- Biomedical Sciences Graduate Program | Stefanie Redemann

Stefanie Redemann

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Research Interest(s)

Spindle assembly, the structure function relation and the basics of the huge variability of spindle size, architecture and mechanics between different tissues as well as different species

Research Description

Mitotic spindles are highly dynamic, microtubule based constructions that function to segregate the chromosomes during cell division. The dynamic properties of microtubules in spindles are modulated by many factors, including polymerases, depolymerases, motor proteins, cross-linkers and other microtubule associated proteins, of which many are conserved throughout eukaryotic organisms. Despite this evolutionary conservation of essential factors, there is a remarkable variability in spindle organization and mechanics between organisms and tissues within species. The Redemann Lab is interested in uncovering and understanding the underlying principles of spindle assembly, the structure function relation and the basics of the huge variability of spindle size, architecture and mechanics between different tissues as well as different species. In particular we are very interested in the adaptation of spindle architecture and function during cell differentiation. We are using a combination of large scale 3D reconstruction of spindles by electron tomography and state-of-the-art light microscopy to investigate the mechanisms and principles of spindle assembly and chromosome segregation. Ultimately we are using the dynamic and ultra structural data to develop and test models of spindle formation and mechanics. Main Projects 1) Intrinsic regulation of spindle assembly in C. elegans Using reconstructions of wildtype spindles during the first mitosis in C. elegans as reference data, we are studying the functional roles of selected proteins involved in spindle assembly. Based on the ultra structural data in combination with light microscopy we will investigate mechanisms of spindle assembly and the role of other components involved in spindle assembly. The direct effect on spindle morphology of for example polymerases, depolymerases, phosphatases, kinases, motor proteins, cross-linkers and many other microtubule-associated proteins can be assessed based on comparisons to reference datasets. 2) Extrinsic regulation of spindle assembly in C. elegans Mitotic spindles are located within the cytoplasm and surrounded by and interacting with a large number of membranes, such as the endoplasmatic reticulum and the nuclear envelope. In addition also other cytoskeletal components like actin can be found interacting with mitotic spindles. A number of recent studies have indicated the importance of the interaction of the two cytoskeleton systems, microtubules and actin, as well as the different membrane compartments during meiosis and mitosis. As an example, the interaction of astral microtubules with the cortex and the plasma membrane plays an essential role during asymmetric spindle positioning and therewith cell differentiation in the C. elegans embryo. However, the molecular and mechanical properties of these interactions are poorly understood. In this context we are investigating the interaction of different cytoskeletal elements, such as actin and microtubules, as well as the plasma membrane during mitosis in C. elegans. 3) Adaptation of spindle assembly during cell differentiation A mayor step towards understanding the underlying principles of spindle assembly and mechanics is to analyze how spindles adapt to different cell sizes, shapes and content during differentiation and development. Using the technology of spindle reconstructions and detailed analysis of the ultrastructure in combination with light microscopy we are investigating spindle assembly and the interaction of spindles with the actin cytoskeleton during cell differentiation in C. elegans and various other cell types and embryonic systems. This will provide important information about the role of the cytoskeletal elements during differentiation as well as information about adaptation to changes in size, architecture and function. 4) Simulation The data obtained by light and electron microscopy is used to develop simulations of spindle assembly and chromosome segregation in collaboration with a group of biophysicists and mathematicians (LINK).

Selected Publications

  • Redemann S, Baumgart J, Lindow N, Shelley M, Nazockdast E, Kratz A, Prohaska S, Brugués J, Fürthauer S, Müller-Reichert T. C. elegans chromosomes connect to centrosomes by anchoring into the spindle network. Nature communications. 2017;8 15288. PMID: 28492281 | PMCID: PMC5437269
  • Pécréaux J, Redemann S, Alayan Z, Mercat B, Pastezeur S, Garzon-Coral C, Hyman A, Howard J. The Mitotic Spindle in the One-Cell C. elegans Embryo Is Positioned with High Precision and Stability. Biophysical journal. 2016;111(8): 1773-1784. PMID: 27760363 | PMCID: PMC5071606
  • Redemann S, Weber B, Möller M, Verbavatz J, Hyman A, Baum D, Prohaska S, Müller-Reichert T. The segmentation of microtubules in electron tomograms using Amira. Methods in molecular biology (Clifton, N.J.). 2014;1136 261-78. PMID: 24633801
  • Redemann S, Müller-Reichert T. Correlative light and electron microscopy for the analysis of cell division. Journal of microscopy. 2013;251(2): 109-12. PMID: 23734865
  • Redemann S, Schloissnig S, Ernst S, Pozniakowsky A, Ayloo S, Hyman A, Bringmann H. Codon adaptation-based control of protein expression in C. elegans. Nature methods. 2011;8(3): 250-2. PMID: 21278743
  • Redemann S, Pecreaux J, Goehring N, Khairy K, Stelzer E, Hyman A, Howard J. Membrane invaginations reveal cortical sites that pull on mitotic spindles in one-cell C. elegans embryos. PloS one. 2010;5(8): e12301. PMID: 20808841 | PMCID: PMC2924899
  • Newby Lambert M, Vöcker E, Blumberg S, Redemann S, Gajraj A, Meiners J, Walter N. Mg2+-induced compaction of single RNA molecules monitored by tethered particle microscopy. Biophysical journal. 2006;90(10): 3672-85. PMID: 16500956 | PMCID: PMC1440748
  • Mendoza M, Redemann S, Brunner D. The fission yeast MO25 protein functions in polar growth and cell separation. European journal of cell biology. 2005;84(12): 915-26. PMID: 16325501