Microtubule-mitochondrial attachment determines cell division symmetry and polarity in fission yeast

Abstract

Association with microtubules inhibits the fission of mitochondria in Schizosachharomyces pombe. Here we show that this attachment of mitochondria to microtubules is an important cell intrinsic factor in determining division symmetry as well as maintaining polarity. By comparing mutant cells that exhibited enhanced attachment and no attachment of mitochondria to microtubules (Dnm1Δ and Mmb1Δ respectively), we show that microtubules in these mutants displayed aberrant dynamics compared to wild-type cells, which resulted in errors in nuclear positioning. This translated to cell division asymmetry in a significant proportion of both Dnm1Δ and Mmb1Δ cells. So too, microtubule pivoting was enhanced in both mitochondrial mutants, resulting in a fraction of the cells in these populations displaying polarity defects. The asymmetric division in Dnm1Δ and Mmb1Δ cells resulted in unequal distribution of mitochondria, with the daughter cell that received more mitochondria growing faster than the other daughter. Taken together, we show the existence of homeostatic feedback controls between mitochondria and microtubules in fission yeast, which directly influence mitochondrial partitioning and thereby, cell growth.