The family of ubiquitin-conjugating enzymes (E2s): deciding between life and death of proteins.

The family of ubiquitin-conjugating (E2) enzymes is characterized by the presence of a highly conserved ubiquitin-conjugating (UBC) domain. These domains accommodate the ATP-activated ubiquitin (Ub) or ubiquitin-like (UBL) protein via a covalently linked thioester onto its active-site residue. E2 enzymes act via selective protein-protein interactions with the E1 and E3 enzymes and connect activation to covalent modification.

Comparison of 18F-fluoro-L-DOPA, 18F-fluoro-deoxyglucose, and 18F-fluorodopamine PET and 123I-MIBG scintigraphy in the localization of pheochromocytoma and paraganglioma.

Context: Besides (123)I-metaiodobenzylguanidine (MIBG), positron emission tomography (PET) agents are available for the localization of paraganglioma (PGL), including (18)F-3,4-dihydroxyphenylalanine (DOPA), (18)F-fluoro-2-deoxy-D-glucose ((18)F-FDG), and (18)F-fluorodopamine ((18)F-FDA).

Objective: The objective of the study was to establish the optimal approach to the functional imaging of PGL and examine the link between genotype-specific tumor biology and imaging.

Design: This was a prospective observational study.

Distinct promoter dynamics of the basal transcription factor TBP across the yeast genome.

Transcription regulation in eukaryotes involves rapid recruitment and proper assembly of transcription factors at gene promoters. To determine the dynamics of the transcription machinery on DNA, we used a differential chromatin immunoprecipitation procedure coupled to whole-genome microarray detection in Saccharomyces cerevisiae. We find that TATA-binding protein (TBP) turnover is low at RNA polymerase I (Pol I) promoters.

In-depth profiling of post-translational modifications on the related transcription factor complexes TFIID and SAGA.

The basal transcription factor TFIID and the chromatin-modifying complex SAGA, which have several subunits in common, are crucial for transcription regulation. Here, we describe an in-depth profiling of post-translational modifications (PTMs) on both TFIID and SAGA from yeast. We took a multipronged approach using high-resolution mass spectrometry (LC-MS) in combination with the proteases Trypsin, Chymotrypsin and Glu-C.

Regulation of vitamin D receptor function in MEN1-related parathyroid adenomas.

Multiple endocrine neoplasia type 1 (MEN1) is a heriditary syndrome characterised by the occurrence of parathyroid, gastroenteropancreatic and pituitary tumours. The MEN1 gene product, menin, co-activates gene transcription by recruiting histone methyltransferases for lysine 4 of histone H3 (H3K4). We investigated whether in MEN1 tumours global changes in H3K4 trimethylation (H3K4me3) occur or whether alterations in gene expression can be observed.

A comprehensive framework of E2-RING E3 interactions of the human ubiquitin-proteasome system.

Covalent attachment of ubiquitin to substrates is crucial to protein degradation, transcription regulation and cell signalling. Highly specific interactions between ubiquitin-conjugating enzymes (E2) and ubiquitin protein E3 ligases fulfil essential roles in this process. We performed a global yeast-two hybrid screen to study the specificity of interactions between catalytic domains of the 35 human E2s with 250 RING-type E3s.

The multiple endocrine neoplasia type 1 (MEN1) tumor suppressor regulates peroxisome proliferator-activated receptor gamma-dependent adipocyte differentiation.

Menin, the product of the MEN1 (multiple endocrine neoplasia type 1) tumor suppressor gene, is involved in activation of gene transcription as part of an MLL1 (mixed-lineage leukemia 1)/MLL2 (KMT2A/B)-containing protein complex which harbors methyltransferase activity for lysine 4 of histone H3 (H3K4). As MEN1 patients frequently develop lipomas and peroxisome proliferator-activated receptor gamma (PPARgamma) is expressed in several MEN1-related tumor types, we investigated regulation of PPARgamma activity by menin. We found that menin is required for adipocyte differentiation of murine 3T3-L1 cells and PPARgamma-expressing mouse embryonic fibroblasts.

Human Ccr4-Not complexes contain variable deadenylase subunits.

The Ccr4-Not complex is evolutionarily conserved and important for regulation of mRNA synthesis and decay. The composition of the yeast complex has been well described. Orthologues of the yeast Ccr4-Not components have been identified in human cells including multiple subunits with mRNA deadenylase activity.

Multiple endocrine neoplasia type 1: a chromatin writer's block.

Multiple endocrine neoplasia type 1 (MEN1) is caused by inactivating germ line mutations of the MEN1 tumour suppressor gene. The MEN1 gene product, menin, participates in many cellular processes, including regulation of gene transcription. As part of a protein complex that writes a trimethyl mark on lysine 4 of histone H3 (H3K4me3), menin is involved in activating gene transcription.

Penetrance and clinical consequences of a gross SDHB deletion in a large family.

Mutations in the gene encoding subunit B of the mitochondrial enzyme succinate dehydrogenase (SDHB) are inherited in an autosomal dominant manner and are associated with hereditary paraganglioma (PGL) and pheochromocytoma. The phenotype of patients with SDHB point mutations has been previously described. However, the phenotype and penetrance of gross SDHB deletions have not been well characterized as they are rarely described.

Clinical aspects of SDHx-related pheochromocytoma and paraganglioma.

Paragangliomas (PGLs) derive from either sympathetic chromaffin tissue in adrenal and extra-adrenal abdominal or thoracic locations, or from parasympathetic tissue of the head and neck. Mutations of nuclear genes encoding subunits B, C, and D of the mitochondrial enzyme succinate dehydrogenase (SDHB 1p35-p36.1, SDHC 1q21, SDHD 11q23) give rise to hereditary PGL syndromes PGL4, PGL3, and PGL1 respectively.

Use of 6-[18F]-fluorodopamine positron emission tomography (PET) as first-line investigation for the diagnosis and localization of non-metastatic and metastatic phaeochromocytoma (PHEO).

Objective: Imaging modalities available for the localization of phaeochromocytoma (PHEO) include computed tomography (CT), magnetic resonance imaging (MRI), [(123)I]- or [(131)I]-labelled metaiodobenzylguanidine ((123/131)I-MIBG) scintigraphy and 6-[(18)F]-fluorodopamine ((18)F-FDA) positron emission tomography (PET). Our aim was to investigate the yield of (18)F-FDA PET vs. biochemical testing and other imaging techniques to establish the diagnosis and location of PHEO.

Brief communication: radiographic contrast infusion and catecholamine release in patients with pheochromocytoma.

Background: Contrast-enhanced computed tomography (CT) is useful for localizing pheochromocytoma. However, in patients with suspected pheochromocytoma, CT is often canceled or not performed because of the strong belief that intravenous contrast may induce hypertensive crisis.

Objective: To examine whether intravenous low-osmolar contrast administration during CT induces catecholamine release that increases blood pressure or heart rate.

Detection and treatment of pheochromocytomas and paragangliomas: current standing of MIBG scintigraphy and future role of PET imaging.

Pheochromocytomas are rare tumors arising from chromaffin cells of adrenal medullary or extra-adrenal paraganglionic tissue. These tumors are characterized by synthesis, storage, metabolism and secretion of catecholamines. Similar to the sympathetic nervous system, pheochromocytomas express cellular norepinephrine transporters (NET) through which catecholamines can enter pheochromocytoma cells to be stored in vesicles.

E2-c-Cbl recognition is necessary but not sufficient for ubiquitination activity.

The E2 ubiquitin-conjugating enzymes UbcH7 and UbcH5B both show specific binding to the RING (really interesting new gene) domain of the E3 ubiquitin-protein ligase c-Cbl, but UbcH7 hardly supports ubiquitination of c-Cbl and substrate in a reconstituted system. Here, we found that neither structural changes nor subtle differences in the E2-E3 interaction surface are possible explanations for the functional specificity of UbcH5B and UbcH7 in their interaction with c-Cbl. The quick transfer of ubiquitin from the UbcH5B-Ub thioester to c-Cbl or other ubiquitin acceptors suggests that UbcH5B might functionally be a relatively pliable E2 enzyme.

Gender-related differences in the clinical presentation of malignant and benign pheochromocytoma.

Signs and symptoms associated with pheochromocytomas are predominantly caused by catecholamine excess, but tend to be highly variable and non-specific. In this study, we evaluated 23 male and 35 female pheochromocytoma patients for symptoms and signs of pheochromocytoma with special regard to gender-related differences in presentation. Total symptom score comparison between genders showed significant differences (12.

Biochemically silent abdominal paragangliomas in patients with mutations in the succinate dehydrogenase subunit B gene.

Context: Patients with adrenal and extra-adrenal abdominal paraganglioma (PGL) almost invariably have increased plasma and urine concentrations of metanephrines, the O-methylated metabolites of catecholamines. We report four cases of biochemically silent abdominal PGL, in which metanephrines were normal despite extensive disease.

Objective: Our objective was to identify the mechanism underlying the lack of catecholamine hypersecretion and metabolism to metanephrines in biochemically silent PGL.

Metastases but not cardiovascular mortality reduces life expectancy following surgical resection of apparently benign pheochromocytoma.

The treatment of choice for non-metastatic pheochromocytoma is surgical resection. Its goals are to abolish catecholamine hypersecretion, normalize blood pressure, and prevent further tumor growth or progression to metastatic disease. Data on long-term mortality and morbidity after pheochromocytoma surgery are limited.

Cooperative action of NC2 and Mot1p to regulate TATA-binding protein function across the genome.

Promoter recognition by TATA-binding protein (TBP) is an essential step in the initiation of RNA polymerase II (pol II) mediated transcription. Genetic and biochemical studies in yeast have shown that Mot1p and NC2 play important roles in inhibiting TBP activity. To understand how TBP activity is regulated in a genome-wide manner, we profiled the binding of TBP, NC2, Mot1p, TFIID, SAGA, and pol II across the yeast genome using chromatin immunoprecipitation (ChIP)-chip for cells in exponential growth and during reprogramming of transcription.

Structural insight into the recognition of the H3K4me3 mark by the TFIID subunit TAF3.

Trimethylation of lysine residue K4 of histone H3 (H3K4me3) strongly correlates with active promoters for RNA polymerase II-transcribed genes. Several reader proteins, including the basal transcription factor TFIID, for this nucleosomal mark have been identified. Its TAF3 subunit specifically binds the H3K4me3 mark via its conserved plant homeodomain (PHD) finger.

Repeated transsphenoidal pituitary surgery (TS) via the endoscopic technique: a good therapeutic option for recurrent or persistent Cushing's disease (CD).

Background: No data on results of repeated transsphenoidal surgery via the endoscopic technique for patients with persistent or recurrent Cushing's disease are available.

Design And Patients: We retrospectively evaluated the remission rates and complications of repeated transsphenoidal surgery via the endoscopic technique in 14 patients with persistent (N = 6) or recurrent (N = 8) Cushing's disease treated in our centre between 1999 and 2007.

Main Outcomes: Remission was defined as the disappearance of symptoms of hypercortisolism with basal plasma cortisol level < or = 50 nmol/l 24-48 h after glucocorticoid withdrawal and/or suppression of plasma cortisol level < or = 50 nmol/l after 1 mg dexamethasone overnight within the first 3 months after transsphenoidal surgery.

Role of positron emission tomography and bone scintigraphy in the evaluation of bone involvement in metastatic pheochromocytoma and paraganglioma: specific implications for succinate dehydrogenase enzyme subunit B gene mutations.

We performed a retrospective analysis of 71 subjects with metastatic pheochromocytoma and paraganglioma (30 subjects with mutation of succinate dehydrogenase enzyme subunit B (SDHB) gene and 41 subjects without SDHB mutation). Sixty-nine percent presented with bone metastases (SDHB +/-: 77% vs 63%), 39% with liver metastases (SDHB +/-: 27% vs 47%), and 32% with lung metastases (SDHB +/-: 37% vs 29%). The most common sites of bone involvement were thoracic spine (80%; SDHB+/-: 83% vs 77%), lumbar spine (78%; SDHB +/-: 78% vs 75%), and pelvic and sacral bones (78%; SDHB +/-: 91% vs 65%, P=0.

Dubbing SAGA unveils new epigenetic crosstalk.

In a recent issue of Molecular Cell, two independent studies (Zhang et al., 2008; Zhao et al., 2008) provide compelling evidence that targeted deubiquitylation of histones is intimately linked to transcription activation, epigenetic regulation, and cancer progression.

Improved genome-wide localization by ChIP-chip using double-round T7 RNA polymerase-based amplification.

Chromatin immunoprecipitation combined with DNA microarrays (ChIP-chip) is a powerful technique to detect in vivo protein-DNA interactions. Due to low yields, ChIP assays of transcription factors generally require amplification of immunoprecipitated genomic DNA. Here, we present an adapted linear amplification method that involves two rounds of T7 RNA polymerase amplification (double-T7).