Biology subjects

Sialana, F.

Publications and source records attributed to Sialana, F..

3 recordsLinked to original sources

bioRxiv2026

High resolution interaction surface mapping by PRISMA reveals novel ARID1A interactions

The SWI/SNF chromatin remodelling complex controls proliferation and cell fate determination by regulating chromatin accessibility at promoters and enhancers, thereby modulating programs of gene expression, and has roles in DNA damage response, replication, splicing, and translation, and cell plasticity. The cBAF-exclusive subunit ARID1A acts as scaffold for the assembly of cBAF SWI/SNF complexes through its C-terminal globular domain and is the most frequently mutated SWI/SNF subunit in cancer. More than half of the ARID1A protein sequence contains regions of intrinsic disorder which are important for protein interactions, often mediated by short linear motifs. However, these interactions are notoriously difficult to study. Whilst hundreds of ARID1A interactions have been reported in the literature, their molecular basis remains obscure, and only a few have been explored functionally or mapped at an interface level. Here, we use a PRotein Interaction Screen on a peptide MAtrix (PRISMA) combined with quantitative mass spectrometry to identify novel ARID1A interactions and map amino acid residues and motifs that mediate interactions at high sequence resolution. The ARID1A PRISMA assay recapitulates binding of BAF subunits to ARID1A and detects the previously described binding of YAP1 transcriptional coactivator to a PPXY motif. Our PRISMA data reveals binding sites for transcriptional repressor SIN3A and identifies TOX4, CDK2 and CCNA2 as novel interactors. Mutation of a cell cycle-dependent CDK2 phosphorylation site in ARID1A leads to altered gene expression of microtubule factors and defects in cell proliferation. Our work underscores the utility of PRISMA to uncover weak or low abundance interactions that are not detectable by traditional affinity purification strategies. Together, our results characterise novel interactors and a new mode of regulation of ARID1A, and provide a useful resource to further explore mechanistic aspects of ARID1A function.

biochemistry↗

bioRxiv2025

Identification of molecular pathways involved in the anti-liver cancer activity of madecassic acid

Natural products are a time-tested source of medicinal compounds, and there is huge interest in discovery of new drugs from plant sources. However, in many cases the effects are not as well understood, strong, or selective, as would be hoped. An example of this is madecassic acid (MA), which has promising activity against liver cancer, activity which can be improved through chemical modifications, although a molecular understanding of its mechanism of action is unknown. In this report we have used chemical proteomics to identify the proteins with which madecassic interacts in liver cancer cells, and used RNAseq to support those findings, as well as showing more precisely how chemical modifications can focus and amplify MA activity. Our results show that madecassic acid interacts with a number of proteins relating to metabolism, nucleic acid processing, and protein folding, which have been previously identified as linked to liver cancer. This provides a route from phenotypic- to target based-drug discovery and develop new potential treatments for a globally challenging disease.

pharmacology and toxicology↗

bioRxiv2024

Degradation of LMO2 in T cell leukaemia causes collateral breakdown of transcription complex partners and LMO2-dependent apoptosis

LMO2 is an intrinsically disordered transcription factor activated in T cell leukaemia that is difficult to target. It forms part of a multiprotein complex that has bipartite DNA binding through heterodimeric bHLH and GATA proteins. To determine if degradation of LMO2 in the context of T-ALL has therapeutic potential, a chimaeric intracellular antibody has been developed fusing an anti-LMO2 single domain variable region with one of three E3 ligases to create biodegraders. The intracellular binary interaction of these biodegraders with LMO2 leads to its proteosomal degradation but, in addition, concomitant loss of bHLH proteins that associate with LMO2 in the DNA-binding complex. Chemical compound surrogates of the intracellular antibody paratope (called Abd compounds) have been modified to create proteolysis targeting chimaeras (PROTACs) for orthogonal assays of effects of LMO2 degradation. These form a ternary complex with LMO2 and E3 ligase in leukaemia cells that induces degradation of LMO2, and is also accompanied by loss of associated bHLH proteins. This is accompanied by T-ALL growth inhibition, alterations in proteins involved in cell cycling and instigation of apoptosis. These effects do not occur in the absence of LMO2. Our work demonstrates that degradation of LMO2 affects T-ALL and the lead compounds can eventually be developed into drugs for patient treatment. Our work describes methods for drug discovery starting with antibody fragments.

cancer biology↗