, powders, and other collections of visible-sized grains are found throughout daily life, from food and pharmaceuticals to soils and industrial materials. When grains of similar size are arranged regularly, they can form a strong crystal-like solid. Yet what happens inside such an ordered structure immediately before it begins to break has remained unclear.

Researchers at the University of Osaka, Shimane University, and Kyoto Sangyo University have now theoretically identified an unusual pattern of vibrations that emerges just before a crystal made of regularly arranged grains yields. Many vibrational modes soften simultaneously along particular directions, while long-wavelength waves travel more slowly than shorter ones. The findings reveal a possible physical precursor to failure in highly ordered particulate materials.

The team studied a two-dimensional model in which particles were arranged in a triangular crystal and slowly sheared, similar to sliding the top of a deck of cards sideways. By taking advantage of the crystal’s regular structure, the researchers analyzed its vibrational modes mathematically as it approached yielding—the point at which deformation becomes irreversible.

Before shear, low-frequency vibrations were concentrated near the center of wave-number space, corresponding to long wavelengths, as expected for an ordinary solid. Close to yielding, however, soft vibrations extended along two specific directions, forming a cross-shaped pattern in wave-number space. “Soft” means that even a small force can cause a large vibrational response.

The researchers also found a striking change in how waves travel through the crystal. In ordinary solids, sufficiently long acoustic waves travel at nearly the same speed regardless of wavelength. Immediately before yielding, waves traveling along the soft direction instead followed a quadratic frequency-wavenumber relationship; longer, gentler waves propagated more slowly than shorter ones. The number of low-frequency vibrations also increased beyond the level predicted by the conventional Debye law.

The team derived these relationships analytically, including their numerical prefactors, and confirmed similar behavior using another type of interaction between particles. This suggests that the behavior may occur broadly in defect-free, ordered particulate systems.

“Granular materials are familiar, but many aspects of their physical behavior remain poorly understood,” says lead author Fumiaki Nakai. “By studying a simple, regularly ordered system, we were able to describe in detail how it approaches yielding. We hope this work will provide a foundation for exploring more complex effects such as disorder, friction, and energy dissipation.”

The findings provide a foundation for understanding and eventually predicting when and how ordered granular materials and colloidal crystals begin to fail. Such knowledge could ultimately contribute to safer and more reliable handling and design of materials made from regularly arranged particles. Because the study considered an ideal crystal without defects, further work will be needed to determine whether similar warning signs appear in real materials.

Maps of the vibration frequency across wavenumber space. Before shear (γ = 0, left), low-frequency vibrations gather near the center. Just before the crystal breaks (Δγ = 10⁻⁴, right), a cross-shaped low-frequency region appears, showing that the crystal becomes soft along particular directions.

The article, “Anomalous phonon dispersion near yielding in athermal crystals,” will be published in Physical Review E at DOI:  https://doi.org/10.1103/3lnj-1ml1

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]]> https://www.sci.osaka-u.ac.jp/en/researchs/11359_1/feed/ 0 Interlocking molecular propellers create stable “islands” in “sea” of lipid https://www.sci.osaka-u.ac.jp/en/researchs/11344_1/ https://www.sci.osaka-u.ac.jp/en/researchs/11344_1/#respond Mon, 17 Aug 2026 00:27:27 +0000 https://www.sci.osaka-u.ac.jp/en/?post_type=researchs&p=11344 Osaka, Japan – Cells are enclosed by a cell membrane, which is a sophisticated structure mainly made of lipids and is vital for fundamental biological processes. Artificial lipid membranes have many practical applications, such as drug delivery, but engineering the properties of these membranes is a huge challenge. Now, a team in Japan has found a new way to control the membrane structure.
In work to be published in the Journal of the American Chemical Society, researchers at the University of Osaka, Gunma University and Kyushu University have created a propellor-shaped lipid mimic molecule (called triptycene) that interlocks to make stable “islands” in “sea” of lipid (lipid membrane).
Lipid molecules that form cell membranes have a water-loving head and an oil-loving tail. The molecules self-assemble into a double layer, called a bilayer, with the tails pointing to the middle of the bilayer and the heads forming the surfaces. Natural membranes contain many types of lipids with different functions. In a process called phase separation, lipids of the same type group together to form “islands”, known as domains, with distinct properties.
Phase separation is fundamental to vital cell functions, and artificial membranes with domains have different properties from those with uniformly distributed components. Therefore, understanding and manipulating phase separation is key to improving artificial lipid membrane materials. However, lipids mix easily, and it is difficult to form thermally stable lipid domains in an artificial lipid membrane.
“To get lipid molecules of the same type to cluster together in a membrane, they need to interact with each other specifically,” says one of main authors Takayuki Iwata. “We thought that we could form these lipid domains by exploiting the tendency of a molecule shaped like a propellor with three blades to self-assemble.”
The researchers made a new lipid mimic molecule, the most effective of several designs tested, by attaching the propellor-shaped molecule to oil-loving tails and a water-loving head, so that the tails slotted into the membrane and the head formed part of the membrane surface.
“The propellor-shaped moiety interlocked with each other like gears and the surrounding lipids fitted into the gaps between them, which is a new way of achieving phase separation,” adds another main author Masanao Kinoshita. “The strong interlocking and incorporation of the other lipids also meant that our lipid mimic formed really stable domains in the membrane.”
In fact, the artificial membranes kept their lipid mimic domains up to 58 °C, well above temperatures found in the body. This high thermal stability could be useful in practical applications.
The lipid mimic molecule could have uses in many types of functional membrane materials. Creating domains on an artificial membrane could concentrate catalysts or other functional molecules in specific areas, which could be used to create membranes for catalyzing chemical reactions, capturing specific molecules, or delivering drugs. The new design principle of using interlocking lipid mimic molecules adds a valuable tool for engineering domains in artificial membrane materials.

Formation of lipid domains using triptycene-based lipid mimic

The article, “Triptycene-Based Lipid Mimics for Thermally Stable Membrane Phase Separation,” was published in the Journal of the American Chemical Society at DOI:
https://doi.org/10.1021/jacs.6c05364

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]]> https://www.sci.osaka-u.ac.jp/en/researchs/11344_1/feed/ 0 Unlocking the secrets of individual cells one molecule at a time https://www.sci.osaka-u.ac.jp/en/researchs/11311_1/ https://www.sci.osaka-u.ac.jp/en/researchs/11311_1/#respond Fri, 10 Jul 2026 08:22:06 +0000 https://www.sci.osaka-u.ac.jp/en/?post_type=researchs&p=11311 Osaka, Japan – Cells sitting side by side in the same tissues are not identical. Each cell carries its own subtly different chemical signature — a hidden individuality that can reveal how diseases take root and spread. Now, researchers from the University of Osaka have developed a technique sensitive enough to capture this cell-by-cell diversity within tissues, with unprecedented precision and stability.
Changes in the chemical makeup of cells can indicate the onset and progression of disorders such as neurodegenerative diseases, making it important to examine such changes in detail, focusing on the smallest possible areas. In the past, ambient sampling and ionization methods using electrospray ionization (ESI) for mass spectrometry imaging (MSI) has been developed.
ESI-based MSI uses a small probe to deliver solvent (a liquid that dissolves and releases chemical components) to a cell, detaching molecules that become charged and are then separated and counted in a mass spectrometer. Because mammalian cells can be as small as 10 micrometers, this imaging technique must be able to produce pixel sizes of less than this value.
“One issue with mass spectrometry imaging is that, as we focus on smaller and smaller regions within the cell, we require increasingly high sensitivity and stability,” says lead author Takao Yasuda.
To address this issue, the researchers looked at ways to improve the performance of ESI-based MSI system named tapping-mode scanning probe ESI (t-SPESI), which was originally invented by a corresponding author, Yoichi Otsuka. In t-SPESI process, an extremely fine fused silica probe “taps” the cell repeatedly, alternately delivering a solvent and extracting components for analysis. This tapping motion enables the use of an extremely small amount of solvent to examine smaller areas but requires high sensitivity and good stability.
“Two factors currently limit the performance of this technique,” points out senior author Yoichi Otsuka. “These are the long pathway between the probe and the mass spectrometer, and the tendency for cell components to adhere to the probe surface over time.”
On this basis, higher sensitivity was realized by the research team through miniaturization of the complex analytical apparatus, reducing device mass by 45% and ion pathway length by 56%. Shortening the tube more than doubled the signal intensity. To ensure long-term stability by reducing the adhesion of sample to the probe, the silica probe surface was coated with a fluorine-containing chemical, somewhat like a nonstick coating on a kitchen implement.
As a test of this new system, mouse brain tissue samples were analyzed, and the team successfully visualized lipid distributions, including lipid classes previously implicated in Alzheimer’s and Parkinson’s disease, with a pixel size of 5 micrometers, corresponding to fine tissue structures, and with good stability.
The team expects that examining cells within tissues using this technology will provide new insights for disease research and treatment. With further optimization, e.g., of probe size, even better performance could be achieved, helping future studies uncover the mechanisms behind many disorders and advancing understanding of many disorders.

(a) Rendered image of the developed measurement system. (b) Enlarged view of the t-SPESI unit and the sample stage unit. (c) Photograph of the conventional ion transfer tube. (d) Photograph of the developed ion transfer tube. (ed) Comparison of the signal intensities of NaI cluster ions. In the legend, O and N indicate the results obtained using the ion transfer tubes shown in (c) and (d), respectively, and the numbers indicate the heater temperature.

 

The article, “Development of a Tapping-Mode Scanning Probe Electrospray Ionization Platform for High-Sensitivity and Long-Term Stability in Single-Cell Mass Spectrometry Imaging of Tissue,” was published in Analytical Chemistry at https://doi.org/10.1021/acs.analchem.6c02386.

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]]> https://www.sci.osaka-u.ac.jp/en/researchs/11311_1/feed/ 0 Abnormally long mitochondria leak RNA: activating anti-tumor immunity https://www.sci.osaka-u.ac.jp/en/researchs/11304_1/ https://www.sci.osaka-u.ac.jp/en/researchs/11304_1/#respond Thu, 02 Jul 2026 05:16:37 +0000 https://www.sci.osaka-u.ac.jp/en/?post_type=researchs&p=11304 Osaka, Japan – Mitochondria are constantly dividing and fusing within our cells, reshaping themselves to keep up with the cell’s changing needs. Sometimes, though, things go awry and mitochondria can grow abnormally long. Are these long mitochondria harmful, or might they serve a purpose?

Mitochondria are famously known as the powerhouse of the cell, but their functions go beyond energy generation: they also act as signaling centers, helping the cell to sense and respond to trouble. When mitochondria are ‘hyperfused’, i.e., the stressed, abnormally long state described above, they release their genetic material into the cytosol, where the cell treats it as a warning sign in the same way it would treat a virus.

Recent studies have highlighted that mitochondrial DNA and RNA released into the cytosol can activate innate immune signaling. However, how changes in mitochondrial morphology influence the release of mitochondrial RNA (mtRNA) and the resulting innate immune response has remained poorly understood. Researchers from the University of Osaka set out to clarify these mitochondrial mysteries, and their findings have now been published in Cell Reports.

By using cells engineered to lack DRP1 – preventing mitochondria from dividing – the team triggered hyperfusion and explored the subsequent gene activity. The RNA sequencing analysis demonstrated that genes activated during a typical immune response, interferon-stimulated genes, were upregulated. However, when the hyperfused mitochondria were restored to their normal morphology, the expression of these immune-related genes returned to baseline levels.

“We determined that the trigger was mtRNA leaking into the cytosol, activating RNA-sensing proteins, such as RIG-I and MDA5, which also activate when detecting RNA viruses,” explains lead author Tatsuki Yasuda. “Given the evolutionary origin of mitochondria as descendants of ancient bacteria, it is fascinating that mitochondrial RNA can activate the same surveillance pathways that normally detect invading pathogens.”

These results point to other settings where mitochondrial hyperfusion can arise, including some cancers. Exploring existing cancer datasets, the researchers found that tumors with low DRP1 levels showed higher activity of the same immune-activating genes. In the lab, cancer cells with hyperfused mitochondria were more readily destroyed by natural killer immune cells and failed to grow efficiently after implantation in mice, pointing to a mitochondrial route for stronger anti-tumor immunity.

“Our study identifies a previously unknown molecular mechanism linking mitochondrial morphology to innate immune activation,” says senior author Naotada Ishihara. “We hope these findings will stimulate further research into how mitochondrial dynamics regulate immune responses. Because mtRNA release may contribute to cancer as well as inflammatory and age-related diseases, this mechanism could have broad implications across a range of human disorders.”

The team hopes these findings open new avenues for research into mitochondrial biology and innate immunity. By revealing how mitochondrial shape influences immune signaling, the study provides a new framework for understanding not only cancer but also inflammatory and age-related diseases associated with mitochondrial dysfunction.

Mitochondrial hyperfusion triggers innate immune responses.

 

The article, “Disrupted mitochondrial dynamics activate RNA sensing innate immunity through mitochondrial RNA release”, was published in Cell Reports at DOI: https://doi.org/10.1016/j.celrep.2026.117607.

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]]> https://www.sci.osaka-u.ac.jp/en/researchs/11304_1/feed/ 0 Polymers change structure to avert failure and keep elastomers tough https://www.sci.osaka-u.ac.jp/en/researchs/11302_1/ https://www.sci.osaka-u.ac.jp/en/researchs/11302_1/#respond Wed, 01 Jul 2026 10:00:49 +0000 https://www.sci.osaka-u.ac.jp/en/?post_type=researchs&p=11302 Osaka, Japan – Your shock-absorbing sneaker soles are likely made of polyurethane, a highly elastic and tough polymer. The ability of these elastomers to absorb impact without breaking is extremely important for practical applications, and while multiple strategies exist for enhancing elastomer toughness, each has its limitations. However, achieving synergistic toughening by integrating all three mechanisms within a single material remains challenging.

Now, researchers at the University of Osaka have overcome these limitations by developing a multipath synergistic strategy to toughen elastomers. This study has been published in Nature Communications.

Elastomers are polymers that are exceptionally elastic, i.e., they can deform strongly under external stress and revert to their original shape when the stress is removed. However, traditional elastomers are not very tough, as microscopic cracks can cause the material to tear.
Consequently, strategies are employed to enhance the toughness of elastomers by dissipating energy. That is, during deformation, the polymer absorbs mechanical energy and dissipates it by converting it into other forms of energy.

To reduce the likelihood of tears, three types of energy dissipation strategies can be employed.
i) Molecular sliding – Rotaxane molecules are incorporated into the elastomer, which slide and rotate under an external force, redistributing stress across the network and preventing breakage.
ii) Force-induced bond scission – Molecules are embedded in elastomers with “sacrificial” bonds that break under an applied stress, delaying damage to the elastomer.
iii) Chain entanglement – Molecular design is used to introduce structurally well-defined chain entanglements, which allow chains to slide and rearrange tension across the network when stress occurs.

Individual energy-dissipation strategies provide only a limited improvement in elastomer toughness. Although multiple mechanisms have been incorporated into a single material, achieving synergistic toughening by activating them sequentially as the applied stress increases remains challenging.

“We integrated three energy dissipation pathways that become activated in sequence under increasing stress to prevent failure of the elastomer,” explains lead author Xue Li. “Thus, we synergistically combined three toughening mechanisms.”

In this study, the authors introduced ring molecules with sacrificial bonds into an elastomer. Under applied stress, ring sliding occurs in the elastomer first to absorb force. As the stress increases, the rings cleave to form linear chains. Under even higher stress, the linear chains entangle with other chains, maintaining network connectivity and dissipating energy via chain slippage.

This novel strategy can be used to create materials that are both soft and durable, with uses such as tires, gloves, and adhesives. The superior toughness of these materials translates into improved service life and reliability.

Under an applied force, sequential molecular transformations suppress material failure

 

The article, “Toughening Elastomer via Sequentially Activated Multi-Pathway Energy Dissipation,” has been published in Nature Communications at DOI:
https://doi.org/10.1038/s41467-026-74148-z.

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]]> https://www.sci.osaka-u.ac.jp/en/researchs/11302_1/feed/ 0 Bringing ancient light-sensing proteins back to life https://www.sci.osaka-u.ac.jp/en/researchs/11288_1/ https://www.sci.osaka-u.ac.jp/en/researchs/11288_1/#respond Thu, 18 Jun 2026 01:22:59 +0000 https://www.sci.osaka-u.ac.jp/en/?post_type=researchs&p=11288 Osaka, Japan – Resurrecting dinosaurs using DNA retrieved from a mosquito trapped in amber is a great movie plot, though it’s less likely to happen in the real world. However, researchers have been trying to unlock the secrets behind the evolution of a single protein family, to understand the evolution of ancestral proteins.

Now, researchers from The University of Osaka have reported a new way to bring ancient proteins back to life. The study, published in ACS Omega, has revealed that the developed methodology can help generate ancestral rhodopsins that can be tested experimentally in bacteria.

A wide range of microbes express proteins called microbial rhodopsins, which are embedded in the cell membrane and play a variety of roles, including pumping ions across the membrane or sensing light. Scientists have long wondered how members of this single family can possess such a wide array of functions, with investigations involving analyzing the protein sequences to determine their evolutionary history.

“Rhodopsins all have seven transmembrane domains that are very similar, but their extramembrane domains, which extend inside and outside of the cell, vary dramatically,” says lead author, Haruto Ishikawa. “This makes it very challenging to use standard sequence alignment techniques to trace the evolution of rhodopsin sequences from their shared ancestral proteins.”

To tackle this problem, the researchers analyzed the sequences of two different microbial rhodopsins, schizorhodopsins and heliorhodopsins, using an approach that specifically accounts for insertions and deletions in the extramembrane domains. Based on this technique, they reconstructed ancestral schizorhodopsin and heliorhodopsin sequences and expressed them in bacteria.

“The results were very exciting,” explains Yasuhisa Mizutani, senior author. “Both the ancestral schizorhodopsin sequence and the ancestral heliorhodopsin sequence produced stable, mature proteins in Escherichia coli that had a distinctive color and showed characteristic spectral properties, just like existing rhodopsins.”

Similar to contemporary schizorhodopsins, the ancestral schizorhodopsin showed light-driven proton-transport activity. In contrast, the ancestral heliorhodopsin did not pump ions, consistent with current heliorhodopsins.

“Our findings show that sequence reconstruction that takes insertions and deletions into account can successfully generate full-length ancestral rhodopsins that can be experimentally produced and tested,” explains Ishikawa.

The researchers have made their analytical pipeline, ConsistASR, available for other investigators to use. The ConsistASR workflow could help reconstruct and engineer other ancestral proteins, providing functional insight into protein evolution.

When E. coli cells producing ancestral rhodopsin (Anc-SzR) were illuminated, the pH of the surrounding solution increased. This result supports that the ancestral rhodopsin absorbs light and, like extant schizorhodopsins, transports hydrogen ions (H⁺) into the cells.

 

The article, “Resurrecting Full-length Ancestral Schizorhodopsins and Heliorhodopsins with Structure-guided, Indel-aware Sequence Reconstruction,” has been published in ACS Omega at https://doi.org/10.1021/acsomega.6c03010.

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]]> https://www.sci.osaka-u.ac.jp/en/researchs/11288_1/feed/ 0 Visit from the University of Turin https://www.sci.osaka-u.ac.jp/en/news/11285_1/ https://www.sci.osaka-u.ac.jp/en/news/11285_1/#respond Mon, 15 Jun 2026 00:36:28 +0000 https://www.sci.osaka-u.ac.jp/en/?post_type=news&p=11285 On Monday, June 8, 2026, a delegation from the University of Turin, Italy—including Prof. Luisella Celi (Vice Rector for Research) and Prof. David Lembo (Vice Rector for International Relations)-paid a courtesy visit to our Graduate School of Science.

They were welcomed by Prof. Tadashi Kondo, Dean of the Graduate School of Science and Atsushi Takahashi, Vice Dean and Chair of the International Exchange Committee, along with members of the International Affairs Committee and related staff. The two sides held discussions aimed at moving toward full-scale implementation of the Double Degree Program (DDP) agreement concluded in June 2024. During the meeting, they shared information on laboratories that already have ongoing exchanges, as well as laboratories in overlapping research fields and areas in which they hope to further expand collaboration.
Taking this visit as an opportunity, both universities confirmed that they will make use of the DDP agreement to proceed with concrete arrangements for student acceptance and dispatch. They also shared various operational issues that need to be addressed in order to implement these exchanges.

Based on these discussions, we will continue to strengthen the cooperative relationship between the two universities and further examine concrete steps toward student and research exchanges, including the DDP.

(Scenes from the DDP signing ceremony:https://www.sci.osaka-u.ac.jp/en/news/9991_1/ )

[Visitors]
Prof. Luisella Celi, Vice Rector for Research
(Department of Agricultural, Forest and Food Sciences）
Prof. David Lembo, Vice Rector for International Relations
(Department of Clinical and Biological Sciences）
Prof. Federico Maria Petrucci, Rector’s Delegate for Humanities and Social Sciences Strategic Research
(Department of Philosophy and Education Sciences）
Prof. Stefania Maria Beolé, Rector’s Delegate for Natural and Life Sciences Strategic Research
(Department of Physics）
Mr. Stefano Palmieri, Press Office
Ms. Mariasilvia Ciola, Rector’s Advisor for International Projects
Dr. Ugo Falciola, Head of Commercial Office, the Consulate General of Italy in Osaka

[The University of Osaka]
Prof. Tadashi Kondo, Dean, the Graduate School of Science
(Department of Earth and Space Science)
Prof. Atsushi Takahashi , Vice Dean and Chair of the International Exchange Committee
(Department of Mathematics)
Prof. Hajime Nanjo, Member of the International Exchange Committee
(Department of Physics)
Prof. Nobuto Yoshinari , Member of the International Exchange Committee
(Department of Chemistry)
Prof. Yasuhiro Funahashi, Member of the International Exchange Committee
(Department of Chemistry)
Assoc. Prof. Osamu Urakawa , Member of the International Exchange Committee
(Department of Macromolecular Science)
Assoc. Prof. Tomoyuki Furuya, Member of the International Exchange Committee
(Department of Biological Sciences)
Assoc. Prof. Hirokazu Odaka, Member of the International Exchange Committee
(Department of Earth and Space Science)
Dr. Yuri Kamon(Lecturer), Member of the International Exchange Committee
(Center for International Affairs, Office of Research Administration)
Assoc. Prof. Luca Baiotti , International College

See the back number.

]]> https://www.sci.osaka-u.ac.jp/en/news/11285_1/feed/ 0 [Call for participants] English Café 2026 from June 18 (total 5 lessons) For All students at the School and Graduate School of Science, The University of Osaka https://www.sci.osaka-u.ac.jp/en/news/11280_1/ https://www.sci.osaka-u.ac.jp/en/news/11280_1/#respond Tue, 09 Jun 2026 10:11:37 +0000 https://www.sci.osaka-u.ac.jp/en/?post_type=news&p=11280 Are you interested in speaking English? Join the English Café!
Target: All students at the School and Graduate School of Science (For students at other Schools, please contact us at first.)
Host: International Affairs Committee at School and Graduate School of Science
Free of charge.

Registration >> https://forms.cloud.microsoft/r/MZJafQufit
Please register in advance so we can prepare! However, walk-ins are also very welcome.

<Contents>
This event is for all you who want to overcome your weaknesses in English while having fun, who are interested in English, and who want to practice communicating in the English you learn, this is a great opportunity for you! You can get together to play games in English with international students and Japanese students and improve your English skills by receiving appropriate feedback from a native English-speaking instructor.
We are looking forward to your participation.

<Date>
Thursdays, June 18, 25, July 2, 9, and 23

<Time>
12:20〜13:05 Lesson offered by English instructor
13:05〜13:20 Free chat (you can leave any time if you take 3rd period class)

<Location>
Science Bldg. B208

<Instructor>
Shawn Andersson

<Contact>
ri-international@sci.osaka-u.ac.jp (Graduate School of Science, A115)

Back number: English Café 2025, English Café 2024

Note: This information is also available on KOAN.

]]> https://www.sci.osaka-u.ac.jp/en/news/11280_1/feed/ 0 Visit from the University of Bremen https://www.sci.osaka-u.ac.jp/en/news/11277_1/ https://www.sci.osaka-u.ac.jp/en/news/11277_1/#respond Mon, 08 Jun 2026 04:48:40 +0000 https://www.sci.osaka-u.ac.jp/en/?post_type=news&p=11277 On Thursday, May 28, 2026, Dr. Mandy Boehnke, Vice President for International Affairs, Academic Qualification, and Diversity at the University of Bremen, visited our Graduate School of Science.

She was welcomed by Prof. Atsushi Takahashi, Vice Dean and Chair of the International Exchange Committee, and Lecturer Yuri Kamon, a member of the International Exchange Committee, from the Graduate School of Science, as well as Prof. Noriko Okubo and Prof. Mari Shimizu from the Graduate School of Law and Politics. During the meeting, the participants discussed future collaboration.

Building on the academic exchange agreements that our Graduate School of Science and the Graduate School of Law and Politics have concluded with the University of Bremen, the participants introduced the distinctive features of their respective faculties/graduate schools and shared information on the current status of international student acceptance. They also exchanged views on further developing educational and research collaboration.

It was also noted that Japanese can be studied at the University of Bremen’s Language Center and that these courses are very popular. In addition, it was shared that our Graduate School of Science is currently hosting two exchange students from the University of Bremen.

Taking this visit as an opportunity, we will further strengthen cooperation between the two universities and promote international research exchange and human resource development.

[Visitor]
Dr. Mandy Boehnke
（Vice President for International Affairs, Academic Qualification, and Diversity, University of Bremen）

See the back number.

]]> https://www.sci.osaka-u.ac.jp/en/news/11277_1/feed/ 0 Two proteins, one goal: new findings on stem cell differentiation https://www.sci.osaka-u.ac.jp/en/researchs/11268_1/ https://www.sci.osaka-u.ac.jp/en/researchs/11268_1/#respond Wed, 13 May 2026 07:36:59 +0000 https://www.sci.osaka-u.ac.jp/en/?post_type=researchs&p=11268 Osaka, Japan – Stem cells are the original cell type that all other cells and tissues in the body develop from, carried out through a very tightly regulated process. However, how stem cells differentiate in addition to gene-control systems, such as canonical REST repression, which prevents gene expression in inappropriate tissues, has remained unknown.

Now, researchers from Japan have found an overlapping two-factor system that plays an important role in controlling when and how these cells differentiate. In a study published this month in Cell Reports, researchers from The University of Osaka have revealed that two proteins with very similar functions are key regulators of early steps in cellular development and maturation.

Embryonic stem cells can develop into all the different types of cells present in the adult body, from brain cells to liver cells, through a process called differentiation. This process is tightly regulated by activating and repressing factors that bind to the promoters of developmental genes to maintain them in a ‘poised’ state, where these genes can either be switched on or kept off as needed.

“A key mechanism for inhibiting the expression of genes associated with stem cell differentiation involves repressor complexes such as CoREST,” says lead author, Takamasa Ito. “However, it remains unclear how CoREST-mediated repression is stably maintained and which other factors help in repressing expression of these genes.”

To explore this, the researchers tested the role of two proteins, RLF and ZFP292, which previous studies had suggested may help regulate stem cell gene expression. They looked at where these factors bound themselves across the genome and deleted these factors, both individually and together, to determine the effect on gene expression.

“The results were very striking,” explains senior author, Chikashi Obuse. “We found that RLF and ZFP292 play virtually the same role, in that they stabilize the CoREST complex at gene promoters in embryonic stem cells to repress gene expression.”

The presence of either RLF or ZFP292, or both together, at these promoters prevented stem cells from drifting toward differentiation. When these proteins were lost, promoters that were normally repressed became active, leading to the expression of genes associated with differentiation.

“Our results show that RLF and ZFP292 modulate the activity of the CoREST complex to carefully control gene expression in stem cells,” says Ito.

These findings may lead to the development of new techniques for maintaining stem cell quality for research and clinical applications. They also help advance our understanding of diseases caused by dysregulated gene expression and could potentially be applied to develop new treatments.

Overview of the study.
Left: In wild-type cells, RLF/ZFP292 support the proper function of the CoREST complex, leading to the removal of active histone marks and preventing excessive expression of differentiation-associated genes.
Right: In the absence of RLF/ZFP292, CoREST complex function is impaired, resulting in an increase in active histone marks and elevated expression of differentiation-associated genes. Consequently, the undifferentiated state cannot be maintained, and cells undergo differentiation.

 

The article, “RLF/ZFP292 stabilize CoREST-linked LSD1 engagement at bivalent promoters to safeguard pluripotency,” was published this month in Cell Reports at DOI: https://doi.org/10.1016/j.celrep.2026.117293

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