NEOPLASM study: Real-life use of lacosamide in patients with brain tumor-related epilepsy.

BACKGROUND: The choice of antiepileptic drug (AED) therapy in patients with brain tumor-related epilepsy (BTRE) is complicated, and there are a lack of robust clinical trial data to date. METHODS: The NEOPLASM (Neuroncologic Patients treated with LAcoSaMide) study was a 6-month, multicenter, retrospective, observational study in patients with BTRE treated with lacosamide. Patients were started on lacosamide because of a lack of efficacy or adverse events (AEs) with prior AEDs or suitability versus other AEDs, according to clinical practice. The primary efficacy variable was the seizure-free rate at 6months. Safety variables included the proportion of patients with an AE and the proportion with an AE that led to discontinuation. RESULTS: Overall, 105 patients from 14 hospital centers were included in the analysis. Treatment with lacosamide for 6months resulted in a 30.8% seizure-free rate, and 66.3% of patients had a ≥50% seizure reduction (responders). In the subset of patients included because of a lack of efficacy with prior AEDs, seizure-free rates were 28.0%, and 66.7% of patients were responders. No statistically significant differences in efficacy were observed according to the mechanism of action or enzyme-inducing properties of concomitant AEDs. Adverse events were reported by 41.9% of patients at 6months, and 4.7% of them led to discontinuation. The most common AEs were somnolence/fatigue and dizziness. Notably, 57.1% of the patients who were switched to lacosamide because of AEs with their previous therapy did not report any AE at 6-month follow-up. CONCLUSIONS: In this open-label, observational study, lacosamide appeared to be effective and well tolerated in a large population of patients with BTRE. Lacosamide may therefore be a promising option for the treatment of patients with BTRE.

Association of diffuse idiopathic skeletal hyperostosis and aortic valve sclerosis.

The principal objective of this investigation was to analyze the association between diffuse idiopathic skeletal hyperostosis (DISH) and the presence of aortic valve sclerosis (AVS). For this study we used results from 1000 consecutive outpatients (473 males), older than 50 years of age (average 67.6 years), that had been examined with Doppler echocardiogram and anterior and lateral chest radiographs. Overall, 195 patients (19.5%) were diagnosed with DISH and 283 (28.3%) with AVS. DISH was more prevalent than AVS in males (66.7% vs. 42.6%, p< 0.0001) and in older patients (73.6 ± 9 years vs. 66.1 ± 9 years, p < 0.0001). Furthermore, 55.4% of patients with dorsal DISH presented aortic sclerosis calcification vs. 21.7% of patients free of DISH (OR = 4.47; 95% CI = 3.22-6.21). The adjusted odds ratio (OR) was calculated by sex and age resulting in 3.04 (95% CI = 2.12-4.36; p < .0001). A statistically significant association was found between DISH and AVS in accordance to age and sex. The biological plausibility of this association is based on similar risk factors, pathogenic mechanisms and vascular complications.

Prolyl hydroxylase-dependent modulation of eukaryotic elongation factor 2 activity and protein translation under acute hypoxia.

Early adaptive responses to hypoxia are essential for cell survival, but their nature and underlying mechanisms are poorly known. We have studied the post-transcriptional changes in the proteome of mammalian cells elicited by acute hypoxia and found that phosphorylation of eukaryotic elongation factor 2 (eEF2), a ribosomal translocase whose phosphorylation inhibits protein synthesis, is under the precise and reversible control of O(2) tension. Upon exposure to hypoxia, phosphorylation of eEF2 at Thr(56) occurred rapidly (<15 min) and resulted in modest translational arrest, a fundamental homeostatic response to hypoxia that spares ATP and thus facilitates cell survival. Acute inhibitory eEF2 phosphorylation occurred without ATP depletion or AMP kinase activation. Furthermore, eEF2 phosphorylation was mimicked by prolyl hydroxylase (PHD) inhibition with dimethyloxalylglycine or by selective PHD2 siRNA silencing but was independent of hypoxia-inducible factor α stabilization. Moreover, overexpression of PHD2 blocked hypoxic accumulation of phosphorylated eEF2. Therefore, our findings suggest that eEF2 phosphorylation status (and, as a consequence, translation rate) is controlled by PHD2 activity. They unravel a novel pathway for cell adaptation to hypoxia that could have pathophysiologic relevance in tissue ischemia and cancer.

Hypoxia compromises the mitochondrial metabolism of Alzheimer's disease microglia via HIF1.

Genetic Alzheimer's disease (AD) risk factors associate with reduced defensive amyloid ß plaque-associated microglia (AßAM), but the contribution of modifiable AD risk factors to microglial dysfunction is unknown. In AD mouse models, we observe concomitant activation of the hypoxia-inducible factor 1 (HIF1) pathway and transcription of mitochondrial-related genes in AßAM, and elongation of mitochondria, a cellular response to maintain aerobic respiration under low nutrient and oxygen conditions. Overactivation of HIF1 induces microglial quiescence in cellulo, with lower mitochondrial respiration and proliferation. In vivo, overstabilization of HIF1, either genetically or by exposure to systemic hypoxia, reduces AßAM clustering and proliferation and increases Aß neuropathology. In the human AD hippocampus, upregulation of HIF1α and HIF1 target genes correlates with reduced Aß plaque microglial coverage and an increase of Aß plaque-associated neuropathology. Thus, hypoxia (a modifiable AD risk factor) hijacks microglial mitochondrial metabolism and converges with genetic susceptibility to cause AD microglial dysfunction.

Non-productive angiogenesis disassembles Aß plaque-associated blood vessels.

The human Alzheimer's disease (AD) brain accumulates angiogenic markers but paradoxically, the cerebral microvasculature is reduced around Aß plaques. Here we demonstrate that angiogenesis is started near Aß plaques in both AD mouse models and human AD samples. However, endothelial cells express the molecular signature of non-productive angiogenesis (NPA) and accumulate, around Aß plaques, a tip cell marker and IB4 reactive vascular anomalies with reduced NOTCH activity. Notably, NPA induction by endothelial loss of presenilin, whose mutations cause familial AD and which activity has been shown to decrease with age, produced a similar vascular phenotype in the absence of Aß pathology. We also show that Aß plaque-associated NPA locally disassembles blood vessels, leaving behind vascular scars, and that microglial phagocytosis contributes to the local loss of endothelial cells. These results define the role of NPA and microglia in local blood vessel disassembly and highlight the vascular component of presenilin loss of function in AD.

Evaluation of an array-based method for human papillomavirus detection and genotyping in comparison with conventional methods used in cervical cancer screening.

Cervical cancer is the second-most prevalent cancer in young women around the world. Infection with human papillomavirus (HPV), especially high-risk HPV types (HR-HPV), is necessary for the development of this cancer. HPV-DNA detection is increasingly being used in cervical cancer screening programs, together with the Papanicolau smear test. We evaluated the usefulness of introducing this new array-based HPV genotyping method (i.e., Clinical Arrays Papillomavirus Humano) in the cervical cancer screening algorithm in our center. The results obtained using this method were compared to those obtained by the hybrid capture II high-risk HPV DNA test (HC-II) and Papanicolau in a selected group of 408 women. The array-based assay was performed in women that were HC-II positive or presented cytological alterations. Among 246 array-positive patients, 123 (50%) presented infection with >or=2 types, and HR-HPV types were detected in 206 (83.7%), mainly HPV-16 (24.0%). Up to 132 (33.2%) specimens were classified as ASCUS (for atypical squamous cells of undetermined significance), and only 48 (36.4%) of them were HPV-DNA positive by either assay; however, 78.7% of these cases were caused by HR-HPV types. The agreement between both HPV-DNA detection techniques was fairly good (n = 367). Screening with Papanicolau smear and HC-II tests, followed by HPV detection and genotyping, provided an optimal identification of women at risk for the development of cervical cancer. Furthermore, with the identification of specific genotypes, either in single or multiple infections, a better prediction of disease progression was achieved. The array method also made allowed us to determine the possible contribution of the available vaccines in our setting.

A new MR radiological sign in HaNDL syndrome. A case report.

BACKGROUND: One of the classical diagnostic criteria of the syndrome of transient headache and neurologic deficits with cerebrospinal fluid lymphocytosis (HaNDL syndrome) is the normality of imaging studies except from some reversible alterations as leptomeningeal enhancement or focal hypoperfusion. CASE: We present a 41 year-old man who abruptly started with a set of right parietal symptoms, meeting the diagnostic criteria for HaNDL syndrome. An electroencephalographic record showed a slowing of the right hemisphere. MR susceptibility weighted sequences demonstrated a reduced venous signal in the symptomatic hemisphere, unlike other transient disorders as migraine aura where an opposite pattern with prominence of the venous structures in the symptomatic hemisphere has been reported. This sign could reflect a decrease in metabolic demands or a fail in oxygen employment by the affected tissue. CONCLUSION: To our knowledge, this finding has not been described yet, and it may provide a new insight on the pathogenesis of HaNDL syndrome.

The Cornelia de Lange Syndrome-associated factor NIPBL interacts with BRD4 ET domain for transcription control of a common set of genes.

Mutations in NIPBL are the major cause of Cornelia de Lange Syndrome (CdLS). NIPBL is the cohesin-loading factor and has recently been associated with the BET (bromodomains and extra-terminal (ET) domain) proteins BRD2 and BRD4. Related to this, a CdLS-like phenotype has been described associated to BRD4 mutations. Here, we show direct interaction of NIPBL with different BET members in yeast, and selective interaction with BRD4 in cells, being the ET domain involved in the interaction. To understand the relationship between NIPBL and BET proteins, we have performed RNA-Seq expression analysis following depletion of the different proteins. Results indicate that genes regulated by NIPBL largely overlap with those regulated by BRD4 but not with those regulated by BRD2. ChIP-Seq analysis indicates preferential NIPBL occupancy at promoters, and knockdown experiments show mutual stabilization of NIPBL and BRD4 on co-regulated promoters. Moreover, human fibroblasts from CdLS probands with mutations in NIPBL show reduced BRD4 at co-occupied promoters. Functional analysis in vivo, using mutants of Drosophila melanogaster, confirmed the genetic interaction between Nipped-B and fs(1)h, the orthologs of human NIPBL and BRD4, respectively. Thus, we provide evidence for NIPBL and BRD4 cooperation in transcriptional regulation, which should contribute to explain the recently observed CdLS-like phenotype associated with BRD4 mutations.

Acute and Chronic Sustained Hypoxia Do Not Substantially Regulate Amyloid-ß Peptide Generation In Vivo.

BACKGROUND: Recent epidemiological evidence has linked hypoxia with the development of Alzheimer disease (AD). A number of in vitro and in vivo studies have reported that hypoxia can induce amyloid-ß peptide accumulation through various molecular mechanisms including the up-regulation of the amyloid-ß precursor protein, the ß-secretase Bace1, or the γγ-secretase complex components, as well as the down-regulation of Aß-degrading enzymes. OBJECTIVES: To investigate the effects of acute and chronic sustained hypoxia in Aß generation in vivo. METHODS: 2-3 month-old C57/Bl6J wild-type mice were exposed to either normoxia (21% O2) or hypoxia (9% O2) for either 4 to 72 h (acute) or 21-30 days (chronic sustained) in a hermetic chamber. Brain mRNA levels of Aß-related genes were measured by quantitative real-time PCR, whereas levels of Bace1 protein, full length AßPP, and its C-terminal fragments (C99/C88 ratio) were measured by Western blot. In addition, 8 and 14-month-old APP/PS1 transgenic mice were subjected to 9% O2 for 21 days and levels of Aß40, Aß42, full length AßPP, and soluble AßPPα (sAßPPα) were measured by ELISA or WB. RESULTS: Hypoxia (either acute or chronic sustained) did not impact the transcription of any of the Aß-related genes in young wild-type mice. A significant reduction of Bace1 protein level was noted with acute hypoxia for 16 h but did not correlate with an increased level of full length AßPP or a decreased C99/C83 ratio. Chronic sustained hypoxia did not significantly alter the levels of Bace1, full length AßPP or the C99/C83 ratio. Last, chronic sustained hypoxia did not significantly change the levels of Aß40, Aß42, full length AßPP, or sAßPPα in either young or aged APP/PS1 mice. DISCUSSION: Our results argue against a hypoxia-induced shift of AßPP proteolysis from the non-amyloidogenic to the amyloidogenic pathways. We discuss the possible methodological caveats of previous in vivo studies.

QuEChERS Adaptability for the Analysis of Pesticide Residues in Beehive Products Seeking the Development of an Agroecosystem Sustainability Monitor.

Beehive products could be powerful monitors of pesticide residues originating in agroecosystems during production cycles. Their ready availability provides enough samples to perform analytical determinations, but their chemical complexity makes residue analysis a real challenge. Taking advantage of the plasticity of QuEChERS coupled to LC-MS/MS, validated methodologies were developed for bees, honey, beeswax, and pollen and applied to real samples for the simultaneous determination of 19 of the most employed pesticides in intensive cropping fields. Beehives placed in Uruguayan agroecosystems accumulated the pesticides thiacloprid, imidacloprid, methomyl, carbaryl, hexythiazox, azoxystrobin, pyraclostrobin, tebuconazole, and haloxyfop-methyl at 0.0001-0.01 mg/kg levels. The oscillations on the amount and occurrence of residue findings for specific apiaries were correlated statistically with the sampling season and the agroecosystem where the beehives were located, showing the potential of bees and bee products to record relevant information to survey the chemicals applied in their surroundings.

Periodic lateralized epileptiform discharges: etiology, clinical aspects, seizures, and evolution in 130 patients.

The purpose of this study was to analyze the clinical aspects in 130 patients presenting periodic lateralized epileptiform discharges (PLEDs) in their EEG and to compare these results with those found in the literature. Etiology, neurologic deficit, seizure occurrence, and evolution were studied in each patient by historical review. The recordings were obtained on 8- or 16-channel EEGs with electrode placement according to the International 10-20 System. Recordings containing PLEDs were selected. PLEDs were defined as repetitive periodic, focal, or hemispheric epileptiform discharges (spikes, spike and waves, polyspikes, sharp waves) usually recurring every 1 to 2 seconds. The statistical study was carried out via the chi(2) test using the computer program SPSS. The main etiology found in this group of patients was stroke (61 of 130 patients). Other processes found were brain infections, tumors, hematomas, and several other entities grouped together as miscellaneous (anoxic encephalopathy, subarachnoid hemorrhage, craniocerebral trauma, Creutzfeldt-Jacob disease, migraine, multiple sclerosis, and aminophylline intoxication). Half of these patients (65 of 130) developed seizures, mostly partial motor seizures. No significant relation between etiology and seizures was found (chi(2) = 2.81, P = 0.4222). Seizures recurred in 14 of 130 patients during a follow-up of 14.5 months. PLEDs were not recorded in any EEG at the time of seizure recurrence. PLEDs constitute a distinctive but uncommon EEG phenomenon of repetitive, periodic, and stereotyped lateralized complexes. In agreement with the literature, PLEDs were associated with an acute process and occurred early during the course of the illness in all patients studied and were usually associated with structural lesions, with stroke being the main etiology. Traditionally, seizures occur with PLEDs but it is also accepted that they can exist in patients who never develop epileptic activity, either clinically or electrically, as demonstrated in 50% of the patients studied. No significant association between seizures and any etiology could be found. It was not demonstrated that the occurrence of seizures may influence the outcome in any way.

Effects of alprazolam on cortical activity and tremors in patients with essential tremor.

BACKGROUND: Essential tremor (ET) is characterised by postural and action tremors with a frequency of 4-12 Hz. Previous studies suggest that the tremor activity originates in the cerebello-thalamocortical pathways. Alprazolam is a short-acting benzodiazepine that attenuates tremors in ET. The mechanisms that mediate the therapeutic action of alprazolam are unknown; however, in healthy subjects, benzodiazepines increase cortical beta activity. In this study, we investigated the effect of alprazolam both on beta and tremor-related cortical activity and on alterations in tremor presentation in ET patients. Therefore, we characterised the dynamics of tremor and cortical activity in ET patients after alprazolam intake. METHODS: We recorded hand tremors and contralateral cortical activity in four recordings before and after a single dose of alprazolam. We then computed the changes in tremors, cortico-muscular coherence, and cortical activity at the tremor frequency and in the beta band. RESULTS: Alprazolam significantly attenuated tremors (EMG: 76.2 ± 22.68%), decreased cortical activity in the tremor frequency range and increased cortical beta activity in all patients (P<0.05). At the same time, the cortico-muscular coherence at the tremor frequency became non-significant (P<0.05). We also found a significant correlation (r = 0.757, P<0.001) between the reduction in tremor severity and the increased ratio of cortical activity in the beta band to the activity observed in the tremor frequency range. CONCLUSIONS: This study provides the first quantitative analysis of tremor reduction following alprazolam intake. We observed that the tremor severity decreased in association with an increased ratio of beta to tremor-related cortical activity. We hypothesise that the increase in cortical beta activity may act as a blocking mechanism and may dampen the pathological oscillatory activity, which in turn attenuates the observed tremor.

Brahma is required for proper expression of the floral repressor FLC in Arabidopsis.

BACKGROUND: BRAHMA (BRM) is a member of a family of ATPases of the SWI/SNF chromatin remodeling complexes from Arabidopsis. BRM has been previously shown to be crucial for vegetative and reproductive development. METHODOLOGY/PRINCIPAL FINDINGS: Here we carry out a detailed analysis of the flowering phenotype of brm mutant plants which reveals that, in addition to repressing the flowering promoting genes CONSTANS (CO), FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRESSION OF CO1 (SOC1), BRM also represses expression of the general flowering repressor FLOWERING LOCUS C (FLC). Thus, in brm mutant plants FLC expression is elevated, and FLC chromatin exhibits increased levels of histone H3 lysine 4 tri-methylation and decreased levels of H3 lysine 27 tri-methylation, indicating that BRM imposes a repressive chromatin configuration at the FLC locus. However, brm mutants display a normal vernalization response, indicating that BRM is not involved in vernalization-mediated FLC repression. Analysis of double mutants suggests that BRM is partially redundant with the autonomous pathway. Analysis of genetic interactions between BRM and the histone H2A.Z deposition machinery demonstrates that brm mutations overcome a requirement of H2A.Z for FLC activation suggesting that in the absence of BRM, a constitutively open chromatin conformation renders H2A.Z dispensable. CONCLUSIONS/SIGNIFICANCE: BRM is critical for phase transition in Arabidopsis. Thus, BRM represses expression of the flowering promoting genes CO, FT and SOC1 and of the flowering repressor FLC. Our results indicate that BRM controls expression of FLC by creating a repressive chromatin configuration of the locus.

The beauty of being a variant: H2A.Z and the SWR1 complex in plants.

Numerous studies have shown that the nucleosome is a dynamic structure that strongly influences gene expression. Dynamism concerns different nucleosomal characteristics, including position, posttranslational modifications, and histone composition. Thus, within the nucleosome, canonical histones can be exchanged by histone variant proteins with specific functions-a process known as 'histone replacement'. The histone variant H2A.Z has an important function in transcription and, during the last few years, its role in plant development and immune response has become evident. Compiling genetic and biochemical studies from several laboratories has revealed that plants contain a multiprotein complex, similar to the SWR1/SRCAP complex from yeast and animals, involved in H2A.Z deposition. Despite intense research in different organisms, the mechanism by which H2A.Z influences transcription is still unknown. However, recent results from Arabidopsis have shown a strong inverse correlation between H2A.Z and DNA methylation, suggesting that H2A.Z might protect genes from silencing.

Association of diffuse idiopathic skeletal hyperostosis and aortic valve sclerosis / Asociación de hiperostosis esquelética idiopática difusa y esclerosis valvular aórtica

The principal objective of this investigation was to analyze the association between diffuse idiopathic skeletal hyperostosis (DISH) and the presence of aortic valve sclerosis (AVS). For this study we used results from 1000 consecutive outpatients (473 males), older than 50 years of age (average 67.6 years), that had been examined with Doppler echocardiogram and anterior and lateral chest radiographs. Overall, 195 patients (19.5%) were diagnosed with DISH and 283 (28.3%) with AVS. DISH was more prevalent than AVS in males (66.7% vs. 42.6%, p< 0.0001) and in older patients (73.6 ± 9 years vs. 66.1 ± 9 years, p < 0.0001). Furthermore, 55.4% of patients with dorsal DISH presented aortic sclerosis calcification vs. 21.7% of patients free of DISH (OR = 4.47; 95% CI = 3.22-6.21). The adjusted odds ratio (OR) was calculated by sex and age resulting in 3.04 (95% CI = 2.12-4.36; p < .0001). A statistically significant association was found between DISH and AVS in accordance to age and sex. The biological plausibility of this association is based on similar risk factors, pathogenic mechanisms and vascular complications.

El objetivo principal fue analizar la asociación entre la hiperostosis esquelética idiopática difusa (DISH) y la presencia de esclerosis valvular aórtica (AVS). Se evaluaron los resultados de 1000 pacientes ambulatorios consecutivos (473 varones), mayores de 50 años (promedio, 67.6 años), que habían sido examinados con un ecocardiograma Doppler y radiología torácica anterior y lateral. Globalmente, 195 pacientes (19.5%) tuvieron diagnóstico de DISH y 283 (28.3%) de AVS. DISH fue más prevalente que AVS en varones (66.7% vs. 42.6%, p < 0.0001) y en pacientes de mayor edad (73.6 ± 9 años vs. 66.1 ± 9 años, p < 0.0001). Además, 55.4% de los pacientes con DISH dorsal presentaron AVS vs. 21.7% de los pacientes sin DISH (OR = 4.47; 95% CI = 3.22-6.21). El odds ratio (OR) ajustado por sexo y edad fue 3.04 (95% CI = 2.12-4.36; p < 0.0001). Se encontró una asociación estadísticamente significativa entre DISH y AVS, que se mantuvo después de ajustar por sexo y edad. La plausibilidad biológica de esta asociación se basa en los factores de riesgo, mecanismos patogénicos y complicaciones vasculares compartidos.

Association of diffuse idiopathic skeletal hyperostosis and aortic valve sclerosis / Asociación de hiperostosis esquelética idiopática difusa y esclerosis valvular aórtica

The principal objective of this investigation was to analyze the association between diffuse idiopathic skeletal hyperostosis (DISH) and the presence of aortic valve sclerosis (AVS). For this study we used results from 1000 consecutive outpatients (473 males), older than 50 years of age (average 67.6 years), that had been examined with Doppler echocardiogram and anterior and lateral chest radiographs. Overall, 195 patients (19.5%) were diagnosed with DISH and 283 (28.3%) with AVS. DISH was more prevalent than AVS in males (66.7% vs. 42.6%, p< 0.0001) and in older patients (73.6 ± 9 years vs. 66.1 ± 9 years, p < 0.0001). Furthermore, 55.4% of patients with dorsal DISH presented aortic sclerosis calcification vs. 21.7% of patients free of DISH (OR = 4.47; 95% CI = 3.22-6.21). The adjusted odds ratio (OR) was calculated by sex and age resulting in 3.04 (95% CI = 2.12-4.36; p < .0001). A statistically significant association was found between DISH and AVS in accordance to age and sex. The biological plausibility of this association is based on similar risk factors, pathogenic mechanisms and vascular complications.(AU)

El objetivo principal fue analizar la asociación entre la hiperostosis esquelética idiopática difusa (DISH) y la presencia de esclerosis valvular aórtica (AVS). Se evaluaron los resultados de 1000 pacientes ambulatorios consecutivos (473 varones), mayores de 50 años (promedio, 67.6 años), que habían sido examinados con un ecocardiograma Doppler y radiología torácica anterior y lateral. Globalmente, 195 pacientes (19.5%) tuvieron diagnóstico de DISH y 283 (28.3%) de AVS. DISH fue más prevalente que AVS en varones (66.7% vs. 42.6%, p < 0.0001) y en pacientes de mayor edad (73.6 ± 9 años vs. 66.1 ± 9 años, p < 0.0001). Además, 55.4% de los pacientes con DISH dorsal presentaron AVS vs. 21.7% de los pacientes sin DISH (OR = 4.47; 95% CI = 3.22-6.21). El odds ratio (OR) ajustado por sexo y edad fue 3.04 (95% CI = 2.12-4.36; p < 0.0001). Se encontró una asociación estadísticamente significativa entre DISH y AVS, que se mantuvo después de ajustar por sexo y edad. La plausibilidad biológica de esta asociación se basa en los factores de riesgo, mecanismos patogénicos y complicaciones vasculares compartidos.(AU)

The PHD domain of plant PIAS proteins mediates sumoylation of bromodomain GTE proteins.

Covalent attachment of small ubiquitin-like modifier (SUMO) to proteins regulates multiple processes in the eukaryotic cell. In numerous cases sumoylation is facilitated by protein inhibitor of activated STAT (PIAS) proteins, characterized by the presence of a SP-RING domain related to the RING finger of many ubiquitin E3 ligases. The importance of SP-RING relies on its capacity to bind the E2 enzyme of the pathway. Additional domains may participate in SUMO ligase function and target selection. We have studied the Arabidopsis SUMO ligase AtSIZ1, belonging to the PIAS family, and describe self-sumoylation and AtSIZ1-mediated sumoylation of the E2 enzyme AtSCE1 and GTE3, a bromodomain protein interacting with AtSIZ1. Modification of GTE3 modulates its capacity to bind acetyl-histone H3 in vitro. Interestingly, AtSIZ1, as other plant PIAS proteins, also includes a PHD domain. We found that the PHD domain binds AtSCE1 and contributes to the SUMO ligase function, being partially and absolutely required for AtSCE1 and GTE3 sumoylation, respectively. Based on the capacity of AtSCE1 and GTE3 to associate with both the PHD and SP-RING domains, we propose a model of interactions to explain AtSIZ1-mediated sumoylation of GTE3 and ligase function of the PHD domain.

Histone H2A.Z and homologues of components of the SWR1 complex are required to control immunity in Arabidopsis.

One of the mechanisms involved in chromatin remodelling is so-called 'histone replacement'. An example of such a mechanism is the substitution of canonical H2A histone by the histone variant H2A.Z. The ATP-dependent chromatin remodelling complex SWR1 is responsible for this action in yeast. We have previously proposed the existence of an SWR1-like complex in Arabidopsis by demonstrating genetic and physical interaction of the components SEF, ARP6 and PIE1, which are homologues of the yeast Swc6 and Arp6 proteins and the core ATPase Swr1, respectively. Here we show that histone variant H2A.Z, but not canonical H2A histone, interacts with PIE1. Plants mutated at loci HTA9 and HTA11 (two of the three Arabidopsis H2A.Z-coding genes) displayed developmental abnormalities similar to those found in pie1, sef and arp6 plants, exemplified by an early-flowering phenotype. Comparison of gene expression profiles revealed that 65% of the genes differentially regulated in hta9 hta11 plants were also mis-regulated in pie1 plants. Detailed examination of the expression data indicated that the majority of mis-regulated genes were related to salicylic acid-dependent immunity. RT-PCR and immunoblotting experiments confirmed constitutive expression of systemic acquired resistance (SAR) marker genes in pie1, hta9 hta11 and sef plants. Variations observed at the molecular level resulted in phenotypic alterations such as spontaneous cell death and enhanced resistance to the phytopathogenic bacteria Pseudomonas syringae pv. tomato. Thus, our results support the existence in Arabidopsis of an SWR1-like chromatin remodelling complex that is functionally related to that described in yeast and human, and attribute to this complex a role in maintaining a repressive state of the SAR response.

SEF, a new protein required for flowering repression in Arabidopsis, interacts with PIE1 and ARP6.

The SWR1/SRCAP complex is a chromatin-remodeling complex that has been shown to be involved in substitution of histone H2A by the histone variant H2A.Z in yeast (Saccharomyces cerevisiae) and animals. Here, we identify and characterize SERRATED LEAVES AND EARLY FLOWERING (SEF), an Arabidopsis (Arabidopsis thaliana) homolog of the yeast SWC6 protein, a conserved subunit of the SWR1/SRCAP complex. SEF loss-of-function mutants present a pleiotropic phenotype characterized by serrated leaves, frequent absence of inflorescence internodes, bushy aspect, and flowers with altered number and size of organs. sef plants flower earlier than wild-type plants both under inductive and noninductive photoperiods. This correlates with strong reduction of FLOWERING LOCUS C and MADS-AFFECTING FLOWERING4 transcript levels and up-regulation of FLOWERING LOCUS T and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 gene expression. The sef phenotype is similar to that of the photoperiod-independent early flowering1 (pie1) and the actin-related protein 6 (arp6) mutants. PIE1 and ARP6 proteins are also homologs of SWR1/SRCAP complex subunits. Analysis of sef pie1 double mutants demonstrates genetic interaction between these two genes. We also show physical interactions between SEF, ARP6, and PIE1 proteins. Taken together, our data indicate that SEF, ARP6, and PIE1 might form a molecular complex in Arabidopsis related to the SWR1/SRCAP complex identified in other eukaryotes.

Venous angioma associated with atypical ophthalmoplegic migraine.

BACKGROUND: Ophthalmoplegic migraine is a rare syndrome in which episodic headaches are associated with ophthalmoplegia. Several recent reports emphasize the possibility, especially in atypical cases, of a heterogeneous type of ophthalmoplegic migraine. METHODS: We describe the case of an 18-year-old woman with recurrent episodic headache accompanied by binocular diplopia due to left third cranial nerve palsy. The symptoms resolve in hours. A diagnosis of atypical ophthalmoplegic migraine was established. RESULTS: Digital angiography revealed a venous angioma draining into the left cavernous sinus. CONCLUSIONS: This case reveals the importance of differential diagnosis in atypical migraine in which the symptomatology could be secondary to intracranial lesions. We propose venous stasis as a cause of symptoms.