Laura Caccianini

MIT, Cambridge

I was trained as a physicist at La Sapienza. I spent one year of master in Paris as an Erasmus student. There I worked as a bartender to survive, I learned French and I realized I might enjoy doing science for a living. During my PhD at the Curie Institute I studied the dynamics of transcription factors and other DNA binding proteins with single molecule tracking and super resolution microscopy and I became interested in the interplay between transcription and genome organization. For my postdoc I joined the Vos lab at MIT Biology, where I am learning biochemistry and electron microscopy.


Wednesday April 19th

Looping DNA: a study on the cohesin complex with light and electron microscopy

Throughout a cell’s life, DNA must be accessed to express genes, copied and equally partitioned when the cell divides, and simultaneously this 2 meter long fiber is compacted in a micron-scale space. DNA looping is a preferential mechanism of DNA-related compaction across species. In eukaryotes, some DNA-loops are generated by cohesin. The cohesin complex is known to keep sister chromatids together through cell division and to extrude DNA loops in an ATP-dependent manner. During my PhD I used single molecule tracking, in live mouse embryonic stem cells, to characterize the diffusive behavior and the DNA-binding kinetics of cohesin and its cofactors. Optical microscopy is a powerful technique that enables target-specific imaging in living organisms, but it has an intrinsic resolution limit set by diffraction. Wanting to understand the molecular mechanisms behind cohesin-based looping, I turned to cryo-electron microscopy (EM). I am currently working on solving the structure of the reconstituted cohesin complex bound to DNA. In parallel I am pursuing a Correlative Light and Electron Microscopy (CLEM) approach with the goal of studying the cohesin complex in its native environment. Combining the use of target specific live cell imaging and EM will reveal the mechanism of cohesin complex function.