Molecular Physiology and Biological Physics
Biophysics, Cell and Developmental Biology
Spindle assembly, the structure function relation and the basics of the hugevariability of spindle size, architecture and mechanics between different tissues as wellas different species
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
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.
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).
<a href="https://www.ncbi.nlm.nih.gov/pubmed/?term=Redemann+S" target="_blank" rel="noopener">List of Publications in Pubmed</a>