Cortical PAR polarity proteins promote robust cytokinesis during asymmetric cell division

Abstract

In asymmetrically dividing C. elegans embryos, the core cortical PAR proteins are required to retain septin and anillin at the anterior cortex away from the contractile ring and to promote normal F-actin levels at the contractile ring and successful cytokinesis.

A network of conserved formins, regulated by the guanine exchange factor EXC-5 and the GTPase CDC-42, modulates tubulogenesis in vivo

“…To bypass the synthetic lethality of genetic combinations with cyk-1(0), we used a recessive, fast-acting and strong temperature-sensitive (ts) allele of cyk-1 (Davies et al, 2014;Jordan et al, 2016). We shifted cyk-1(ts) mutant embryos to the non-permissive temperature and maintained them at the restrictive temperature until they were L4 larvae or young adults, so that EC development occurred primarily or exclusively at the restrictive temperature (see Materials and Methods).…”

“…2B, C,D,F, animals were grown at 22 or 25°C and imaged by spinning disk confocal microscopy (see below). All strains in Figs 3 and 4 were analyzed using a temperature-shift strategy: adult hermaphrodites were allowed to lay eggs at 15°C for ∼24 h, then the adults were removed and F1 embryos were grown at 25°C, the restrictive temperature (Davies et al, 2014;Jordan et al, 2016), until L4 to young adult stage, when they were scored. We always examined the youngest animals in our temperature-shift experiments (i.e.…”

Meeting report – New York Symposium on Quantitative Biology of the Cell

“…Combining RNA interference and temperature-sensitive mutants, Canman and colleagues further demonstrated that PAR-based cortical polarity is required for ordinary cytokinesis in the presence of a weakened actomyosin contractile ring. Remarkably, anterior-posterior polarity maintains proper F-actin levels at the contractile ring by promoting the anterior cortical localization of anillin and septintwo actomyosin-binding and crosslinking proteins that unexpectedly inhibit F-actin accumulation at the ring (Jordan et al, 2016). With seminal temperature-sensitive mutants and the Therminator, Canman and colleagues have addressed a longstanding mystery in the field by providing direct genetic evidence that cortical polarity actively regulates the contractile machinery of cytokinesis during asymmetric cell division.…”

Cell polarity is on PAR with cytokinesis

“…This suggests that in the asymmetrically dividing C. elegans zygote, septin and anillin are negative regulators of contractile ring f-actin, an unexpected result for proteins previously thought to play a positive role in contractile ring assembly during cytokinesis. Consistent with a negative role, both septin and anillin are dispensable for contractile ring assembly and constriction in many cell types, including C. elegans embryos, 5 budding and fission yeast, some Drosophila cell types, and many human cell lines 6 (for more references, see discussion in 7 ).…”