Mitochondria have an inner and outer membrane, with the inner membrane being made up of folds known as ‘cristae’ , a structure which increases the efficiency of energy production necessary for the cell. The structural changes of these cristae are heavily involved in cell functions and responses, but it has not been possible to observe the cristae inside a living cell using existing techniques.

The ITbM research group has successfully developed a highly colorfast fluorescent probe (MitoPB Yellow) that specifically dyes the mitochondrion’ s inner membran e, and w ith the use of a sup er high resolution STED microscope able to pick out minute structures, were successfully able to capture the fine details of the cristae within a living cell. Following the discovery of this molecule, it is hoped that it will find a practical use in the diagnosis and treatment of diseases related to mitochondrial damage.

A mechanism for dying only the inner membrane,

and high colorfastness

MitoPB Yellow exhibits high fluorescence in hydrophobic environments such as lipid structures. Based on the molecule’ s particular properties, when it gathers in the mitochondria, it is able to bond with proteins present in the inner membrane, and produces a strong observable fluorescence. Because

the pigment is able to pass through the cellular membrane, it is able to highly selectively dye the mitochondria simply by being added to the cell. Moreover, because it is extremely colorfast, it is possible to repeatedly capture the same area with a strong laser such as that of a STED microscope without the color fading. Thus, with the use of super resolution imaging, it is possible to observe the changes in the structure of the cristae as a result of mitochondrial fusion and swelling.

Reference:

“A photostable fluorescent marker for the super-resolution live imaging of the dynamic structure of the mitochondrial cristae” by Chenguang Wang, Masayasu Taki, Yoshikatsu Sato, Yasushi Tamura, Hideyuki Yaginuma, Yasushi Okada, Shigehiro Yamaguchi, PNAS 2019, 201905924. DOI: 10.1073/pnas.1905924116

Link:

ITbM Research Highlight (JP)