Anillin/Mid1p interacts with the ESCRT-associated protein Vps4p and mitotic kinases to regulate cytokinesis in fission yeast

Abstract

Cytokinesis is the final stage of the cell cycle which separates cellular constituents to produce two daughter cells. Using the fission yeast Schizosaccharomyces pombe we have investigated the role of various classes of proteins involved in this process. Central to these is anillin/Mid1p which forms a ring-like structure at the cell equator that predicts the site of cell separation through septation in fission yeast. Here we demonstrate a direct physical interaction between Mid1p and the endosomal sorting complex required for transport (ESCRT)-associated protein Vps4p, a genetic interaction of the mid1 and vps4 genes essential for cell viability, and a requirement of Vps4p for the correct cellular localization of Mid1p. Furthermore, we show that Mid1p is phosphorylated by aurora kinase, a genetic interaction of the mid1 and the aurora kinase ark1 genes is essential for cell viability, and that Ark1p is also required for the correct cellular localization of Mid1p. We mapped the sites of phosphorylation of Mid1p by human aurora A and the polo kinase Plk1 and assessed their importance in fission yeast by mutational analysis. Such analysis revealed serine residues S332, S523 and S531 to be required for Mid1p function and its interaction with Vps4p, Ark1p and Plo1p. Combined these data suggest a physical interaction between Mid1p and Vps4p important for cytokinesis, and identify phosphorylation of Mid1p by aurora and polo kinases as being significant for this process.

Anillin Related Mid1 as an Adaptive and Multimodal Contractile Ring Anchoring Protein: A Simulation Study

“…For example, human anillin, drosophila anillin, and Mid2 PH are known to recruit septins [44][45][46][47]. However, little is known about Mid1 PH's possible role in protein-protein interactions, but it has been suggested it may directly or indirectly interact with ESCRTassociated protein Vps4 [48]. The Mid1 PH domain's preference for negatively charged PI lipids may indicate a potential role in regulation by phosphorylation, which adds a negatively charged phosphate group to an amino acid.…”

The role of anillin/Mid1p during medial division and cytokinesis: from fission yeast to cancer cells

“…Mid1p phospho-regulation was examined by combining three approaches: in vitro phosphorylation studies, tandem mass spectrometry (nLC-MS [13,17], Cdc2p [13], Pak1p [16], Ark1p [17], and Sid2p [19]. Please see Table S2 for description of each phosphorylation event.…”

“…Mid1p is non-essential for viability in S. pombe , however, the absence of Mid1p leads to cytokinesis failure at higher temperatures [ 4 ]. Since the identification and characterization of Mid1p, its localization pattern throughout the cell cycle of S. pombe has been extensively studied [ 12–16 ] [ 17 , 18 ] [ 19 ].…”

“… Schematic of S. pombe Mid1p phospho-regulation. Phosphorylation sites of Mid1p - see Figure 5 legend for Mid1p domain structure - by Plo1p [ 13 , 17 ], Cdc2p [ 13 ], Pak1p [ 16 ], Ark1p [ 17 ], and Sid2p [ 19 ]. Please see Table S2 for description of each phosphorylation event.…”

“…Over the past decade, studies with S. pombe have led to a comprehensive understanding of Mid1p’s function during ACR assembly and cytokinesis [ 12–16 ] [ 17 , 18 ] [ 19 ].…”