Matteo De March

The SNF2-family Helicase-Like Transcription Factor (HLTF) has been implicated in tumorigenesis, with evidence suggesting both tumour-suppressive and oncogenic functions. To clarify the nature of this increasingly emerging double function, we analysed the full HLTF’s alterome across TCGA cohorts combining first gene expression with genomic and epigenomic layers of de-regulation, and investigating further their determinants through the integration of DNA methylation profiles - both at promoter-proximal and distal regions, the copy-number alterations, and all somatic mutations. This multi-layered analysis highlighted specific context-dependent HLTF’s regulatory configurations across human cancers, even modulated by either dosage effects or loss-of-function events. The clinical relevance of HLTF’s alterations, identified through tumour-specific associations with patient outcomes, supports its potential as new biomarker in cancer overall.

Human zinc finger Ran-binding protein 3 (ZRANB3) is crucial for DNA damage tolerance (DDT), as it prevents excessive damage, restores fork progression, and ultimately maintains genome stability. This unique and ancient architecture mainly exerts its function during replication fork reversal (RFR) and within the p53/Polι axis; thus, ZRANB3 is considered a tumour suppressor. However, possible additional roles in DNA synthesis and cell metabolism have been proposed. In tumour cells, ZRANB3 gene expression is deregulated, a condition that is frequently associated with poor survival and adverse clinical outcomes. ZRANB3 can be altered by functional mutations, gene copy number alterations, and a combination of the two. Although its mRNA levels typically correlate with p53 expression, this correlation breaks down in the context of p53 mutations and high proliferative activity. This comprehensive review integrates the currently available yet fragmented literature on ZRANB3, both at the gene and protein levels, examines its regulation in cancer development, and discusses the evidence supporting its role as a tumour suppressor and prognostic biomarker.

Background: Fluorescent proteins (FPs) are pivotal reagents for flow cytometry analysis or fluorescent microscopy. A new generation of immunoreagents (fluobodies/chromobodies) has been developed by fusing recombinant nanobodies to FPs. Methods: We analyzed the quality of such biomolecules by a combination of gel filtration and SDS-PAGE to identify artefacts due to aggregation or material degradation. Results: In the SDS-PAGE run, unexpected bands corresponding to separate fluobodies were evidenced and characterized as either degradation products or artefacts that systematically resulted in the presence of specific FPs and some experimental conditions. The elimination of N-terminal methionine from FPs did not impair the appearance of FP fragments, whereas the stability and migration characteristics of some FP constructs were strongly affected by heating in loading buffer, which is a step samples undergo before electrophoretic separation. Conclusions: In this work, we provide explanations for some odd results observed during the quality control of fluobodies and summarize practical suggestions for the choice of the most convenient FPs to fuse to antibody fragments.

Background: Adhirons are small (10 kDa) synthetic ligands that might represent an alternative to antibody fragments and to alternative scaffolds such as DARPins or affibodies. Methods: We prepared a conceptionally new adhiron phage display library that allows the presence of cysteines in the hypervariable loops and successfully panned it against antigens possessing different characteristics. Results: We recovered binders specific for membrane epitopes of plant cells by panning the library directly against pea protoplasts and against soluble C-Reactive Protein and SpyCatcher, a small protein domain for which we failed to isolate binders using pre-immune nanobody libraries. The best binders had a binding constant in the low nM range, were produced easily in bacteria (average yields of 15 mg/L of culture) in combination with different tags, were stable, and had minimal aggregation propensity, independent of the presence or absence of cysteine residues in their loops. Discussion: The isolated adhirons were significantly stronger than those isolated previously from other libraries and as good as nanobodies recovered from a naïve library of comparable theoretical diversity. Moreover, they proved to be suitable reagents for ELISA, flow cytometry, the western blot, and also as capture elements in electrochemical biosensors.

Here, we present the crystal structure of the synthetic peptide KE1, which contains four K‐coil heptads separated in the middle by the QFLMLMF heptad. The structure determination reveals the presence of a canonical parallel three stranded coiled coil. The geometric characteristics of this structure are compared with other coiled coils with the same topology. Furthermore, for this topology, the analysis of the propensity of the single amino acid to occupy a specific position in the heptad sequence is reported. A number of viral proteins use specialized coiled coil tail needles to inject their genetic material into the host cells. The simplicity and regularity of the coiled coil arrangement made it an attractive system for de novo design of key molecules in drug delivery systems, vaccines, and therapeutics.

The interaction between avidin and its counterpart biotin is one of central importance in biology and has been reproposed and studied at length. However, the binding pocket of avidin is prone to promiscuous binding, able to accommodate even non‐biotinylated ligands. Comprehending the factors that distinguish the extremely strong interaction with biotin to other ligands is an important step to fully picture the thermodynamics of these low‐affinity complexes. Here, we present the complex between chicken white egg avidin and theophylline (TEP), the xanthine derivative used in the therapy of asthma. In the crystal structure, TEP lies in the biotin‐binding pocket with the same orientation and planarity of the aromatic ring of 8‐oxodeoxyguanosine. Indeed, its affinity for avidin measured by isothermal titration calorimetry is in the same μM range as those obtained for the previously characterized nucleoside derivatives. By the use of molecular dynamic simulations, we have investigated the most important intermolecular interactions occurring in the avidin‐TEP binding pocket and compared them with those obtained for the avidin 8‐oxodeoxyguanosine and avidin‐biotin complexes. These results testify the capability of avidin to complex purely aromatic molecules.

Extracellular vesicles (EVs) have enormous potential for the implementation of liquid biopsy and as effective drug delivery means, but the fulfilment of these expectations requires overcoming at least two bottlenecks relative to their purification, namely the finalization of reliable and affordable protocols for: (i) EV sub-population selective isolation and (ii) the scalability of their production/isolation from complex biological fluids. In this work, we demonstrated that these objectives can be achieved by a conceptually new affinity chromatography platform composed of a macroporous epoxy monolith matrix functionalized with anti-CD63 nanobodies with afflux of samples and buffers regulated through a pump. Such a system successfully captured and released integral EVs from urine samples and showed negligible unspecific binding for circulating proteins. Additionally, size discrimination of eluted EVs was achieved by different elution approaches (competitive versus pH-dependent). The physical characteristics of monolith material and the inexpensive production of recombinant nanobodies make scaling-up the capture unit feasible and affordable. Additionally, the availability of nanobodies for further specific EV biomarkers will allow for the preparation of monolithic affinity filters selective for different EV subclasses.