Central Spindle Self-Organization and Cytokinesis in Artificially Activated Sea Urchin Eggs

Abstract

Abstract. The ability of microtubules of the mitotic apparatus to control the positioning and initiation of the cleavage furrow during cytokinesis was first established from studies on early echinoderm embryos. However, the identity of the microtubule population that imparts cytokinetic signaling is unclear. The two main--and not necessarily mutually exclusive--candidates are the central spindle and the astral rays. In the present study, we examined cytokinesis in ammonia-activated sea urchin eggs, which lack paternally derived centrosomes and undergo mitosis mediated by unusual anastral, bipolar mini-spindles. Live cell imaging and immunolabeling for microtubules and the centralspindlin constituent and kinesin-related protein, MKLP1, demonstrated that furrowing in ammonia-activated eggs was associated with aligned arrays of centralspindlin-linked, opposed bundles of antiparallel microtubules. These autonomous, zipper-like arrays were not associated with a mitotic apparatus, but did possess characteristics similar to the central spindle region of control, fertilized embryos. Our results highlight the self-organizing nature of the central spindle region and its ability to induce cytokinesis-like furrowing, even in the absence of a complete mitotic apparatus.

Prc1E and Kif4A control microtubule organization within and between large Xenopus egg asters

“…MKLP2) transports the chromosome passenger complex (CPC) ( Gruneberg et al ., 2004 ). Centralspindlin and the CPC then signal locally to the equatorial cortex to initiate the furrow ( Jantsch-Plunger et al ., 2000 ; Yüce et al ., 2005 ; Canman et al ., 2008 ; Lewellyn et al ., 2011 ; Argiros et al ., 2012 ; Basant et al ., 2015 ; Henson et al 2016 ). In addition, astral microtubules and/or kinetochores may relax the cortex and inhibit furrow formation at the poles in some systems ( White and Borisy, 1983 ; Rodrigues et al ., 2015 ).…”

KIFC1 promotes proliferation and pseudo-bipolar division of ESCC through the transportation of Aurora B kinase

“…However, our understanding of the composition and function of the centrosome is still in its early stages. Currently, we do not know the mechanisms behind its assembly and the proteins that regulate it [ 25 , 26 ], further research is needed. Using co-immunoprecipitation (Co-IP) with cells disrupted physically rather than by detergents (NP40), we identified numerous candidate proteins transported by KIFC1, including TPX4 ( Table 1 ), through proteomics analysis.…”