A study on the process of mitochondrial biogenesis in apoptotic cells observed significant enhancement of mitochondrial biogenesis in the early process of radiation-induced apoptosis.

"It proved biological process observation is important to the study of biological effects,” said Prof. HUANG Qing, who led the research group. They are from Hefei Institutes of Physical Science, Chinese Academy of Sciences (CAS).

The result has been published in iScience.

Mitochondrial biogenesis is the physiological response of cells to external stresses that may cause increased energy demand and is important in maintaining cellular homeostasis. Previous studies have shown that mitochondrial biogenesis usually inhibits apoptosis, but it is not clear whether there is mitochondrial biogenesis or changes in the early stages of apoptotic cells. This requires real-time observation of mitochondrial changes during apoptosis.

In this work, the team constructed a dual fluorescent reporter system, which can be used for real-time in situ observation of mitochondrial changes. The system was applied to the observation of apoptosis caused by ionizing radiation, and mitochondrial changes were determined by observing changes in the fluorescence ratio of dual fluorescent proteins.

"We detected cell viability, apoptosis, cell cycle, mitochondrial biogenesis, DNA damage repair proteins,” Huang said, explaining the detailed observation of cellular processes, "and carefully analyzed the process of mitochondrial dynamic changes.”

In the end, they found that there was a significant enhancement of mitochondrial biogenesis in the early stage of radiation apoptotic cells, that is, mitochondrial biogenesis in early stage cells under certain conditions was positively correlated with apoptosis occurring at a later stage. This result revised the previous generalized notion of negative correlation between them.

This work not only provides an effective method to study mitochondrial biogenesis, but also demonstrates how biological effects can be properly assessed at the right time points, highlighting the importance of the observation of dynamic processes in living cells.

This research was mainly supported by the National Natural Science Foundation of China.

Link to paper: In-situ observation of mitochondrial biogenesis as the early event of apoptosis

Mechanism schematic (Image by SHAO Chengsheng)

In situ observation of biological effects of ionizing radiation by dual fluorescence reporting system (Image by SHAO Changsheng)