TORC1 signaling regulates cytoplasmic pH through Sir2 in yeast

Abstract

Glucose controls the phosphorylation of silent information regulator 2 (Sir2), a NAD+‐dependent protein deacetylase, which regulates the expression of the ATP‐dependent proton pump Pma1 and replicative lifespan (RLS) in yeast. TORC1 signaling, which is a central regulator of cell growth and lifespan, is regulated by glucose as well as nitrogen sources. In this study, we demonstrate that TORC1 signaling controls Sir2 phosphorylation through casein kinase 2 (CK2) to regulate PMA1 expression and cytoplasmic pH (pHc) in yeast. Inhibition of TORC1 signaling by either TOR1 deletion or rapamycin treatment decreased PMA1 expression, pHc, and vacuolar pH, whereas activation of TORC1 signaling by expressing constitutively active GTR1 (GTR1Q65L) resulted in the opposite phenotypes. Deletion of SIR2 or expression of a phospho‐mutant form of SIR2 increased PMA1 expression, pHc, and vacuolar pH in the tor1Δ mutant, suggesting a functional interaction between Sir2 and TORC1 signaling. Furthermore, deletion of TOR1 or KNS1 encoding a LAMMER kinase decreased the phosphorylation level of Sir2, suggesting that TORC1 signaling controls Sir2 phosphorylation. It was also found that Sit4, a protein phosphatase 2A (PP2A)‐like phosphatase, and Kns1 are required for TORC1 signaling to regulate PMA1 expression and that TORC1 signaling and the cyclic AMP (cAMP)/protein kinase A (PKA) pathway converge on CK2 to regulate PMA1 expression through Sir2. Taken together, these findings suggest that TORC1 signaling regulates PMA1 expression and pHc through the CK2–Sir2 axis, which is also controlled by cAMP/PKA signaling in yeast.

Gentirigeoside B from Gentiana rigescens Franch Prolongs Yeast Lifespan via Inhibition of TORC1/Sch9/Rim15/Msn Signaling Pathway and Modification of Oxidative Stress and Autophagy

“…The TOR signaling pathway is a central regulator that connects nutrient availability and stress condition to control cell growth and lifespan. Inhibition of the TORC1 signaling pathway delays aging and extends lifespan by manipulating the activities of downstream kinase proteins, transcription factors and NAD + -dependent deacetylase enzyme Sir2 in Saccharomyces cerevisiae [ 5 , 6 , 12 ]. Inhibition of TORC1 signaling reduces expression of ribosomal protein genes such as RPS26A and RPL9A, indicating downregulation of protein synthesis and upregulation of the anti-aging process [ 12 , 25 ].…”

“…The target of rapamycin (TOR) is a nutrient-sensing protein kinase which is evolutionarily conserved in eukaryotic organisms [ 4 ]. Evidence indicates that the TOR signaling pathway is a central regulator that connects nutrient availability and stress condition to control cell growth and lifespan [ 4 , 5 , 6 ]. The inhibition of the TORC1 signaling pathway can delay aging and extend the lifespan of different species such as Saccharomyces cerevisiae , Caenorhabditis elegans , Drosophila melanogaster and mice [ 6 , 7 , 8 , 9 ].…”

“…Silent information regulator 2 (Sir2), an NAD + -dependent deacetylase protein, controls replicative lifespan in yeast [ 5 ]. Activation of Sir2 plays an indispensable role in yeast lifespan extension via inhibition of extrachromosomal rDNA circle formations.…”

“…These repetitive combinations of rDNA are stabilized under normal conditions by Sir2 [ 4 ]. Several studies reported that the TORC1 signaling pathway controls the activity of Sir2 in regulating the lifespan of S. cerevisiae [ 4 , 5 , 12 ].…”

The role of NAD and NAD precursors on longevity and lifespan modulation in the budding yeast, Saccharomyces cerevisiae

“…Early studies revealed the Sirtuins and TOR (Target of Rapamycin) signaling as longevity regulators (Longo and Kennedy 2006 ; Powers et al 2006 ; Wierman and Smith 2014 ). These proteins (the Sirtuins and TOR factors) provide insight on and have revolutionized aging biology (Deprez et al 2018 ; Devare et al 2020 ). Besides playing a key role in identifying over 1000 genes through the CLS paradigm in S. cerevisiae (Jung et al 2015 ), genetic techniques have revealed several pathways and regulatory networks that intersect to modulate lifespan.…”