Renata Nascimento Gomes

Lys49 phospholipase A2 (Lys49-PLA₂) homologues are catalytically inactive snake venom toxins with diverse biological activities, but their functional characterization requires recombinant production strategies to overcome the limitations inherent to native venom-derived proteins. Here, we produced recombinant BaMtx (rBaMtx), a Lys49-PLA₂ homologue from Bothrops atrox, in the Pichia pastoris KM71 expression system and evaluated whether its biochemical and biological properties were preserved. rBaMtx was secreted into the culture medium, purified by cation-exchange chromatography, and characterized by SDS-PAGE, Western blotting, RP-HPLC (85.9% purity), and MALDI-TOF mass spectrometry, confirming a molecular mass of 13,821 Da. Despite lacking PLA₂ activity, rBaMtx retained pronounced myotoxicity in vivo, inducing dose-dependent plasma creatine kinase release and skeletal muscle damage comparable to or greater than native BaMtx. In vitro, rBaMtx reduced viability of murine 4T1 breast carcinoma cells (IC₅₀ = 60.94 µg/mL), altered cell morphology, modestly increased IL-1β release, and produced context-dependent effects in paired human tumor and non-tumor cell models, differing from native BaMtx and crude venom. These findings establish rBaMtx as a reproducible model for investigating the mechanisms and biomedical potential of catalytically inactive Lys49-PLA₂ homologues.

Mitochondria are central hubs of antiviral immunity and cellular metabolism, yet the links between SARS-CoV-2–induced mitochondrial remodeling, antiviral gene regulation, and post-translational control remain incompletely understood. Here, we investigated mitochondrial–immune remodeling in SARS-CoV-2–infected lung-derived LC-HK2 cells at 48 and 96 h post-infection using confocal and high-content imaging, colocalization analysis, CellProfiler quantification, RT-qPCR, proteomics, cytokine profiling, and conditioned-medium analysis. Infection induced a time-dependent mitochondrial phenotype. At 48 hpi, cells displayed early mitochondrial stress and fission-associated signatures, including increased DRP1, transient upregulation of mitochondrial respiratory genes, and reduced MFN1/2. At 96 hpi, mitochondria shifted toward elongated perinuclear networks, accompanied by increased fusion/biogenesis markers and partial ISG15–MFN2 colocalization, indicating a spatial association between ISG15-related antiviral/stress responses and mitochondrial remodeling. Antiviral and ISG-related transcripts were consistently upregulated, but IFN-α2 secretion remained limited, suggesting partial uncoupling between antiviral transcriptional activation and downstream interferon output. SUMO2/3 was dynamically modulated and showed time-dependent colocalization with mitochondrial dynamics proteins and MAVS. Together, these data support a coordinated mitochondrial–immune regulatory axis involving mitochondrial remodeling, ISG15-associated responses, and SUMO-dependent regulation during SARS-CoV-2 infection.

Osteoarthritis (OA) is a degenerative joint disease characterized by progressive cartilage loss, extracellular matrix degradation, chondrocyte apoptosis, and elevated inflammatory mediators. Chondrocytes respond to IL-1β and other inflammatory signals by secreting cytokines and activating transcriptional pathways that perpetuate inflammation. Because current therapies do not prevent OA progression, bioactive compounds with cytoprotective and immunomodulatory activity are of considerable interest. Lonomia obliqua bristle extract (LOCBE) and its recombinant proteins rLOPAP and rLOSAC exhibit cytoprotective, proliferative, and antioxidant effects in mammalian cells, as well as the ability to influence cytoskeletal dynamics. Given the importance of Rac-1, RhoA, Rab9, and β-catenin in chondrocyte function and cartilage homeostasis, we evaluated LOCBE, rLOPAP, and rLOSAC in human chondrocytes stimulated or not with IL-1β. LOCBE and rLOPAP induced IL-6 and IL-8 secretion, although at lower levels than IL-1β. LOCBE exerts a cytoprotective effect in IL-1β-treated chondrocytes and reduces β-catenin, RhoA, and Rab9 expression without affecting NF-κB p65 translocation. rLOPAP increased mitochondrial activity, cytokine secretion, Rab9 expression, and membrane-associated β-catenin, and under inflammatory conditions, enhanced Rac-1 levels. In contrast, rLOSAC did not induce inflammatory cytokines and decreased RhoA and Rac-1 expression while increasing membrane-associated β-catenin. These findings suggest that L. obliqua extract and its derived-proteins rLOPAP and rLOSAC modulate cytoskeletal regulatory pathways and inflammatory responses in chondrocytes, supporting their potential as therapeutic leads for targeting mechanisms relevant to OA progression.