Asymmetric distribution of glucose transporter mRNA provides a growth advantage in yeast. (25th March 2019) - Stahl, Timo
Abstract: Asymmetric localization of mRNA is important for cell fate decisions in eukaryotes and provides the means for localized protein synthesis in a variety of cell types. Here, we show that hexose transporter mRNAs are retained in the mother cell of S. cerevisiae until metaphase–anaphase transition (MAT) and then are released into the bud. The retained mRNA was translationally less active but bound to ribosomes before MAT. Importantly, when cells were shifted from starvation to glucose‐rich conditions, HXT2 mRNA, but none of the other HXT mRNAs, was enriched in the bud after MAT. This enrichment was dependent on the Ras/cAMP/PKA pathway, the APC ortholog Kar9, and nuclear segregation into the bud. Competition experiments between strains that only expressed one hexose transporter at a time revealed that HXT2 only cells grow faster than their counterparts when released from starvation. Therefore, asymmetric distribution of HXT2 mRNA provides a growth advantage for daughters, who are better prepared for nutritional changes in the environment. Our data provide evidence that asymmetric mRNA localization is an important factor in determining cellular fitness. Synopsis: Asymmetric localization of mRNA is important for cell fate decisions in eukaryotes and provides the means for localized protein synthesis in a variety of cell types. This study reveals that glucose transporter Hxt2 mRNA is enriched in the yeast bud following quiescence exit, thereby favoring growth of the daughter cell. Hxt2 mRNA is retained in the mother cell until metaphase‐anaphase transition. During logarithmic growth, HXT2 mRNA is equally distributed between mother and bud in mitosis. Upon exit from quiescence or glucose starvation, Hxt2 mRNA is enriched in the daughter cell via cAMP increase and PKA activation. Forced localization of Hxt2 mRNA into the bud is sufficient to confer a growth advantage. Abstract : Enrichment of the glucose transporter Hxt2 mRNA in the yeast bud following quiescence exit favors growth of daughter cells.