In Vivo Analysis of Disease-Associated Point Mutations Unveils Profound Differences in mRNA Splicing of Peripherin-2 in Rod and Cone Photoreceptors.

Point mutations in peripherin-2 (PRPH2) are associated with severe retinal degenerative disorders affecting rod and/or cone photoreceptors. Various disease-causing mutations have been identified, but the exact contribution of a given mutation to the clinical phenotype remains unclear. Exonic point mutations are usually assumed to alter single amino acids, thereby influencing specific protein characteristics; however, they can also affect mRNA splicing. To examine the effects of distinct PRPH2 point mutations on mRNA splicing and protein expression in vivo, we designed PRPH2 minigenes containing the three coding exons and relevant intronic regions of human PRPH2. Minigenes carrying wild type PRPH2 or PRPH2 exon 2 mutations associated with rod or cone disorders were expressed in murine photoreceptors using recombinant adeno-associated virus (rAAV) vectors. We detect three PRPH2 splice isoforms in rods and cones: correctly spliced, intron 1 retention, and unspliced. In addition, we show that only the correctly spliced isoform results in detectable protein expression. Surprisingly, compared to rods, differential splicing leads to lower expression of correctly spliced and higher expression of unspliced PRPH2 in cones. These results were confirmed in qRT-PCR experiments from FAC-sorted murine rods and cones. Strikingly, three out of five cone disease-causing PRPH2 mutations profoundly enhanced correct splicing of PRPH2, which correlated with strong upregulation of mutant PRPH2 protein expression in cones. By contrast, four out of six PRPH2 mutants associated with rod disorders gave rise to a reduced PRPH2 protein expression via different mechanisms. These mechanisms include aberrant mRNA splicing, protein mislocalization, and protein degradation. Our data suggest that upregulation of PRPH2 levels in combination with defects in the PRPH2 function caused by the mutation might be an important mechanism leading to cone degeneration. By contrast, the pathology of rod-specific PRPH2 mutations is rather characterized by PRPH2 downregulation and impaired protein localization.

Gene therapy restores vision and delays degeneration in the CNGB1(-/-) mouse model of retinitis pigmentosa.

Retinitis pigmentosa (RP) is a severe retinal disease characterized by a progressive degeneration of rod photoreceptors and a secondary loss of cone function. Here, we used CNGB1-deficient (CNGB1(-/-)) mice, a mouse model for autosomal recessive RP, to evaluate the efficacy of adeno-associated virus (AAV) vector-mediated gene therapy for the treatment of RP. The treatment restored normal expression of rod CNG channels and rod-driven light responses in the CNGB1(-/-) retina. This led to a substantial delay of retinal degeneration and long-term preservation of retinal morphology. Finally, treated CNGB1(-/-) mice performed significantly better than untreated mice in a rod-dependent vision-guided behavior test. In summary, this study holds promise for the treatment of rod channelopathy-associated retinitis pigmentosa by AAV-mediated gene replacement.

Cell Banking of hiPSCs: A Practical Guide to Cryopreservation and Quality Control in Basic Research.

The reproducibility of stem cell research relies on the constant availability of quality-controlled cells. As the quality of human induced pluripotent stem cells (hiPSCs) can deteriorate in the course of a few passages, cell banking is key to achieve consistent results and low batch-to-batch variation. Here, we provide a cost-efficient route to generate master and working cell banks for basic research projects. In addition, we describe minimal protocols for quality assurance including tests for sterility, viability, pluripotency, and genetic integrity. © 2020 The Authors. Basic Protocol 1: Expansion of hiPSCs Basic Protocol 2: Cell banking of hiPSCs Support Protocol 1: Pluripotency assessment by flow cytometry Support Protocol 2: Thawing control: Viability and sterility Support Protocol 3: Potency, viral clearance, and pluripotency: Spontaneous differentiation and qRT-PCR Support Protocol 4: Identity: Short tandem repeat analysis.

Effective relief of malignant ascites in patients with advanced ovarian cancer by a trifunctional anti-EpCAM x anti-CD3 antibody: a phase I/II study.

PURPOSE: Malignant ascites in ovarian carcinoma patients is associated with poor prognosis and reduced quality of life. The trifunctional antibody catumaxomab (anti-EpCAM x anti-CD3) enhances the antitumor activity by redirecting T cells and Fcgamma receptor I/III--positive accessory cells to the tumor. This multicenter phase I/II dose-escalating study investigated tolerability and efficacy of i.p. catumaxomab application in ovarian cancer patients with malignant ascites containing epithelial cell adhesion molecule (EpCAM)--positive tumor cells. EXPERIMENTAL DESIGN: Twenty-three women with recurrent ascites due to pretreated refractory ovarian cancer were treated with four to five i.p. infusions of catumaxomab in doses of 5 to 200 microg within 9 to 13 days. RESULTS: The maximum tolerated dose was defined at 10, 20, 50, 200, and 200 microg for the first through fifth doses. Side effects included transient fever (83%), nausea (61%), and vomiting (57%), mostly CTCAE (Common Terminology Criteria for Adverse Events) grade 1 or 2. A total of 39 grade 3 and 2 grade 4 treatment-related adverse events (AE), 9 of them after the highest dose level (200 microg), were observed in 16 patients. Most AEs were reversible without sequelae. Treatment with catumaxomab resulted in significant and sustained reduction of ascites flow rate. A total of 22/23 patients did not require paracentesis between the last infusion and the end of study at day 37. Tumor cell monitoring revealed a reduction of EpCAM-positive malignant cells in ascites by up to 5 log. CONCLUSION: I.p. immunotherapy with catumaxomab prevented the accumulation of ascites and efficiently eliminated tumor cells with an acceptable safety profile. This suggests that catumaxomab is a promising treatment option in ovarian cancer patients with malignant ascites.

A µ-biomimetic flow sensor for medical and pharmaceutical applications.

Flow sensing is pivotal in many medical and pharmaceutical applications. Most commercial flow sensors are either expensive, complex, or consume a lot of energy, while low cost sensors usually lack sensitivity, robustness, or long-term stability. In addition, the maintenance and sterilization of most commercial flow sensors is difficult to perform. Here, we present a new µ-biomimetic flow sensor based on the fish lateral line. It measures flow velocity and detects the transition between laminar and turbulent flow, thereby fulfilling most requirements for medical and pharmaceutical applications. Additionally, it has a modular setup featuring a screened or passive bypass configuration, enabling it not only to meter flow in medical applications but also under harsh or well-defined environmental conditions, such as found in pharmaceutical applications. The sensor is robust and can be easily cleaned. Individual parts of the sensor can even be replaced or sterilized. In sum, this sensor opens up a whole new field of applications in the area of medical and pharmaceutical related flow monitoring.

TET3 is recruited by REST for context-specific hydroxymethylation and induction of gene expression.

Ten-eleven translocation hydroxylases (TET1-3) oxidize 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC). In neurons, increased 5hmC levels within gene bodies correlate positively with gene expression. The mechanisms controlling TET activity and 5hmC levels are poorly understood. In particular, it is not known how the neuronal TET3 isoform lacking a DNA-binding domain is targeted to the DNA. To identify factors binding to TET3, we screened for proteins that co-precipitate with TET3 from mouse retina and identified the transcriptional repressor REST as a highly enriched TET3-specific interactor. REST was able to enhance TET3 hydroxylase activity after co-expression and overexpression of TET3-activated transcription of REST target genes. Moreover, we found that TET3 also interacts with NSD3 and two other H3K36 methyltransferases and is able to induce H3K36 trimethylation. We propose a mechanism for transcriptional activation in neurons that involves REST-guided targeting of TET3 to the DNA for directed 5hmC generation and NSD3-mediated H3K36 trimethylation.

The role of relative lymphocyte count as a biomarker for the effect of catumaxomab on survival in malignant ascites patients: results from a phase II/III study.

PURPOSE: We report the role of relative lymphocyte count (RLC) as a potential biomarker with prognostic impact for catumaxomab efficacy and overall survival (OS) based on a post hoc analysis of the pivotal phase II/III study of intraperitoneal catumaxomab treatment of malignant ascites. EXPERIMENTAL DESIGN: The impact of treatment and RLC on OS was evaluated using multivariate Cox models. Kaplan-Meier and log-rank tests were used for group comparisons. Survival analyses were performed on the safety population [patients with paracentesis plus ≥ 1 dose of catumaxomab (n = 157) and paracentesis alone (n = 88)]. Determination of the optimal cutoff value for RLC was based on five optimality criteria. RESULTS: OS was significantly longer with catumaxomab versus paracentesis alone (P = 0.0219). The 6-month OS rate with catumaxomab was 28.9% versus 6.7% with paracentesis alone. RLC had a positive impact on OS and was an independent prognostic factor (P < 0.0001). In patients with RLC > 13% (n = 159: catumaxomab, 100 and control, 59), catumaxomab was associated with a favorable effect on OS versus paracentesis alone (P = 0.0072), with a median/mean OS benefit of 41/131 days and an increased 6-month survival rate of 37.0% versus 5.2%, respectively. In patients with RLC ≤ 13% at screening (n = 74: catumaxomab, 50 and control, 24), the median (mean) OS difference between the catumaxomab and the control group was 3 (16) days, respectively (P = 0.2561). CONCLUSIONS: OS was significantly improved after catumaxomab treatment in patients with malignant ascites. An RLC > 13% at baseline was a significant prognostic biomarker.