Biology subjects

Owa, M.

Publications and source records attributed to Owa, M..

3 recordsLinked to original sources

bioRxiv2023

A mechanism that integrates microtubule motors of opposite polarity at the kinetochore corona

Chromosome biorientation on the mitotic spindle is prerequisite to errorless genome inheritance. CENP-E (kinesin 7) and Dynein-Dynactin (DD), microtubule motors with opposite polarity, promote biorientation from the kinetochore corona, a polymeric structure whose assembly requires MPS1 kinase. The coronas building block consists of ROD, Zwilch, ZW10, and the DD adaptor Spindly (RZZS). How CENP-E and DD are scaffolded and mutually coordinated in the corona remains unclear. Here, we report near-complete depletion of RZZS and DD from kinetochores after depletion of CENP-E and the outer kinetochore protein KNL1. With inhibited MPS1, CENP-E, which we show binds directly to RZZS, is required to retain kinetochore RZZS. An RZZS phosphomimetic mutant bypasses this requirement. With active MPS1, CENP-E is dispensable for corona expansion, but strictly required for physiological kinetochore accumulation of DD. Thus, we identify the corona as an integrated scaffold where CENP-E kinesin controls DD kinetochore loading for coordinated bidirectional transport of chromosome cargo.

cell biology↗

bioRxiv2020

A non-canonical function for Centromere-associated protein-E (CENP-E)controls centrosome integrity and orientation of cell division

Centromere-associated protein-E (CENP-E) is a kinesin motor localizing at kinetochores. Although its mitotic functions have been well studied, it has been challenging to investigate direct consequences of CENP-E removal using conventional methods because CENP-E depletion results in mitotic arrest. In this study, we harnessed an auxin-inducible degron system to achieve acute degradation of CENP-E. We revealed a kinetochore-independent role for CENP-E that removes pericentriolar material 1 (PCM1) from centrosomes in G2 phase. After acute loss of CENP-E, centrosomal Polo-like kinase 1 (Plk1) is sequestered by accumulated PCM1, resulting in aberrant phosphorylation and destabilization of centrosomes, which triggers loss of astral microtubules and oblique cell divisions. Furthermore, we also observed centrosome and cell division defects in cells from a microcephaly patient with mutations in CENPE. Orientation of cell division is deregulated in some microcephalic patients, and our unanticipated findings provide a unifying principle that explains how microcephaly can result from centrosomal defects.

cell biology↗

bioRxiv2018

Inner lumen proteins stabilize doublet microtubules in cilia/flagella

Motile cilia are microtubule-based organelles that play important roles in most eukaryotes. Although it is known that microtubules in cilia are sufficiently stable to withstand their beating motion, it remains unknown how they are stabilized while serving as tracks for axonemal dynein and intraflagellar transport. To address this question, we identified a new class of microtubule-associated proteins, named FAP45 and FAP52, in Chlamydomonas. These proteins are conserved among eukaryotes with motile cilia. Using cryo-electron tomography (cryo-ET) and high-speed atomic force microscopy (HS-AFM), we established that lack of these proteins leads to a loss of inner protrusions in B-tubules and less stable microtubules. These inner protrusions are located near the inner junctions of doublet microtubules and lack of FAP45, FAP52, and FAP20 results in detachment of the B-tubule from the A-tubule, as well as flagellar shortening. These results demonstrated that FAP45 and FAP52 bind to the inside of microtubules and stabilize ciliary axonemes.

cell biology↗