POST-TRANSCRIPTIONAL REGULATION AND mRNA LOCALIZATION OF PKA SUBUNITS IN Saccharomyces cerevisiae

PORTELA P; PAUTASSO C.; ROSSI S; BARDECI N; GALELLO F; CAÑONERO L

Congreso; REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIAS; 2017

In the yeast Saccharomyces cerevisiae, the protein kinase A (PKA) controls a variety of cellular events as a consequence of particular stimulus. The specificity of the cAMP signal transduction is maintained by several levels of control acting simultaneously. Our aim is to study the regulation of PKA subunits expression as one of such control levels, which is directed by the promoter?s activity and the mRNA stability and localization. The balance among transcription, degradation and translation of individual mRNAs can be differentially regulated in response to environmental conditions such as heat stress. PKA holoenzyme from S.cerevisiae is composed by a dimer of regulatory subunit encoded by BCY1 gene and two catalytic subunits encoded by TPK1, TPK2 and TPK3 genes. Previously we have shown that the promoter of each PKA subunit is differentially regulated during heat shock, particularly TPK1 promoter is the only promoter activated. Here we demonstrate that BCY1 mRNA half-life is longer than TPK1 mRNA half-life and that TPK1 and BCY1 mRNAs are stabilized upon heat stress, as shown by Northern blot analysis. In contrast, Western blot analysis showed that Tpk1 protein abundance is not increased during heat shock. We also demonstrate that TPKs and BCY1 promoter sequences can influence the levels of mRNAs abundance. TPK1 mRNA localization was analyzed in vivo using the m-TAG methodology, showing the formation of ribonucleoprotein foci upon heat shock. Overall, the results suggest that in response to heat shock stress PKA subunit mRNAs increase their abundance and are concentrated in foci allowing a faster response once the environment is again favorable. Keywords: PKA, mRNA, heat stress, localization, stability