Expression of Active Apurinic Apyrimidinic Endodeoxyribonuclease 1 in Human Platelets

Molecular Striptease of a Thiadiazolopyrimidine Hit Yields a Streamlined, Artifact-Free NADPH Mimic for NOX Inhibition

The convergence of oxidative stress and inflammation drives neurodegeneration and cancer, positioning NADPH oxidases (NOXs) as critical therapeutic targets. Starting from the polyfunctional thiadiazolopyrimidine hit 1, we systematically truncated its peripheral arms to map minimum pharmacophoric requirements. While extensive clipping compromised activity, strategic optimization yielded the streamlined analogue 5. In silico, 5 acted as a competitive NADPH mimic; in cell-free assays, it maintained multi-isoform potency, inhibiting NOX1 and NOX5 at low-micromolar concentrations. In rat brain subcellular fractions, 1 and 5 demonstrated concentration-dependent neuroprotective and antioxidant efficacy (1–10 μM) by suppressing lipid peroxidation and preserving mitochondrial and synaptosomal viability. Notably, chemical profiling proved that 5 successfully stripped away the pro-oxidant liabilities and radical-scavenging artifacts inherent to 1. In cancer, 1 displayed some antiproliferative activity, mainly in hematological malignancies. Compound 5, although aqueous solubility issues limited its cellular antiproliferative performance, represents a specific, artifact-free architectural starting point for future selective NOX inhibitor development.

Complement drives PNH red cell hemolysis independently of inflammasome activation

Paroxysmal Nocturnal Hemoglobinuria (PNH) is characterized by hemolysis due to the loss of GPI-anchored complement regulators. While terminal complement inhibitors improve survival, the precise intracellular mechanisms driving the destruction of PNH erythrocytes remain controversial. A recently proposed model suggests PNH cells undergo an inflammatory programmed cell death ("spectosis") driven by an NLRP3-Caspase-8 signaling cascade. Here, we use a whole packed cell lysis approach to map the cytoskeletal degradation of primary erythrocytes across a 22-patient PNH cohort. Our data show that membrane attack complex (MAC) pore formation drives targeted {beta}-spectrin fragmentation, which correlates with rapid intracellular potassium (K+) efflux. Notably, when probing these primary patient samples, we detected a complete absence of the NLRP3 protein and found no functional evidence of Caspase-8 activation during MAC pore formation. Furthermore, caspase inhibition did not alter cytoskeletal degradation or K+ efflux. Instead, our data demonstrate that MAC-induced membrane perforation permits a rapid influx of calcium, which activates calpain, the dominant calcium-dependent protease in erythrocytes. Rather than an inflammatory cascade, this calcium-dependent calpain activity executes the degradation of {beta}-spectrin. These findings challenge current models of PNH hemolysis. We show that the destruction of PNH erythrocytes is a consequence of the MAC-calcium-calpain axis, rather than an inflammatory programmed cell death event. Consequently, therapeutic strategies aimed at targeting the inflammasome or caspase signaling will likely offer no clinical benefit for PNH patients.

Effect of Glycosylphosphatidylinositol-specific phospholipase D1 knockout on the expression of antioxidant enzymes and sirtuin

A Procoagulant Peptide Analog of the SARS-CoV-2 Nucleocapsid C-terminal Domain

The results support a model in which N389 functions as a stable, charge-based scaffold that coordinates divalent cations and/or directly nucleates fibrin(ogen), while highlighting limitations of bulk clotting assays and the need for targeted thrombin generation, binding, aggregation, and contact-activation studies.

Antimicrobial cetylpyridinium chloride disrupts the mitochondrial electron transport chain as potently as cyanide, via cardiolipin interference at cytochrome C

Adenylosuccinate acts as a novel pro-angiogenic factor

We recently demonstrated a dramatic 77-fold increase in brain adenylosuccinate (AdSucc) concentration during ischemia, reaching ~0.56 mM levels. Previously, the role of AdSucc induction under decreased energy charge was attributed to the activation of purine nucleotide (PNC) and the tricarboxylic acid cycle (TCA). However, careful analysis of metabolomic alterations in the ischemic brain under decreased energy charge did not confirm this role. To begin addressing the additional biological significance of the increased AdSucc under low-energy conditions associated with ischemia, we tested its angiogenic properties. Using a mouse in vivo angiogenesis assay, we discovered that AdSucc, but not its metabolites such as adenosine or AMP accumulated during the assay, promotes angiogenesis in vivo at concentrations found in ischemic tissues. Further, using in vitro angiogenesis assay with human umbilical vein endothelial cells (HUVEC), we demonstrated that AdSucc promotes the formation of capillary-like structures (tubes) on extracellular matrix support. We also report, for the first time, that AdSucc increases cAMP levels, supporting its signaling role, which may be linked to pro-angiogenic mechanisms. Together, our data indicate a novel mechanism of angiogenesis regulation, in which AdSucc may serve as a new signaling molecule under low-energy conditions. Further studies are required to confirm the role of endogenously produced AdSucc in tissue angiogenesis as an adaptation mechanism to low-energy conditions and repair after injury.