Role of Mip6 in TPK1 expression levels

GAREIS, DANIELA; JARASLASKY, IVÁN; ORTOLÁ MARTÍNEZ, MARÍA CLARA; GALELLO, FIORELLA

Congreso; Reunión Anual Edición LIX SAIB; 2023

SAIB

In eukaryotic cells, mRNA export from the nucleus is crucial to ensure the correct levels of protein expression. This process is connected withdownstream and upstream events that regulate the mRNA fate and, among other factors, RNA-binding proteins (RBPs) are involved in all this steps. Ithas been demonstrated that the RBP Mip6 plays a major role in the nuclear export and the expression levels of the Msn2/4 dependent mRNAs undernon stress conditions. Mip6 interacts with different factors that participate in several steps of mRNA homeostasis, as the exonuclease Xrn1. InSaccharomyces cerevisiae, PKA signalling pathway is involved in the coordination of different cellular functions and biological process in response toenvironmental fluctuations. The specificity of the response is extremely important in the cAMP-PKA pathway. Transcriptional and post-transcriptionalregulation, as well as expression levels of PKA subunits, are crucial to maintain the specificity of the response. We have demonstrated that TPK1promoter is upregulated under heat stress in an Msn2/4 dependent manner. TPK1 mRNA levels are also increased under heat stress; however proteinlevels showed no change. In other hand, we also have demonstrated that Xrn1 regulates TPK1 mRNA levels during heat stress. In order to shed light onthe different factors involved in the specificity of the cAMP-PKA pathway, we propose to evaluate the role of the RBP Mip6 on TPK1 expression understress and non-stress conditions. Using qRT-PCR we evaluate TPK1 mRNA levels in wild type and mip6 strains under non stress and heat stressconditions. TPK1 mRNA levels increase in mip6 strain both in non-stress conditions and during thermal stress. Tpk1 protein levels in mip6 strain arelower than wild type both under non-stress and thermal stress conditions. This results indicates that Mip6 could participate both in regulation of TPK1mRNA levels and mRNA export. Since RBPs can participate in several steps of gene expression, we asked if Mip6 is recruited to TPK1 promoter. ChIPassay reveals that Mip6 is recruited to TPK1 promoter under non-stress and heat stress condition. Overall, we conclude that Mip6 is involved in TPK1expression regulation both under non-stress and stress condition.