Fission yeast TRP channel Pkd2p localizes to the cleavage furrow and regulates cell separation during cytokinesis

Abstract

Force plays a central role in separating daughter cells during cytokinesis, the last stage of cell division. However, the mechanism of force-sensing during cytokinesis remains unknown. Here we discovered that Pkd2p, a putative force-sensing TRP channel, localizes to the cleavage furrow during cytokinesis of the fission yeast, Schizosaccharomyces pombe. Pkd2p, whose human homologues are associated with Autosomal Polycystic Kidney Disease, is an essential protein whose localization depends on the contractile ring and the secretory pathway. We identified and characterized a novel pkd2 mutant pkd2-81KD. The pkd2 mutant cells show signs of osmotic stress, including temporary shrinking, paused turnover of the cytoskeletal structures and hyper-activated MAPK signaling. During cytokinesis, although the contractile ring constricts more rapidly in the pkd2 mutant than the wild-type cells (50% higher), the cell separation in the mutant is slower and often incomplete. These cytokinesis defects are also consistent with mis-regulated turgor pressure. Lastly, the pkd2 mutant exhibits strong genetic interactions with two mutants of the SIN pathway, a signaling cascade essential for cytokinesis. We propose that Pkd2p modulates osmotic homeostasis and is potentially a novel regulator of cytokinesis.Highlight summary for TOCFission yeast TRP channel Pkd2p is the homologue of human polycystins. The pkd2 mutant exhibits defects in the contractile ring closure and cell separation during cytokinesis. This essential protein localizes to the cleavage furrow where it likely regulates osmotic homeostasis during cytokinesis.

Fission yeast polycystin Pkd2p promotes the cell expansion and antagonizes the Hippo pathway SIN

“…Among the mutants that we examined (Table 1 and Morris et al, 2019), two SIN mutants sid2-250 and mob1-R4, stood out exhibiting the strongest genetic interaction (Morris et al, 2019). The pkd2 mutation rescued the viability of these two SIN mutants at semi-permissive temperatures.…”

“…To understand the role of pkd2 in the fission yeast cytokinesis, we carried out a genetic screen to identify the interactions between a pkd2 mutant and a collection of more than thirty cytokinetic mutants. pkd2-81KD is a hypomorphic mutant in which the expression of pkd2 is suppressed by replacing the endogenous promoter with a weak promoter P81nmt1 (Morris et al, 2019).…”

“…Our recent study has identified another essential component of the cytokinetic machinery, the fission yeast homologue of polycystin channels (Morris et al, 2019). Polycystins have been found in both multi-cellular and unicellular eukaryotes since their initial discovery through the genetic studies of one of the most common human genetic disorders, Autosomal Dominant Polycystic kidney disease (ADPKD) (Hughes et al, 1995; Mochizuki et al, 1996).…”

“…Pkd2p localizes to the plasma membrane in a cell-cycle dependent manner. It concentrates at the cell tips during interphase and the cleavage furrow during cytokinesis (Morris et al, 2019). Knock-down of this essential gene leads to mis-regulation of the contractile ring constriction and failed cell separation (Morris et al, 2019).…”

Microtubule Nucleation Promoters Mto1 and Mto2 Regulate Cytokinesis in Fission Yeast

“…Mutations compromising the contractility or tension in the ring decrease the constriction rate (Pelham and Chang, 2002;Proctor et al, 2012;Laplante et al, 2015;Tebbs and Pollard, 2013;Li et al, 2016). Ring constriction is faster if the internal pressure against which the furrow ingresses is reduced through mutation or increasing the osmolarity of the growth medium (Morris et al, 2019;Proctor et al, 2012). Bgs1, activated by Rho1, synthesizes the primary septum (Cortés et al, 2007).…”