CAREER: Dissecting the Role of Mechanical Forces in the Regulation of Cytoskeletal Dynamics during Mitosis

University Of Minnesota-Twin Cities, Minneapolis MN

Investigators

Abstract

1350741 Gardner The biomechanical properties of cellular proteins and nucleic acids at the nanoscale are critical for regulating key cellular processes, including cell division. In particular, the centromeres on sister chromosomes are stretched apart during mitosis, and this stretching generates a tension force, which is important for ensuring proper chromosome segregation into two daughter cells. However, an integrated mechanistic understanding for how mitotic centromere stretching tension is established and maintained is lacking. The overall objective of the proposed work is to study how mitotic microtubule dynamics generate and respond to tension forces during mitosis, and to begin to dissect the role of tension forces in establishing kinetochore and chromosome positioning during mammalian cell mitosis. This work will ultimately lead to a better understanding of how proteins and nucleic acids work as a nanomechanical system to mediate proper chromosome segregation during cell division. The overarching hypothesis to be tested is that microtubules, which are the cellular cytoskeletal polymers responsible for aligning and segregating duplicated chromosomes during mitosis, can self-regulate their dynamics by both generating and responding to tension forces. The hypothesis and overall objective will be addressed by pursuing the following specific aims. Aim 1: Determine whether in vivo tension forces regulate kinetochore microtubule dynamics to control chromosome alignment during budding yeast mitosis; Aim 2: Determine whether tension generated by purified in vitro microtubules can intrinsically self-regulate microtubule dynamics; and Aim 3: Distinguish important anti-poleward forces in mammalian cell mitosis. Intellectual Merit: The proposed research will develop tools to better understand the origin and role of internally generated mitotic spindle forces during cell division. Specifically, microtubules are a key element in the mitotic spindle, and are thus responsible for generating and responding to forces which regulate the proper progression of cell division. Because uncontrolled cell division is a hallmark of cancer, and many cancer therapeutic interventions work by disrupting microtubule dynamics, dissection of the relationship between force and microtubule dynamics has the potential to lead to more rational approaches in cancer treatment. The proposed research will make use of physical principles and advanced microscopy to evaluate forces inside of living cells, and then use these methods to dissect the relationship between these forces and microtubule-based chromosome segregation during mitosis. In addition, biophysical reconstitution and computational modeling at both cellular and molecular scales will be used to directly test the hypotheses, and to provide a framework for interpreting experimental results. The generated results are expected to be applicable both in better understanding the fundamental biophysics of cell division, and in providing quantitative data on potential cancer therapies. Broader Impacts: The proposed work has significant broader impacts on advancing the quantitative understanding of the role of molecular forces during cell mitosis, which has substantial implications in cell biology and cancer research. The integration of quantitative engineering methods, computer programming, and physical principles into the study of fundamental problems in biology has been demonstrated to increase the productivity and insights available to researchers in the life sciences. A strong thrust of this proposal is aimed at instilling quantitative engineering approaches into Cell Biology education and research, at both the undergraduate and graduate levels, which will contribute to development of a diverse, globally competitive STEM workforce. In particular, the education aims are integrated with the research proposal to (1) introduce quantitative engineering approaches to cell biology graduate students at the earliest point in their graduate careers; (2) build coursework and research opportunities for both graduate and undergraduate biology students to implement quantitative engineering methods into their current studies, and subsequently into their future careers; and (3) fund undergraduate and underrepresented minority students to perform quantitative research projects in Cell Biology or Biomedical Engineering laboratories.