Iván López-Montero

Boron Neutron Capture Therapy (BNCT) relies on the accumulation of boron‐10 within tumor cells to induce highly localized cytotoxicity upon neutron irradiation. The development of boron delivery systems with high boron content, biocompatibility, and efficient cellular uptake remains a critical challenge. Herein, we report the design and synthesis of unprecedented fullerene–boron cluster hybrids that integrate the multivalent scaffold of [60]fullerene with anionic boron clusters. Two [60]fullerene hexakis‐adducts bearing twelve peripheral cobaltabisdicarbollide (COSAN) or closo ‐dodecaborate boron clusters have been prepared through a Cu(I)‐catalyzed azide–alkyne cycloaddition strategy. The resulting nanostructures incorporate up to 216 boron atoms while preserving the structural integrity of both the fullerene core and the anionic boron clusters. Comprehensive spectroscopic and electrochemical characterization confirms the successful formation of the hybrids. To enable biological evaluation, the compounds are formulated into liposomes, showing excellent cytocompatibility and efficient cellular internalization in mouse embryonic fibroblasts and Cal33 human head and neck cancer cells. Confocal microscopy reveals predominant endolysosomal localization without significant cytotoxicity at therapeutically relevant boron concentrations. These results establish fullerene–boron cluster conjugates as a new class of boron‐rich nanomaterials and highlight their potential as boron delivery agents for future BNCT studies.

Golgins are coiled-coil proteins that decorate Golgi with highly specific spatial distribution acting as vesicle tethers through their extended, semiflexible architectures. Among them, GM130 is also known to undergo phase separation, yet the molecular basis of this behavior remains poorly understood. Here, we use atomic force microscopy (AFM) to directly visualize individual GM130 molecules adsorbed onto attractive surfaces. We find that GM130 is highly flexible and undergoes conformational transitions from extended chains to collapsed coils—globular structures that serve as building blocks for the submicrometric two-dimensional and dynamic domains when anchored to lipid bilayers. Molecular-dynamics simulations predict a supramolecular scaffold for GM130 domains composed of coiled-coil intermolecular nodes surrounded by a dispersed phase of intrinsically disordered regions with electrostatic interactions acting as chief drivers of phase-separation. These assemblies are experimentally validated under high-force AFM measurements. Our findings establish the structural basis linking GM130 conformational polymorphism to its phase separation capacity.

Easily accessible and stable (dimethylamino)methyl BODIPYs unlock broad methylene-linked BODIPY functionalization with neutral protic nucleophiles.

The interplay between ATP synthase dimers and the four-tailed lipid cardiolipin (CL) shapes mitochondrial cristae structure and function. In the mitochondrial disorder Barth syndrome (BTHS), cristae membranes accumulate a less unsaturated, three-tailed form of cardiolipin (MLCL). These cristae become structurally and functionally compromised through mechanisms poorly understood. We have studied through molecular dynamics simulations how BTHS lipid composition affects the conformation of the ATP synthase dimer. The wedge-shaped transmembrane region of the ATP synthase dimer attracts cardiolipins through shape complementarity. MLCL showed decreased affinity for the dimer interface than CLs of the healthy model. A more heterogeneous lipid environment with a higher elastic strain promoted a dimer conformation that would stabilize wider intracrista spaces, and hence, less efficient OXPHOS reactions in BTHS. Our results provide clues on the role played by the CL acyl chain composition in the architecture and function of mitochondria in health and BTHS.

Our work presents a simple and efficient method to impart water solubility to BODIPY dyes while preserving their key properties, enabling broader applications in aqueous environments.

Mitofusins (Mfn1 and Mfn2) are the mitochondrial outer-membrane fusion proteins in mammals and belong to the dynamin superfamily of multidomain GTPases. Recent structural studies of truncated variants lacking alpha helical transmembrane domains suggested that Mfns dimerize to promote the approximation and the fusion of the mitochondrial outer membranes upon the hydrolysis of guanine 5′-triphosphate disodium salt (GTP). However, next to the presence of GTP, the fusion activity seems to require multiple regulatory factors that control the dynamics and kinetics of mitochondrial fusion through the formation of Mfn1–Mfn2 heterodimers. Here, we purified and reconstituted the full-length murine Mfn2 protein into giant unilamellar vesicles (GUVs) with different lipid compositions. The incubation with GTP resulted in the fusion of Mfn2-GUVs. High-speed video-microscopy showed that the Mfn2-dependent membrane fusion pathway progressed through a zipper mechanism where the formation and growth of an adhesion patch eventually led to the formation of a membrane opening at the rim of the septum. The presence of physiological concentration (up to 30 mol%) of dioleoyl-phosphatidylethanolamine (DOPE) was shown to be a requisite to observe GTP-induced Mfn2-dependent fusion. Our observations show that Mfn2 alone can promote the fusion of micron-sized DOPE-enriched vesicles without the requirement of regulatory cofactors, such as membrane curvature, or the assistance of other proteins.

Statins are known to be anti-inflammatory, but the mechanism remains poorly understood. Here, we show that macrophages, either treated with statin in vitro or from statin-treated mice, have reduced cholesterol levels and higher expression of Jmjd3, a H3K27me3 demethylase. We provide evidence that lowering cholesterol levels in macrophages suppresses the adenosine triphosphate (ATP) synthase in the inner mitochondrial membrane and changes the proton gradient in the mitochondria. This activates nuclear factor kappa-B (NF-κB) and Jmjd3 expression, which removes the repressive marker H3K27me3. Accordingly, the epigenome is altered by the cholesterol reduction. When subsequently challenged by the inflammatory stimulus lipopolysaccharide (M1), macrophages, either treated with statins in vitro or isolated from statin-fed mice, express lower levels proinflammatory cytokines than controls, while augmenting anti-inflammatory Il10 expression. On the other hand, when macrophages are alternatively activated by IL-4 (M2), statins promote the expression of Arg1, Ym1, and Mrc1. The enhanced expression is correlated with the statin-induced removal of H3K27me3 from these genes prior to activation. In addition, Jmjd3 and its demethylase activity are necessary for cholesterol to modulate both M1 and M2 activation. We conclude that upregulation of Jmjd3 is a key event for the anti-inflammatory function of statins on macrophages.

Expansion microscopy (ExM) is a new super-resolution technique based on embedding the biological sample within a hydrogel and its physical expansion after swelling. This allows increasing its size by several times while preserving its structural details. Applied to prokaryotic cells, ExM requires digestion steps for efficient expansion as bacteria are surrounded by a rigid cell wall. Furthermore, bacteria can live in social groups forming biofilms, where cells are protected from environmental stresses by a self-produced matrix. The extracellular matrix represents an additional impenetrable barrier for ExM. Here we optimize the current protocols of ExM and apply them to mono- and dual-species biofilms formed by clinical isolates of Limosilactobacillus reuteri, Enterococcus faecalis, Serratia marcescens and Staphylococcus aureus. Using scanning electron microscopy for comparison, our results demonstrate that embedded bacteria expanded 3-fold. Moreover, ExM allowed visualizing the three-dimensional architecture of the biofilm and identifying the distribution of different microbial species and their interactions. We also detected the presence of the extracellular matrix after expansion with a specific stain of the polysaccharide component. The potential applications of ExM in biofilms will improve our understanding of these complex communities and have far-reaching implications for industrial and clinical research.