SPONSORED CONTENT

reprint collection
March 2015

Keio University Medical Science Reprint Collection | Web Edition

CONTENTS SELECTED BY
KEIO UNIVERSITY

Keio University School of Medicine in central Tokyo

SPONSORED CONTENT

reprint collection
March 2015

Keio University Medical Science Reprint Collection

reprint collection
Keio University Medical Science Reprint Collection
March 2015
CONTENTS SELECTED BY
KEIO UNIVERSITY

keio covers.indd 3

23/1/15 6:08 PM

COVER: The Old University Library locatedon the Mita Campus was built in 1912 tocommemorate the 50th anniversary of Keio
University’s founding. It has been designated an
Important Cultural Property of Japan.

Nature Reprint Collection
Keio University Medical Science
Reprint Collection | Web Edition
Publisher: Antoine Bocquet
Managing Editor: Stephen Pincock
Editors: Smriti Mallapaty, Simon Pleasants,
Amanda Rider
Contributors: Bianca Nogrady, Clare Pain
Project Manager: Chandler Gibbons
Production Manager: Chris Gilloch
Business Development: Nobuko Miyairi,
Mike Brunke, Tommy Yim
Nature Publishing Group
Chiyoda Building, 2-37 Ichigayatamachi
Shinjuku-ku, Tokyo 162-0843, Japan
Tel: +81 (0)3 3267 8751
CITING THE COLLECTION
All papers have previously been publishedin Nature, Nature Medicine, Nature Genetics,
Nature Reviews Molecular Cell Biology, Nature
Reviews Rheumatology, Nature Immunology,
Nature Neuroscience, Nature Biotechnology
or Nature Methods. Please use the originalcitation, which can be found in the tableof contents.
SUBSCRIPTIONS AND CUSTOMER SERVICE
Japan/China/Korea
Tel: +81 (0)3 3267 8751
Email: subscriptions@natureasia.com
UK/Europe
Tel: +44 (0)1256 329242
Email: subscriptions@nature.com
USA/Canada/Latin America
Tel: +1 866 363 7860 (USA/Canada)
Tel: +1 212 726 9223 (Latin America)
Email: subscriptions@us.nature.com
Produced for Custom Publishing & Solutions,
Nature Publishing Group.
Email: custompub_tokyo@nature.com© 2015 Nature Japan K.K.
This publication may be reproduced in its original form for personal use only. Modification orcommercial use without prior permission fromthe copyright holder is prohibited.

ForewordIn the more than 150 years since its
founding by renowned educator
Yukichi Fukuzawa, Keio University
has emphasized research andeducation based on jitsugaku, bywhich Fukuzawa meant science. Our
School of Medicine is a testament tothis legacy of critical thinking and the
pursuit of knowledge that benefitssociety, especially during these times ofgreat change.
Keio University maintains a strong
and growing international networkof over 250 partners, three researchhubs in Singapore and France, anda high school in the United States. We also have plans to expand our joint
degree programmes and diverse selection of courses in English. The university
is ranked ninth in the global Times Higher Education Alma Mater Index forthe number of degrees awarded to chief executives in top companies, and theprestigious Keio Medical Science Prize has recognized many researchers, six ofwhom have gone on to win Nobel prizes.
In 2014, Keio University was selected as one of 13 universities under the Top
Global University Project funded by the Japanese government. The universities
were chosen based on innovation, reputation, international outlook and potential to rise up the global ranks.
Under this project, Keio has committed itself to an important ten-year programme to enhance global sustainability through the principles of jitsugaku, specifically in the areas of longevity, security and creativity. Japan has one of the highest proportions of elderly people worldwide, which represents both a challenge
and an opportunity for the country to establish itself as a model for health andprosperity supporting citizens of all ages. To develop this resilience, the Schoolof Medicine will further pursue interdisciplinary research under Keio’s Longevity
Initiative in the areas of regenerative medicine, public policy and robotics.
The Keio University Medical Science Reprint Collection contains a selection of
23 papers published by researchers at Keio University in Nature and the Naturefamily of primary research journals between 2006 and 2014. The discoveries
in these papers have had an important impact on the fields of disease models,genome integrity, immunology, neuroscience and stem cells, as highlighted in
the five feature articles written exclusively for this collection. In the coming
years, Keio University will continue to make critical advances in medical science and publish research that stands the test of time.
Atsushi Seike
President, Keio University

This supplement is published by Nature Publishing Group on behalf of Keio University.
All content is chosen by Keio University.

reprint collection
Keio University Medical Science Reprint Collection | Web Edition

Table of Contents
Editorial
4 A century-long pursuit of excellence

Feature articles
9 Transgenic model primates
10 Distinguishing good angiogenesis from bad
1 1 Breaking the silence
12 Hair follicles recruit immune cells
13 Buying time for stroke therapy

Links to papers published by Keio researchers
14 Keio University Medical Science Reprint Collection papers
16 Other featured papers by Keio University Medical ScienceKeio Research Highlights
A new website, bringing Keio University
science to the world
Research highlights

Informative and accessible articles that engage the wider public withsome of the groundbreaking research at the university.

Features

An in-depth look at some of the latest discoveries that contribute to
Keio University’s ‘spirit of science’.

Newsletter

Subscribe to receive regular email updates to keep abreast of theinnovations produced by our researchers

Visit: research-highlights.keio.ac.jp

A CENTURY-LONG
PURSUIT OF EXCELLENCE
Formally founded in 1917, Keio University School of Medicine is regarded as one ofJapan’s top medical schools. Its long-standing reputation for excellence stems fromits unique history and its leading role in promoting the practice of advanced Western
medicine in Japan. The school’s leadership in this area is evidenced by the fact thatit has produced two presidents of the Japan Medical Association and one of the two
Japanese who have been presidents of the World Medical Association.
The School of Medicine has established a formidable reputation in the international
medical community, not only for its hospital — the largest university hospital in Japan —but also for its promotion of excellence in medical research through the prestigious
annual Keio Medical Science Prize.
As it approaches its centenary, the school will build on its past achievements toplay a leading role in addressing such global problems as rapidly ageing populations.
The construction of a new state-of-the-art hospital building will be key to promoting‘Keio Medicine’, an important feature of which is the unique interdisciplinary teamapproach to patient-oriented medical care currently being realized at Keio.

First dean of Keio
University Schoolof Medicine andrenowned microbiologist
Shibasaburo Kitasato

Keio founder
Yukichi Fukuzawa

F

ounded in 1858, Keio University is Japan’s oldest
institution of higher education, predating eventhe Meiji-era national imperial universities.
Today, Keio University is one of Japan’s mostpopular and prestigious universities, and its alumni
include two prime ministers and a long list of prominent political, administrative, legal, medical and corporate leaders.
The university’s high standing in Japanese society hasmuch to do with its eminent founder, Yukichi Fukuzawa— a visionary whose face appears on Japan’s 10,000 yen
note and whose remarkable contribution to Japanesesociety helped shape the modern nation (see image, topleft). A man of remarkable capacity, Fukuzawa founded
the original school when he was just 23. Within four
years, he had journeyed across Europe and the UnitedStates, returning to Japan with texts and concepts that
helped modernize Japan. In 1867 he renamed his school
after the Keio Era of its foundation and changed its focus to Western-oriented higher education.
Fukuzawa’s endeavours defied the established powers of the time. He believed that independence, prosperity and even catching up with Western technology andsocial organization could be achieved only by making
education available to all. By sowing the seeds for the
democratization of knowledge, Fukuzawa contributed
to the emergence of a large workforce of well-educatedcitizens, and ultimately to Japan’s rapid industrialization in the twentieth century. For his remarkable accomplishments he is upheld as Japan’s luminary of themodern era, and Keio University today embodies his
legacy to the Japanese people.

Modernizing medical training in Japan

Fukuzawa incorporated medical teachings at his schoolfrom as early as 1873, and in 1917 the university’s Schoolof Medicine was formally established by renowned
physician and microbiologist Shibasaburo Kitasato(see image, top right). Himself a recipient of Fukuzawa’s generosity in establishing an institute for infectious diseases many years earlier, Kitasato embraced
his benefactor’s progressive approach to education andwas determined to form a medical school at Keio in hishonour. Kitasato had always stressed the importance ofmaking medical practice accessible to ordinary citizens
and thus strove to establish a medical school that dismantled the boundaries between clinicians and medical
scientists. This led to a new, integrated approach to
medical training in Japan and laid the foundations forthe modernization of Japanese medicine.
Today, as the School of Medicine approaches its centenary, this same spirit of united purpose continues todrive innovation in medical training. Drawing directlyfrom international examples and standards, the school

Keio University Medical Science Reprint Collection | Web Edition |reprint collection | 5

Keio University Hospitaloffers minimally invasive
treatments for a rangeof conditions using
advanced technologies
and surgical techniquesseeks to resolve the key deficiencies in traditional Japanese medical education by introducing universal clinical skills training and emphasizing evidence-based
medicine. In this, it is supported by its close academic
partnerships and international student exchange programmes with many leading medical schools aroundthe world, including Dana-Farber Cancer Institute,
Columbia University and the Karolinska Institute. The
university has begun implementing an ambitious programme to reform medical education in Japan, witha nation-leading curriculum incorporating problem-

based learning, observance of strict ethical standards
and early clinical exposure.

Innovation in medical research

Fundamental to the School of Medicine’s success are
its facilities. Keio’s indivisible relationship between
research and clinical practice is centred on Keio University Hospital, one of the largest and most well-known
general hospitals in Japan. At the forefront of Japanese
medicine for almost a century, the hospital offers someof Japan’s most advanced medical services and most

New Keio University Hospital building
The original university hospital, establishedin 1920, is one of Japan’s leading institutions of Western medicine. It is also one ofits busiest with over 1,000 general beds and29 specialist departments and other centers.
At this hospital, Keio medical researchersand clinicians undertake much of their work
together, sharing state-of-the-art facilities toprovide the highest level of medical care.
Such is the demand for treatment at Keiothat a new hospital building is now underconstruction. Due to be opened in 2017 aspart of the School of Medicine’s centenary
celebrations, it has been designed to facilitateclose collaboration among medical, nursing
and pharmaceutical professionals, practition6 |ers and researchers to support Keio’s worldleading training programmes and to realize
a unique style of patient-oriented medical
cluster care, one facet of ‘Keio Medicine’. The
new hospital will also focus on developing coreurban-disaster-response capabilities.
The ‘Keio Medicine’ approach brings
together for each patient a tailored team ofphysicians, nurses, pharmacists, physicaltherapists and researchers from all specialties.
Regarded as the future of leading patient care,
this approach ensures that the best possible
care is provided to each and every patient, andserves as the basis for Keio’s integrated basic
and clinical medical programmes, which areamong the most advanced in the world.

reprint collection | Keio University Medical Science Reprint Collection | Web Edition

comprehensive array of facilities for research, development, evaluation and training. A new university
hospital building planned for completion in 2017 will
facilitate a ‘cluster’ approach, which emphasizes interdisciplinary therapy through cooperation between
departments with the latest medical treatments (see“New Keio University Hospital building”).
Two other innovative medical research centres havegiven Keio a significant edge in global competitiveness.
The school’s Center for Integrated Medical Research(CIMR), established in 2001, provides a shared environment for collaborative translational research and scientific work, integrating basic science, clinical research andpatient care through the creation of related clusters acrossacademia and industry. The Keio-Med Open Access Facility is part of the CIMR and makes available state-of-theart technologies such as laser capture microdissection,
advanced imaging and genetic sequencing. It has sharedfacility arrangements with several research partners.
The second of the medical school’s major researchfacilities, the Center for Clinical Research (CCR), is agovernment-funded Center of Excellence (COE) for thepromotion of global clinical research with a focus onearly and exploratory clinical trials. As a flagship medical research centre in Japan, the CCR contributes to thedevelopment of novel advanced medical technologies
and innovative new drugs through specialized implementation of high-quality clinical trials, large-scaleobservational studies, translational studies of new technologies and other biomedical research.
In recognition of its research strength, Keio was also
awarded generous government funding for two ‘Global
COE’ programmes carried out over a period of five years,
from 2008 to 2013. The Global COE for Human Metabolomic Systems Biology focused on the regulatory mechanisms of metabolism in human physiology and pathology, with the ultimate goal of establishing a world-classTokyo’s Shinjuku
skyline, as seen from
Keio University Hospital

Keio Medical Science Prize
Since 1996, Keio University has been recognizing the outstanding and creative achievements of researchers from around the world
in medicine and the life sciences through theannual Keio Medical Science Prize. Establishedwith a generous donation from one of theuniversity’s eminent alumni, Mitsunada Sakaguchi, this distinguished prize acknowledges
significant contributions to scientific developments in medicine to promote advances in
the field and improve global health. The Keio
Medical Science Prize is the only international medical science award bestowed by aJapanese university.
The prize selection committee, consisting of 13 members from Keio University
and other leading medical institutions inJapan, is renowned for its ability to recognize truly great advances in medical science
across the international research community— in the 19 years of the prize, no fewer thansix recipients have subsequently been awarded aNobel Prize: Jules Hoffmann, Thomas Steitz, Roger Tsien,
Barry Marshall, Elizabeth Blackburn and Stanley Prusiner.
The 2014 award recipients are Karl Deisseroth (seeimage, centre left) for the development of optogenetics and Hiroshi Hamada (see image, centre right) for his
discovery of the molecular and cellular mechanisms ofleft–right asymmetry.

Keio University Medical Science Reprint Collection | Web Edition |reprint collection | 7

Towards a new age of medicine

Hideyuki Okano(centre) andresearchers in hislaboratory conduct
stem cell research
to improve ourunderstanding of
human diseases and forregenerative medicine

interdisciplinary research and education centre in thisfield. The Education and Research Center for Stem Cell
Medicine was a leading centre for stem cell research inJapan, supporting specialized research in experimental
stem-cell regulation, inflammation and tissue regeneration, new cancer treatments targeting cancer stem cells,
and regenerative medicine for intractable diseases.

With a rapidly ageing population and more than an estimated 50,000 centenarians, Japan faces significant andgrowing healthcare challenges. Keio University’s current
president, Atsushi Seike, a labour economist specializedin population ageing, understands only too well the tests
that lie ahead. This situation, however, places Keio in aunique position to conduct cohort studies on the factors
contributing to longevity, and a number of studies are
now underway exploring the phenotype of centenarians and supercentenarians with obvious implications
for us all.
By taking up the challenge of this new age of medicine, Keio University School of Medicine is perpetuating Fukuzawa’s legacy through a continuous process ofevolution that mirrors the great teacher’s doctrine ofcontinuous learning. The new hospital building will be
yet another manifestation of this evolution, breaking
down the barriers between medical disciplines and further enshrining Kitasato’s continuity between medical
research and clinical practice.

Help for victims of the 2011 earthquake and tsunami
The Tohoku–Pacific Ocean earthquake and resulting
tsunami that struck on the afternoon of 11 March 2011
was a disaster of unimaginable proportions in which
thousands lost their lives and hundreds of thousands
were left homeless. Keio University, led by its president
Atsushi Seike, immediately rallied in support of thoseaffected. Within a week of the disaster, teams of medical
professionals from Keio University School of Medicine
were on the ground in the hardest-hit areas to provide
medical support as part of the nation’s massive response.
Doctors, nurses, pharmacists and logistical staff all participated in these teams.
In the ensuing weeks, donations from students andalumni raised the equivalent of about JPY 190 million(US$1.6 million) to assist disaster relief through theJapanese Red Cross Society. The university also chartered a bus service that allowed over 260 students aswell as faculty and staff to contribute to volunteer relief
efforts on the ground in one of the most devastated areas,
Minamisanriku.
In the year following the disaster, Keio University
provided special scholarships to students from affectedareas. These scholarships covered tuition and academic
fees, as well as entrance fees.
Keio University continues to provide medical support
to the disaster-stricken area, with over 500 teams dispatched to the prefectures of Fukushima, Miyagi and
Iwate by November 2014.

8 |Doctors provide care for local victims at a temporary medical facility on 20 March 2011

reprint collection | Keio University Medical Science Reprint Collection | Web Edition

for Genomic
Medicine
Nature | Vol ###Center| 19 November
1960 | Letter| doi##

Center for Genomic Medicine

The common marmoset is an ideal model animal
for understanding human disease

Transgenic model primatesL

ike humans, marmoset monkeys(Callithrix jacchus) are raised by theirfamilies. Infants clutch the furrybacks of their parents and elder siblings,
who also forage to feed them. Group
members communicate through direct eye
contact and audible calls, taking breaks tolisten to each other. “These are highly social
behaviors,” says Hideyuki Okano, dean of
the Graduate School of Medicine at Keio
University, “which makes the common
marmoset an excellent model for studying
human psychiatric disorders such as autism
and schizophrenia.”
Un l i ke t he bra i ns of mice — t hemodel animal most commonly used inresearch — marmoset brains containregions essential for higher cognitive
functions, Okano explains. Marmosets
are New-World natives and valuable candidates for biomedical research due toseveral practical reasons: they reach sexual
maturity shortly after their first birthday,
females can produce between 40 and
80 offspring during their lifetime, andthe species is smaller and gentler overall.
“A cat is much easier to handle than a lion,
isn’t it?” says Okano for comparison.
But to exploit these attractive attributes
for research, scientists needed to develop
marmosets capable of expressing foreign

genes and bequeathing them to their offspring. Erika Sasaki’s laboratory at theCentral Institute for Experimental Animals
and Okano’s laboratory at Keio University
attempted this challenge in early 2006.
They injected a virus carrying a gene forgreen fluorescent protein (GFP) directly
into fertilized marmoset eggs using what
Okano describes as a “cheap trick — scientists a century ago could have come up
with the idea.” They dipped the fertilized
eggs in a sucrose solution, which caused
the cytoplasm to shrink, tearing the cell
membrane away from the extracellular
coating called the zona pellucida. The
researchers were then able to inject manyof their virus particles into the expanded
interstitial zone known as the perivitelline
space. The visible green fluorescence ofthe expressed transgenes allowed them toeasily screen candidate embryos up until
their transfer into surrogate mothers.
After 144 days of gestation, four transgenic founder marmosets were bornwith patches of green hair and skin.
The researchers waited a year for the
animals to reach sexual maturity and theninseminated a normal egg with a spermfrom one of the transgenic males. After
another transfer to a surrogate motherand another 144 days, an infant marmosetwith green skin and the GFP-transgene inits genome was born. The study, publishedin Nature in 2009, represented the firstreport of a transgenic non-human primate
with germline transmission1.
Marmoset research has since expanded
exponentially and could soon lead totherapies for as-yet-incurable humandisorders. Proving the superiority of the
primate for research, Okano’s lab recently
found t hat a marmoset model of an
immunological disease captured humanpathophysiology much better than mousemodels do. Marmosets will also play acentral role in a ten-year national project
launched in June 2014, for which Okano’slaboratory is mapping the structure andfunction of the marmoset brain, including
models for diseases such as Alzheimer’sand Parkinson’s. The laboratory is also
separately screening drugs using induced
pluripotent stem cel ls derived frompatients with these diseases and plans totest any promising compounds on theirdisease models. Okano is hopeful: “In thisway, we can identify new drugs that work
to cure these diseases.”

Reference
1. Sasaki, E. et al. Generation of transgenic non-humanprimates with germline transmission. Nature 459,
523–527 (2009).

Keio University Medical Science Reprint Collection | Web Edition |reprint collection | 9© gracethang/iStock/Thinkstock

Marmosets that express introduced genes and pass them on to their offspringare invaluable for understanding, and potentially treating, human disorders

Center for Genomic Medicine

Nature | Vol ### | 19 November 1960 | Letter | doi##

The retina of mice lacking a key blood vessel
enzyme showed almost no production oftumour-like vessels during restricted oxygen flow

Distinguishing good angiogenesis from bad
Reproduced, with permission, from Ref. 1 © 2012 Y. Okuno et al.

Keio scientists discover a possible target for controlling pathological growthof new blood vessels without hindering healthy processesT

he growth of new blood vessels intumours has long been a tempting
target for cancer treatments. But
scientists testing anti-angiogenic agents
such as vascular endothelial growth factor(VEGF) inhibitors face a problem: how toinhibit pathological angiogenesis associatedwith tumours without hindering thehealthy growth of blood vessels in the restof the body. Yoshiaki Kubota from theLaboratory of Vascular Biology at Keio
University explains: “The VEGF blockade
not only targets tumour vessels but it also
damages normal healthy vessels.”
In 2012, his team made an unexpecteddiscovery that revealed a possible way totarget pathological blood vessel growth
without harming healthy blood vessels1.
Their finding has revived the prospects oftreating cancer and other diseases such as
macular degeneration in this way.
Kubota’s team focused on an enzyme
called ataxia telangiectasia mutated (ATM)kinase, which plays a key role in the development and maintenance of blood vessels.
Mutations in the ATM gene in humans arelinked with ataxia telangiectasia, an inherited disease whose features include dilated
and leaky blood vessels.
To understand the function of ATM
in normal and pathological blood vessels,
10 |Kubota’s team induced ischemic retinopathy by limiting oxygen f low to theretina. The resulting accumulation ofreactive oxygen species activated Atm
expression in immature blood vessels
t hat a re si m i la r to t u mou r vessels.
Importantly, the hy poxic conditions
did not affect Atm production in surrounding non-pathological blood vessels.
W hen t he researchers repeated t hissame process in mice engineered tolack endothelial Atm, they saw noneof the pathological retinal angiogenesis apparent in the normal mice (seeimage), showing clearly that Atm playeda pivotal role in the grow th of thesedestructive blood vessels.
The researchers then tested the impactof the relationship between Atm and angiogenesis in a mouse model of melanoma,
and found similarly that angiogenesis
and tumour growth were inhibited inmice lacking endothelial-specific Atm. In
addition, Atm deficiency enhanced theanti-angiogenic action of VEGF inhibitors.
“Most importantly, the disruptionof Atm signalling prevented pathological neovasculogenesis without affecting
normal vascular regeneration,” commented Bethany Kerr and Tatiana Byzova
in an article in Nature Medicine2. “Thus,

reprint collection | Keio University Medical Science Reprint Collection | Web Edition

Atm activation could be an ideal target
for new therapies to combat pathologicalangiogenesis in a variety of diseases.”
Because ATM kinase is associatedwith a well-known cellular mechanism
for managing the damage caused by free
radicals — known as the DNA damage
response pathway — the researchers firstsuspected that loss of this pathway may
have been responsible for the lack of pathogenic blood vessel growth in the knockout
mice. But on looking more closely, theyfound that a completely different pathway
was implicated, one involving activation of
the stress-associated kinase p38.
“Endothelial metabolism is now being
focused on worldwide as a target for antiangiogenic therapy,” Kubota says. His
2012 paper is cited as a pioneering study
in the field, and his lab has been inundatedwith requests for the mouse lines used in
the paper, including the Atm knockout
mice, by researchers intent on studying theexciting new cancer target.

References
1. Okuno, Y., Nakamura-Ishizu, A., Otsu, K., Suda, T. &Kubota, Y. Pathological neoangiogenesis depends onoxidative stress regulation by ATM. Nature Medicine
8, 1208–1216 (2012).
2. Kerr, B. A. & Byzova, T. V. The dark side of theoxidative force in angiogenesis. Nature Medicine 18,
1184–1185 (2012).

Center for Genomic Medicine

Center for Genomic Medicine

Ovarian somatic cells developed at
Keio University are used globally to study
epigenetic mechanisms in reproductive cells

Breaking the silenceIn the reproductive cells of all animals,
small RNA molecules known as Piwiinteracting RNA (piRNA) play a key rolein the epigenetic control of gene expression.
Until recently, however, researchers had
only a vague idea of how these molecules
are produced and regulated.
In 2009, Haruhiko Siomi from Keio
University’s School of Medicine and hislaboratory helped clear up this picturewith a publication in Nature that revealeda regulatory circuit that gives rise toboth piRNAs and the Piwi proteins theyinteract with1.
Underst a nd i ng t he biogenesis ofpiRNA is important because these molecules and their associated proteins playsuch a significant role in reproduction,
explains Siomi. Recent studies have shownthat they silence DNA sequences known
as transposable elements, which canjump from one location to another in the
genome. Left to their own devices, thesetransposable elements can wreak havoc in
the genome, potentially leading to chromosome breakage and major mutations
that jeopardize the survival and reproductive capacity of germ cells.
“Many men and women have infert i lit y problems of un k now n cause,”says Siomi. “Maybe these problems are

due to errors or even mutations in thepiRNA pathway.”
The Keio publication began with “amatter of serendipity,” explains Siomi. One
day, a researcher in his lab noticed thata small subpopulation of the notoriously
fragile cell line used to generate Drosophila
germline stem cells was spreading vigorously across the dish. He isolated andcarefully nurtured the colony, which continued to grow at an even faster pace, andeventually developed a stable population ofovarian somatic cells (see image).
This stable cell line saved researchers from having to meticulously dissect
hundreds of flies under a microscope tocollect enough ovaries and testes for adecent experiment. “My students used tohate the job,” recalls Siomi. Researchers as
far flung as the United States and Europe
have shared in the relief, using the cells to
study the silencing mechanism of piRNAs.
Using this new cell line, Siomi’s team
was able to show that piRNA stifles theexpression of not only transposable
elements, but also protein-coding genes.
His team established that this new classof piRNA, named ‘genic piRNA’, derives
from a region of certain protein-coding
messenger RNAs that is typically nottranslated. On closer investigation, a geneappropriately named traffic jam was foundto be closely involved with piRNA’s fate.
Traffic jam plays the dual function of producing genic piRNA and triggering production of Piwi, one of the proteins thatpiRNA binds with to suppress transposable elements.
The 2009 paper led to more questions, which Siomi’s team has since beenanswering with in vitro experiments. They
identified several proteins that interact
with the Piwi–piRNA complex to silencetransposable elements. And most recently,
in research that is yet to be published,
they determined the sequence withintraffic jam messenger RNA that directs
genic piRNA production. The implications of this latest finding are enormous,
explains Siomi.
“We can now express piRNAs withsequences of interest to target and silencealmost any gene without changing theactual gene sequence.” What’s more,such an artificial system could be applied
across the species divide, from egglaying flies to fast-breeding mice and evenlarger primates.

Reference
1. Saito, K. et al. A regulatory circuit for piwi by thelarge Maf gene traffic jam in Drosophila. Nature 461,
1296–1299 (2009).

Keio University Medical Science Reprint Collection | Web Edition |reprint collection | 11

© 2015 Haruhiko Siomi, Keio University

Keio researchers reveal a regulatory pathway for RNA molecules that silence
genes in reproductive cells

Center for Genomic Medicine

Skin dendritic cells (orange and green)accumulate around hair follicles(blue nuclear staining) in mice

Hair follicles recruit immune cells© 2015 Masayuki Amagai, Keio University

Combing the epidermis for clues, Keio researchers found that hair follicles
are critical gateways in the fight against infectionH

air follicles function as entr ypoints to the outer layer of skinfor cel ls t hat prote c t against
infections, Keisuke Nagao and his teamfrom the Department of Dermatology,
Keio University School of Medicine,
reported in 20121. The cells in question
are members of a specialized class of whiteblood cells known as Langerhans cells.
They form part of the first line of defence
in the body’s fight against infections,sampling antigens in the epidermis andtransporting them to the lymph nodes.
When Nagao first proposed exploring how populations of Langerhans cells
are maintained and replenished in theepidermis, Masayuki Amagai, the chairof the Department of Dermatology, wasinitially very hesitant. “I felt that thequestion was too fundamental for dermatologists to pursue,” he recalls. But
after five years of investigation, Nagao
was able to discover that the precursors
of Langerhans cells enter the skin via
hair follicles — a very surprising findingt hat no one had pred ic ted . “Na gao
a nswered t he question beautif u l ly,”says Amagai.
The researchers captured images ofmouse skin showing Langerhans cells
clustering around hair follicles in skin
12 |that was depleted of Langerhans cells(see image). The images clearly showedthat colonies of Langerhans cells formaround hair follicles, but as they were
only snapshots in time, the researchers could not tell whether the cells werebeing produced at the follicles or recruited from elsewhere.
Nagao’s team then used two-photon
electron microscopy to obtain videos
that showed white blood cells, including
Langerhans cells, congregating aroundha i r fol l icles w it h i n 30 m i nutes to
4.5 hours of applying stress to the skin.
The videos also revealed cells entering
hair follicles and migrating upward to
repopulate the epidermis. “When wesaw these movies, we were astonished,”
Amagai says.
The Keio team went on to find further
evidence of the important role of hairfollicles in Langerhans cell repopulation. For example, mice that are unable
to produce hair follicles show limited
repopulation of Langerhans cells after
depletion, while human patients with
autoimmune disorders that result in
the destruction of hair follicles show
a similar absence of Langerhans cells.
Furthermore, they found that Langerhans cells repopulate the hairless paws ofreprint collection | Keio University Medical Science Reprint Collection | Web Edition

normal mice by migrating from adjacent
hairy regions. The team also showedthat intercellular signalling proteins
known as chemokines are involved in
attracting Langerhans cell precursors tohair follicles.
Since its publication two and a halfyears ago, the paper has been highly citedin the scientific literature — 57 times
according to Google Scholar — and has
been ranked in the 90th percentile forarticles published around the same timein Nature Immunology.
The findings have forced scientists
to re-evaluate the importance of hairfollicles — they are no longer considered merely sites of hair growth; they
are now t hought of as being important gateways in the body’s immune
response, Amagai says. The findings also
raise the question of whether hair follicles function as conduits between thedermis and the epidermis for other cells
and substances. Hair may turn out tobe even more critical than even Nagao’s
research suggests.

Reference
1. Nagao, K. et al. Stress-induced production ofchemokines by hair follicles regulates the traffickingof dendritic cells in skin. Nature Immunology 13,
744–752 (2012).

for Genomic
Medicine
Nature | Vol ###Center| 19 November
1960 | Letter| doi##

Center for Genomic Medicine

Inflammation could be the key to curbing brain
injury caused by stroke

Buying time for stroke therapySt roke is a s e ve re, of te n f at a l,condition that affects an estimated
15 million people worldwide eachyear. It is the second most common causeof disability and of death in people aged
60 and over. Developing new approaches
for treating stroke is particularly criticalin Japan, which is rapidly becoming theworld’s most ‘super-aged’ nation, withmore than one-fifth of its population
over the age of 65 as a result of long life
expectancies and low fertility rates.
Currently, the only widely approved
drug for stroke treatment is tissue plasminogen activator. To be effective, this drug
must be administered within approximately three to five hours from the onsetof a stroke — a very short time frame inwhich to diagnose the condition, transport the patient to hospital, and select andadminister the drug. Hence, researchers
have tried to find other points at which
therapeutic intervention is possible.
This question has occupied
Akihiko Yoshimura and Takashi Shichitaof Keio University’s School of Medicine
for many years. “Inf lammation after
stroke was known to promote further
injury of the brain, but it was not wellunderstood,” notes Yoshimura, “so we
decided to clarif y the inf lammation

mechanism in order to find a new target
for stroke therapy.”
In 2009, Yoshimura and colleagues
published a paper in Nature Medicine that
established the role of a major inflammation system known as the interleukin-23–
interleuk in-17 a xis in brain injuries
resulting from ischemic stroke, the mostcommon form of stroke that occurs whenblood vessels in the brain are blocked. The
researchers also identified T lymphocytes,
a group of white blood cells that localize
in infarction areas after brain injury, asa therapeutic target for reducing inflammation and damage resulting from insufficient blood supply1.
Using a mouse model, they showedthat another class of white blood cells,
called macrophages, produced interleukin-23, a protein that is active during
the initial phases of brain injury. In
add it ion, a nd cont ra r y to prev ious
thinking, they discovered that the main
source of interleukin-17 was a subset of
T lymphocytes known as γδT cells. This
was a significant finding since interleukin-17 was found to play an importantrole in inf lammation, which amplifies
the damaging effects of an infarction
during the delayed phase of ischemic
brain injury.

The researchers showed that brain
injury can be curbed by reducing thenumber of γδT cel ls, even 24 hours
after stroke onset. Yoshimura notes thatafter these results were published, more
researchers have begun investigating
inflammation after stroke events.
Since the 2009 study, Yoshimura andShichita’s team has been investigating the mechanism of interleukin-23
expression in infiltrated macrophages2 .
They are currently exploring the role ofinf lammation in order to develop ways
to repair damage to the brain. “Thepathology of brain injury depends on
the balance between destructive tissue
inflammation and repairing inflammation,” explains Yoshimura.
He hopes that these f indings will
enable researchers to develop new drugs
that will both block fatal strokes andspeed the recovery of stroke victims
from neural disorders.

References
1. Shichita, T. et al. Pivotal role of cerebral interleukin17-producing γδT cells in the delayed phase ofischemic brain injury. Nature Medicine 15,
946–950 (2009).
2. Shichita, T. et al. Peroxiredoxin family proteins
are key initiators of post-ischemic
inflammation in the brain. Nature Medicine 18,
911–917 (2012).

Keio University Medical Science Reprint Collection | Web Edition |reprint collection | 13

© Johan Swanepoel/iStock/ThinkstockResearch on the role of brain inflammation induced by stroke spurs workon therapeutic targets

reprint collection
Keio University Medical Science Reprint Collection | Web Edition

Keio University Medical Science Reprint Collection papers
Click titles to access journal pages
Note: Access to full papers requires journal subscription

Disease Models

Conditional ablation of Stat3 or Socs3 discloses a dual rolefor reactive astrocytes after spinal cord injury
S. Okada et al.

Non-canonical inhibition of DNA damage-dependentubiquitination by OTUB1
S. Nakada et al.
Nature 466, 941–946 (2010)

Nature Medicine 12, 829–834 (2006)

Generation of transgenic non-human primates with
germline transmission
E. Sasaki et al.

PIWI-interacting small RNAs: the vanguard of
genome defence
M. C. Siomi, K. Sato, D. Pezic & A. A. Aravin
Nature Reviews Molecular Cell Biology 12, 246-258 (2011)

Nature 459, 523–527 (2009)

Pathological neoangiogenesis depends on oxidative stressregulation by ATM
Y. Okuno, A. Nakamura-Ishizu, K. Otsu, T. Suda & Y. Kubota
Nature Medicine 18, 1208–1216 (2012)

Genetic variants in GPR126 are associated with adolescentidiopathic scoliosis

Structure and function of Zucchini endoribonuclease inpiRNA biogenesis
H. Nishimasu et al.
Nature 491, 284–287 (2012)

Immunology

I. Kou et al.

A homozygous frameshift mutation in the mouse
Flg gene facilitates enhanced percutaneousallergen priming

Nature Genetics 45, 676–679 (2013)

P. G. Fallon et al.
Nature Genetics 41, 602–608 (2009)

Renal tubular Sirt1 attenuates diabetic albuminuria by
epigenetically suppressing Claudin-1 overexpressionin podocytes

Innate production of TH2 cytokines by adipose
tissue-associated c-Kit+Sca-1+ lymphoid cells

K. Hasegawa et al.

K. Moro et al.

Nature Medicine 19, 1496–1504 (2013)

Nature 463, 540–544 (2010)

Genome Integrity

14 |Biogenesis of small RNAs in animals

The Japanese experience with biologic therapies forrheumatoid arthritis

V. N. Kim, J. Han & M. C. Siomi

T. Takeuchi & H. Kameda

Nature Reviews Molecular Cell Biology 10, 126–139 (2009)

Nature Reviews Rheumatology 6, 644–652 (2010)

A regulatory circuit for piwi by the large Maf genetraffic jam in Drosophila

Stress-induced production of chemokines by hair follicles
regulates the trafficking of dendritic cells in skin

K. Saito et al.

K. Nagao et al.

Nature 461, 1296–1299 (2009)

Nature Immunology 13, 744–752 (2012)

reprint collection | Keio University Medical Science Reprint Collection | Web Edition

Nr4a receptors are essential for thymic regulatory T cell
development and immune homeostasis

Sema3A regulates bone-mass accrual throughsensory innervations

T. Sekiya et al.

T. Fukuda et al.

Nature Immunology 14, 230–237 (2013)

Nature 497, 490–493 (2013)

Neuroscience

Stem Cells

Requirement for COUP-TFI and II in the temporal specificationof neural stem cells in CNS development

Variation in the safety of induced pluripotent stem cell lines
K. Miura et al.
Nature Biotechnology 27, 743–745 (2009)

H. Naka, S. Nakamura, T. Shimazaki & H. Okano
Nature Neuroscience 11, 1014–1023 (2008)

Pivotal role of cerebral interleukin-17–producing γδT cells inthe delayed phase of ischemic brain injury

Nongenetic method for purifying stem cell–derived
cardiomyocytes
F. Hattori et al.
Nature Methods 7, 61–66 (2010)

T. Shichita et al.
Nature Medicine 15, 946–950 (2009)

DISC1-dependent switch from progenitor proliferation to
migration in the developing cortex

Metabolic requirements for the maintenance of self-renewing
stem cells
K. Ito & T. Suda
Nature Reviews Molecular Cell Biology 15, 243–256 (2014)

K. Ishizuka et al.
Nature 473, 92–96 (2011)
D-Serine regulates cerebellar LTD and motor coordination

through the δ2 glutamate receptor
W. Kakegawa et al.
Nature Neuroscience 14, 603–611 (2011)

Keio University Medical Science Reprint Collection | Web Edition |reprint collection | 15

reprint collection
Keio University Medical Science Reprint Collection | Web Edition

Other featured papers by Keio University Medical Science
Note: Access to full papers requires journal subscription

Interferon regulatory factor-2 protects quiescent hematopoietic
stem cells from type I interferon–dependent exhaustion

Chromatin-associated RNA interference components
contribute to transcriptional regulation in Drosophila

T. Sato et al.

F. M. Cernilogar et al.

Nature Medicine 15, 696–700 (2009)

Nature 480, 391–395 (2011)

An essential role of the aPKC–Aurora A–NDEL1 pathway inneurite elongation by modulation of microtubule dynamics

Controlled gene expression in primary Lgr5
organoid cultures

D. Mori et al.

B.-K. Koo et al.

Nature Cell Biology 11, 1057–1068 (2009)

Nature Methods 9, 81–83 (2012)

A genome-wide association study identifies genetic variants in
the CDKN2BAS locus associated with endometriosis
in Japanese

Extrathymically generated regulatory T cells control mucosal
TH 2 inflammation

S. Uno et al.

Nature 482, 395–399 (2012)

S. Z. Josefowicz et al.

Nature Genetics 42, 707–710 (2010)

A direct role for Hsp90 in pre-RISC formation
in Drosophila
T. Miyoshi, A. Takeuchi, H. Siomi & M. C. Siomi

Neural circuits in the brain that are activated when mitigating
criminal sentences
M. Yamada et al.
Nature Communications 3, 759 (2012)

Nature Structural & Molecular Biology 17, 1024–1026 (2010)

Prostaglandin E2 and SOCS1 have a role in intestinal
immune tolerance
T. Chinen et al.

Vitamin E decreases bone mass by stimulating
osteoclast fusion
K. Fujita et al.
Nature Medicine 18, 589–594 (2012)

Nature Communications 2, 190 (2011)

The nuclear orphan receptor Nr4a2 induces Foxp3 andregulates differentiation of CD4+ T cells
T. Sekiya et al.

Meta-analysis identifies nine new loci associated withrheumatoid arthritis in the Japanese population
Y. Okada et al.
Nature Genetics 44, 511–516 (2012)

Nature Communications 2, 269 (2011)

TACE (ADAM17) inhibits Schwann cell myelination

Peroxiredoxin family proteins are key initiators of postischemic inflammation in the brain

R. La Marca et al.

Takashi Shichita et al.

Nature Neuroscience 14, 857–865 (2011)

Nature Medicine 18, 911–917 (2012)

Isolation and in vitro expansion of human colonic stem cells
P. Jung et al.

Alternative splicing of CD44 mRNA by ESRP1 enhances lungcolonization of metastatic cancer cell

Nature Medicine 17, 1225–1227 (2011)

T. Yae et al.
Nature Communications 3, 883 (2012)16 |A genome-wide association study identifies common
variants near LBX1 associated with adolescentidiopathic scoliosis

Hydrogen sulfide anion regulates redox signaling via
electrophile sulfhydration

Y. Takahashi et al.

M. Nishida et al.

Nature Genetics 43, 1237–1240 (2011)

Nature Chemical Biology 8, 714–724 (2012)

reprint collection | Keio University Medical Science Reprint Collection | Web Edition

A PML–PPAR-δ pathway for fatty acid oxidation regulates
hematopoietic stem cell maintenanceFunctional lacrimal gland regeneration by transplantation of abioengineered organ germ

K. Ito et al.

M. Hirayama et al.

Nature Medicine 18, 1350–1358 (2012)

Nature Communications 4, 2497 (2013)

Direct isolation and RNA-seq reveal environment-dependent
properties of engrafted neural stem/progenitor cells

Functional salivary gland regeneration by transplantation of abioengineered organ germ

H. Kumamaru et al.

Miho Ogawa et al.

Nature Communications 3, 1140 (2012)

Nature Communications 4, 2498 (2013)

Genome-wide association study identifies eight new
susceptibility loci for atopic dermatitis in theJapanese population

Thymic stromal lymphopoietin induces corticosteroid
resistance in natural helper cells during airway inflammation

T. Hirota et al.

Nature Communications 4, 2675 (2013)

Hiroki Kabata et al.

Nature Genetics 44, 1222–1226 (2012)

Adenoma-linked barrier defects and microbial products drive
IL-23/IL-17-mediated tumour growth

TAG-1–assisted progenitor elongation streamlines nuclear
migration to optimize subapical crowding
M. Okamoto et al.
Nature Neuroscience 16, 1556–1566 (2013)

S. I. Grivennikov et al.
Nature 491, 254–258 (2012)

Exhaustion of nucleus pulposus progenitor cells with ageing
and degeneration of the intervertebral disc

Mepenzolate bromide displays beneficial effects in a mousemodel of chronic obstructive pulmonary disease
K.-I. Tanaka et al.
Nature Communications 4, 2686 (2013)

D. Sakai et al.
Nature Communications 3, 1264 (2012)

Structure of the human ATG12~ATG5 conjugate required forLC3 lipidation in autophagy

Chondroitin sulphate N-acetylgalactosaminyl-transferase-1
inhibits recovery from neural injury
K. Takeuchi et al.
Nature Communications 4, 2740 (2013)

C. Otomo, Z. Metlagel, G. Takaesu & T. Otomo
Nature Structural & Molecular Biology 20, 59–66 (2013)

Helicobacter pylori infection in functional dyspepsia

Stargazin regulates AMPA receptor trafficking throughadaptor protein complexes during long-term depression

H. Suzuki & P. Moayyedi

S. Matsuda et al.

Nature Reviews Gastroenterology and Hepatology 10, 168–174 (2013)

Nature Communications 4, 2759 (2013)

CLP1 links tRNA metabolism to progressive motor-neuron loss
T. Hanada et al.

Regulation of MKL1 via actin cytoskeleton dynamics drives
adipocyte differentiation

Nature 495, 474–480 (2013)

H. Nobusue et al.
Nature Communications 5, 3368 (2014)

Max is a repressor of germ cell-related gene expression inmouse embryonic stem cells
I. Maeda et al.

Reduced methylation of PFKFB3 in cancer cells shunts glucose
towards the pentose phosphate pathway

Nature Communications 4, 1754 (2013)

T. Yamamoto et al.
Nature Communications 5, 3480 (2014)

Zscan4 restores the developmental potency of embryonicstem cells

A promoter-level mammalian expression atlas

T. Amano et al.

The FANTOM Consortium and the RIKEN PMI and CLST (DGT)

Nature Communications 4, 1966 (2013)

Nature 507, 462–470 (2014)

Keio University Medical Science Reprint Collection | Web Edition |reprint collection | 17

Cherry blossom season at Keio Universityreprint collectionwww.med.keio.ac.jp
Keio University School of Medicine