Retraction of rod-like mitochondria during microtubule-dependent transport

DE ROSSI M.C.; LEVI V; BRUNO L

Puerto Madryn, Chubut

Congreso; Statistical Physics in Biological Networks; 2020

INFERNET, Universidad de Gral. Sarmiento

Molecular motors transport a wide variety of cellular components positioning them in the cytoplasm with high spatial?temporal precision. These proteins bind to specific cargoes and step along cytoskeletal filaments (i.e., microtubules or actin filaments) using energy provided by ATP hydrolysis. Biophysical properties of molecular motors have been extensively studied by single molecule/particle techniques which provided extremely valuable information in in vitro systems and in living cells. Here, we explore the interplay of the opposed polarity motors kinesin and cytoplasmic dynein during mitochondria transport along microtubules in Xenopus laevis melanophores. Mitochondria are fascinating organelles from a biophysical perspective since they form an interconnected network with cell-type specific morphologies that span from small rounded vesicles to branched tubular networks. Even in a single cell, the mitochondrial network is continuously remodeled as a consequence of events of fission, fusion, and motility. Molecular motors play relevant roles on the regulation of mitochondria size and shape, essential properties for the cell homeostasis. In this work, we tracked single rod-shaped mitochondria with nanometer precision to explore the performance of microtubule motor teams during processive anterograde and retrograde transport. We analyzed simultaneously the organelle size and verified that mitochondria retracted during retrograde transport with their leading tip moving slower in comparison with the rear tip. In contrast, mitochondria preserved their size during anterograde runs indicating a different performance of plus-end directed teams. These results were interpreted considering the different performance of dynein and kinesin teams and provide valuable information on the collective action of motors during mitochondria transport.