by Heidi Hehnly in Papers
The paper is finally up at PLoS Genetics, congrats to everyone involved! You can check out the study titled “Rab8, Rab11, and Rab35 coordinate lumen and cilia formation during zebrafish left-right organizer development” here.
Figure 1 from the study that argues Left-Right Organizer cells start making cilia before they start assembling a lumen! This observations was first found by undergraduate Julie Manikas, who is an author on the study. Check it out!
by Heidi Hehnly in Papers
Title: Rab11 endosomes and Pericentrin coordinate centrosome movement during pre-abscission in vivo
The story can be found here.
We found that conserved between the zebrafish embryo and human cells, the oldest centrosome moves in a Rab11-dependent manner towards the cytokinetic bridge sometimes followed by the youngest. Rab11-endosomes are organized in a Rab11-GTP dependent manner at the mother centriole during pre-abscission, with Rab11 endosomes at the oldest centrosome being more mobile compared with the youngest. The GTPase activity of Rab11 is necessary for the centrosome protein, Pericentrin, to be enriched at the centrosome. Reduction in Pericentrin expression or optogenetic disruption of Rab11-endosome function inhibited both centrosome movement towards the cytokinetic bridge and abscission, resulting in daughter cells prone to being binucleated and/or having supernumerary centrosomes. These studies suggest that Rab11-endosomes contribute to centrosome function during pre-abscission by regulating Pericentrin organization resulting in appropriate centrosome movement towards the cytokinetic bridge and subsequent abscission.
Differences in mitotic centrosome movement towards the cytokinetic bridge during pre-abscission between zebrafish embryos and human cells.(A) Zebrafish embryo (5 h post fertilization) with centrin-GFP (gray) and PLK1-mCh (cyan). Scale bar, 50 μm. (a’) Inset of dividing cell in (A). Time-lapse of centrin-GFP (inverted grays, top panel; grays, bottom panel) and PLK1-mCh (cyan). Video 1 Pink arrow, centrosome. Orange arrow, midbody. Dashed lines, cell boundaries. Scale bar, 10 μm. (B) Model depicting centrosome (green) movement towards the cytokinetic bridge in dividing cells within the Kupffer’s vesicle (KV) during its development. Cyan, Nucleus. Purple, Midbody. Orange, Lumen. Dark lines, KV membranes. (C) Time-lapse of a dividing cell within the KV. KV cell membranes marked with Sox17:GFP-CAAX (gray). Cyan star, rosette center. Cyan arrow, centrosome. Dashed lines, cell boundaries. Scale Bar, 10 μm. (c’) Dividing cell depicted with PLK1-mCh (fire LUT). Cyan arrow, centrosome. (D) A KV pre-abscising cell fixed and immunostained for ZO-1 (gray), γ-tubulin (cyan) and DNA (DAPI, blue). Yellow arrow, centrosome. Dashed lines, cell boundaries. Scale bar, 10 μm. (E) Number of centrosomes per pre-abscising cell with bridge directed centrosome movement calculated as both centrosomes (2 centrosomes), only one centrosome (1 centrosome) and neither centrosome (0 centrosomes) moved shown as a violin plot with median (orange) and quartiles (dark dotted lines). Two-tailed t test between Centrin-GFP and DsRed-PACT in Human (HeLa) cells (pink background). n > 10 cells across n > 3 experiments n.s. not significant. One-way ANOVA across zebrafish epiboly cells and KV cells (green background), n.s. not significant. n > 10 cells across n > 2 embryos. One-way ANOVA, across all columns, **P < 0.01. Two-tailed t test between Human (HeLa) cells and zebrafish (Epiboly, KV) cells, **P < 0.01. n-values.
by Heidi Hehnly in Papers, News
Check out Nikhila’s paper titled “Rab11 endosomes coordinate centrosome number and movement following mitotic exit” here. Its got cool new stuff linking endosomes with centrosomes during the last stage of cell division, the cleavage of the cytokinetic bridge. This was done in collaboration with the Patteson lab.
Model depicting centrosomes (green) containing Rab11-endosomes (orange) reorienting towards the cytokinetic bridge with associated middy (purple) during pre-abscission.