IQUIBICEN   23947
INSTITUTO DE QUIMICA BIOLOGICA DE LA FACULTAD DE CIENCIAS EXACTAS Y NATURALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
TPK1 promoter regulation by inositol phosphates during heat stress in Saccharomyces cerevisiae
Autor/es:
ORTOLA MC; ROSSI S; RECA S; GALELLO F,
Lugar:
Salta
Reunión:
Congreso; Reunión Anual de SAIB-PABMB 2019; 2019
Institución organizadora:
SAIB-PABMB
Resumen:
In Saccharomyces cerevisiae, Protein Kinase A (PKA) pathway controls several functions and biological processes in response to different stimuli. PKA from S. cerevisiae is composed of two catalytic subunits encoded by TPK1, TPK2 and TPK3 genes, and two regulatory subunits, encoded by BCY1 gene. The specificity of the PKA pathway depends on several factors as substrates specificity and the PKA localization by interaction with anchoring proteins (AKAPs). However, transcriptional regulation and expression levels of PKA subunits are also events involved in maintaining specificity. In response to environmental variations, cells must respond through changes that occur at transcriptional and post-transcriptional levels in order to adapt to the new conditions. We have previously demonstrated that a negative mechanism of autoregulation directs TPKs and BCY1 gene expression and that only TPK1 promoter activity is positively regulated during heat stress. Results from our group showed that the TPK1 promoter presents three positioned nucleosomes that upon heat stress they are no longer detectable, according to TPK1 promoter activation. On the other hand, it has been described that inositol phosphates can modulate the activities of several chromatin remodeling complexes. In order to identify additional factors involved in PKA subunits transcriptional regulation, we analyzed TPK1 promoter activity, mRNA levels and nucleosomes positioning in null mutant strains for the components of the inositol phosphates pathway (Δplc1, Δipk1, Δipk2, Δkcs1) in heat stress. Our results showed that TPK1 is not upregulated and there was not chromatin remodeling during heat shock in null mutant strains for the components of the inositol phosphates pathway. It has also been demonstrated that Plc1p regulates the recruitment of the SAGA complex to stress-responsive genes promoters in order to facilitate transcriptional initiation. Then, we decided to evaluate the relationship between the inositol phosphates pathway and chromatin remodelers on the expression regulation of TPK1. Using β-galactosidase reporter assays and RT-qPCR in null mutant strains for subunits of the SAGA complex, we evaluated TPK1 promoter activity and mRNA level. We demonstrated that TPK1 promoter activity and mRNA levels decreased in Δgcn5, Δada2, and Δspt20 strains during heat shock. We evaluated the recruitment of the SAGA complex to the TPK1 promoter and the dependence on Plc1p using ChIP assays. Finally, other authors have demonstrated that the inositol phosphates pathway modulates the expression of several stress-responsive genes through the activation of the HDAC Rpd3L. Thus, we evaluated the participation of HDAC Rpd3L in TPK1 and BCY1 transcriptional regulation during heat stress. Taken together, these results strongly suggest that the inositol phosphate pathway is involved in the regulation of TPK1 gene expression during heat stress.