Homorepeats are motifs with reiterations of the same amino acid. They are prevalent in proteins associated with diverse physiological functions but also linked to several pathologies. Structural characterization of homorepeats has remained largely elusive, primarily because they generally occur in the disordered regions or proteins.
View Article and Find Full Text PDFImmunotherapy has revolutionized cancer treatment but its efficacy depends on a robust immune response in the tumor. Silencing of the tumor suppressor p53 is common in tumors and can affect the recruitment and activation of different immune cells, leading to immune evasion and poor therapy response. We found that the p53 activating stapled peptide MDM2/MDMX inhibitor Sulanemadlin (ALRN-6924) inhibited p53 wild-type cancer cell growth and .
View Article and Find Full Text PDFThe c-MYC oncogene is activated in over 70% of all human cancers. The intrinsic disorder of the c-MYC transcription factor facilitates molecular interactions that regulate numerous biological pathways, but severely limits efforts to target its function for cancer therapy. Here, we use a reductionist strategy to characterize the dynamic and structural heterogeneity of the c-MYC protein.
View Article and Find Full Text PDFCancer Discov
February 2024
Mutant p53 proteins are often highly expressed in human cancers and have been thought to have oncogenic driver gain-of-function (GOF) properties. Wang and colleagues show, surprisingly, that this is not the case because removing the TP53-mutant gene from human and mouse cancer cells using CRISPR technology has no effect on cancer cell growth in vitro or in vivo. See related article by Wang et al.
View Article and Find Full Text PDFAlthough stapled α-helical peptides can address challenging targets, their advancement is impeded by poor understandings for making them cell permeable while avoiding off-target toxicities. By synthesizing >350 molecules, we present workflows for identifying stapled peptides against Mdm2(X) with in vivo activity and no off-target effects. Key insights include a clear correlation between lipophilicity and permeability, removal of positive charge to avoid off-target toxicities, judicious anionic residue placement to enhance solubility/behavior, optimization of C-terminal length/helicity to enhance potency, and optimization of staple type/number to avoid polypharmacology.
View Article and Find Full Text PDFPeptides are promising drug modalities that can modulate protein-protein interactions, but their application is hampered by their limited ability to reach intracellular targets. Here, we improved the cytosolic delivery of a peptide blocking p53:MDM2/X interactions using a cyclotide as a stabilizing scaffold. We applied several design strategies to improve intracellular delivery and found that the conjugation of the lead cyclotide to the cyclic cell-penetrating peptide cR10 was the most effective.
View Article and Find Full Text PDFPurpose: Molecular radiotherapy is a treatment modality that is highly suitable for targeting micrometastases and [Lu]Lu-DOTATATE is currently being explored as a potential novel treatment option for high-risk neuroblastoma. p53 is a key player in the proapoptotic signalling in response to radiation-induced DNA damage and is therefore a potential target for radiosensitisation.
Methods: This study investigated the use of the p53 stabilising peptide VIP116 and [Lu]Lu-DOTATATE, either alone or in combination, for treatment of neuroblastoma tumour xenografts in mice.
Streptococcus pneumoniae (the pneumococcus) is well known for its ability to develop competence for natural DNA transformation. Competence development is regulated by an autocatalytic loop driven by variations in the basal level of transcription of the comCDE and comAB operons. These genes are part of the early gene regulon that controls expression of the late competence genes known to encode the apparatus of transformation.
View Article and Find Full Text PDFCyclic peptides are poised to target historically difficult to drug intracellular protein-protein interactions, however, their general cell impermeability poses a challenge for characterizing function. Recent advances in microfluidics have enabled permeabilization of the cytoplasmic membrane by physical cell deformation (i.e.
View Article and Find Full Text PDFEngineering liquid-liquid phase separation (LLPS) of proteins and peptides holds great promise for the development of therapeutic carriers with intracellular delivery capability but requires accurate determination of their assembly properties , usually with fluorescently labeled cargo. Here, we use mass spectrometry (MS) to investigate redox-sensitive coacervate microdroplets (the dense phase formed during LLPS) assembled from a short His- and Tyr-rich peptide. We can monitor the enrichment of a reduced peptide in dilute phase as the microdroplets dissolve triggered by their redox-sensitive side chain, thus providing a quantitative readout for disassembly.
View Article and Find Full Text PDFMany protein condensates can convert to fibrillar aggregates, but the underlying mechanisms are unclear. Liquid-liquid phase separation (LLPS) of spider silk proteins, spidroins, suggests a regulatory switch between both states. Here, we combine microscopy and native mass spectrometry to investigate the influence of protein sequence, ions, and regulatory domains on spidroin LLPS.
View Article and Find Full Text PDFMis-sense mutations affecting TP53 promote carcinogenesis both by inactivating tumor suppression, and by conferring pro-carcinogenic activities. We report here that p53 DNA-binding domain (DBD) and transactivation domain (TAD) mis-sense mutants unexpectedly activate pro-carcinogenic epidermal growth factor receptor (EGFR) signaling via distinct, previously unrecognized molecular mechanisms. DBD- and TAD-specific TP53 mutants exhibited different cellular localization and induced distinct gene expression profiles.
View Article and Find Full Text PDFActivation of p53 by small molecule MDM2 inhibitors can induce cell cycle arrest or death in p53 wildtype cancer cells. However, cancer cells exposed to hypoxia can develop resistance to other small molecules, such as chemotherapies, that activate p53. Here, we evaluated whether hypoxia could render cancer cells insensitive to two MDM2 inhibitors with different potencies, nutlin-3a and navtemadlin.
View Article and Find Full Text PDFWe have previously shown that proteasome inhibitor bortezomib stabilizes p53 in stem and progenitor cells within gastrointestinal tissues. Here, we characterize the effect of bortezomib treatment on primary and secondary lymphoid tissues in mice. We find that bortezomib stabilizes p53 in significant fractions of hematopoietic stem and progenitor cells in the bone marrow, including common lymphoid and myeloid progenitors, granulocyte-monocyte progenitors, and dendritic cell progenitors.
View Article and Find Full Text PDFUnlabelled: The tumor suppressor protein p53 is mutated in close to 50% of human tumors and is dysregulated in many others, for instance by silencing or loss of p14. Under steady-state conditions, the two E3 ligases MDM2/MDM4 interact with and inhibit the transcriptional activity of p53. Inhibition of p53-MDM2/4 interaction to reactivate p53 in tumors with wild-type (WT) p53 has therefore been considered a therapeutic strategy.
View Article and Find Full Text PDFHow the self-assembly of partially disordered proteins generates functional compartments in the cytoplasm and particularly in the nucleus is poorly understood. Nucleophosmin 1 (NPM1) is an abundant nucleolar protein that forms large oligomers and undergoes liquid-liquid phase separation by binding RNA or ribosomal proteins. It provides the scaffold for ribosome assembly but also prevents protein aggregation as part of the cellular stress response.
View Article and Find Full Text PDFResearch indicates that coping styles mediate self-control and health outcomes. Emotion- and problem-focused coping strategies (eg, getting advice or planning) are used to address stressors. In contrast, avoidance-focused strategies (eg, substance use) are used to escape distress and are associated with greater alcohol problems.
View Article and Find Full Text PDFp53 mutant proteins are widely expressed in human cancer. In this issue, Guiley and Shokat describe the development of compounds that rescue the function of the Y220C mutant p53 protein by forming covalent complexes with the target protein. See related article by Guiley and Shokat, p.
View Article and Find Full Text PDFThe RON receptor tyrosine kinase is an exceptionally interesting target in oncology and immunology. It is not only overexpressed in a wide variety of tumors but also has been shown to be expressed on myeloid cells associated with tumor infiltration, where it serves to dampen tumour immune responses and reduce the efficacy of anti-CTLA4 therapy. Potent and selective inhibitory antibodies to RON might therefore both inhibit tumor cell growth and stimulate immune rejection of tumors.
View Article and Find Full Text PDFThe need to forensically search soil for small artefacts at a burial site or traces of evidence in a deposition site is a common task shared by investigators and forensic archaeologists. In forensic casework, the importance of finding small pieces of evidence, such as personal effects or ballistic fragments, cannot be overstated as it can assist in the positive identification of the deceased, give an insight into the manner and cause of death, and identify any perpetrators. The soil search methods known as wet and dry sieving, are cumbersome, time-consuming and have limited success for some soil types.
View Article and Find Full Text PDFAn attractive approach to target intracellular macromolecular interfaces and to model putative drug interactions is to design small high-affinity proteins. Variable domains of the immunoglobulin heavy chain (VH domains) are ideal miniproteins, but their development has been restricted by poor intracellular stability and expression. Here we show that an autonomous and disufhide-free VH domain is suitable for intracellular studies and use it to construct a high-diversity phage display library.
View Article and Find Full Text PDFThe process of sprouting angiogenesis can be measured using endothelial cells in sprouting assays such as the fibrin bead assay and the spheroid-based assay. While the technical aspects of these sprouting assays have been well-optimized, the analysis aspects have been limited to manual methods, which can be time-consuming and difficult to reproduce. Here, we developed an automated analysis tool called AQuTAS to quantify sprouting parameters from the spheroid-based sprouting assay.
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