Theonella: A Treasure Trove of Structurally Unique and Biologically Active Sterols

The marine environment is considered a vast source in the discovery of structurally unique bioactive secondary metabolites. Among marine invertebrates, the sponge Theonella spp. represents an arsenal of novel compounds ranging from peptides, alkaloids, terpenes, macrolides, and sterols. In this review, we summarize the recent reports on sterols isolated from this amazing sponge, describing their structural features and peculiar biological activities. We also discuss the total syntheses of solomonsterols A and B and the medicinal chemistry modifications on theonellasterol and conicasterol, focusing on the effect of chemical transformations on the biological activity of this class of metabolites. The promising compounds identified from Theonella spp. possess pronounced biological activity on nuclear receptors or cytotoxicity and result in promising candidates for extended preclinical evaluations. The identification of naturally occurring and semisynthetic marine bioactive sterols reaffirms the utility of examining natural product libraries for the discovery of new therapeutical approach to human diseases.

Chemical Proteomics-Guided Identification of a Novel Biological Target of the Bioactive Neolignan Magnolol

Understanding the recognition process between bioactive natural products and their specific cellular receptors is of key importance in the drug discovery process. In this outline, some potential targets of Magnolol, a natural bioactive compound, have been identified by proteomic approaches. Among them, Importin-β1 has been considered as the most relevant one. A direct binding between Magnolol and this nuclear chaperone has been confirmed by DARTS and molecular docking, while its influence on Importin-β1 translocation has been evaluated by in vitro assays.

The essential player in adipogenesis GRP78 is a novel KCTD15 interactor

KCTD15 is a member of the K+ Channel Tetramerization Domain family, implicated in crucial physio-pathological processes. Recent evidences suggest that KCTD15 is an obesity-linked protein in humans and its Drosophila homologue is involved in food uptake. KCTD15 molecular mechanism in these processes is still unknown. To fill this gap, KCTD15 was biophysically characterized showing a folded, pentameric region endowed with a remarkable thermal stability. Notably, the C-terminal domain significantly contributes to the stabilization of the BTB N-terminal domain. The availability of large amount of stable recombinant protein also made possible a functional proteomic approach in 3T3-L1 cells to search for novel KCTD15 interactors. These investigations led to the discovery that GRP78 is a KCTD15 partner in all the adipogenesis phases. Our data clearly prove the physical interaction of the two proteins and also indicate that GRP78 plays an active role in the stabilization of KCTD15. Furthermore, the presence in Drosophila of a GRP78 homologue corroborates the physiological role played by the complex KCTD15-GRP78 in the adipogenesis process and indicates that it is evolutionarily conserved. Present results also suggest that KCTD15 may be a new target for obesity control.

Identification of Trombospondin-1 as a Novel Amelogenin Interactor by Functional Proteomics

Amelogenins are a set of low molecular-weight enamel proteins belonging to a group of extracellular matrix (ECM) proteins with a key role in tooth enamel development and in other regeneration processes, such as wound healing and angiogenesis. Since only few data are actually available to unravel amelogenin mechanism of action in chronic skin healing restoration, we moved to the full characterization of the human amelogenin isoform 2 interactome in the secretome and lysate of Human Umbilical Vein Endothelial cells (HUVEC), using a functional proteomic approach. Trombospondin-1 has been identified as a novel and interesting partner of human amelogenin isoform 2 and their direct binding has been validated thought biophysical orthogonal approaches.

Roles of peroxiredoxins in cancer, neurodegenerative diseases and inflammatory diseases

Peroxiredoxins (PRDXs) are antioxidant enzymes, known to catalyze peroxide reduction to balance cellular hydrogen peroxide (H₂O₂) levels, which are essential for cell signaling and metabolism and act as a regulator of redox signaling. Redox signaling is a critical component of cell signaling pathways that are involved in the regulation of cell growth, metabolism, hormone signaling, immune regulation and variety of other physiological functions. Early studies demonstrated that PRDXs regulates cell growth, metabolism and immune regulation and therefore involved in the pathologic regulator or protectant of several cancers, neurodegenerative diseases and inflammatory diseases. Oxidative stress and antioxidant systems are important regulators of redox signaling regulated diseases. In addition, thiol-based redox systems through peroxiredoxins have been demonstrated to regulate several redox-dependent process related diseases. In this review article, we will discuss recent findings regarding PRDXs in the development of diseases and further discuss therapeutic approaches targeting PRDXs. Moreover, we will suggest that PRDXs could be targets of several diseases and the therapeutic agents for targeting PRDXs may have potential beneficial effects for the treatment of cancers, neurodegenerative diseases and inflammatory diseases. Future research should open new avenues for the design of novel therapeutic approaches targeting PRDXs.