Dial M(icrotubule) for Mitochondria

Most of us remember from our early years of learning biology that mitochondria are the ‘power house of the cell’. The textbook representation of mitochondria that we are familiar with is not entirely accurate. Within a cell, mitochondria are actually present in the form of an intricate network of tubes that are constantly moving about, bumping into each other and tearing apart. This dynamic nature of mitochondria is characteristic to any healthy, living eukaryotic cell. To enable these dynamics, separate players – molecular scissors which cut the mitochondria, and molecular glues which enable fusion of mitochondria – are essential. All these players come together to maintain a perfect balance of fission and fusion for the proper functioning of the cell.

Recent work from our lab has shown that another component of cells, the cytoskeleton, which can be thought of as the skeleton inside your cells, plays an important role in controlling mitochondrial dynamics. This class of cytoskeletal structures called ‘microtubules’, are self-organizing tubes that can grow and shrink. In the model organism we used in this study, called the fission yeast, mitochondria remain bound to the microtubules. We discovered that this attachment to microtubules is essential to maintain the balance between fission and fusion of mitochondria. When microtubules shrink, mitochondria undergo fission, and conversely, when microtubules grow, mitochondrial fission is prevented. Why is this important? In several diseases including neurodegeneration, mitochondrial form, and therefore function, is affected. This work gives us insight into how we might be able to restore mitochondrial function in disease states by changing microtubule dynamics.

Reference: Mehta⁺, Chacko⁺, Chug, Jhunjhunwala and Ananthanarayanan*. (2019) Association of mitochondria with microtubules inhibits mitochondrial fission by precluding assembly of the fission protein Dnm1. (in press) (⁺, equal contribution; *, corresponding author)

Website: www.be.iisc.ac.in/~vaish