CROSSTALK BETWEEN cAMP-PKA AND HOG-MAPK PATHWAYS IN THE REGULATION OF THE OSMOTIC STRESS RESPONSE IN S. CEREVISIAE

OJEDA, LUCAS; GULIAS, FACUNDO; ORTOLÁ MARTÍNEZ MARÍA CLARA; GALELLO, FIORELLA; ROSSI, SILVIA; BERMUDEZ MORETTI, MARIANA; PORTELA, PAULA

Simposio; SAIB 2021; 2021

S. cerevisiae osmoadaptation response involves several signaling mechanisms that couple stimuli to coordinate responses,thereby ensuring its homeostasis. Previously, we have described a crosstalk between the cAMP-PKA and HOG-MAPKsignaling pathways on the cell survival response to osmotic stress. Under osmotic stress, TPK2 gene deletion improves thedefective cellular growth showed by HOG1 deleted strain. Here, we perform several experiments to elucidate the interplaybetween the two catalytic subunits of PKA, Tpk2 and Tpk1, and Hog1 kinase on the osmotic stress adaptation program. Wecompared the glycogen and trehalose accumulation- two important glucose stores- in the PKA and Hog1 mutant strainsgrowing under normal and osmotic stress conditions. HOG1 deletion promotes a high glycogen accumulation in responseto osmotic stress. Both double mutant strains, hog1Δtpk1Δ and hog1Δtpk2Δ, show a similar glycogen accumulation to wildtype cells. Under normal growth conditions, the hog1Δ strain shows low trehalose content in comparison to wild-type cells,though both strains similarly increase the trehalose levels under osmotic stress. When trehalose level is compared betweenthe different strains under osmotic stress conditions, the following order is apparent: tpk2Δ > hog1Δtpk2Δ > hog1Δtpk1Δ>hog1Δ = tpk1Δ= wild-type. The hog1Δ mutant cells shmoo-like growth form under osmotic stress is inhibited by TPK2gene deletion but not by TPK1 gene deletion. HOG1 deletion promotes the invasive growth in high salt-containing medium.Here, the double mutant hog1Δtpk1Δ abolishes the phenotype, whereas hog1Δtpk2Δ mutant strain increases the invasivegrowth under osmotic stress conditions. In addition, we analyzed the role of PKA and HOG-MAPK pathways onchronological lifespan (CLS). TPK2 deletion, but not HOG1 or TPK1, produces a reduction in CLS. HOG1 deletionsuppresses the tpk2Δ reduced CLS, revealing a PKA isoform-specific role on CLS. Previously, we described that Tpk2 andHog1 are recruited to the promoter regions of osmostress responsive genes as HSP42 and RPS29B and its kinase activityare required to gene expression pattern in response to stress. Now, we analyzed the in vivo kinetic recruitment of the Snf2-catalytic subunit of the SWI/SNF complex and stressresponsive transcription factor, Msn2, to the HSP42, RPS29B, andSTL1 promoter regions. ChIP assays, using tpk2Δ, hog1Δ and hog1Δtpk2Δ strains, indicate a crosstalk between both Tpk2and Hog1 kinases activity on Snf2 and Msn2 recruitment to the analyzed gene promoters. Our results contribute to thequestion of how signals from multiple pathways become integrated into a coordinated response. cAMP-PKA pathwayspecificity- via Tpk1 or Tpk2 catalytic isoforms - and HOG-MAPK pathway have an opposite role during the cellularadaptation to osmotic stresses.