Cleavage-furrow formation without F-actin – new publication in PNAS

A new paper on cytokinesis in Chlamydomonas has been published in PNAS.

In this paper, we demonstrated that F-actin is enriched in the cleavege-furrow region of dividing Chlamydomonas cells by using Lifeact marker.  Interestingly, however, there is no myosin co-localizing with F-actin in the furrow, suggesting that no “actomyosin” structure is directly involved in furrowing.  Moreover, complete removal of F-actin by a combination of an actin toxin latrunculin B and a mutation in NAP1 (which encodes a latrunculin-resistant, unconventional actin – see our previous publications 1,2) did not completely block furrow ingression.  Because microtubules are still associated with the furrows formed in the absence of F-actin, we believe that this cytoskeleton plays a major role in cytokinesis, which may have been inherited from very early ancestors of eukaryotes, or even earlier ancestors shared with archaea and bacteria.