An Interview with Isabelle Arnal
We recently spoke to Isabelle Arnal, of the Grenoble Institute of Neurosciences, about her paper, "Tau co-organizes dynamic microtubule and actin networks", and the motivations behind her work.
Q. What are you working on?
A. Our team focuses on the mechanisms by which neuronal proteins organize the cytoskeleton. We are particularly interested in effectors interacting with both microtubules and actin, two major elements of the neuronal cytoskeletons and whose interactions are crucial for the development and activity of neuronal cells.
Q. What is the motivation for your research?
A. One of our main thematic is to understand at the molecular level how the neuronal effector tau regulates microtubule and actin properties. Tau is mainly expressed in the brain and is required for the normal functions of neurons. Tau deregulation, caused by its truncation and/or abnormal phosphorylation, is associated with neurodegenerative disorders such as Alzheimer’s disease. Tau is known for years to regulate microtubules, and has also been reported more recently to interact with actin. Thus tau represents a good candidate to mediate direct interactions between microtubules and actin. The motivation of our study, published in Scientific Reports in May 2015, was to investigate whether and how tau coordinates microtubules and actin.
Q. Why did you need the Linkam MC60 controller?
A. For this study, we reconstitute cytoskeleton properties in cell-free systems using purified proteins. Cytoskeleton dynamics and organization are visualized by live-TIRF (Total Internal Reflection Fluorescence) microscopy. These experiments require a tight control of the temperature on the microscope stage since the polymerisation of microtubules and actin is temperature-dependent. We usually work at 32°C.
Q. What is gained from the results?
A. We identified tau as a direct linker between microtubules and actin, and we proposed a molecular mechanism explaining how tau connects the two cytoskeletal polymers. Besides, our in vitro assay represents an original system to visualize the concomitant polymerisation of both microtubules and actin.
Q. What are your future plans?
A. We plan to investigate how altered forms of tau (as found in Alzheimer’s disease) modify the properties of microtubules and actin.