"Dissecting the mechanical heterogeneity of intracellular organelles and their contribution to development and disease"

Abstract:

The ability to sense and respond to mechanical information is pivotal for tissue organization, organismal development and neuronal function. Research over the last decades has informed us that the mechanical property of the cytoplasm is extremely heterogenous and that different organelles contribute to the cellular mechanoresponse. Even though it is well understood how the the plasma membrane and the actin cortex endow the cell with the ability to measure forces, measuring how the nucleus, mitochondria and the ER respond to forces is still a formidable challenge [1].

The reason for this is the difficulty to simultaneously apply and measure mechanical stresses at a region of interest, with high spatial and temporal resolution directly inside the cell, without the confounding perturbation of other structures. In this talk, I will focus on our efforts to develop a versatile optical tweezer technique to characterize the intracellular rheology of various biosystems. This technique uses a single, time-shared laser beam to measure both, stress and strain, from which we obtain the viscoelastic response function of the intracellular compartment in real time [2]. To demonstrate this TimSOM (Time-Shared Optical tweezer Microrheology) technique, I will showcase results how the viscoelasticity of the cytoplasm, nuclear interface, and nucleoplasm of zebrafish cells change in various conditions. Lastly, I will mention our efforts to understand how the mechanical properties of the cytoplasm and the nucleus change over the lifespan of the genetic model Caenorhabditis elegans and in mutations that are know to cause premature aging in humans. 

Bio:

Prof. Dr. Michael Krieg is a group leader at ICFO, where he heads the Neurophotonics and Mechanical Systems Biology Lab. His research focuses on how cells and neurons sense and respond to mechanical forces. He earned his PhD in biotechnology from TU Dresden and completed postdoctoral work at the Max Planck Institute and Stanford University. At ICFO, he develops advanced tools like microfluidics and optogenetics to study mechanosensation in living organisms, using models such as C. elegans. His work has applications in understanding neurodegeneration, force transmission, and synthetic cellular communication. In 2024, he was granted tenure at ICFO.