The molecular diversity of many gene products functioning in the nervous system is enhanced by alternative splicing and adenosine-toinosine editing of pre-mRNA. Using RDL, a Drosophila melanogaster GABA-gated ion channel, we examined the functional impact of RNA editing at several sites along with alternative splicing of more than one exon. We show that alternative splicing and RNA editing have a combined influence on the potency of the neurotransmitter GABA, and the editing isoforms detected in vivo span the entire functional range of potencies seen for all possible edit variants expressed in Xenopus laevis oocytes. The extent of RNA editing is developmentally regulated and can also be linked to the choice of alternative exons. These results provide insights into how the rich diversity of signaling necessary for complex brain function can be achieved by relatively few genes.
SummaryB-catenin is the central effector molecule of the canonical Wnt signalling pathway, which controls self-renewal of haematopoietic stem cells. Deregulation of this pathway occurs in various malignancies including myeloid leukaemias. The present study examined the functional outcome of stable b-catenin down-regulation through lentivirus-mediated expression of short hairpin RNA (shRNA). Reduction of the b-catenin levels in acute myeloid leukaemia (AML) cell lines and patient samples decelerated their in vitro proliferation ability without affecting cell viability. Transplantation of leukaemic cells with control or reduced levels of b-catenin in non-obese diabetic severe combined immunodeficient animals indicated that, while the immediate homing of the cells was unaffected, the bone marrow engraftment was directly dependent on b-catenin levels. Subsequent examination of bone sections revealed that b-catenin was implicated in the localization of AML to the endosteum. Examination of adhesion molecule expression before and after transplantation, revealed down-regulation of CD44 expression, accompanied by reduced in vitro adhesion. Gene expression analysis disclosed the presence of an autocrine compensatory mechanism, which responds to the reduced b-catenin levels by altering the expression of positive and negative pathway regulators. In conclusion, our study showed that b-catenin comprises an integral part of AML cell proliferation, cell cycle progression, and adhesion, and influences disease establishment in vivo.
The complex pathology of consortium fatigue provides diagnostic data on how to improve collaboration in biomedical innovation.
For the nascent field of advanced therapies, collaboration will be a game-changer, turning scientific progress that was once unimaginable into transformative medical practice. Despite promise for lifelong management and even cure of disease, skepticism remains about the feasibility of their delivery to patients, fueling investment risks. With the potential for long-term effectiveness in need of frequent reassessment, current approaches to predict real-life drug performance bear little relevance, necessitating novel and iterative schemes to monitoring the benefit–risk profiles throughout the life span of advanced therapies. This work explains that reinventing an adoption route for Advanced Therapy Medicinal Products is as much about the scientific and clinical components, as it is about the organizational structures, requiring an unprecedented level of interactions between stakeholders not traditionally connected; from developers and regulators, to payers, patients, and funders. By reflecting on the successes and lessons learned from the growing space of global precompetitive consortia and public–private partnerships, as well as a number of emerging accelerated development pathways, this work aims to inform the foundations for a future roadmap that can smooth the path to approval, reimbursement, and access, while delivering value to all stakeholders. Echoing the growing demands to bring these transformative products to patients, it provides critical insights to enhance our capacity in three fundamental domains: deploying the operational flexibilities offered by the growing space of collaborations, utilizing emerging flexible and accelerated pathways to tackle challenges in quantifying long-term effectiveness, and building the necessary digital and clinical infrastructure for knowledge development.
In the pathophysiology of b-thalassemia, globin chain imbalance plays a central role in predicting red blood cell (RBC) life span and disease severity. Strategies to improve globin chain imbalance are therefore a legitimate target in the management of this incurable genetic disorder. Classical gene addition with the available retroviral vectors can alter one of the two variables while combined reduction of achains could provide a more potent therapeutic effect. We developed foamy virus (FV) vectors for the production of b-globin and vectors targeting the a-globin transcript using the shRNA technology. Using FVderived vectors, we expressed human anti-a-globin short hairpin RNAs, off a potent PolIII promoter (H1); of the 4 different shRNAs tested, a-globin mRNA reduction varied from 6.3 to 54% of the control CD34+ cells. Similarly, vectors developed for the mouse a-globin, resulted in a significant reduction (range 15-28% of the control) of aglobin in erythroid colonies of Lin-cells. To assay vector performance in vivo, we investigated the hematological parameters in thal3+/-mice transpalnted with FV-transduced Lin-cells, transduced with anti-a-globin shRNA. Despite low chimerism and low vector copy numbers (<0.5 per cell), we observed a 10% reduction in red cell distribution width, a marker for distorted erythropoiesis. We finally developed a combination FV vector expressing b-globin off a HS40 enhancer and anti-a-globin shRNA and tested its performance in human CD34+ cells from a thalassemic patient. Globin chain imbalance was ameliorated from a b/a ratio of 0.12 to the level of 0.5, clearly indicating a therapeutic benefit.. Overall, shRNA control of a-globin excess is a feasible target but requires improvements since the RNAi effect is tough to predict and should ideally be combined with controllable elements.
The promise of the RNA interference (RNAi) technology is equally dependent on the efficiency and stability of gene silencing. The aim of the present study was the development of foamy virus (FV) vectors for stable RNAi, utilizing two potent RNA polymerase III (Pol III) promoters. Using green fluorescent protein as a target gene, we examined the efficiency of mouse U6 (mU6) and human H1 Pol III promoters in different human cell lines and mouse hematopoietic stem cells (HSCs) ex vivo and in vivo, following bone marrow transplantation. Both our mU6 and H1 FV vectors mediated very efficient gene silencing with as low as one vector copy per cell. However, transduction of human cell lines with FV vectors expressing short hairpin RNA from mU6 led to the gradual elimination of cells in culture, as opposed to H1-harboring cells, underscoring the importance of the expression system or cellular context in the evaluation of the overall RNAi effects. The efficiency and stability of the H1 vectors were further shown by the successful silencing of BCR-ABL in K562 cells. Accordingly, mU6 vectors induced efficient and stable gene silencing in mouse HSCs following bone marrow transplantation. Our work is the first in vivo study on the efficiency and stability of RNAi gene silencing in HSCs with FV vectors, currently a safe alternative for viral gene transfer.
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