Stem cells have the extraordinary capacity to divide producing two very distinct cells: one retains stem cell identity and continues to undergo asymmetric division, while the other specializes for a specific function and shows limited capacity to divide. This strategy allows a single stem cell to generate great amounts of tissue during a lifetime.
To ensure the correct differential identity of the resulting cells, the complex apparatus that divides that stem cell in two must form along a pre-established axis. If this does not occur, the division may be symmetric, which will generate two identical stem cells. That is to say, instead of producing tissue, the stem cells with a “disoriented” division axis may give rise to more stem cells; this is potentially dangerous for the organism as it would lead to uncontrolled proliferation of this type of cell.
How is this danger avoided? Researchers headed by Cayetano González, ICREA Research Professor at IRB Barcelona, have studied stem cell division and discovered that one of the key factors lies in the behaviour of the intracellular structure known as the centrosome. Most animal cells have two centrosomes before division takes place and their position governs the direction of the division. In cells that divide symmetrically (giving rise to two identical cells), the two centrosomes of cell are practically identical. Surprisingly, Gonzalez and his team found striking differences in the two centrosomes of the stem cells they were studying. One is located in a fixed position and is very active during the entire cell cycle, while the other moves around the cell before coming to a standstill, becoming activated only seconds before division.
The most surprising aspect of this complex behaviour is its precise regulation. The imaginary line that passes through the centrosomes once they are both in position, coincides perfectly with the orientation in which the stem cell must divide to guarantee the asymmetry of daughter cells. The intracellular asymmetry of two functionally distinct centrosomes is a decisive factor in the regulation of asymmetric stem cell division and prevents the proliferation of these cells.
These studies have been possible thanks to sophisticated technology that combines the generation of genetically modified flies in which normally colourless cell components are stained, with advanced high resolution microscopy techniques, thereby allowing in vivo observations.
Elena Rebollo, member of the research team and first author of the study, explains that “thanks to these techniques and to hundreds of hours of filming, we have been able to observe the step-by-step process of stem cell division. We’ve even been able to identify one of the proteins that differentiates the centrosomes of the stem cell”. “This protein”, explains González, “is one of the tumour suppressors that we described in 2005, which suggests that the centrosome plays a key role in preventing these stem cells from becoming malignant; a question to which we are currently devoting considerable research effort”. These studies form part of a research line on the relation between stem cells and cancer followed by this laboratory (see press release: A new link between stem cells and cancer, 5 september 2005).
Sarah Sherwood | alfa
What the world's tiniest 'monster truck' reveals
23.08.2017 | American Chemical Society
Treating arthritis with algae
23.08.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
23.08.2017 | Life Sciences
23.08.2017 | Life Sciences
23.08.2017 | Physics and Astronomy