The Meiosis-Specific Crs1 Cyclin Is Required for Efficient S-Phase Progression and Stable Nuclear Architecture.

Luisa F Bustamante-Jaramillo,Cristina Martín-Castellanos,Celia Ramos

doi:10.3390/ijms22115483

Abstract

Cyclins and CDKs (Cyclin Dependent Kinases) are key players in the biology of eukaryotic cells, representing hubs for the orchestration of physiological conditions with cell cycle progression. Furthermore, as in the case of meiosis, cyclins and CDKs have acquired novel functions unrelated to this primal role in driving the division cycle. Meiosis is a specialized developmental program that ensures proper propagation of the genetic information to the next generation by the production of gametes with accurate chromosome content, and meiosis-specific cyclins are widespread in evolution. We have explored the diversification of CDK functions studying the meiosis-specific Crs1 cyclin in fission yeast. In addition to the reported role in DSB (Double Strand Break) formation, this cyclin is required for meiotic S-phase progression, a canonical role, and to maintain the architecture of the meiotic chromosomes. Crs1 localizes at the SPB (Spindle Pole Body) and is required to stabilize the cluster of telomeres at this location (bouquet configuration), as well as for normal SPB motion. In addition, Crs1 exhibits CDK(Cdc2)-dependent kinase activity in a biphasic manner during meiosis, in contrast to a single wave of protein expression, suggesting a post-translational control of its activity. Thus, Crs1 displays multiple functions, acting both in cell cycle progression and in several key meiosis-specific events.

Highlights

Cell cycle progression is governed by the modulation of CDK activity, a kinase activity formed by a catalytic subunit (CDK-Cyclin Dependent Kinase) and a regulatory subunit
It has been shown that a single Cyclin-CDK complex is sufficient to organize a “minimal” mitotic and meiotic cycle [3,4], suggesting that the additional complexes, and functions, originated from an ancestral component
Crs1 was described as a meiosis-specific Cyclin-like protein Regulated via Splicing [27]

Summary

Introduction

Cell cycle progression is governed by the modulation of CDK activity, a kinase activity formed by a catalytic subunit (CDK-Cyclin Dependent Kinase) and a regulatory subunit (cyclin) In unicellular eukaryotes such as yeasts, a unique CDK binds to several cyclins, and the cellular level of kinase activity temporally orders the different cell cycle phases, ensuring that cells first replicate their DNA before proceeding to segregate it into two identical daughter cells [1,2,3]. This general principle applies to cell cycle progression during meiosis, the specialized cellular program that generates haploid gametes from diploid cells as an obligated reduction of the genome content prior to fertilization [4]. The meiotic program has exploited CDK activity for a variety of meiosis-specific events that in some cases are even regulated by meiosis-specific variants

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Results

Conclusion