Erratum to: The loop-less Cdc34 E2 mutant defective polyubiquitination in vitro and in vivo supports yeast growth in a manner dependent on Ubp14 and Cka2.

[This corrects the article DOI: 10.1186/1747-1028-6-7.].

SIMPL enhancement of tumor necrosis factor-α dependent p65-MED1 complex formation is required for mammalian hematopoietic stem and progenitor cell function.

Significant insight into the signaling pathways leading to activation of the Rel transcription factor family, collectively termed NF-κB, has been gained. Less well understood is how subsets of NF-κB-dependent genes are regulated in a signal specific manner. The SIMPL protein (signaling molecule that interacts with mouse pelle-like kinase) is required for full Tumor Necrosis Factor-α (TNFα) induced NF-κB activity.

Amot130 adapts atrophin-1 interacting protein 4 to inhibit yes-associated protein signaling and cell growth.

The adaptor protein Amot130 scaffolds components of the Hippo pathway to promote the inhibition of cell growth. This study describes how Amot130 through binding and activating the ubiquitin ligase AIP4/Itch achieves these effects. AIP4 is found to bind and ubiquitinate Amot130 at residue Lys-481.

Nutrient sensing kinases PKA and Sch9 phosphorylate the catalytic domain of the ubiquitin-conjugating enzyme Cdc34.

Cell division is controlled in part by the timely activation of the CDK, Cdc28, through its association with G1 and G2 cyclins. Cdc28 complexes are regulated in turn by the ubiquitin conjugating enzyme Cdc34 and SCF ubiquitin ligase complexes of the ubiquitin-proteasome system (UPS) to control the initiation of DNA replication. Here we demonstrate that the nutrient sensing kinases PKA and Sch9 phosphorylate S97 of Cdc34.

The loop-less tmCdc34 E2 mutant defective in polyubiquitination in vitro and in vivo supports yeast growth in a manner dependent on Ubp14 and Cka2.

Background: The S73/S97/loop motif is a hallmark of the Cdc34 family of E2 ubiquitin-conjugating enzymes that together with the SCF E3 ubiquitin ligases promote degradation of proteins involved in cell cycle and growth regulation. The inability of the loop-less Δ12Cdc34 mutant to support growth was linked to its inability to catalyze polyubiquitination. However, the loop-less triple mutant (tm) Cdc34, which not only lacks the loop but also contains the S73K and S97D substitutions typical of the K73/D97/no loop motif present in other E2s, supports growth.

New insight into the role of the Cdc34 ubiquitin-conjugating enzyme in cell cycle regulation via Ace2 and Sic1.

The Cdc34 ubiquitin-conjugating enzyme plays a central role in progression of the cell cycle. Through analysis of the phenotype of a mutant missing a highly conserved sequence motif within the catalytic domain of Cdc34, we discovered previously unrecognized levels of regulation of the Ace2 transcription factor and the cyclin-dependent protein kinase inhibitor Sic1. In cells carrying the Cdc34(tm) mutation, which alters the conserved sequence, the cyclin-dependent protein kinase inhibitor Sic1, an SCF(Cdc4) substrate, has a shorter half-life, while the cyclin Cln1, an SCF(Grr1) substrate, has a longer half-life than in wild-type cells.

The antibiotic gentamicin inhibits specific protein trafficking functions of the Arf1/2 family of GTPases.

Gentamicin is a highly efficacious antibiotic against Gram-negative bacteria. However, its usefulness in treating infections is compromised by its poorly understood renal toxicity. Toxic effects are also seen in a variety of other organisms.

Loss of SIMPL compromises TNF-alpha-dependent survival of hematopoietic progenitors.

Objective: Emerging work has revealed an integral role of the tumor necrosis factor-alpha (TNF-alpha) nuclear factor (NF)-kappaB pathway in the regulation of hematopoiesis. TNF-alpha inhibition of hematopoietic stem/progenitor cell growth involves type I TNF-alpha receptor (TNF-RI) and type II TNF-alpha receptor (TNF-RII). However, the role of TNF-RI vs TNF-RII in mediating this response is less clear.

Identification, analysis, and prediction of protein ubiquitination sites.

Ubiquitination plays an important role in many cellular processes and is implicated in many diseases. Experimental identification of ubiquitination sites is challenging due to rapid turnover of ubiquitinated proteins and the large size of the ubiquitin modifier. We identified 141 new ubiquitination sites using a combination of liquid chromatography, mass spectrometry, and mutant yeast strains.

Transient membrane recruitment of IRAK-1 in response to LPS and IL-1beta requires TNF R1.

The transcription factor NF-kappaB is an essential regulator of the innate immune response that functions as the first line of defense against infections. Activation of the innate immune response by bacterial lipopolysaccharide (LPS) triggers production of tumor necrosis factor-alpha (TNF-alpha) followed by interleukin-1 (IL-1). The IL-1 receptor associated kinase-1 (IRAK-1) is an integral component of the LPS, TNF-alpha, and IL-1 signaling pathways that regulate NF-kappaB.

SCF E3-mediated autoubiquitination negatively regulates activity of Cdc34 E2 but plays a nonessential role in the catalytic cycle in vitro and in vivo.

One of the several still unexplained aspects of the mechanism by which the Cdc34/SCF RING-type ubiquitin ligases work is the marked stimulation of Cdc34 autoubiquitination, a phenomenon of unknown mechanism and significance. In in vitro experiments with single-lysine-containing Cdc34 mutant proteins of Saccharomyces cerevisiae, we found that the SCF-mediated stimulation of autoubiquitination is limited to specific N-terminal lysines modified via an intermolecular mechanism. In a striking contrast, SCF quenches autoubiquitination of C-terminal lysines catalyzed in an intramolecular manner.

Tumor Necrosis Factor-alpha- and interleukin-1-induced cellular responses: coupling proteomic and genomic information.

The pro-inflammatory cytokines, Tumor Necrosis Factor-alpha (TNFalpha) and Interleukin-1 (IL-1) mediate the innate immune response. Dysregulation of the innate immune response contributes to the pathogenesis of cancer, arthritis, and congestive heart failure. TNFalpha- and IL-1-induced changes in gene expression are mediated by similar transcription factors; however, TNFalpha and IL-1 receptor knock-out mice differ in their sensitivities to a known initiator (lipopolysaccharide, LPS) of the innate immune response.

The expression level of luciferase within tumour cells can alter tumour growth upon in vivo bioluminescence imaging.

In vivo bioluminescence imaging is becoming a very important tool for the study of a variety of cellular and molecular events or disease processes in living systems. In vivo bioluminescence imaging is based on the detection of light emitted from within an animal. The light is generated as a product of the luciferase-luciferin reaction taking place in a cell.

Phosphorylation of SIMPL modulates RelA-associated NF-kappaB-dependent transcription.

Epidemiological data have implicated perturbations in the regulation of NF-kappaB activity to diseases that affect a large number of Americans today. Specifically, chronic activation of genes involved in the inflammatory response is associated with the progression of and complications in diabetes, arthritis, atherosclerosis, and cancer. Insight into the mechanisms governing the regulation of NF-kappaB transcriptional activity will provide the molecular link between NF-kappaB and these pathological states.

Alpha-lipoic acid modulates ovarian surface epithelial cell growth.

Objective: The intracellular redox state plays an important role in controlling inflammation. Clinical and laboratory data suggest that inflammation can lead to tumor progression. We hypothesized that restoring intracellular redox control would inhibit inflammation and subsequently tumor progression.

Loss of the homotypic fusion and vacuole protein sorting or golgi-associated retrograde protein vesicle tethering complexes results in gentamicin sensitivity in the yeast Saccharomyces cerevisiae.

Gentamicin continues to be a primary antibiotic against gram-negative infections. Unfortunately, associated nephro- and ototoxicity limit its use. Our previous mammalian studies showed that gentamicin is trafficked to the endoplasmic reticulum in a retrograde manner and subsequently released into the cytosol.

The ubiquitin ligase SCFGrr1 is necessary for pheromone sensitivity in Saccharomyces cerevisiae.

The presence of the appropriate pheromone induces alpha and a cells of the yeast Saccharomyces cerevisiae to activate both changes in transcriptional expression and cell polarity that eventually lead to the mating of alpha and a cells to form a/alpha diploid cells. A third response after exposure to mating pheromone is a transient cell cycle arrest, allowing synchronization of the two cell types in G1 prior to cell fusion. At least in part, this cell cycle arrest requires the inactivation of Cln-kinase activity through transcriptional inactivation of the CLN1 and CLN2 genes, degradation of the Cln proteins and direct inhibition of Cln-kinase complexes.

Tumor necrosis factor alpha induction of NF-kappaB requires the novel coactivator SIMPL.

A myriad of stimuli including proinflammatory cytokines, viruses, and chemical and mechanical insults activate a kinase complex composed of IkappaB kinase beta (IKK-beta), IKK-alpha, and IKK-gamma/N, leading to changes in NF-kappaB-dependent gene expression. However, it is not clear how the NF-kappaB response is tailored to specific cellular insults. Signaling molecule that interacts with mouse pelle-like kinase (SIMPL) is a signaling component required for tumor necrosis factor alpha (TNF-alpha)-dependent but not interleukin-1-dependent NF-kappaB activation.

Necessity's sharp pinch.

In a recent issue of Cell, Hughes and coworkers (Mnaimneh et al., 2004) provide a great leap forward in the analysis of essential yeast genes by constructing a strain set that expresses each essential gene from a tetracycline-regulatable promoter.

Rub1p processing by Yuh1p is required for wild-type levels of Rub1p conjugation to Cdc53p.

In Saccharomyces cerevisiae, Rub1p, like ubiquitin, is conjugated to proteins. Before protein conjugation, the carboxyl-terminal asparagine residue of Rub1p is removed. Rub1p conjugation is dependent on the carboxyl-terminal processing enzyme Yuh1p, whereas Rub1p lacking the asparagine residue is conjugated without Yuh1p.

Cutting edge: mouse pellino-2 modulates IL-1 and lipopolysaccharide signaling.

Pellino is a Drosophila protein originally isolated in a two-hybrid screen for proteins interacting with the serine/threonine kinase, pelle. Although mammalian homologs have been identified in mouse and man, the function of pellino is as yet unknown. In this study, the cloning, expression pattern, and a preliminary characterization of mouse pellino-2 is described.

Overexpression of a stabilized mutant form of the cyclin-dependent kinase inhibitor p27(Kip1) inhibits cell growth.

Objective: The purpose of this study was to test the hypothesis that the expression of the mutant p27(Kip1) protein enhances cell growth inhibition and is more stable than that of the wild-type p27(Kip1).

Methods: Site-directed mutagenesis was used to mutate threonine 187 to an alanine residue, generating the mutant p27(Kip1). To study the effects of the p27(Kip1) mutant on cell growth, luciferase assays were performed.