Truncating Mutations in UBAP1 Cause Hereditary Spastic Paraplegia.

The diagnostic gap for rare neurodegenerative diseases is still considerable, despite continuous advances in gene identification. Many novel Mendelian genes have only been identified in a few families worldwide. Here we report the identification of an autosomal-dominant gene for hereditary spastic paraplegia (HSP) in 10 families that are of diverse geographic origin and whose affected members all carry unique truncating changes in a circumscript region of UBAP1 (ubiquitin-associated protein 1). HSP is a neurodegenerative disease characterized by progressive lower-limb spasticity and weakness, as well as frequent bladder dysfunction. At least 40% of affected persons are currently undiagnosed after exome sequencing. We identified pathological truncating variants in UBAP1 in affected persons from Iran, USA, Germany, Canada, Spain, and Bulgarian Roma. The genetic support ranges from linkage in the largest family (LOD = 8.3) to three confirmed de novo mutations. We show that mRNA in the fibroblasts of affected individuals escapes nonsense-mediated decay and thus leads to the expression of truncated proteins; in addition, concentrations of the full-length protein are reduced in comparison to those in controls. This suggests either a dominant-negative effect or haploinsufficiency. UBAP1 links endosomal trafficking to the ubiquitination machinery pathways that have been previously implicated in HSPs, and UBAP1 provides a bridge toward a more unified pathophysiology.

Automated Detection of Autophagy Response Using Single Cell-Based Microscopy Assays.

The fluorescence microscopy-based detection of intracellular LC3, p62, and/or WIPI punctate structures is a robust tool to monitor and assess macroautophagy/autophagy in single cells. This method was established for automated high-throughput/content analysis to reliably detect narrow differences in autophagy activity/capacity and to provide screening opportunities for biological and chemical libraries.

WIPI ß-propellers function as scaffolds for STK11/LKB1-AMPK and AMPK-related kinase signaling in autophagy.

The article discusses new findings on the role of the 4 human WIPI proteins at the onset of macroautophagy/autophagy. New insights revealing a circuit scaffold function of WIPI ß-propellers that interconnect autophagy signaling control with appropriate autophagosome formation are summarized.

Minimal and deep sedation during ablation of ventricular tachycardia.

BACKGROUND: Catheter ablation is a curative treatment option for ventricular premature contractions (VPC) and ventricular tachycardia (VT). Procedures require different sedation levels, depending on duration, ablation approach and patient characteristics. The aim of our study was to evaluate feasibility of minimal and deep sedation for ablation of VPC/VT. METHODS: Patients underwent catheter ablation of VPC/VT under minimal or deep sedation. Events of hypotension, hypoxia, bradycardia, procedural complications and VT inducibility were compared between the groups. RESULTS: 120 patients were included. In 42 patients (53.6 ± 17.1 years, 47.6% male) ablation was performed under minimal sedation with midazolam, and in 78 patients (54.2 ± 17.5 years, 67.9% male) ablation was performed under deep sedation with propofol/midazolam. There were significantly fewer patients with idiopathic VT (62.8 vs. 88.1%, p=0.011) in the deep sedation group, LVEF was significantly lower (47 ± 14.4 vs. 53.1 ± 11.7) and the procedure duration was significantly longer (201.9 ± 85.9 vs. 137.9 ± 98.7). No significant differences in procedural complications or sedation related events (hypotension: 0 vs. 3.8%, p=0.2, no hypoxia, no bradycardia) were detected. CONCLUSIONS: Minimal sedation and deep sedation are both feasible during VPC/VT ablation procedures. Propofol does not increase complications even in a collective with pre-existing impairment of LVEF. Adequate monitoring and trained personnel should be present.

Defects of Vps15 in skeletal muscles lead to autophagic vacuolar myopathy and lysosomal disease.

The complex of Vacuolar Protein Sorting 34 and 15 (Vps34 and Vps15) has Class III phosphatidylinositol 3-kinase activity and putative roles in nutrient sensing, mammalian Target Of Rapamycin (mTOR) activation by amino acids, cell growth, vesicular trafficking and autophagy. Contrary to expectations, here we show that Vps15-deficient mouse tissues are competent for LC3-positive autophagosome formation and maintain mTOR activation. However, an impaired lysosomal function in mutant cells is traced by accumulation of adaptor protein p62, LC3 and Lamp2 positive vesicles, which can be reverted to normal levels after ectopic overexpression of Vps15. Mice lacking Vps15 in skeletal muscles, develop a severe myopathy. Distinct from the autophagy deficient Atg7(-/-) mutants, pathognomonic morphological hallmarks of autophagic vacuolar myopathy (AVM) are observed in Vps15(-/-) mutants, including elevated creatine kinase plasma levels, accumulation of autophagosomes, glycogen and sarcolemmal features within the fibres. Importantly, Vps34/Vps15 overexpression in myoblasts of Danon AVM disease patients alleviates the glycogen accumulation. Thus, the activity of the Vps34/Vps15 complex is critical in disease conditions such as AVMs, and possibly a variety of other lysosomal storage diseases.