Abstract Objectives: This study aims to explore the effect of silencing Beclin-1 gene on autophagy and apoptosis of Benign Prostatic Hyperplasia (BPH) (BPH-1) cells under the condition of Androgen Deprivation (AD) and Autophagy Inhibition (AI). Methods: Control group (BPH-1 group), empty carrier group (sh-RNA-BPH-1 group) and Beclin-1 silenced group (sh-Beclin1-BPH-1 group) were set. The Beclin-1 gene silencing efficiency was detected by RT-PCR and Western blot. Autophagic flux was monitored by GFP-LC3 cleavage assay and cell apoptosis was analyzed by flow cytometry. The protein expression levels of LC3, Caspase-3, PARP-1, Bcl-2, and Bax were detected by Western blot. Results: The transfection of sh-Beclin-1 obviously down-regulated the expression of Beclin-1 at both mRNA and protein levels. Under the conditions of AD and AI, silencing of Beclin-1 restrained the autophagy of BPH-1 cells, as evidenced by a decreased number of autophagosomes and down-regulation of LC3-II protein (p < 0.001). The results of flow cytometry showed that the apoptotic rate of sh-Beclin-1 group was elevated significantly compared to the other two groups (p < 0.01). Western blot results showed that silencing of Beclin-1 promoted 89 kd fragmentation of PARP-1 (p < 0.001) and Caspase-3 activation (p < 0.01). Moreover, silencing of Beclin-1 resulted in declined Bcl-2 and augmented Bax protein expression in BPH-1 cells (p < 0.01), which ultimately led to a decreased Bcl-2/Bax ratio. Conclusions: The results indicated that the silencing of Beclin-1 gene hampered autophagy while activating apoptosis in BPH-1 cells. Thus, Beclin-1 may participate in an antagonistic relationship between autophagy and apoptosis in BPH.

OBJECTIVE: This study aimed to identify novel PITX2c mutations responsible for idiopathic atrial fibrillation. METHODS: A cohort of 210 unrelated patients with idiopathic atrial fibrillation and 200 unrelated, ethnically matched healthy individuals used as controls were recruited. The whole coding exons and splice junctions of the PITX2c gene, which encodes a paired-like homeobox transcription factor required for normal cardiovascular morphogenesis, were sequenced in 210 patients and 200 control subjects. The causative potentials of the identified mutations were automatically predicted by MutationTaster and PolyPhen-2. The functional characteristics of the PITX2c mutations were explored using a dual-luciferase reporter assay system. RESULTS: Two novel heterozygous PITX2c mutations (p.Q105L and p.R122C) were identified in 2 of the 210 unrelated patients with idiopathic atrial fibrillation. These missense mutations were absent in the 400 control chromosomes and were both predicted to be pathogenic. Multiple alignments of PITX2c protein sequences across various species showed that the altered amino acids were highly evolutionarily conserved. A functional analysis demonstrated that the mutant PITX2c proteins were both associated with significantly reduced transcriptional activity compared with their wild-type counterparts. CONCLUSION: The findings of this study associate PITX2c loss-of-function mutations with atrial fibrillation, supporting the hypothesis that dysfunctional PITX2c confers enhanced susceptibility to atrial fibrillation and suggesting potential implications for early prophylaxis and allele-specific therapy for this common arrhythmia.

OBJECTIVE: The aim of this study was to evaluate the prevalence and spectrum of Nkx2.5 mutations associated with idiopathic atrial fibrillation (AF). METHODS: A cohort of 136 unrelated patients with idiopathic atrial fibrillation and 200 unrelated, ethnically matched healthy controls were enrolled. The coding exons and splice junctions of the Nkx2.5 gene were sequenced in 136 atrial fibrillation patients, and the available relatives of mutation carriers and 200 controls were subsequently genotyped for the identified mutations. The functional characteristics of the mutated Nkx2.5 gene were analyzed using a dual-luciferase reporter assay system. RESULTS: Two novel heterozygous Nkx2.5 mutations (p.N19D and p.F186S) were identified in 2 of the 136 unrelated atrial fibrillation cases, with a mutational prevalence of approximately 1.47%. These missense mutations co-segregated with atrial fibrillation in the families and were absent in the 400 control chromosomes. Notably, 2 mutation carriers also had congenital atrial septal defects and atrioventricular block. Multiple alignments of the Nkx2.5 protein sequences across various species revealed that the altered amino acids were completely conserved evolutionarily. Functional analysis demonstrated that the mutant Nkx2.5 proteins were associated with significantly reduced transcriptional activity compared to their wild-type counterpart. CONCLUSION: These findings associate the Nkx2.5 loss-of-function mutation with atrial fibrillation and atrioventricular block and provide novel insights into the molecular mechanism involved in the pathogenesis of atrial fibrillation. These results also have potential implications for early prophylaxis and allele-specific therapy of this common arrhythmia.