Fig. 6. Excess Mfn2 redistributes and clusters mitochondria in a process independent of the cytoskeleton. Immunofluorescence analysis of untransfected HeLa cells (A,B) and of Hela cells expressing mtGFP and/or Mfn2 (C,D). (A) The distribution and morphology of elongated mitochondria (COX2) is mildly perturbed upon deplymerazation of microtubules (tub) with nocodazole. (B) Addition of cytochalasin B (cytochalasin) leads to the dissappearance of elongated stress fibers (act) and to the appearance of punctated mitochondria scattered throughout the cell (COX2). Both drug treatments lasted 2 hours. (C,D) Mfn2-overexpression leads to mitochondrial redistribution and clustering (mtGFP, COX2) in the presence (control) and absence (nocodazole, cytochalasin) of a tubulin or actin cytoskeleton. Drug treatments started 9 hours after transfection, before significant expression of exogenous Mfn2. Cells were processed for immunofluorescence after a further 15 hours. Bars, 15 µm.