Nucleophosmin (NPM1) is a multifunctional phospho-protein with critical roles in ribosome biogenesis, tumor suppression, and nucleolar stress response. Here we show that the N-terminal oligomerization domain of NPM1 (Npm-N) exhibits structural polymorphism by populating conformational states ranging from a highly ordered, folded pentamer to a highly disordered monomer. The monomerpentamer equilibrium is modulated by posttranslational modification and protein binding. Phosphorylation drives the equilibrium in favor of monomeric forms, and this effect can be reversed by Npm-N binding to its interaction partners. We have identified a short, arginine-rich linear motif in NPM1 binding partners that mediates Npm-N oligomerization. We propose that the diverse functional repertoire associated with NPM1 is controlled through a regulated unfolding mechanism signaled through posttranslational modifications and intermolecular interactions.NMR | X-ray crystallography N ucleophosmin (NPM1) is a highly abundant nucleolar phosphoprotein with functions associated with ribosome biogenesis (1, 2), maintenance of genome stability (1), nucleolar stress response (3), modulation of the p53 tumor suppressor pathway (4), and regulation of apoptosis (5). Importantly, genetic alterations that affect the NPM1 protein sequence or expression level are associated with oncogenesis. For example, NPM1 overexpression was observed in a variety of solid tumors, and mutations within the protein and genetic translocations involving NPM1 are associated with hematological malignancies (reviewed in ref. 6).NPM1 primarily resides in the nucleolus which is a membraneless compartment and the site of rRNA synthesis, processing, and assembly with ribosomal proteins (7). In the nucleolus, NPM1 is involved in processing preribosomal RNA (4), chaperoning the nucleolar entry of ribosomal (1, 8) and viral (9) proteins, and stabilizing the alternate reading frame (ARF) tumor suppressor protein (4, 5, 10, 11), while also playing a role in the shuttling of preribosomal particles assembled in the nucleolus to the cytoplasm (12-14).NPM1 is a member of the nucleoplasmin protein family, which includes the histone chaperones NPM2 and NPM3. These proteins share a conserved N-terminal oligomerization domain that mediates homopentamerization (15). Disruption of NPM1 oligomerization by a small molecule (16) or an RNA aptamer (17) causes exclusive nucleoplasmic localization, loss of colocalization with ARF, and induction of p53-dependent apoptosis (16, 17). These observations suggest that changes in the oligomeric state of NPM1 may influence its biological functions. However, although it is hypothesized (1) that NPM1 function is modulated through control of its oligomeric state, experimental data are currently lacking. Intriguingly, NPM1 exhibits 40 putative phosphorylation sites, the majority of which are evolutionarily conserved (18,19). Modification of these sites that is influenced by subcellular localization and cell cycle phase (20, 21) modulates the biological function...

In this study we formed and characterized dynamic hydrogel microspheres in which a protein conformational change was used to control microsphere volume changes and the release of an encapsulated drug. In particular, a specific biochemical ligand, trifluoperazine, induced calmodulin's nanometer scale conformation change, which translated to a 48.7% microsphere volume decrease. This specific, ligand‐induced volume change triggered the release of a model drug, vascular endothelial growth factor (VEGF), at pre‐determined times. After release from the microspheres, 85.6 ± 10.5% of VEGF was in its native conformation. Taken together, these results suggest that protein conformational change could serve as a useful mechanism to control drug release from dynamic hydrogels.magnified image

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Medulloblastoma is a malignant tumor diagnosed in 12-25% of pediatric brain tumors, 77% before the age of 19. In adulthood, the rate sharply declines with increasing age to be only diagnosed in 0.4-1% of adult brain tumors.These tumors are diagnosed typically after symptoms are noted consistent with increased intracranial pressure. We present a case of a young adult who was followed with serial MRI scans due to history of headaches and over time developed a lesion in the cerebellum that was later diagnosed as a medulloblastoma. We present this case as a natural history of medulloblastoma and will include a review of the literature. Patient AG had the original MRI brain scan for chronic headaches yielding only a right posterior fossa arachnoid cyst. Four years later, persistent headaches warranted another scan showing a new lesion with T2 FLAIR hyperintensity in the left cerebellar hemisphere. Serial scans over two years showed progression in size and complexity of this new lesion originally thought benign. AG underwent craniotomy with mass resection that resulted in cytoplasmic beta-catenin positive medulloblastoma without anaplasia on neuropathology. It was also without metastasis or CSF involvement. Post-operative imaging showed a small suspicious area near the resection cavity which biopsies later proved positive for residual medulloblastoma greater than 1.5 cm, thus placing this patient into the high-risk treatment category. AG elected proton therapy (36 in the craniospinal region with posterior fossa boost) with vincristine following protocol ACNS0331 with maintenance therapy afterward. AG has since been followed with serial MRI scans without evidence of residual disease. After reviewing the literature, low occurrences of incidental CNS tumors have been found in trauma and research cases. It is rare to have radiographic evidence of the onset of a malignant brain tumor. We present our case and literature review of this entity.

Recent advancements in molecular characterisation have identified four principal molecular groups of medulloblastoma: WNT, SHH, group 3 and group 4. Each has its characteristic clinical features, signature genetic alterations and distinct DNA methylome profiles. Thus far, CTNNB1 mutations have been considered pathognomonic of WNTactivated medulloblastoma. Furthermore, it has been shown that CTNNB1 mutations dominantly drive the WNT-activated phenotype in medulloblastoma, even in the presence of alterations in the SHH pathway. We herein report an illustrative case that challenges this belief-a medulloblastoma with a pathogenic CTNNB1 mutation that otherwise showed the histopathology, immunophenotype and methylation and transcriptomic profiles of an SHH-activated medulloblastoma. Detailed molecular analyses, including whole exome sequencing, transcriptome analysis and DNA methylation profiling with DKFZ brain tumour classifier and St. Jude MLPnet neural network classifier analyses, have been performed on the tumour. Our example emphasises the diagnostic value of the immunohistochemistry panel with YAP1, GAB1 and β-catenin and DNA methylation profiling, combined with exome sequencing, in the characterisation of medulloblastoma. CTNNB1 mutations are not specific for WNT-activated medulloblastoma, and different CTNNB1 mutations have diverse oncogenic potential.