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Teori asal baru untuk sel yang memunculkan vertebrata

pigmentasi hidup Zebra  dan insting melawan atau terbang . Ini dan fitur lain dari dunia vertebrata  berasal dari sel pial neural , tetapi sedikit yang diketahui tentang asal-usul mereka . Para ilmuwan mengusulkan model baru untuk sel pial neural , dan dengan demikian vertebrata , muncul lebih dari 500 juta tahun yang lalu . Mereka melaporkan bahwa sel-sel ini mempertahankan dasar-dasar molekuler yang mengontrol pluripotency - kemampuan untuk menimbulkan semua jenis sel yang membentuk tubuh ....read more

New origin theory for cells that gave
rise to vertebrates

Date:

April 30, 2015

Source:

Northwestern University

Summary:

Zebras' vivid pigmentation and the fight or flight instinct. These and
other features of the world's vertebrates stem from neural crest cells, but
little is known about their origin. Scientists propose a new model for how
neural crest cells, and thus vertebrates, arose more than 500 million years
ago. They report that these cells retain the molecular underpinnings that
control pluripotency -- the ability to give rise to all the cell types that
make up the body.

.......................

The vivid pigmentation of zebras, the massive jaws of sharks, the fight or
flight instinct and the diverse beaks of Darwin's finches. These and other
remarkable features of the world's vertebrates stem from a small group of
powerful cells, called neural crest cells, but little is known about their
origin.

Now Northwestern University scientists propose a new model for how neural
crest cells, and thus vertebrates, arose more than 500 million years ago.

The researchers report that, unlike other early embryonic cells that have
their potential progressively restricted as an embryo develops, neural crest
cells retain the molecular underpinnings that control pluripotency -- the
ability to give rise to all the cell types that make up the body.

"This study provides deep new insights into the evolutionary origins
of humans and other vertebrates," said evolutionary molecular biologist
Carole LaBonne, who led the research. "It also provides critical new
information about the molecular circuitry of stem cells, including cancer stem
cells."

Regenerative medicine scientists now have an updated framework for future
studies aiming to harness the power of stem cells to treat human diseases and
congenital defects, LaBonne said.

The study also turns conventional thought on its head. Previously,
scientists thought neural crest cells had to evolve to gain their incredible
properties, but the Northwestern work shows the power was there all along.
Researchers now can focus on the molecular mechanisms by which neural crest
cells escaped having their potential restricted.

In a study using embryos from the frog Xenopus, a powerful
model system used in studies of development, LaBonne and her team found that
neural crest cells and the early pluripotent cells present in blastula embryos
have surprising similarities, including shared expression of a key set of genes
which work together to endow the cells with their unique properties.

The findings will be published as a Science Express
article by the journal Science. The article also will be the cover
story of the journal's June 19 issue.

"Neural crest cells never had their potential restricted at all,"
LaBonne said. "We believe a small population of early stem cells were set
aside, so that when the time came, their immense developmental potential could
be unleashed to create new features characteristic of vertebrates."

LaBonne is a professor of molecular biosciences in the Weinberg College of
Arts and Sciences. She holds the Arthur Andersen Teaching and Research Chair
and is co-leader of the Tumor Invasion and Metastasis program of the Robert H.
Lurie Comprehensive Cancer Center of Northwestern University.

Acquisition of neural crest cells more than 500 million years ago led
vertebrates to evolve and leave behind less complex life forms (simple aquatic
filter feeders, much like today's sea squirts and lancelets). With these cells,
animals developed important new features such as a skull to house a complex
brain, jaws for predation, a complex peripheral nervous system and many other
cell types essential to the vertebrate body.

In their study, LaBonne and her research team studied the genetic toolkit
that early embryonic cells use to promote pluripotency or "stemness"
and compared it to the one used by neural crest cells. They found that the
toolkit used by neural crest cells also is used by pluripotent blastula cells,
and they showed that it is essential for pluripotency in both cell types. The
proteins that derive from this toolkit work together to enable a dizzying array
of tissues to arise from a population of single cells.

One of these proteins, called Snail1, has been the focus of previous
studies by LaBonne's lab. They and others had shown that Snail1 plays key roles
in controlling not only the immense developmental potential of neural crest
cells but also their capacity for migratory and invasive behavior.

Cancer cells co-opt the function of Snail1 and other neural crest
regulatory proteins to allow the formation of cancer stem cells and mediate the
process of metastasis, whereby cancer cells disperse throughout the body to
form new tumors, LaBonne said. Researchers therefore gain insights into
Snail1's role in cancer by studying its function in the developing embryo.

In early blastula embryos, pluripotent cells were thought to exist only
transiently; as an embryo develops, cells become restricted into categories of
cells called germ layers and then into specialized cell types. The Northwestern
study suggests that not all cells get restricted at those early stages.
Instead, neural crest cells may have evolved as a consequence of a subset of
blastula cells retaining activity of the regulatory network underlying
pluripotency.

The study underscores just how much remains to be discovered about
embryonic development. The human body has more than 10 trillion cells
elaborately organized into tissues and organs that are intricate and highly
complex, yet it all is self-assembled from a single cell, the fertilized egg.

"It's a fascinating process," LaBonne said. "One of the
great frontiers in biology is understanding both how complexity is generated
and how it evolves to create what Charles Darwin memorably called 'endless
forms most beautiful.'"







Story Source:

The above story is based on materials provided byNorthwestern
University. Note: Materials may be edited for content and length.







Journal Reference:

1.   
Elsy Buitrago-Delgado, Kara Nordin, Anjali Rao, Lauren Geary, and Carole
LaBonne. Shared Regulatory Programs Suggest Retention of Blastula-Stage
Potential in Neural Crest Cells. Science, April 2015 DOI:10.1126/science.aaa3655




sumber


http://www.sciencedaily.com/releases/2015/04/150430145125.htm

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