Observing dynamic changes in actin filaments during cell division

Laboratory equipment supplier Curiosis has used the Celloger Pro live cell imaging system to demonstrate dynamic changes in cell structure upon cytochalasin B treatment. By enabling real-time cell monitoring, the system allows for seamless observation and tracking of cellular dynamics without disrupting the environment.

Cytokinesis is the final stage in cell division, during which the cytoplasm of one cell is physically divided into two separate cells. Actin filaments play a crucial role in supporting cell structure and facilitating division; just before cell separation, these filaments constrict the cell membrane, leading to the formation of two daughter cells.¹ Cytochalasin B, a compound widely used in cell division and movement research, significantly affects the structure and dynamics of actin filaments, primarily hindering cytokinesis by blocking the formation of contractile microfilaments.

Interestingly, cytochalasin B exhibits distinct effects on cell behaviour when employed at different concentrations, despite being the same drug. At high concentrations, it induces a transformation in cell morphology, including contraction of actin cables and rounding up of fibroblastic cells.² At low concentrations, it inhibits cell migration and membrane ruffling without major morphological changes.³ Additionally, previous studies have shown that cytochalasin B can lead to incomplete cell division, resulting in the formation of multinucleated cells.⁴

Real-time live imaging is essential for monitoring various cellular motility and responses to drugs such as cytochalasin B — but this can be particularly labour-intensive when it comes to obtaining different images for different drug concentrations. Nevertheless, in order to understand the dynamic changes and structural characteristics of actin filaments induced by cytochalasin B during cell division, Curiosis used a HeLa cell line stably expressing tdTomato-tagged actin and observed it in real time over 48 h. Images were captured using the Celloger Pro with a 10x lens at 1 h intervals and were cropped for analysis.

In the control group, cells were divided from two cells to four daughter cells, undergoing a normal cell division. Conversely, cells treated with a low concentration of cytochalasin B (1.25 μM) failed to complete cell membrane separation, leading to the formation of multiple nuclei within a single cell. However, cells treated with high concentrations of cytochalasin B (10 μM) exhibited severe disruption in actin filament structures, leading to irreversible cell rounding. Quantitatively, a higher ratio of multinucleated cells was observed in the low-concentration group compared to the control group.

In conclusion, actin filaments within cells play a crucial role not only in cellular structure, but also in the processes of cell replication and division. Using the Celloger Pro’s multi-positioning features and user-friendly lens exchange capability, the Curiosis team were able to observe actin dynamics at high magnification, confirming cell structure changes due to cytochalasin B.

_{1. Pier Paolo D’Avino, et al. “Cytokinesis in Animal Cells”. Cold Spring Harbor Perspectives in Biology (2015): 7: a015834}

_{2. J. W. Sanger. “The Use of Cytochalasin B to Distinguish Myoblasts from Fibroblasts in Cultures of Developing Chick Striated Muscle”. Proceedings of the National Academy of Sciences of the United States of America, Volume 71 no. 9, September (1974): 3621-3625.}

_{3. Yahara, Ichiro, et al. “Correlation between Effects of 24 different cytochalasins on cellular structures and cellular events and those on actin in vitro”. The Journal of Cell Biology, Volume 92, January (1982): 69-78.}

_{4. Awtar Krishan, “Fine structure of cytochalasin-induced multinucleated cells”. Journal of Ultrastructure Research, Volume 36, July (1971): 191-204.}