Yeast Glycogen Synthase Kinase-3 Activates Msn2p-dependent Transcription of Stress Responsive Genes

Abstract

The yeast Saccharomyces cerevisiae has four genes, MCK1, MDS1 (RIM11), MRK1, and YOL128c, that encode homologues of mammalian glycogen synthase kinase 3 (GSK-3). A gsk-3 null mutant in which these four genes are disrupted showed growth defects on galactose medium. We isolated several multicopy suppressors of this growth defect. Two of them encoded Msn2p and phosphoglucomutase (PGM). Msn2p is a transcription factor that binds to the stress-response element (STRE). PGM is an enzyme that interconverts glucose-1 phosphate and glucose-6 phosphate and is regulated by Msn2p at the transcriptional level. Expression of the mRNAs of PGM2 and DDR2, whose promoter regions possess STRE sequences, on induction by heat shock or salt stress was reduced not only in an msn2 msn4 (msn2 homologue) double mutant but also in the gsk-3 null mutant. STRE-dependent transcription was greatly inhibited in the gsk-3 null mutant or mck1 mds1 double mutant, and this phenotype was suppressed by the expression of Mck1p but not of a kinase-inactive form of Mck1p. Although Msn2p accumulated in the nucleus of the gsk-3 null mutant as well as in the wild-type strain under various stress conditions, its STRE-binding activity was reduced in extracts prepared from the gsk-3 null mutant or mck1 mds1 double mutant. These results suggest that yeast GSK-3 promotes formation of a complex between Msn2p and DNA, which is required for the proper response to different forms of stress. Because neither Msn2p–GSK-3 complex formation nor GSK-3–dependent phosphorylation of Msn2p could be detected, the regulation of Msn2p by GSK-3 may be indirect

GSK-3 kinases enhance calcineurin signaling by phosphorylation of RCNs

“…3A, lanes 6-9). Most of the Mck1-dependent genes were found in other studies to be targets of the stress-activated transcription factors Msn2 and Msn4 (Gasch et al 2000;Causton et al 2001), which depend on Mck1 for maximal transcription activity in a variety of stressful environments (Hirata et al 2003). Of the 54 members of this group that depended on Mck1 in both strain backgrounds, none was affected reproducibly by the loss of either Tcn1/Crz1 or Rcn1 (lanes 2-5,10,11), suggesting that cross talk from the calcium signaling pathway was not necessary for Mck1 function.…”

“…6A). A large fraction of these Mck1-dependent genes was found to be targets of the Msn2 and Msn4 transcription activators (Gasch et al 2000;Causton et al 2001) that are highly dependent on Mck1 in response to a variety of cellular stresses (Hirata et al 2003). A recent study suggested high Ca 2+ conditions increase MCK1 gene expression and Mck1 function (Mizunuma et al 2001).…”

Metabolic Reprogramming in Dietary Restriction

“…Activation of p38 increases insulin sensitivity in skeletal muscle in a manner that is independent of contractile induced insulin sensitivity [105], p38 activates the transcriptional coactivator PGC-1α by phosphorylation, thereby regulating the induction of mitochondrial respiration in muscle [106,107] where PGC-1α plays a role in fiber type switching [108]. The yeast homologue of GSK3β is involved in nutrient sensing and the stress response [109], In mammals, GSK3β is a negative regulator of JNK [110] and is involved in insulin sensitivity in skeletal muscle [111]. Interestingly both JNK and p38 are activated by ROS signaling from the mitochondria [112].…”

A Single-Cell Study of a Highly Effective Hog1 Inhibitor for in Situ Yeast Cell Manipulation

“…In order to identify that the array is indeed treated with sorbitol, a column of control cells expressing Msn2-GFP can in our setup be added to the cell array when a complete Hog1 nuclear localization is anticipated. Msn2 is a transcription factor that regulates the yeast general stress responses and is regulated by several pathways [27][28][29]. Msn2 activation is thus induced by several different stresses of which one is high osmolarity.…”