SummarySex has a role in the incidence and outcome of neurological illnesses, also influencing the response to treatments. Neuroinflammation is involved in the onset and progression of several neurological diseases, and the fact that estrogens have anti-inflammatory activity suggests that these hormones may be a determinant in the sex-dependent manifestation of brain pathologies. We describe significant differences in the transcriptome of adult male and female microglia, possibly originating from perinatal exposure to sex steroids. Microglia isolated from adult brains maintain the sex-specific features when put in culture or transplanted in the brain of the opposite sex. Female microglia are neuroprotective because they restrict the damage caused by acute focal cerebral ischemia. This study therefore provides insight into a distinct perspective on the mechanisms underscoring a sexual bias in the susceptibility to brain diseases.

Abstract-Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited disease characterized by life threatening arrhythmias and mutations in the gene encoding the ryanodine receptor (RyR2). Disagreement exists on whether (1) RyR2 mutations induce abnormal calcium transients in the absence of adrenergic stimulation; (2) decreased affinity of mutant RyR2 for FKBP12.6 causes CPVT; (3) K201 prevent arrhythmias by normalizing the FKBP12.6-RyR2 binding. We studied ventricular myocytes isolated from wild-type (WT) and knock-in mice harboring the R4496C mutation (RyR2 R4496Cϩ/Ϫ ). Pacing protocols did not elicit delayed afterdepolarizations (DADs) (nϭ20) in WT but induced DADs in 21 of 33 (63%) RyR2R4496Cϩ/Ϫ myocytes (Pϭ0.001). Superfusion with isoproterenol (30 nmol/L) induced small DADs (45%) and no triggered activity in WT myocytes, whereas it elicited DADs in 87% and triggered activity in 60% of RyR2R4496Cϩ/Ϫ myocytes (Pϭ0.001). DADs and triggered activity were abolished by ryanodine (10 mol/L) but not by K201 (1 mol/L or 10 mol/L). In vivo administration of K201 failed to prevent induction of polymorphic ventricular tachycardia (VT) in RyR2R4496Cϩ/Ϫ mice. Measurement of the FKBP12.6/RyR2 ratio in the heavy sarcoplasmic reticulum membrane showed normal RyR2-FKBP12.6 interaction both in WT and RyR2R4496Cϩ/Ϫ either before and after treatment with caffeine and epinephrine. We suggest that (1) triggered activity is the likely arrhythmogenic mechanism of CPVT; (2) K201 fails to prevent DADs in RyR2R4496Cϩ/Ϫ myocytes and ventricular arrhythmias in RyR2R4496Cϩ/Ϫ mice; and (3) RyR2-FKBP12.6 interaction in RyR2 R4496Cϩ/Ϫ is identical to that of WT both before and after epinephrine and caffeine, thus suggesting that it is unlikely that the R4496C mutation interferes with the RyR2/FKBP12.6 complex. Key Words: cardiac electrophysiology Ⅲ ryanodine receptor Ⅲ sudden death Ⅲ transgenic mice Ⅲ ventricular tachycardia C atecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmogenic disease characterized by adrenergically mediated bidirectional or polymorphic ventricular tachycardia leading to syncope and/or sudden cardiac death in individuals without structural heart disease. 1,2 In 2001, we reported that the autosomal dominant form of CPVT is caused by mutations in the ryanodine receptor gene (RyR2). 3 Based on the evidence that the morphology of ventricular tachycardia observed in CPVT resembles that of digitalis induced ventricular tachycardia (VT), it had been suggested that arrhythmogenesis in CPVT could be mediated by delayed afterdepolarizations (DADs) and triggered activity. Although the discovery that CPVT is caused by mutations in the ryanodine receptor has substantiated this hypothesis, up to now no conclusive demonstration that DADs cause CPVT is available.Furthermore, although several authors have characterized in vitro the functional consequences of RyR2 mutations, 4 -6 the molecular and electrophysiological derangements leading to arrhythmias in CPVT patients are still uncl...

Heat shock triggers the assembly of nuclear stress bodies that contain heat shock factor 1 and a subset of RNA processing factors. These structures are formed on the pericentromeric heterochromatic regions of specific human chromosomes, among which chromosome 9. In this article we show that these heterochromatic domains are characterized by an epigenetic status typical of euchromatic regions. Similarly to transcriptionally competent portions of the genome, stress bodies are, in fact, enriched in acetylated histone H4. Acetylation peaks at 6 h of recovery from heat shock. Moreover, heterochromatin markers, such as HP1 and histone H3 methylated on lysine 9, are excluded from these nuclear districts. In addition, heat shock triggers the transient accumulation of RNA molecules, heterogeneous in size, containing the subclass of satellite III sequences found in the pericentromeric heterochromatin of chromosome 9. This is the first report of a transcriptional activation of a constitutive heterochromatic portion of the genome in response to stress stimuli.

Abstract-Cardiac] i transients Ⅲ ryanodine receptor Ⅲ excitation-contraction coupling Ⅲ CPVT C atecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmogenic disease characterized by stress-induced, adrenergically mediated bidirectional or polymorphic ventricular tachycardia occurring in structurally normal hearts. 1 During exercise or acute emotions, CPVT patients develop life-threatening ventricular arrhythmias, leading to syncope or sudden death. The first cardiac ryanodine receptor (RyR2) mutation identified in a CPVT family was R4497C. 2 Today, more than 70 RyR2 mutations have been reported (http://www.fsm.it/cardmoc), and they comprise the most common genetic subtype of CPVT, 3-7 although mutations in the calsequestrin gene can also cause CPVT. 8,9 Diverging results and conclusions have been generated from expression studies of RyR2 R4496C in heterologous systems. Jiang et al showed that RyR2 R4496C (the mouse equivalent of the human RyR2 R4497C mutation), when expressed in human embryonic kidney (HEK) cells, exhibits increased basal activity and increased sensitivity to luminal Ca 2ϩ . 10 However, other authors found no difference in the basal activity of RyR2 R4497C but, instead, showed increased activity and gating frequency after protein kinase A phosphorylation 11 or sarcoplasmic reticulum (SR) Ca 2ϩ overload. 12 The expression studies were carried out in a variety of models, which may explain the inhomogeneous findings. Furthermore, heterologous systems lack cardiac intracellular environment with all the RyR2 accessory proteins 13 and most Ca 2ϩ -handling proteins, so analysis in native cardiac myocytes is now critical to elucidate the mechanisms by which the mutation leads to cardiac arrhythmia.Recently, a knock-in mouse model carrier of the RyR2 R4496C mutation was developed. 14 Their phenotype presents extraordinary similarity with the clinical manifestations of patients carrying the RyR2 R4497C mutation, including the development of bidirectional ventricular tachycardia. When exposed to adrenaline and caffeine, the RyR2 R4496C cardiomyocytes develop delayed afterdepolarizations (DADs), 15 suggesting that triggered arrhythmias are elicited by adrenergic activation. 16 Here we demonstrate that untreated RyR2 R4496C myocytes have increased spontaneous Ca 2ϩ release in diastole during electric pacing, because of the enhanced Ca 2ϩ sensitivity of mutant RyR2; this abnormality is further augmented by exposure to isoproterenol and increasing pacing rates. Materials and Methods Ventricular cardiomyocytes from male and female RyR2R4496Cϩ/Ϫ mice (RyR2 R4496C ) and their wild-type (WT) RyR2 R4496CϪ/Ϫ littermates were isolated using a standard enzymatic digestion. 17 [Ca 2ϩ ] i transients and Ca 2ϩ sparks were viewed in isolated myocytes by confocal microscopy and analyzed using homemade routines. All experiments were carried out according to the ethical principles laid down by the French (Ministry of Agriculture) and European Union

Background— Four distinct mutations in the human cardiac calsequestrin gene ( CASQ2 ) have been linked to catecholaminergic polymorphic ventricular tachycardia (CPVT). The mechanisms leading to the clinical phenotype are still poorly understood because only 1 CASQ2 mutation has been characterized in vitro. Methods and Results— We identified a homozygous 16-bp deletion at position 339 to 354 leading to a frame shift and a stop codon after 5aa (CASQ2 G112+5X ) in a child with stress-induced ventricular tachycardia and cardiac arrest. The same deletion was also identified in association with a novel point mutation (CASQ2 L167H ) in a highly symptomatic CPVT child who is the first CPVT patient carrier of compound heterozygous CASQ2 mutations. We characterized in vitro the properties of CASQ2 mutants: CASQ2 G112+5X did not bind Ca 2+ , whereas CASQ2 L167H had normal calcium-binding properties. When expressed in rat myocytes, both mutants decreased the sarcoplasmic reticulum Ca 2+ -storing capacity and reduced the amplitude of I Ca -induced Ca 2+ transients and of spontaneous Ca 2+ sparks in permeabilized myocytes. Exposure of myocytes to isoproterenol caused the development of delayed afterdepolarizations in CASQ2 G112+5X . Conclusions— CASQ2 L167H and CASQ2 G112+5X alter CASQ2 function in cardiac myocytes, which leads to reduction of active sarcoplasmic reticulum Ca 2+ release and calcium content. In addition, CASQ2 G112+5X displays altered calcium-binding properties and leads to delayed afterdepolarizations. We conclude that the 2 CASQ2 mutations identified in CPVT create distinct abnormalities that lead to abnormal intracellular calcium regulation, thus facilitating the development of tachyarrhythmias.

The luminal Ca2+ regulation of cardiac ryanodine receptor (RyR2) was explored at the single channel level. The luminal Ca2+ and Mg2+ sensitivity of single CSQ2-stripped and CSQ2-associated RyR2 channels was defined. Action of wild-type CSQ2 and of two mutant CSQ2s (R33Q and L167H) was also compared. Two luminal Ca2+ regulatory mechanism(s) were identified. One is a RyR2-resident mechanism that is CSQ2 independent and does not distinguish between luminal Ca2+ and Mg2+. This mechanism modulates the maximal efficacy of cytosolic Ca2+ activation. The second luminal Ca2+ regulatory mechanism is CSQ2 dependent and distinguishes between luminal Ca2+ and Mg2+. It does not depend on CSQ2 oligomerization or CSQ2 monomer Ca2+ binding affinity. The key Ca2+-sensitive step in this mechanism may be the Ca2+-dependent CSQ2 interaction with triadin. The CSQ2-dependent mechanism alters the cytosolic Ca2+ sensitivity of the channel. The R33Q CSQ2 mutant can participate in luminal RyR2 Ca2+ regulation but less effectively than wild-type (WT) CSQ2. CSQ2-L167H does not participate in luminal RyR2 Ca2+ regulation. The disparate actions of these two catecholaminergic polymorphic ventricular tachycardia (CPVT)–linked mutants implies that either alteration or elimination of CSQ2-dependent luminal RyR2 regulation can generate the CPVT phenotype. We propose that the RyR2-resident, CSQ2-independent luminal Ca2+ mechanism may assure that all channels respond robustly to large (>5 μM) local cytosolic Ca2+ stimuli, whereas the CSQ2-dependent mechanism may help close RyR2 channels after luminal Ca2+ falls below ∼0.5 mM.

Although 17β-estradiol (E2) anti-inflammatory activity has been well described, very little is known about the effects of this hormone on the resolution phase of the inflammatory process. Here, we identified a previously unreported ERα-mediated effect of E2 on the inflammatory machinery. The study showed that the activation of the intracellular estrogen receptor shortens the LPS-induced pro-inflammatory phase and, by influencing the intrinsic and extrinsic programs, triggers the resolution of inflammation in RAW 264.7 cells. Through the regulation of the SOCS3 and STAT3 signaling pathways, E2 facilitates the progression of the inflammatory process toward the IL10-dependent “acquired deactivation” phenotype, which is responsible for tissue remodeling and the restoration of homeostatic conditions. The present study may provide an explanation for increased susceptibility to chronic inflammatory diseases in women after menopause, and it suggests novel anti-inflammatory treatments for such disorders.

Abstract-Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmogenic disordercharacterized by life threatening arrhythmias elicited by physical and emotional stress in young individuals. The recessive form of CPVT is associated with mutation in the cardiac calsequestrin gene (CASQ2). We engineered and characterized a homozygous CASQ2 R33Q/R33Q mouse model that closely mimics the clinical phenotype of CPVT patients. CASQ2R33Q/R33Q mice develop bidirectional VT on exposure to environmental stress whereas CASQ2 R33Q/R33Q myocytes show reduction of the sarcoplasmic reticulum (SR) calcium content, adrenergically mediated delayed (DADs) and early (EADs) afterdepolarizations leading to triggered activity. Furthermore triadin, junctin, and CASQ2-R33Q proteins are significantly decreased in knock-in mice despite normal levels of mRNA, whereas the ryanodine receptor (RyR2), calreticulin, phospholamban, and SERCA2a-ATPase are not changed. Trypsin digestion studies show increased susceptibility to proteolysis of mutant CASQ2. Despite normal histology, CASQ2 R33Q/R33Q hearts display ultrastructural changes such as disarray of junctional electron-dense material, referable to CASQ2 polymers, dilatation of junctional SR, yet normal total SR volume. Based on the foregoings, we propose that the phenotype of the CASQ2 R33Q/R33Q CPVT mouse model is portrayed by an unexpected set of abnormalities including (1) reduced CASQ2 content, possibly attributable to increased degradation of CASQ2-R33Q, (2) reduction of SR calcium content, (3) dilatation of junctional SR, and (4) 4 The identification of the genes underlying CPVT has had implications that extend beyond those impacting clinical management of patients inasmuch as it stimulated fundamental research targeted to understand the links between intracellular calcium regulation and arrhythmogenesis. We recently developed 5 a knock-in mouse model carrying the R4496C RyR2 mutation identified in the first genotyped CPVT family and demonstrated that the RyR2 R4496C mice develop bidirectional and polymorphic VT similar to those observed in patients. In this model we also demonstrated 6 the occurrence of delayed after depolarizations (DADs) induced by adrenergic stimulation in isolated myocytes from the heart of heterozygous mice, suggesting that arrhythmias are elicited by triggered activity. Recently 2 mutants CASQ2 knock-in mice models were developed by Song et al 7 : the first strain carries the homozygous point mutation discovered by Lahat et al 3 in the first recessive CPVT family (D307H), and the second strain carries a homozygous deletion ⌬E9/⌬E9; in analogy with RyR2 mice, 5 both models develop bidirectional-polymorphic Materials and MethodsDetailed methods for mouse generation, electrophysiological measurements, immunofluorescence, real-time PCR, microarray, protein and electron microscopy analysis are reported in the online supplement (available online at http://circres.ahajournals.org). Generation of Knock-In of R33Q CASQ2 in Mouse ModelThe kno...