Regulation of Classical Cadherin Membrane Expression and F-Actin Assembly by Alpha-Catenins, during Xenopus Embryogenesis

Alpha (α)-E-catenin is a component of the cadherin complex, and has long been thought to provide a link between cell surface cadherins and the actin skeleton. More recently, it has also been implicated in mechano-sensing, and in the control of tissue size. Here we use the early Xenopus embryos to explore functional differences between two α-catenin family members, α-E- and α-N-catenin, and their interactions with the different classical cadherins that appear as tissues of the embryo become segregated from each other. We show that they play both cadherin-specific and context-specific roles in the emerging tissues of the embryo. α-E-catenin interacts with both C- and E-cadherin. It is specifically required for junctional localization of C-cadherin, but not of E-cadherin or N-cadherin at the neurula stage. α-N-cadherin interacts only with, and is specifically required for junctional localization of, N-cadherin. In addition, α -E-catenin is essential for normal tissue size control in the non-neural ectoderm, but not in the neural ectoderm or the blastula. We also show context specificity in cadherin/ α-catenin interactions. E-cadherin requires α-E-catenin for junctional localization in some tissues, but not in others, during early development. These specific functional cadherin/alpha-catenin interactions may explain the basis of cadherin specificity of actin assembly and morphogenetic movements seen previously in the neural and non-neural ectoderm

Mutant IDH1 promotes glioma formation in vivo

Isocitrate dehydrogenase 1 (IDH1) is the most commonly mutated gene in grade II-III glioma and secondary glioblastoma (GBM). A causal role for IDH1R132H in gliomagenesis has been proposed, but functional validation in vivo has not been demonstrated. In this study, we assessed the role of IDH1R132H in glioma development in the context of clinically relevant cooperating genetic alterations in vitro and in vivo. Immortal astrocytes expressing IDH1R132H exhibited elevated (R)-2-hydroxyglutarate levels, reduced NADPH, increased proliferation, and anchorage-independent growth. Although not sufficient on its own, IDH1R132H cooperated with PDGFA and loss of Cdkn2a, Atrx, and Pten to promote glioma development in vivo. These tumors resembled proneural human mutant IDH1 GBM genetically, histologically, and functionally. Our findings support the hypothesis that IDH1R132H promotes glioma development. This model enhances our understanding of the biology of IDH1R132H-driven gliomas and facilitates testing of therapeutic strategies designed to combat this deadly disease

Mutant IDH1 promotes glioma formation in vivo

Isocitrate dehydrogenase 1 (IDH1) is the most commonly mutated gene in grade II-III glioma and secondary glioblastoma (GBM). A causal role for IDH1R132H in gliomagenesis has been proposed, but functional validation in vivo has not been demonstrated. In this study, we assessed the role of IDH1R132H in glioma development in the context of clinically relevant cooperating genetic alterations in vitro and in vivo. Immortal astrocytes expressing IDH1R132H exhibited elevated (R)-2-hydroxyglutarate levels, reduced NADPH, increased proliferation, and anchorage-independent growth. Although not sufficient on its own, IDH1R132H cooperated with PDGFA and loss of Cdkn2a, Atrx, and Pten to promote glioma development in vivo. These tumors resembled proneural human mutant IDH1 GBM genetically, histologically, and functionally. Our findings support the hypothesis that IDH1R132H promotes glioma development. This model enhances our understanding of the biology of IDH1R132H-driven gliomas and facilitates testing of therapeutic strategies designed to combat this deadly disease

Late seizures in cerebral venous thrombosis.

Objective To examine the incidence, characteristics, treatment, and predictors of late seizures (LS) after cerebral venous thrombosis (CVT), we described these features in a registry of 1,127 patients with CVT. Methods We included consecutive adult patients from an international consortium of 12 hospital-based CVT registries. We excluded patients with a history of epilepsy or with 7 days after diagnosis of CVT. We used multivariable Cox regression to identify predictors of LS. Results We included 1,127 patients with CVT. During a median follow-up of 2.0 years (interquartile range [IQR] 1.0-6.3), 123 patients (11%) experienced >= 1 LS (incidence rate for first LS 30 per 1,000 person-years, 95% confidence interval [CI] 25-35). Median time to first LS was 5 months (IQR 1-16 months). Baseline predictors of LS included status epilepticus in the acute phase (hazard ratio [HR] 7.0, 95% CI 3.9-12.6), decompressive hemicraniectomy (HR 4.2, 95% CI 2.4-7.3), acute seizure(s) without status epilepticus (HR 4.1, 95% CI 2.5-6.5), subdural hematoma (HR 2.3, 95% CI 1.1-4.9), and intracerebral hemorrhage (HR 1.9, 95% CI 1.1-3.1). Eighty-five patients (70% of patients with LS) experienced a recurrent seizure during follow-up, despite the fact that 94% received antiepileptic drug treatment after the first LS. Conclusion During a median follow-up of 2 years, approximate to 1 in 10 patients with CVT had LS. Patients with baseline intracranial bleeding, patients with acute symptomatic seizures, and those who underwent decompressive hemicraniectomy were at increased risk of developing LS. The high recurrence risk of LS justifies epilepsy diagnosis after a first LS

Acute symptomatic seizures in cerebral venous thrombosis.

Objective To identify characteristics, predictors, and outcomes of acute symptomatic seizures (ASS) in cerebral venous thrombosis (CVT), we investigated 1,281 consecutive adult patients with CVT included from 12 hospitals within the International CVT Consortium. Methods We defined ASS as any seizure between symptom onset and 7 days after diagnosis of CVT. We stratified ASS into prediagnosis and solely postdiagnosis ASS. Status epilepticus (SE) was also analyzed separately. We analyzed predictors for ASS and the association between ASS and clinical outcome (modified Rankin Scale) with multivariable logistic regression. Results Of 1,281 eligible patients, 441 (34%) had ASS. Baseline predictors for ASS were intracerebral hemorrhage (ICH; adjusted odds ratio [aOR] 4.1, 95% confidence interval [CI] 3.0-5.5), cerebral edema/infarction without ICH (aOR 2.8, 95% CI 2.0-4.0), cortical vein thrombosis (aOR 2.1, 95% CI 1.5-2.9), superior sagittal sinus thrombosis (aOR 2.0, 95% CI 1.5-2.6), focal neurologic deficit (aOR 1.9, 95% CI 1.4-2.6), sulcal subarachnoid hemorrhage (aOR 1.6, 95% CI 1.1-2.5), and female-specific risk factors (aOR 1.5, 95% CI 1.1-2.1). Ninety-three (7%) patients had solely postdiagnosis ASS, best predicted by cortical vein thrombosis (positive/negative predictive value 22%/92%). Eighty (6%) patients had SE, independently predicted by ICH, focal neurologic deficits, and cerebral edema/infarction. Neither ASS nor SE was independently associated with outcome. Conclusion ASS occurred in one-third of patients with CVT and was associated with brain parenchymal lesions and thrombosis of the superficial system. In the absence of prediagnosis ASS, no subgroup was identified with sufficient risk of postdiagnosis ASS to justify prophylactic antiepileptic drug treatment. We found no association between ASS and outcome