Keeping our cells stable: A closer look at microtubules

IMAGE: Figure 1: A cryo-EM restoration of the microtubule-MAP4-kinesin complex.
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Credit: Kobe University

Microtubules aid to control cell structure throughout our bodies. A group of Japanese scientists have actually utilized cryo-electron microscopy to clarify how a particular protein keeps microtubules steady, and manages microtubule-based transportation withincells The brand-new insights might assist to establish medical treatment for illness such as dementia and cardiac arrest. These findings were released on October 1 in the online edition of the Journal of Cell Biology

The research study group was led by Professor Ryo Nitta and Project Professor Tsuyoshi Imasaki (KobeUniversity Graduate School of Medicine) in partnership with group leader Mikako Shirouzu and Researcher Hideki Shigematsu (RIKEN), and Associate Professor Kiyotaka Tokuraku (MuroranInstitute of Technology).

Cells in our bodies handle specialized shapes in order to operate as part of organs and tissue. For example, nerve cells keep the brain and body carefully connected by making an interactions network in between cell forecasts. Heart cells type lines of cylinders for reliable contraction. To develop these shapes, a structure of complex proteins make the cell”skeletons” The best of these are called microtubules, and their positioning is controlled by microtubule-associated proteins.

Tau and MAP4 (both part of the Tau household) are “classic” microtubule-associated proteins. Tau is discovered in nerve cells, while MAP4 is revealed commonly throughout our bodies such as the heart or skeletal muscle. Excessive expression of these timeless microtubule-associated proteins has actually been connected to Alzheimer’s illness and cardiac arrest. It can obstruct the motion of motor protein kinesin, which utilizes microtubules as “rails” to transfer different compounds withincells


The research study group rebuilded the complicated structure of microtubules, MAP4 and motor protein kinesin under lab conditions, and utilized cryo-electron microscopy to picture the in-depth three-dimensional structure (figure 1). Their analysis exposed that MAP4 connects to the long axes of microtubules and supports them. The bonds in between MAP4 and microtubules lie at 2 kinds of websites: for strong and weak interactions. At the weak websites, kinesin takes on MAP4 to bind with microtubules (see figure 2). If there suffices kinesin, it can displace the MAP4 at the weak websites and bind with the microtubules.

This results in both MAP4 (at the strong anchor websites) and kinesin (at the weak websites) binding with microtubules at the very same time. The group discovered that, along with binding straight with microtubules, MAP4 likewise folds and collects above themicrotubules The MAP4 in this location engages with and protects kinesin, obstructing the motion of kinesin above themicrotubules This demonstrates how MAP4 supports microtubules, and how it likewise obstructs the transportation functions of kinesin.

This research study supplies essential info that might possibly assist to develop a brand-new treatment technique for heart hypertrophy and cardiac arrest triggered by overexpression of MAP4. It is likewise extremely possible that Tau, which has an amino-acid series really just like MAP4, might provide the very same structure. In this case, this research study would likewise clarify neurodegenerative illness such as dementia.

ProfessorNitta remarks: “By revealing the micromorphology of the MAP4 and microtubule complex in cells, we hope this research will provide insights on a cellular level that can help us to combat diseases caused by cell change such as heart failure and dementia.” .


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