How embryo cells gain independence

Date:
February 15, 2022
Source:
University of Freiburg
Summary:
It happens in the first hours after fertilization: The cells of the
early embryo begin to independently produce proteins, the building
blocks for cells and organs. Their own, uniquely composed genetic
material serves as the blueprint. In vertebrates, the starting
signal for this process comes from three maternal proteins that
bind to the DNA of the offspring. New findings now show, using a
zebrafish model, how two of these three start proteins of the egg
cell elicit their roles and how they act in further development.



FULL STORY ==========================================================================
It happens in the first hours after fertilization: The cells of the early embryo begin to independently produce proteins, the building blocks
for cells and organs. Their own, uniquely composed genetic material
serves as the blueprint. In vertebrates, the starting signal for this
process comes from three maternal proteins that bind to the DNA of the offspring. New findings from Dr. Meijiang Gao from a research team led
by Dr. Daria Onichtchouk in the University of Freiburg's Institute of
Biology I now show, using a zebrafish model, how two of these three
start proteins of the egg cell elicit their roles and how they act
in further development. The findings were published in a study in the
journal Nature Communications.


==========================================================================
"We have shown how the proteins Pou5f3 and Sox19b function at different
time points in embryonic development and in different areas of the
embryo," says the biologist of the study's integrative approach. She
conducts her research at the University of Freiburg's Cluster
of Excellence CIBSS -- Centre for Integrative Biological Signalling
Studies, whose scientists are pursuing the goal of understanding signaling processes across scales. Prof. Dr. Jens Timmer und Markus Rosenblatt from
the University of Freiburg's Institute of Physics also participated in
the study.

Important molecules for stem cell research Similar human proteins,
so-called homologues of Pou5f3 and Sox19b, are used in research to
artificially produce stem cells from human skin cells. "The precise role
of these factors in development is highly interesting for research and
medicine for this reason as well," says Onichtchouk.

To determine precisely what genes are controlled in what way by these two proteins and how they interact, the biologist and her team studied the development of zebrafish embryos. They induced mutations in the genes
for Pou5f3 and Sox19b so that the fish would no longer produce these
regulatory proteins. In this way, they succeeded in demonstrating that
the two proteins have independent tasks. However, they both act on the
DNA by binding to gene regulatory regions and making the genes freely accessible to the cellular machinery.

Gene control in sleep mode In addition, the team discovered that Pou5f3
and Sox19b suppress late genetic programs. "They keep important processes
in sleep mode so that they do not start until later, when the appropriate
step in development approaches," describes Onichtchouk. "This concerns
the genes responsible for the development of the organs." However,
Pou5f3 and Sox19b appear to be the determining factors for the
activation of the genes only on the ventral side of the embryo. On
the dorsal side, they are ineffective. Onichtchouk wants to determine
the reason for this: "We are curious to find out what takes over this
function here and whether these proteins also originate from the mother." ========================================================================== Story Source: Materials provided by University_of_Freiburg. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Meijiang Gao, Marina Veil, Marcus Rosenblatt, Aileen Julia Riesle,
Anna
Gebhard, Helge Hass, Lenka Buryanova, Lev Y. Yampolsky,
Bjo"rn Gru"ning, Sergey V. Ulianov, Jens Timmer, Daria
Onichtchouk. Pluripotency factors determine gene expression
repertoire at zygotic genome activation. Nature Communications,
2022; 13 (1) DOI: 10.1038/s41467-022-28434-1 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220215134627.htm

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