The Prevalence of Atrial Fibrillation and Conduction Abnormalities in Chagas’ Disease: A Meta-Analysis

Chagas' disease (CD) has been associated with atrial fibrillation (AF) and electrocardiographic (ECG) conduction defects. However, prior studies have shown conflicting results. We performed a meta-analysis comparing the prevalence of AF and conduction abnormalities between CD and non-CD patients. PubMed, EMBASE, Cochrane Central, and Latin American databases were searched for studies that directly compared the prevalence of AF and conduction defects in CD and non-CD patients. Odds ratios (OR) were computed using random-effects model due to anticipated heterogeneity. We further performed subanalyses limited to studies that included only patients with cardiomyopathy. A total of 17,238 patients from 30 studies were included, of whom 6,840 (40%) had a positive serology for CD. In the pooled data, AF was significantly more prevalent in the CD group (OR 1.62; 95%CI 1.21-2.15; P = 0.001). However, no significant difference was observed between groups when the analysis included only patients with cardiomyopathy (OR 1.21; 95%CI 0.97-1.50; P = 0.08) or heart failure (OR 1.09; 95%CI 0.81-1.47; P = 0.55). The combination of right bundle branch block (RBBB) and left anterior fascicular block (LAFB) had the highest OR for increased prevalence in patients with Chagas' cardiomyopathy compared to non-CD etiologies (OR 5.31; 95%CI 1.23-22.86; P = 0.03). Our meta-analysis suggests that the prevalence of AF in patients with Chagas' cardiomyopathy is not significantly different from non-CD cardiomyopathies. The pattern of RBBB and LAFB in patients with cardiomyopathy of unknown etiology and epidemiologic risk factors should raise the possibility of CD and prompt specific diagnostic testing

SUMOylation of the brain-predominant Ataxin-3 isoform modulates its interaction with p97

BACKGROUND: Machado-Joseph Disease (MJD), a form of dominantly inherited ataxia belonging to the group of polyQ expansion neurodegenerative disorders, occurs when a threshold value for the number of glutamines in Ataxin-3 (Atx3) polyglutamine region is exceeded. As a result of its modular multidomain architecture, Atx3 is known to engage in multiple macromolecular interactions, which might be unbalanced when the polyQ tract is expanded, culminating in the aggregation and formation of intracellular inclusions, a unifying fingerprint of this group of neurodegenerative disorders. Since aggregation is specific to certain brain regions, localization-dependent posttranslational modifications that differentially affect Atx3 might also contribute for MJD. METHODS: We combined in vitro and cellular approaches to address SUMOylation in the brain-predominant Atx3 isoform and assessed the impact of this posttranslational modification on Atx3 self-assembly and interaction with its native partner, p97. RESULTS: We demonstrate that Atx3 is SUMOylated at K356 both in vitro and in cells, which contributes for decreased formation of amyloid fibrils and for increased affinity towards p97. CONCLUSIONS AND GENERAL SIGNIFICANCE: These findings highlight the role of SUMOylation as a regulator of Atx3 function, with implications on Atx3 protein interaction network and self-assembly, with potential impact for further understanding the molecular mechanisms underlying MJD pathogenesis.This work was funded by the Fundação para a Ciência e a Tecnologia (FCT, Portugal) through grants PTDC/BIA-PRO/100059/2008 and PTDC/SAU-NMC/110602/2009 (EU-FEDER funding through COMPETEFCOMP-01-0124-FEDER-009031 and FCOMP-01-0124-FEDER-015860, respectively), and by QREN — Quadro de Referência Estratégica Nacional through Programa Operacional Regional do Norte ON. 2 (Neurodegenerative Disorders — NORTE-01-0124-FEDER-000001). C.M., S.F., I.A.A. and B.A. acknowledge the financial support from FCT through fellowships SFRH/BD/47160/2008, SFRH/BPD/77009/2011, Ciência 2008 Programme, and SFRH/BPD/70783/2010, respectively