Compartmentalized signaling of Ras in fission yeast

Onken, Brian; Wiener, Heidi H.; Philips, Mark R.; Chang, Eric C.

doi:10.1073/pnas.0603318103

Cited by 99 publications

(128 citation statements)

References 33 publications

(36 reference statements)

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“…While the interaction between Ras proteins and a given PAT is selective, some Ras proteins in sc-erf2⌬ budding yeast, as well as in vegetatively growing sp-erf2⌬ fission yeast cells, can still be seen at the PM. We believe that this pool of Ras protein is covalently modified since a Ras1 mutant lacking the cysteine for palmitoylation (C215S) could not be seen at the PM at all (10). It has been shown that palmitoylation can be driven by acyl coenzyme A (CoA) concentration in vitro without PATs (63,64), so we support the idea that this cysteine in Ras proteins could be spontaneously modified to gain PM affinity.…”

Section: Discussionsupporting

confidence: 56%

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Regulation of Ras Localization and Cell Transformation by Evolutionarily Conserved Palmitoyltransferases

Young

Zheng

Wilkins

et al. 2014

Molecular and Cellular Biology

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e Ras can act on the plasma membrane (PM) to mediate extracellular signaling and tumorigenesis. To identify key components controlling Ras PM localization, we performed an unbiased screen to seek Schizosaccharomyces pombe mutants with reduced PM Ras. Five mutants were found with mutations affecting the same gene, S. pombe erf2 (sp-erf2), encoding sp-Erf2, a palmitoyltransferase, with various activities. sp-Erf2 localizes to the trans-Golgi compartment, a process which is mediated by its third transmembrane domain and the Erf4 cofactor. In fission yeast, the human ortholog zDHHC9 rescues the phenotypes of sp-erf2 null cells. In contrast, expressing zDHHC14, another sp-Erf2-like human protein, did not rescue Ras1 mislocalization in these cells. Importantly, ZDHHC9 is widely overexpressed in cancers. Overexpressing ZDHHC9 promotes, while repressing it diminishes, Ras PM localization and transformation of mammalian cells. These data strongly demonstrate that sp-Erf2/zDHHC9 palmitoylates Ras proteins in a highly selective manner in the trans-Golgi compartment to facilitate PM targeting via the transGolgi network, a role that is most certainly critical for Ras-driven tumorigenesis. Mammals have three RAS genes, HRAS, NRAS, and KRAS, which encode membrane-bound GTPases that control a wide range of signal transduction pathways critical for growth, differentiation, and cytoskeleton remodeling (1). The best-known Ras function is to mediate growth factor signaling that occurs at the plasma membrane (PM), and deregulation of this and other Ras functions can promote tumor formation (2, 3). While all Ras proteins are farnesylated to gain general membrane affinity, a second signal is needed to specifically localize to the PM. For HRas and NRas, this signal is provided by palmitoylation at cysteine residues immediately upstream of the C-terminal CAAX motif. This reaction can be catalyzed by protein acyltransferases (PATs) that contain a DHHC domain rich with aspartate, histidine, and cysteine residues. These DHHC-PATs are expected to localize in the Golgi complex to allow the delivery of palmitoylated Ras proteins to the PM through the trans-Golgi system (4) although this concept has not been thoroughly demonstrated in vivo.Humans have 24 DHHC-PATs, but it remains unresolved which of these control palmitoylation of Ras proteins in vivo. In contrast, the Ras pathways are considerably simpler in yeasts. Early studies from the budding yeast Saccharomyces cerevisiae, which has seven DHHC-PATs and two Ras proteins, suggest that only S. cerevisiae Erf2 (sc-Erf2) controls palmitoylation of its Ras proteins (5, 6). By sequence alignment to find putative orthologs, zDHHC9 was predicted to be a human Ras PAT (7). Although zDHHC9 can catalyze Ras palmitoylation in vitro, zDHHC9 cannot rescue sc-erf2 mutant phenotypes in budding yeast (8), and until now there has been no evidence that zDHHC9 or other human DHHC-PATs can control Ras localization in mammalian cells. Furthermore, while ectopically expressed zDHHC9 localizes to the Golgi compl...

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Section: Discussionsupporting

confidence: 56%

“…S. pombe has a single Ras protein, Ras1, which controls two evolutionarily conserved pathways that are spatially segregated (9,10). The Ras1-Byr2-mitogen-activated protein (MAP) kinase pathway (11) functions on the PM to mediate mating, while the Ras1-Scd1/Ral1-Cdc42 pathway (12,13) functions in the endomembrane to mediate cell morphogenesis.…”

mentioning

confidence: 99%

Regulation of Ras Localization and Cell Transformation by Evolutionarily Conserved Palmitoyltransferases

Young

Zheng

Wilkins

et al. 2014

Molecular and Cellular Biology

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“…Despite this dispute over the precise role of intracellular pools of Ras, a recent study using targeted Ras constructs in fission yeast revealed that compartmentalised Ras signalling is evolutionarily conserved. In this case, surface localised Ras supported pathways regulating mating whereas endomembrane Ras supported pathways controlling morphology [100].…”

Section: Compartmentalised Ras Signallingmentioning

confidence: 98%

Ras proteins: paradigms for compartmentalised and isoform-specific signalling

Omerovic

Laude

Prior

2007

Cell. Mol. Life Sci.

117

122

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Ras GTPases mediate a wide variety of cellular processes by converting a multitude of extracellular stimuli into specific biological responses including proliferation, differentiation and survival. In mammalian cells, three ras genes encode four Ras isoforms (H-Ras, K-Ras4A, KRas4B and N-Ras) that are highly homologous but functionally distinct. Differences between the isoforms, including their post-translational modifications and intracellular sorting, mean that Ras has emerged as an important model system of compartmentalised signalling and membrane biology. Ras isoforms in different subcellular locations are proposed to recruit distinct upstream and downstream accessory proteins and activate multiple signalling pathways. Here, we summarise data relating to isoform specific signalling, its role in disease and the mechanisms promoting compartmentalised signalling. Further understanding of this field will reveal the role of Ras signalling in development, cellular homeostasis and cancers and may suggest new therapeutic approaches.

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“…These include preferential isoform coupling to the Raf and phosphoinositide 3-kinase effector pathways and a unique requirement for K-RAS during mouse development (Potenza et al, 2005;Walsh and Bar-Sagi, 2001;Yan et al, 1998). These differences are proposed to be mediated by differential localisation, enabling isoforms to interact with different subcellular pools of effectors and activators (Daniels et al, 2006;Onken et al, 2006;Rocks et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Palmitoylation and localisation of RAS isoforms are modulated by the hypervariable linker domain

Laude

Prior

2008

Journal of Cell Science

114

109

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RAS isoforms have been proposed to exhibit differing biological outputs due to differences in their relative occupancy of cellular organelles and signalling microdomains. The membrane binding and targeting motifs of RAS are encoded by the C-terminal hypervariable region (HVR), and the precise localisation depends upon interactions between the HVR and the host membrane. Classic studies revealed that all RAS proteins rely on farnesylation and either palmitoylation or a polybasic stretch for stable binding to membranes. We now show that, for N-RAS and Ki-RAS4A, mono-palmitoylation and farnesylation are not sufficient for specifying stable cell-surface localisation. A third motif that is present within the linker domain of all palmitoylated RAS HVRs is necessary for stabilising localisation to the plasma membrane. This motif comprises acidic residues that stabilise palmitoylation and basic amino acids that are likely to interact electrostatically with acidic phospholipids enriched at the cell surface. Importantly, altered localisation is achieved without changes in palmitoylation status. Our data provide a mechanism for distinct HVR membrane interactions controlling subcellular distribution. In the context of the full-length RAS proteins, this is likely to be of crucial importance for controlling signalling output and engagement with different pools of effectors.

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Compartmentalized signaling of Ras in fission yeast

Cited by 99 publications

References 33 publications

Regulation of Ras Localization and Cell Transformation by Evolutionarily Conserved Palmitoyltransferases

Regulation of Ras Localization and Cell Transformation by Evolutionarily Conserved Palmitoyltransferases

Ras proteins: paradigms for compartmentalised and isoform-specific signalling

Palmitoylation and localisation of RAS isoforms are modulated by the hypervariable linker domain

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