Northwestern Medicine research has revealed one of biology’s most complex construction projects: how cells construct and coordinate the internal scaffolding needed to create healthy eggs. In the research, published in Journal of Cell BiologyLet’s take a closer look at how the two structural cell systems work together to form the developing egg cell.

“For an egg cell to form, a group of nurse cells all dump their contents into what becomes the egg cell. All the organelles and proteins and everything else goes into the egg cell,” he said.Dr. Wen LuSpecially Appointed Assistant ProfessorCell and developmental biology He is also a co-author of the study. “This is a very dramatic process underlying the development of life, but how exactly this is achieved remains unclear.”

This study Drosophila melanogaster (Drosophila melanogaster) has identified a previously unknown cooperation between two key components of the cytoskeleton, actin filaments and microtubules, during egg development.

Within cells, actin filaments are known to provide flexibility and support, while microtubules act as stiffer “tracks” for transport and shape. Although it has long been understood that the two interact, the mechanisms that guide their coordination during complex developmental stages are not yet well defined, he said. Dr. Vladimir GelfandLeslie B. Alley, professor of cellular, molecular, and anatomical sciences, was co-senior author of the study.

Using state-of-the-art microscopy techniques, the researchers observed that at the same time actin cables begin to form, nurse cells that provide nutrients and substances to the developing egg are building a stable network of acetylated microtubules. Acetylation, a chemical modification that strengthens microtubules, has been shown to be essential for maintaining this network.

Disrupting this microtubule structure impedes both the initiation and elongation of actin cables, revealing that microtubules function as a fundamental scaffold during oogenesis, the process of egg cell development.

This study further showed that the actin cytoskeleton actively supports microtubule organization. The loss of the important actin-bundling protein resulted in fewer and shorter microtubules. This suggests that bundled actin filaments regulate microtubule spacing and orientation, helping to maintain both stability and flexibility within the cell.

Taken together, these findings reveal a complex “conversation” between actin filaments and microtubules. Each system influences the assembly, positioning, and organization of the other systems and creates the structural foundation necessary to transport materials to the developing egg.

“This is a classic example of what we call ‘crosstalk’ in biology,” Gelfand says. “With this study, we understand how these structures work together and are essential for oogenesis. Many aspects of egg development are conserved across species, so understanding this cytoskeletal coordination is essential.”

In the future, Gelfand, Lu, and their collaborators hope to use innovative microscopy techniques to visualize microtubules in greater detail.

“We are very fortunate to have access to the world’s best equipment to help answer these fundamental scientific questions,” Lu said.

Brooke M. McCartney, Ph.D., associate professor in the School of Biological Sciences at Carnegie Mellon University, is the corresponding author of the study.

This research was supported by National Institutes of Health grant R01-GM120378, National Institute of General Medicine grant 2R35GM131752, and the Flatiron Institute/Simons Foundation CCBX Research Initiative.