Clinical, biochemical and molecular characterization of prosaposin deficiency

Prosaposin (PSAP) deficiency is an ultra-rare, fatal infantile lysosomal storage disorder (LSD) caused by variants in the PSAP gene, with 7 subjects reported so far. Here, we provide the clinical, biochemical and molecular characterization of two additional PSAP deficiency cases. Lysoplex, a targeted resequencing approach was utilized to identify the variant in the first patient, while quantification of plasma lysosphingolipids (lysoSLs), assessed by liquid chromatography mass spectrometry (LC-MS/MS) and brain magnetic resonance imaging (MRI), followed by Sanger sequencing allowed to attain diagnosis in the second case. Functional studies were carried out on patients' fibroblast lines to explore the functional impact of variants. The two patients were homozygous for two different truncating PSAP mutations (c.895G>T, p.Glu299*; c.834_835delGA, p.Glu278Aspfs*27). Both variants led to a complete lack of processed transcript. LC-MS/MS and brain MRI analyses consistently provided a distinctive profile in the two children. Quantification of specific plasma lysoSLs revealed elevated levels of globotriaosylsphingosine (lysoGb3) and glucosylsphingosine (GlSph), and accumulation of autophagosomes, due to a decreased autophagic flux, was observed. This report documents the successfully use of plasma lysoSLs profiling in the PSAP deficiency diagnosis, as a reliable and informative tool to obtain a preliminary information in infantile cases with complex traits displaying severe neurological signs and visceral involvement.Prosaposin (PSAP) deficiency is an ultra-rare, fatal infantile lysosomal storage disorder (LSD) caused by variants in the PSAP gene, with seven subjects reported so far. Here, we provide the clinical, biochemical and molecular characterization of two additional PSAP deficiency cases. Lysoplex, a targeted resequencing approach was utilized to identify the variant in the first patient, while quantification of plasma lysosphingolipids (lysoSLs), assessed by liquid chromatography mass spectrometry (LC-MS/MS) and brain magnetic resonance imaging (MRI), followed by Sanger sequencing allowed to attain diagnosis in the second case. Functional studies were carried out on patients' fibroblast lines to explore the functional impact of variants. The two patients were homozygous for two different truncating PSAP mutations (c.895G>T, p.Glu299*; c.834_835delGA, p.Glu278Aspfs*27). Both variants led to a complete lack of processed transcript. LC-MS/MS and brain MRI analyses consistently provided a distinctive profile in the two children. Quantification of specific plasma lysoSLs revealed elevated levels of globotriaosylsphingosine (LysoGb3) and glucosylsphingosine (GlSph), and accumulation of autophagosomes, due to a decreased autophagic flux, was observed. This report documents the successful use of plasma lysoSLs profiling in the PSAP deficiency diagnosis, as a reliable and informative tool to obtain a preliminary information in infantile cases with complex traits displaying severe neurological signs and visceral involvement

Down-regulation of the Mixed-lineage Dual Leucine Zipper-bearing Kinase by Heat Shock Protein 70 and Its Co-chaperone CHIP

Dual leucine zipper-bearing kinase (DLK) is a mixed-lineage kinase family member that acts as an upstream activator of the c-Jun N-terminal kinases. As opposed to other components of this pathway, very little is currently known regarding the mechanisms by which DLK is regulated in mammalian cells. Here we identify the stress-inducible heat shock protein 70 (Hsp70) as a negative regulator of DLK expression and activity. Support for this notion derives from data showing that Hsp70 induces the proteasomal degradation of DLK when both proteins are co-expressed in COS-7 cells. Hsp70-mediated degradation occurs with expression of wild-type DLK, which functions as a constitutively activated protein in these cells but not kinase-defective DLK. Interestingly, the Hsp70 co-chaperone CHIP, an E3 ubiquitin ligase, seems to be indispensable for this process since Hsp70 failed to induce DLK degradation in COS-7 cells expressing a CHIP mutant unable to catalyze ubiquitination or in immortalized fibroblasts derived from CHIP knock-out mice. Consistent with these data, we have found that endogenous DLK becomes sensitive to CHIP-dependent proteasomal degradation when it is activated by okadaic acid and that down-regulation of Hsp70 levels with an Hsp70 antisense attenuates this sensitivity. Therefore, our studies suggest that Hsp70 contributes to the regulation of activated DLK by promoting its CHIP-dependent proteasomal degradation

Targeted gene panel screening is an effective tool to identify undiagnosed late onset Pompe disease

Mutations in the GAA gene may cause a late onset Pompe disease presenting with proximal weakness without the characteristic muscle pathology, and therefore a test for GAA activity is the first tier analysis in all undiagnosed patients with hyperCKemia and/or limb-girdle muscular weakness. By using MotorPlex, a targeted gene panel for next generation sequencing, we analyzed GAA and other muscle diseasegenes in a large cohort of undiagnosed patients with suspected inherited skeletal muscle disorders (n = 504). In this cohort, 275 patients presented with limb-girdle phenotype and/or an isolated hyperCKemia. Mutational analysis identified GAA mutations in ten patients. Further seven affected relatives were identified by segregation studies. All the patients carried the common GAA mutation c.-32-13T > G and a second, previously reported mutation. In the subcohort of 275 patients with proximal muscle weakness and/or hyperCKemia, we identified late-onset Pompe disease in 10 patients. The clinical overlap between Pompe disease and LGMDs or other skeletal muscle disorders suggests that GAA and the genes causing a metabolic myopathy should be analyzed in all the gene panels used for testing neuromuscular patients. However, enzymatic tests are essential for the interpretation and validation of genetic results. (C) 2018 Elsevier B.V. All rights reserved.Peer reviewe

A Young Drosophila Duplicate Gene Plays Essential Roles in Spermatogenesis by Regulating Several Y-Linked Male Fertility Genes

Gene duplication is supposed to be the major source for genetic innovations. However, how a new duplicate gene acquires functions by integrating into a pathway and results in adaptively important phenotypes has remained largely unknown. Here, we investigated the biological roles and the underlying molecular mechanism of the young kep1 gene family in the Drosophila melanogaster species subgroup to understand the origin and evolution of new genes with new functions. Sequence and expression analysis demonstrates that one of the new duplicates, nsr (novel spermatogenesis regulator), exhibits positive selection signals and novel subcellular localization pattern. Targeted mutagenesis and whole-transcriptome sequencing analysis provide evidence that nsr is required for male reproduction associated with sperm individualization, coiling, and structural integrity of the sperm axoneme via regulation of several Y chromosome fertility genes post-transcriptionally. The absence of nsr-like expression pattern and the presence of the corresponding cis-regulatory elements of the parental gene kep1 in the pre-duplication species Drosophila yakuba indicate that kep1 might not be ancestrally required for male functions and that nsr possibly has experienced the neofunctionalization process, facilitated by changes of trans-regulatory repertories. These findings not only present a comprehensive picture about the evolution of a new duplicate gene but also show that recently originated duplicate genes can acquire multiple biological roles and establish novel functional pathways by regulating essential genes

Role of Sam68 in post-transcriptional gene regulation

The STAR family of proteins links signaling pathways to various aspects of post-transcriptional regulation and processing of RNAs. Sam68 belongs to this class of heteronuclear ribonucleoprotein particle K (hnRNP K) homology (KH) single domain-containing family of RNA-binding proteins that also contains some domains predicted to bind critical components in signal transduction pathways. In response to phosphorylation and other post-transcriptional modifications, Sam68 has been shown to have the ability to link signal transduction pathways to downstream effects regulating RNA metabolism, including transcription, alternative splicing or RNA transport. In addition to its function as a docking protein in some signaling pathways, this prototypic STAR protein has been identified to have a nuclear localization and to take part in the formation of both nuclear and cytosolic multi-molecular complexes such as Sam68 nuclear bodies and stress granules. Coupling with other proteins and RNA targets, Sam68 may play a role in the regulation of differential expression and mRNA processing and translation according to internal and external signals, thus mediating important physiological functions, such as cell death, proliferation or cell differentiation

Elective cancer surgery in COVID-19-free surgical pathways during the SARS-CoV-2 pandemic: An international, multicenter, comparative cohort study

PURPOSE As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19–free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19–free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19–free surgical pathways. Patients who underwent surgery within COVID-19–free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19–free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score–matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19–free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION Within available resources, dedicated COVID-19–free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Elective Cancer Surgery in COVID-19-Free Surgical Pathways During the SARS-CoV-2 Pandemic: An International, Multicenter, Comparative Cohort Study.

PURPOSE: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19-free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS: This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19-free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS: Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19-free surgical pathways. Patients who underwent surgery within COVID-19-free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19-free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score-matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19-free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION: Within available resources, dedicated COVID-19-free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks