Joanna Izabela Lachowicz

PC18 – Joanna Izabela Lachowicz

Wroclaw Medical University, Poland
University of Cagliari, Italy

joanna.lachowicz@umw.edu.pl

Thymosin β4 as a Metal‑Responsive Regulator of Ferroptosis and Cellular Stress: Implications for Medicinal Chemistry
Joanna Izabela Lachowicz¹^,2 ¹ Department of Environmental Health, Occupational Medicine and Epidemiology, Wroclaw Medical University, Mikulicza-Radeckiego 7, 50-368 Wroclaw, PL, Poland ² Department of Medical Science and Public Health, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, CA, Italy
Abstract Thymosin β4 (Tβ4) is a highly conserved, intrinsically disordered peptide with established roles in actin dynamics, tissue regeneration, angiogenesis, inflammation, and cancer progression [1]. However, its pleiotropic biological activity cannot be fully explained by G‑actin sequestration alone. Here, we propose an integrated mechanistic model in which Tβ4 functions as a metal‑responsive regulator of cellular stress and ferroptosis, with direct relevance for medicinal chemistry. Using NMR spectroscopy, molecular modeling, and cellular assays, we demonstrate that Tβ4 coordinates essential metal ions—including Fe²⁺/Fe³⁺, Zn²⁺, and Ca²⁺—via multiple low‑affinity, spatially distributed binding sites [1–3]. Structural analyses reveal that metal coordination does not induce major secondary‑structure rearrangements, consistent with the intrinsically disordered nature of the peptide [2]. Functionally, Tβ4 acts as an endogenous iron chelator, forming dynamic complexes that modulate iron availability and redox balance under stress conditions [1]. In macrophage models, extracellular Tβ4 suppresses erastin‑ and glutamate‑induced ferroptosis, reverses mitochondrial ultrastructural damage, and restores cellular organization [1]. At the molecular level, Tβ4 counteracts ferroptotic cell death by upregulating oxidative‑stress response genes (HO‑1, HSP70, BAX, TXNRD1) that are otherwise suppressed during lipid peroxidation‑driven toxicity [1]. Its anti‑ferroptotic efficacy parallels that of reference ferroptosis inhibitors, suggesting a shared metal‑dependent mechanism rather than a purely antioxidant effect. We further show that nutrient starvation profoundly alters Tβ4 trafficking, promoting the cellular uptake of extracellular Tβ4 and its Ca²⁺ complexes [3]. Under these conditions, Ca²⁺/Tβ4 complexes are internalized into the cytoplasm, increasing intracellular calcium availability and potentially activating migration‑ and survival‑associated signaling pathways relevant to early metastatic events [3]. Complementary zinc‑coordination studies support an additional role for Tβ4 in intracellular metal buffering and redox modulation during inflammation and cellular stress [2]. Collectively, these findings establish Tβ4 as a multifunctional, redox‑active metallopeptide that integrates metal coordination, ferroptosis regulation, and stress adaptation. From a medicinal chemistry perspective, Tβ4 provides a biological blueprint for designing non‑toxic, peptide‑based metal modulators, opening new strategies for targeting ferroptosis and metal‑driven pathologies in cancer, neurodegeneration, and tissue injury.
References [1] Lachowicz, J.I.; Pichiri, G.; Piludu, M.; Fais, S.; Orrù, G.; Congiu, T.; Piras, M.; Faa, G.; Fanni, D.; Dalla Torre, G.; et al. Thymosin β4 Is an Endogenous Iron Chelator and Molecular Switcher of Ferroptosis. Int. J. Mol. Sci. 2022, 23, 551. [2] Lachowicz, J.I.; Jaremko, M.; Jaremko, Ł.; Pichiri, G.; Coni, P.; Piludu, M. Metal Coordination of Thymosin β4: Chemistry and Possible Implications. Coord. Chem. Rev. 2019, 396, 117–123. [3] Piludu, M.; Pichiri, G.; Coni, P.; Piras, M.; Congiu, T.; Faa, G.; Lachowicz, J.I. Cell Starvation Increases Uptake of Extracellular Thymosin β4 and Its Complexes with Calcium. Int. Immunopharmacol. 2023, 116, 109743.