Meiotic nuclear movements in fission yeast are regulated by the transcription factor Mei4 downstream of a Cds1-dependent replication checkpoint pathway.

Kun Ruan,Takaharu G Yamamoto,Haruhiko Asakawa,Hisao Masukata,Yuji Chikashige,Tokuko Haraguchi,Yasushi Hiraoka

doi:10.1111/gtc.12207

Abstract

In meiosis, the fission yeast nucleus displays an elongated morphology, moving back and forth within the cell; these nuclear movements continue for approximately 2 h before meiotic nuclear divisions. Meiotic DNA replication occurs in an early phase of the nuclear movements and is followed by meiotic prophase. Here we report that in mutants deficient in meiotic DNA replication, the duration of nuclear movements is strikingly prolonged to four to 5 h. We found that this prolongation was caused by the Cds1-dependent replication checkpoint, which represses expression of the mei4+ gene encoding a meiosis-specific transcription factor. In the absence of Mei4, nuclear movements persisted for more than 8 h. In contrast, overproduction of Mei4 accelerated termination of nuclear movements to approximately 30 min. These results show that Mei4 is involved in the termination of nuclear movements and that Mei4-mediated regulatory pathways link a DNA replication checkpoint to the termination of nuclear movements.

Highlights

Meiosis is a particular type of nuclear division that is essential for sexual reproduction in eukaryotes
As it is known that the Cds1-mediated DNA replication checkpoint suppresses Mei4 (Ogino & Masai 2006), we examined the effects of deletion and overproduction of Mei4 on horsetail nuclear movement
We have shown that abrogation of dNTP biosynthesis, which is caused by csn1Δ, ddb1Δ

Summary

Introduction

Meiosis is a particular type of nuclear division that is essential for sexual reproduction in eukaryotes. Null mutation in either csn1+ or ddb1+ is not lethal for mitotically growing cells, but results in meiotic S-phase arrest (Holmberg et al 2005; Nestoras et al 2010) This meiotic arrest is probably caused by an insufficiency of dNTPs, as the arrest can be suppressed by the deletion of the spd1+ gene (Holmberg et al 2005). This fact may reflect a difference in the RNR activity requirements of mitotic and meiotic S phase (Grallert & Sipiczki 1991; Holmberg et al 2005). These results provide the first demonstration that Mei4-mediated regulatory pathways link a DNA replication checkpoint to the termination of nuclear movements

Results

Discussion

Experimental procedures