How is it that cells are lost from the body?
Department of Genetics, Graduate School of Pharmaceutical Sciences,
The University of Tokyo
Professor Masayuki Miura[My basic science approach]
Organisms make many proteins written in their genes. From my own experience, I had avague feeling that no protein is not interesting to study.

The words of two scientists made it

clear to me why I felt this way.
When Spanish developmental geneticist Ginés Morata was a graduate student, he proposed
the idea of cell competition, in which cells of the same type compete with each other to form thebody and select the best-adapted cells.

He introduced concepts like natural selection intodevelopmental research. In an interview about biological research, Morata said the following(Current Biology 16, R976-7, 2006).
The "science activity is a delightful one, and the goal is to find out how nature solves theproblems of various organisms. The solutions organisms have taken
are unexpected and often not elegant. Organisms have devised many
ingenious solutions, but I believe they were by chance and necessity,
not planned.

Who could have predicted that most genomic DNAwould be of unknown function or that introns would separate theprotein-coding genes? (omitted). To the students, you don't have toinvent anything, but the organisms have already done the inventing;you just have to find the solution chosen by evolution. (omitted).
Science is creative, and how much time one spends obsessing over a
problem is important to its progress.

Even if a subject seems trivial atfirst glance, it is a scientist who can discover unexpected and interesting aspects from it,"
Dr. Katsuma Dan, who studied the development of sea urchinsat Tokyo Metropolitan University, says in his book "Talking with SeaUrchin.
As I continued my work, the theme that had initiallyconfronted me gradually came over to me. Now it seems as if thesmaller cell of the unequal cell division appeal to me. This voicelessappeal is directed to me, and I feel that no one else wouldunderstand it unless I understand it. In this sense, all my researchon sea urchins has been translating their language into humanlanguage, like deciphering the letters left behind by departedCopyright © Ohsumi Frontier Science Foundation. All Rights Reserved.

people and not creating something new. It is painful to face a theme while trying to understandit.

However, when the theme becomes the breath, you breathe and the blood that flows

through your veins, there is no room for impatience or pedantry.
From the words of these two developmental biologists, I think that the mechanisms thatorganisms have created over their long evolution have endless discoveries and charms no matter
where they are explored. The reason why classics and works of art are new to all ages is that theycontain solutions for expressions that allow so many perspectives.

Creatures have amechanism that has endured a more extended history than any human-made work. I want todecipher even one of these fascinating mechanisms.

[About my research]
Our bodies start from a single fertilized egg and reach 37 trillion cells in an adult.
many cells are lost during development.

However,This seemingly futile phenomenon is called

programmed cell death. Programmed cell death occurs even after birth, and large numbers ofblood, intestinal, and skin cells are lost every day.

Today's me has many cells that are differentfrom yesterday's me. We live our lives without being aware of cell death, but this is because cells
are replenished in the same amount as they are lost, and the life and death of cells maintain thebody. So how and why does cell death occur?

This is my research theme.

Development is a creative process in which cells increase and produce individualized cells
such as nerves and muscles.

Thus, few people noticed that cells were lost in the process and wereinterested in the meaning of cell loss.

Even if noticed, cell death mainly was interpreted

negatively that it was lost because it happened to be out of order.

In the 1970s, researchers in

the nematode worm (C. elegans) observed all cell divisions during development and found that in

C. elegans, 1090 cells are born, and 131 are lost at a particular time and place. Programmed cell
death had indeed occurred.

In 1986, the gene required for all 131 cell deaths was identified, andlater similar sequences of gene was found in human and mouse. In 1993, I discovered that the
mammalian gene with sequences similar to the cell death gene in C. elegans cause cell death inmammalian cells. The gene found in C. elegans was also utilized to induce cell death in human,and it turned out that cell death in mammals is also controlled by genes (called apoptosis).

This

made it possible to conduct experiments to answer a question that had been unapproachable
before: "What is the purpose of apoptosis?

This is because it is now possible to inactivate

apoptotic genes in the body and observe apoptotic proteins by in vivo imaging. As a result, it has

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become clear that dying cells send out messages and actively
communicate with the body.

Cell death selectively eliminates

error cells that arise during development, and it also produces
Inflammation

proteins that stimulate proliferation so that lost cells can beproperly replaced by healthy surrounding cells.

Dying cells

also produce proteins that promote tissue regeneration. In

Dying cells
Produce
Proteins

some cases, toxic substances are also released, causing
inflammation.
If you think about it, the dead cells send out messages tothose around them that make the cycle of cell birth and cellProliferation

TissueRegeneration

death possible during development and in adult life. Perhaps
life is possible because of death.

In disease, many life

phenomena are related to the loss of cells, such as the death ofcells that do not need to die or cancer due to the overproliferation of cells that should die. From the research that explores messages from dead cells
and clarifies the active role of cell death, I would like to understand the mechanism of development,
body maintenance, and diseases.

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