Drosophila auditory organ genes and genetic hearing defects

SummaryThe Drosophila auditory organ shares equivalent transduction mechanisms with vertebrate hair cells, and both are specified by atonal family genes. Using a whole-organ knockout strategy based on atonal, we have identified 274 Drosophila auditory organ genes. Only four of these genes had previously been associated with fly hearing, yet one in five of the genes that we identified has a human cognate that is implicated in hearing disorders. Mutant analysis of 42 genes shows that more than half of them contribute to auditory organ function, with phenotypes including hearing loss, auditory hypersusceptibility, and ringing ears. We not only discover ion channels and motors important for hearing, but also show that auditory stimulus processing involves chemoreceptor proteins as well as phototransducer components. Our findings demonstrate mechanosensory roles for ionotropic receptors and visual rhodopsins and indicate that different sensory modalities utilize common signaling cascades

Structural myelin defects are associated with low axonal ATP levels but rapid recovery from energy deprivation in a mouse model of spastic paraplegia.

In several neurodegenerative disorders, axonal pathology may originate from impaired oligodendrocyte-to-axon support of energy substrates. We previously established transgenic mice that allow measuring axonal ATP levels in electrically active optic nerves. Here, we utilize this technique to explore axonal ATP dynamics in the Plpnull/y mouse model of spastic paraplegia. Optic nerves from Plpnull/y mice exhibited lower and more variable basal axonal ATP levels and reduced compound action potential (CAP) amplitudes, providing a missing link between axonal pathology and a role of oligodendrocytes in brain energy metabolism. Surprisingly, when Plpnull/y optic nerves are challenged with transient glucose deprivation, both ATP levels and CAP decline slower, but recover faster upon reperfusion of glucose. Structurally, myelin sheaths display an increased frequency of cytosolic channels comprising glucose and monocarboxylate transporters, possibly facilitating accessibility of energy substrates to the axon. These data imply that complex metabolic alterations of the axon-myelin unit contribute to the phenotype of Plpnull/y mice

Procedural and Short-Term Results With the New Watchman FLX Left Atrial Appendage Occlusion Device

International audienceOBJECTIVES: This study sought to report early experience with the new-generation Watchman FLX device (Boston Scientific, Marlborough, Massachusetts). BACKGROUND: The new-generation Watchman FLX features a reduced height, improved anchoring and fabric coverage, and a closed distal end. These design modifications aim to simplify implantation, allow full recapture and repositioning, and reduce peridevice leak and device-related thrombosis. METHODS: A total of 165 patients undergoing left atrial appendage (LAA) occlusion (LAAO) with Watchman FLX were enrolled in a prospective, multicenter registry at 12 centers participating in the European limited market release program. RESULTS: Mean age was 75.4 ± 8.9 years, and CHA(2)DS(2)-VASc score 4.4 ± 1.4. A total of 128 patients (77.6%) had a history of major bleeding, including previous intracranial hemorrhage in 55 cases (33.3%). LAA landing zone minimal and maximal mean diameters were 19.1 ± 3.6 mm and 22.3 ± 3.7 mm, and 24.2% of LAA were considered complex by dimensions. Technical success was achieved in all patients. Successful implantation at first attempt was achieved in 129 cases (78.2%), and a second device was required in 6 cases (3.6%). Procedure-related complications occurred in 3 patients (1.8%): 2 access-related (1.2%) and 1 pericardial effusion (0.6%). No peri-procedural strokes, deaths, or device embolizations occurred. Forty-nine patients (29.7%) were discharged with single antiplatelet therapy, 105 (63.6%) on dual antiplatelet, and 11 (6.7%) on anticoagulation. Imaging follow-up displayed just 1 peridevice leak ≥5 mm and 7 cases of device-related thrombosis (4.7%). During a median follow-up of 55 days (interquartile range: 45 to 148 days), there were 6 hemorrhagic complications (4.8%), 1 patient (0.8%) had an ischemic stroke, and 1 (0.8%) died. No late device embolizations occurred. CONCLUSIONS: LAAO with the Watchman FLX is safe and effective in a wide range of LAA morphologies, with a low procedural complication rate, high degree of LAA sealing, and favorable short-term efficacy

SLM2 is a novel cardiac splicing factor involved in heart failure due to dilated cardiomyopathy

Alternative mRNA splicing is a fundamental process to increase the versatility of the genome. In humans, cardiac mRNA splicing is involved in the pathophysiology of heart failure. Mutations in the splicing factor RNA binding motif protein 20 (RBM20) cause severe forms of cardiomyopathy. To identify novel cardiomyopathy-associated splicing factors, RNA-seq and tissue-enrichment analysis were performed, which identified upregulation of Sam68-Like Mammalian Protein 2 (SLM2) in the left ventricle of dilated cardiomyopathy (DCM) patients. In the human heart, SLM2 binds to important transcripts of sarcomere constituents, such as myosin light chain 2 (MYL2), troponin I3 (TNNI3), troponin T2 (TNNT2), tropomyosin 1/2 (TPM1/2), and titin (TTN). Mechanistically, SLM2 mediates intron retention, prevents exon exclusion, and thereby mediates alternative splicing of the mRNA regions encoding the variable proline-, glutamate-, valine-, and lysine-rich (PEVK) domain and another part of the I-band region of titin. In summary, SLM2 is a novel cardiac splicing regulator with essential functions for maintaining cardiomyocyte integrity by binding and processing the mRNA of essential cardiac constituents such as titin

Multi-center randomized controlled trial of cognitive treatment, placebo, oxybutynin, bladder training, and pelvic floor training in children with functional urinary incontinence

Objective Functional urinary incontinence causes considerable morbidity in 8.4% of school-age children, mainly girls. To compare oxybutynin, placebo, and bladder training in overactive bladder (OAB), and cognitive treatment and pelvic floor training in dysfunctional voiding (DV), a multi-center controlled trial was designed, the European Bladder Dysfunction Study. Methods Seventy girls and 27 boys with clinically diagnosed OAB and urge incontinence were randomly allocated to placebo, oxybutynin, or bladder training (branch I), and 89 girls and 16 boys with clinically diagnosed DV to either cognitive treatment or pelvic floor training (branch II). All children received standardized cognitive treatment, to which these interventions were added. The main outcome variable was daytime incontinence with/without urinary tract infections. Urodynamic studies were performed before and after treatment. Results In branch I, the 15% full response evolved to cure rates of 39% for placebo, 43% for oxybutynin, and 44% for bladder training. In branch II, the 25% full response evolved to cure rates of 52% for controls and 49% for pelvic floor training. Before treatment, detrusor overactivity (OAB) or pelvic floor overactivity (DV) did not correlate with the clinical diagnosis. After treatment these urodynamic patterns occurred de novo in at least 20%. Conclusion The mismatch between urodynamic patterns and clinical symptoms explains why cognitive treatment was the key to success, not the added interventions. Unpredictable changes in urodynamic patterns over time, the response to cognitive treatment, and the gender-specific prevalence suggest social stress might be a cause for the symptoms, mediated by corticotropin-releasing factor signaling pathways. Neurourol. Urodynam. 33:482-487, 2014. (c) 2013 Wiley Periodicals, Inc

Reduction of A-to-I RNA editing in the failing human heart regulates formation of circular RNAs.

Alterations of RNA editing that affect the secondary structure of RNAs can cause human diseases. We therefore studied RNA editing in failing human hearts. Transcriptome sequencing showed that adenosine-to-inosine (A-to-I) RNA editing was responsible for 80% of the editing events in the myocardium. Failing human hearts were characterized by reduced RNA editing. This was primarily attributable to Alu elements in introns of protein-coding genes. In the failing left ventricle, 166 circRNAs were upregulated and 7 circRNAs were downregulated compared to non-failing controls. Most of the upregulated circRNAs were associated with reduced RNA editing in the host gene. ADAR2, which binds to RNA regions that are edited from A-to-I, was decreased in failing human hearts. In vitro, reduction of ADAR2 increased circRNA levels suggesting a causal effect of reduced ADAR2 levels on increased circRNAs in the failing human heart. To gain mechanistic insight, one of the identified upregulated circRNAs with a high reduction of editing in heart failure, AKAP13, was further characterized. ADAR2 reduced the formation of double-stranded structures in AKAP13 pre-mRNA, thereby reducing the stability of Alu elements and the circularization of the resulting circRNA. Overexpression of circAKAP13 impaired the sarcomere regularity of human induced pluripotent stem cell-derived cardiomyocytes. These data show that ADAR2 mediates A-to-I RNA editing in the human heart. A-to-I RNA editing represses the formation of dsRNA structures of Alu elements favoring canonical linear mRNA splicing and inhibiting the formation of circRNAs. The findings are relevant to diseases with reduced RNA editing and increased circRNA levels and provide insights into the human-specific regulation of circRNA formation