alsterpaullone and Disease-Models--Animal

Podocyte dysfunction and loss is an early event and a hallmark of proteinuric kidney diseases. A podocyte's normal function is maintained via its unique cellular architecture that relies on an intracellular network of filaments, including filamentous actin (F-actin) and microtubules, that provides mechanical support. Damage to this filamentous network leads to changes in cellular morphology and results in podocyte injury, dysfunction, and death. Conversely, stabilization of this network protects podocytes and ameliorates proteinuria. This suggests that stabilization of podocyte architecture via its filamentous network could be a key therapeutic strategy for proteinuric kidney diseases. However, development of podocyte-directed therapeutics, especially those that target the cell's filamentous network, is still lacking, partly because of unavailability of appropriate cellular assays for use in a drug discovery environment. Here, we describe a new high-content screening-based methodology and its implementation on podocytes to identify paullone derivatives as a novel group of podocyte-protective compounds. We find that three compounds, i.e., kenpaullone, 1-azakenpaullone, and alsterpaullone, dose dependently protect podocytes from puromycin aminonucleoside (PAN)-mediated injury in vitro by reducing PAN-induced changes in both the filamentous actin and microtubules, with alsterpaullone providing maximal protection. Mechanistic studies further show that alsterpaullone suppressed PAN-induced activation of signaling downstream of GSK3β and p38 mitogen-activated protein kinase. In vivo it reduced ADR-induced glomerular injury in a zebrafish model. Together, these results identify paullone derivatives as novel podocyte-protective agents for future therapeutic development.

Topics: Actin Cytoskeleton; Animals; Apoptosis; Benzazepines; Cell Line; Disease Models, Animal; Doxorubicin; Drug Discovery; Glycogen Synthase Kinase 3 beta; High-Throughput Screening Assays; Indoles; Kidney Diseases; Mice; Microtubules; p38 Mitogen-Activated Protein Kinases; Podocytes; Protective Agents; Renal Agents; Signal Transduction; Zebrafish

To elucidate the Tau gain-of-toxicity functional mechanism and to search for potential treatments, we overexpressed human Tau variants (hTau) in the dorsal mesothorax (notum) of Drosophila. Overexpression of Tau variants caused loss of notal bristles, and the phenotype was used for evaluating toxicity of ectopic Tau. The bristle loss phenotype was found to be highly associated with the toxicity of hyperphosphoryled Tau in flies. We have shown that the bristle loss phenotype can be rescued either by reducing Glycogen synthase kinase 3beta (GSK3beta)/Shaggy (Sgg) activity or overexpressing Bbeta2 regulatory subunits of PP2A. Elevated expression of the Drosophila Bbeta2 homolog, Twins (Tws), also alleviated neuritic dystrophy of the dorsal arborization (da) neuron caused by Tau aggregation. Additionally, lowering endogenous Tau dosage was beneficial as it ameliorated the bristle loss phenotype. Finally, the bristle loss phenotype was used to evaluate the efficacy of potential therapeutic compounds. The GSK3beta inhibitor, alsterpaullone, was found to suppress toxicity of Tau in a concentration-dependent manner. The notum of Drosophila, thus, provides a new tool and insights into Tau-induced toxicity. It could also potentially assist in screening new drugs for possible therapeutic intervention.

Topics: Animals; Animals, Genetically Modified; Benzazepines; Disease Models, Animal; Drosophila melanogaster; Drosophila Proteins; Drug Evaluation, Preclinical; Glycogen Synthase Kinase 3; Humans; Indoles; Neurofibrillary Tangles; Phosphoprotein Phosphatases; Phosphorylation; Protein Kinase Inhibitors; tau Proteins; Tauopathies