Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A new molecular player involved in T cell activation

07.12.2018

When bacteria or viruses enter the body, proteins on their surfaces are recognized and processed to activate T cells, white blood cells with critical roles in fighting infections.

During T-cell activation, a molecular complex known as the microtubule-organizing center (MTOC) moves to a central location on the surface of the T-cell.


Fluorescence live-cell imaging of the wild-type CLIP-170-TagRFP-T (a,b) or a phosphodeficient S312A mutant CLIP-170-TagREP-T (c) and dynein light chain (DLC)-mEGFP co-expressed in T cells. Increased dynein relocation to the center, which is responsible for MTOC repositioning, requires both stimulation and CLIP-170 phosphorylation. The boxed regions in the merged images are enlarged (right). Scale bars: 5 μm (left, 2nd left, merged) and 2 μm (right).

Credit: Scientific Reports


In resting T cells, the majority of dynein is immobile on the contacted cell surface and is located at the periphery region. T cell stimulation increases the fraction of dynein undergoing minus-end-directed motility ("mobilize"), which is a "weakly processive" state. Then, the dynein is anchored to the surface ("anchor"). Alongside this, stimulation induces some fraction of dynein to colocalize with CLIP-170 and dynactin and follow plus-end tracking ("recruit"). After tracking of one or two micrometers, the dynein is released from the complex and anchored ("release"). As a result, dynein relocation increases to the center region of the contact surface, the immunological synapse, where "anchored" dynein molecules are immobile and or weakly processive at a velocity in good agreement with the velocity of MTOC repositioning. "Anchored" and weakly processive dynein pulls the microtubules and the MTOC ("pull"), which causes MTOC repositioning near the immunological synapse and full activation of T cells. Phosphorylation of CLIP-170 is essential for dynein recruitment to the plus-end and for dynein relocation.

Credit: Scientific Reports

Microtubules have several important functions, including determining cell shape and cell division. Thus, MTOC repositioning plays a critical role in the immune response initiated by activated T cells.

In a recent publication in Scientific Reports, the first authors Lim Wei Ming and Yuma Ito, along with their colleagues at Tokyo Institute of Technology (Tokyo Tech), provide compelling evidence that a key protein responsible for the relocation of the MTOC in activated T cells is a molecule known as CLIP-170, a microtubule-binding protein.

The researchers used live-cell imaging to uncover the mechanism of MTOC relocation. "The use of dual-color fluorescence microscopic imaging of live T cells allowed us to visualize and quantify the molecular interactions and dynamics of proteins during MTOC repositioning," notes Dr. Sakata-Sogawa.

This technique allowed them to confirm that phosphorylation of CLIP-170 is involved in movement of the MTOC to the center of the contacted cell surface (Fig. 1); the findings were confirmed using both cells with phosphodeficient CLIP-170 mutant and cells in which AMPK, the molecule that phosphorylates and activates CLIP-170, was impaired.

Further imaging showed that CLIP-170 is essential for directing dynein, a motor protein, to the plus ends of microtubules and for anchoring dynein in the center of the cell surface (Fig. 2). Dynein then pulls on the microtubules to reposition the MTOC to its new location in the center.

"These findings shed new light on microtubule binding proteins and microtubule dynamics," explains Dr. Tokunaga. Such research is critical, as a deeper understanding of T cell activation in the immune response, and could lead to the development of safer methods for cancer immunotherapy because presentation of CTLA-4, which is found by a 2018 Novel Prize laureate and used as a target of the therapy, is also regulated by MTOC repositioning.

Media Contact

Kazuhide Hasegawa
media@jim.titech.ac.jp
81-357-342-975

http://www.titech.ac.jp/english/index.html 

Kazuhide Hasegawa | EurekAlert!
Further information:
http://dx.doi.org/10.1038/s41598-018-35593-z

More articles from Life Sciences:

nachricht Platinum nanoparticles for selective treatment of liver cancer cells
15.02.2019 | ETH Zurich

nachricht New molecular blueprint advances our understanding of photosynthesis
15.02.2019 | DOE/Lawrence Berkeley National Laboratory

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Regensburg physicists watch electron transfer in a single molecule

For the first time, an international team of scientists based in Regensburg, Germany, has recorded the orbitals of single molecules in different charge states in a novel type of microscopy. The research findings are published under the title “Mapping orbital changes upon electron transfer with tunneling microscopy on insulators” in the prestigious journal “Nature”.

The building blocks of matter surrounding us are atoms and molecules. The properties of that matter, however, are often not set by these building blocks...

Im Focus: University of Konstanz gains new insights into the recent development of the human immune system

Scientists at the University of Konstanz identify fierce competition between the human immune system and bacterial pathogens

Cell biologists from the University of Konstanz shed light on a recent evolutionary process in the human immune system and publish their findings in the...

Im Focus: Transformation through Light

Laser physicists have taken snapshots of carbon molecules C₆₀ showing how they transform in intense infrared light

When carbon molecules C₆₀ are exposed to an intense infrared light, they change their ball-like structure to a more elongated version. This has now been...

Im Focus: Famous “sandpile model” shown to move like a traveling sand dune

Researchers at IST Austria find new property of important physical model. Results published in PNAS

The so-called Abelian sandpile model has been studied by scientists for more than 30 years to better understand a physical phenomenon called self-organized...

Im Focus: Cryo-force spectroscopy reveals the mechanical properties of DNA components

Physicists from the University of Basel have developed a new method to examine the elasticity and binding properties of DNA molecules on a surface at extremely low temperatures. With a combination of cryo-force spectroscopy and computer simulations, they were able to show that DNA molecules behave like a chain of small coil springs. The researchers reported their findings in Nature Communications.

DNA is not only a popular research topic because it contains the blueprint for life – it can also be used to produce tiny components for technical applications.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Global Legal Hackathon at HAW Hamburg

11.02.2019 | Event News

The world of quantum chemistry meets in Heidelberg

30.01.2019 | Event News

Our digital society in 2040

16.01.2019 | Event News

 
Latest News

Gravitational waves will settle cosmic conundrum

15.02.2019 | Physics and Astronomy

Spintronics by 'straintronics'

15.02.2019 | Physics and Astronomy

Platinum nanoparticles for selective treatment of liver cancer cells

15.02.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>