The Stowers Institute's Rong Li Lab has characterized a mechanism that allows for asymmetrical cell division during meiosis in oocytes. By tracking chromosome movement in live mouse oocytes, the team discovered that chromosomes can recruit to their vicinity a protein called formin-2. This protein allows the oocyte to retain the majority of the cytoplasm – a requirement for embryonic development after fertilization – while the other daughter cell (called a polar body) resulting from the asymmetric division gets only a minimal amount and subsequently dies.
The work was published this week in the advance online publication of Nature Cell Biology.
Formin-2 is an actin-nucleating protein that can promote the formation of actin filaments around the chromosomes. Actin filaments undergo dynamic elongation and shortening and, in the process, push the chromosomes towards the outer edge of the oocyte. After the chromosomes reach the periphery, the actin filaments orient the cell division plane so that most of the cytoplasm required to sustain the earliest stages of development stays with the daughter cell that retains the identy of the oocyte.
"This work revealed the general mechanism by which the actin cytoskeleton drives chromosome movement in mammalian meiotic oocytes," said Hongbin Li, Ph.D., Senior Research Associate and lead author on the publication. "Our findings will enable us to carry out even more detailed dissection of the molecular components and mechanisms."
"Infertility and birth defects are often related to problems during oocyte meiotic cell divisions," said Rong Li, Ph.D., Investigator and senior author on the paper. "Failure in the chromosome movement will lead to failed oocyte maturation and infertility. These findings provide an important step toward a better understanding of the process of meiotic divisions and how actin generates the force to power intra-cellular movements."
The work is the result of a collaboration with Stowers Institute's Fengli Guo, Ph.D., Electron Microscopy Specialist, and Boris Rubinstein, Ph.D., Biomathematician, who are co-authors on the paper.
Dr. Rong Li also is a Professor in the Department of Molecular & Integrative Physiology at The University of Kansas School of Medicine. Learn more about her work at www.stowers-institute.org/labs/RongLiLab.asp.
About the Stowers Institute
Housed in a 600,000 square-foot state-of-the-art facility on a 10-acre campus in the heart of Kansas City, Missouri, the Stowers Institute for Medical Research conducts basic research on fundamental processes of cellular life. Through its commitment to collaborative research and the use of cutting-edge technology, the Institute seeks more effective means of preventing, treating, and curing disease. The Institute was founded by Jim and Virginia Stowers, two cancer survivors who have created combined endowments of $2 billion in support of basic research of the highest quality.
Journal
Nature Cell Biology