Effects of 5'-3' Exonuclease Xrn1 on Cell Size, Proliferation and Division, and mRNA Levels of Periodic Genes in Cryptococcus neoformans.

Cell size affects almost all biosynthetic processes by controlling the size of organelles and disrupting the nutrient uptake process. Yeast cells must reach a critical size to be able to enter a new cell cycle stage. Abnormal changes in cell size are often observed under pathological conditions such as cancer disease. Thus, cell size must be strictly controlled during cell cycle progression. Here, we reported that the highly conserved 5′-3′ exonuclease Xrn1 could regulate the gene expression involved in the cell cycle pathway of Cryptococcus neoformans. Chromosomal deletion of XRN1 caused an increase in cell size, defects in cell growth and altered DNA content at 37 °C. RNA-sequencing results showed that the difference was significantly enriched in genes involved in membrane components, DNA metabolism, integration and recombination, DNA polymerase activity, meiotic cell cycle, nuclear division, organelle fission, microtubule-based process and reproduction. In addition, the proportion of the differentially expressed periodic genes was up to 19.8% when XRN1 was deleted, including cell cycle-related genes, chitin synthase genes and transcription factors, indicating the important role of Xrn1 in the control of cell cycle. This work provides insights into the roles of RNA decay factor Xrn1 in maintaining appropriate cell size, DNA content and cell cycle progression.