Intranuclear Function for Protein Phosphatase 2A: Pph21 and Pph22 Are Required for Rapamycin-Induced GATA Factor Binding to the DAL5 Promoter in Yeast

Institut de Recherches Microbiologiques J.-M. Wiame, Laboratoire de Microbiologie, Université Libre de Bruxelles, B1070 Brussels, Belgium.
Molecular and Cellular Biology (Impact Factor: 4.78). 10/2010; 31(1):92-104. DOI: 10.1128/MCB.00482-10
Source: PubMed


Protein phosphatase 2A (PP2A), a central Tor pathway phosphatase consisting of a catalytic subunit (Pph21 or Pph22), a scaffold
subunit (Tpd3), and one of two regulatory subunits (Cdc55 or Rts1), has been repeatedly shown to play important roles in cytoplasmically
localized signal transduction activities. In contrast, its involvement in intranuclear control of mRNA production has heretofore
not been reported. Here, we demonstrate for the first time that binding of the nitrogen catabolite repression-responsive GATA
transcription activators (Gln3 and Gat1) to the DAL5 promoter and DAL5 expression require Pph21/22-Tpd3-Cdc55/Rts1 in rapamycin-treated glutamine-grown cells. This conclusion is supported by the
following observations. (i) Rapamycin-induced DAL5 expression along with Gln3 and Gat1 binding to the DAL5 promoter fails to occur in pph21Δ pph22Δ, tpd3Δ, and cdc55Δ rts1Δ mutants. (ii) The Pph21/22 requirement persists even when Gat1 and Gln3 are rendered constitutively nuclear, thus dissociating
the intranuclear requirement of PP2A from its partial requirement for rapamycin-induced nuclear Gat1 localization. (iii) Pph21-Myc13 (Ppp21 tagged at the C terminus with 13 copies of the Myc epitope) weakly associates with the DAL5 promoter in a Gat1-dependent manner, whereas a similar Pph22-Myc13 association requires both Gln3 and Gat1. Finally, we demonstrate that a pph21Δ pph22Δ double mutant is epistatic to ure2Δ for nuclear Gat1 localization in untreated glutamine-grown cells, whereas for Gln3, just the opposite occurs: i.e., ure2Δ is epistatic to pph21Δ pph22Δ. This final observation adds additional support to our previous conclusion that the Gln3 and Gat1 GATA factor localizations
are predominantly controlled by different regulatory pathways.

Download full-text


Available from: Isabelle Georis
  • Source
    • "(2) In contrast to Gln3, Gat1 nuclear localization is largely Ure2-independent (Georis et al. 2008). (3) Nuclear localization of Gln3 and Gat1 exhibits distinct requirements for the TORC1-regulated phosphatases (Tate et al. 2010; Georis et al. 2011b). Early investigations of Gln3 regulation established that under steady state, nitrogen-rich conditions, cytoplasmic Gln3 was situated within or tightly associated with a cytoplasmic membrane system (Cox et al. 2002). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Nitrogen catabolite repression (NCR) is the regulatory pathway through which Saccharomyces cerevisiae responds to the available nitrogen status and selectively utilizes rich nitrogen sources in preference to poor ones. Expression of NCR-sensitive genes is mediated by two transcription activators, Gln3 and Gat1, in response to provision of a poorly used nitrogen source or following treatment with the TORC1 inhibitor, rapamycin. During nitrogen excess, the transcription activators are sequestered in the cytoplasm in a Ure2-dependent fashion. Here, we show that Vps components are required for Gln3 localization and function in response to rapamycin treatment when cells are grown in defined yeast nitrogen base but not in complex yeast peptone dextrose medium. On the other hand, Gat1 function was altered in vps mutants in all conditions tested. A significant fraction of Gat1, like Gln3, is associated with light intracellular membranes. Further, our results are consistent with the possibility that Ure2 might function downstream of the Vps components during the control of GATA factor-mediated gene expression. These observations demonstrate distinct media-dependent requirements of vesicular trafficking components for wild-type responses of GATA factor localization and function. As a result, the current model describing participation of Vps system components in events associated with translocation of Gln3 into the nucleus following rapamycin treatment or growth in nitrogen-poor medium requires modification.
    Full-text · Article · Jun 2014 · MicrobiologyOpen
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Like all microorganisms, yeast cells spend most of their natural lifetime in a reversible, quiescent state that is primarily induced by limitation for essential nutrients. Substantial progress has been made in defining the features of quiescent cells and the nutrient-signaling pathways that shape these features. A view that emerges from the wealth of new data is that yeast cells dynamically configure the quiescent state in response to nutritional challenges by using a set of key nutrient-signaling pathways, which (1) regulate pathway-specific effectors, (2) converge on a few regulatory nodes that bundle multiple inputs to communicate unified, graded responses, and (3) mutually modulate their competences to transmit signals. Here, I present an overview of our current understanding of the architecture of these pathways, focusing on how the corresponding core signaling protein kinases (i.e. PKA, TORC1, Snf1, and Pho85) are wired to ensure an adequate response to nutrient starvation, which enables cells to tide over decades, if not centuries, of famine.
    Full-text · Article · Jun 2011 · FEMS microbiology reviews
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Bicycle use has increased in some of France's major cities, mainly as a means of transport. Bicycle crashes need to be studied, preferably by type of cycling. Here we conduct a descriptive analysis. A road trauma registry has been in use in France since 1996, in a large county around Lyon (the Rhône, population 1.6 million). It covers outpatients, inpatients and fatalities. All injuries are coded using the Abbreviated Injury Scale (AIS). Proxies were used to identify three types of cycling: learning = children (0-10 years old); sports cycling = teenagers and adults injured outside towns; cycling as means of transport = teenagers and adults injured in towns. The study is based on 13,684 cyclist casualties (1996-2008). The percentage of cyclists injured in a collision with a motor vehicle was 8% among children, 17% among teenagers and adults injured outside towns, and 31% among those injured in towns. The percentage of serious casualties (MAIS 3+) was 4.5% among children, 10.9% among adults injured outside towns and 7.2% among those injured in towns. Collisions with motor-vehicles lead to more internal injuries than bicycle-only crashes. The description indicates that cyclist type is associated with different crash and injury patterns. In particular, cyclists injured in towns (where cycling is increasing) are generally less severely injured than those injured outside towns for both types of crash (bicycle-only crashes and collisions with a motor vehicle). This is probably due to lower speeds in towns, for both cyclists and motor vehicles.
    Full-text · Article · Aug 2011 · BMC Public Health
Show more