dictyNews

Electronic Edition

Volume 49, number 22

September 1, 2023



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Abstracts

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Cleavage furrow positioning in dividing Dictyostelium cells



Akiko Okada & Shigehiko Yumura





Accepted in Cytoskeleton



Accurate placement of the cleavage furrow is crucial for successful 

cell division. Recent advancements have revealed that diverse 

mechanisms have evolved across different branches of the

 phylogenetic tree. Here, we employed Dictyostelium cells to 

validate previous models. We observed that during metaphase and 

early anaphase, mitotic spindles exhibited random rotary movements 

which ceased when the spindle elongated by approximately 7 μm. 

At this point, astral microtubules reached the polar cell cortex and 

fixed the spindle axis, causing cells to elongate by extending polar 

pseudopods and divide along the spindle axis. Therefore, the position 

of the furrow is determined when the spindle orientation is fixed. 

The distal ends of astral microtubules stimulate the extension of 

pseudopods at the polar cortex. One signal for pseudopod extension 

may be phosphatidylinositol trisphosphate in the cell membrane, but 

there appears to be another unknown signal. At the onset of polar 

pseudopod extension, cortical flow began from both poles toward 

the equator. We suggest that polar stimulation by astral microtubules 

determines the furrow position, induces polar pseudopod extension 

and cortical flow, and accumulates the elements necessary for the 

construction of the contractile ring.





Submitted by Shigehiko Yumura [[log in to unmask]]

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[End dictyNews, volume 49, number 22]