The potassium channel Ether à go-go is a novel prognostic factor with functional relevance in acute myeloid leukemia

<p>Abstract</p> <p>Background</p> <p>The voltage-gated potassium channel hEag1 (K_V10.1) has been related to cancer biology. The physiological expression of the human channel is restricted to the brain but it is frequently and abundantly expressed in many solid tumors, thereby making it a promising target for a specific diagnosis and therapy. Because chronic lymphatic leukemia has been described not to express hEag1, it has been assumed that the channel is not expressed in hematopoietic neoplasms in general.</p> <p>Results</p> <p>Here we show that this assumption is not correct, because the channel is up-regulated in myelodysplastic syndromes, chronic myeloid leukemia and almost half of the tested acute myeloid leukemias in a subtype-dependent fashion. Most interestingly, channel expression strongly correlated with increasing age, higher relapse rates and a significantly shorter overall survival. Multivariate Cox regression analysis revealed hEag1 expression levels in AML as an independent predictive factor for reduced disease-free and overall survival; such an association had not been reported before. As a functional correlate, specific hEag1 blockade inhibited the proliferation and migration of several AML cell lines and primary cultured AML cells <it>in vitro</it>.</p> <p>Conclusion</p> <p>Our observations implicate hEag1 as novel target for diagnostic, prognostic and/or therapeutic approaches in AML.</p

Structure and gating behavior of the human integral membrane protein VDAC1 in a lipid bilayer

The voltage-dependent anion channel (VDAC), the most abundant protein in the outer mitochondrial membrane, is responsible for the transport of all ions and metabolites into and out of mitochondria. Larger than any of the beta-barrel structures determined to date by magic-angle spinning (MAS) NMR, but smaller than the size limit of cryo-electron microscopy (cryo-EM), VDAC1's 31 kDa size has long been a bottleneck in determining its structure in a near-native lipid bilayer environment. Using a single two-dimensional (2D) crystalline sample of human VDAC1 in lipids, we applied proton-detected fast magic-angle spinning NMR spectroscopy to determine the arrangement of beta strands. Combining these data with long-range restraints from a spin-labeled sample, chemical shift-based secondary structure prediction, and previous MAS NMR and atomic force microscopy (AFM) data, we determined the channel's structure at a 2.2 angstrom root-mean-square deviation (RMSD). The structure, a 19-stranded beta-barrel, with an N-terminal alpha-helix in the pore is in agreement with previous data in detergent, which was questioned due to the potential for the detergent to perturb the protein's functional structure. Using a quintuple mutant implementing the channel's closed state, we found that dynamics are a key element in the protein's gating behavior, as channel closure leads to the destabilization of not only the C-terminal barrel residues but also the alpha 2 helix. We showed that cholesterol, previously shown to reduce the frequency of channel closure, stabilizes the barrel relative to the N-terminal helix. Furthermore, we observed channel closure through steric blockage by a drug shown to selectively bind to the channel, the Bcl2-antisense oligonucleotide G3139

Effect of the solvent on the conformation of monocrotaline as determined by isotropic and anisotropic NMR parameters.

The conformation in solution of monocrotaline, a pyrrolizidine alkaloid presenting an eleven-membered macrocyclic diester ring, has been investigated using a combination of isotropic and anisotropic NMR parameters measured in four solvents of different polarity (D2 O, DMSO-d6 , CDCl3 , and C6 D6 ). Anisotropic NMR parameters were measured in different alignment media, based on their compatibility with the solvent of interest: cromoglycate liquid crystal solution was used for D2 O, while a PMMA polymer gel was chosen for CDCl3 and C6 D6 , and a poly-HEMA gel for DMSO-d6 . Whereas the pyrrolizidine ring shows an E6 exo-puckered conformation in all of the solvents, the macrocyclic eleven-membered ring adopts different populations of syn-parallel and anti-parallel relative orientation of the carbonyl groups according to the polarity of the solvent

Structural characterization of copper(II) binding to α-Synuclein: Insights into the bioinorganic chemistry of Parkinson's disease

The aggregation of α -synuclein (AS) is characteristic of Parkinson’s disease and other neurodegenerative synucleinopathies. We demonstrate here that Cu(II) ions are effective in accelerating AS aggregation at physiologically relevant concentrations without altering the resultant fibrillar structures. By using numerous spectroscopic techniques (absorption, CD, EPR, and NMR), we have located the primary binding for Cu(II) to a specific site in the N terminus, involving His-50 as the anchoring residue and other nitrogen oxygen donor atoms in a square planar or distorted tetragonal geometry. The carboxylate-rich C terminus, originally thought to drive copper binding, is able to coordinate a second Cu(II) equivalent, albeit with a 300-fold reduced affinity. The NMR analysis of AS–Cu(II) complexes reveals the existence of conformational restrictions in the native state of the protein. The metallobiology of Cu(II) in Parkinson’s disease is discussed by a comparative analysis with other Cu(II)-binding proteins involved in neurodegenerative disorders

Gut thinking: the gut microbiome and mental health beyond the head

Background: In recent decades, dominant models of mental illness have become increasingly focused on the head, with mental disorders being figured as brain disorders. However, research into the active role that the microbiome-gut-brain axis plays in affecting mood and behaviour may lead to the conclusion that mental health is more than an internalised problem of individual brains. Objective: This article explores the implications of shifting understandings about mental health that have come about through research into links between the gut microbiome and mental health problems such as depression and anxiety. It aims to analyse the different ways that the lines between mind and body and mental and physical health are re-shaped by this research, which is starting to inform clinical and public understanding. Design: As mental health has become a pressing issue of political and public concern it has become increasingly constructed in socio-cultural and personal terms beyond clinical spaces, requiring a conceptual response that exceeds biomedical inquiry. This article argues that an interdisciplinary critical medical humanities approach is well positioned to analyse the impact of microbiome-gut-brain research on conceptions of mind. Results: The entanglement of mind and matter evinced by microbiome-gut-brain axis research potentially provides a different way to conceptualise the physical and social concomitants of mental distress. Conclusion: Mental health is not narrowly located in the head but is assimilated by the physical body and intermingled with the natural world, requiring different methods of research to unfold the meanings and implications of gut thinking for conceptions of human selfhood

Insights into the molecular mechanism of amyloid filament formation: Segmental folding of α-synuclein on lipid membranes

Recent advances in the structural biology of disease-relevant α-synuclein fibrils have revealed a variety of structures, yet little is known about the process of fibril aggregate formation. Characterization of intermediate species that form during aggregation is crucial; however, this has proven very challenging because of their transient nature, heterogeneity, and low population. Here, we investigate the aggregation of α-synuclein bound to negatively charged phospholipid small unilamellar vesicles. Through a combination of kinetic and structural studies, we identify key time points in the aggregation process that enable targeted isolation of prefibrillar and early fibrillar intermediates. By using solid-state nuclear magnetic resonance, we show the gradual buildup of structural features in an α-synuclein fibril filament, revealing a segmental folding process. We identify distinct membrane-binding domains in α-synuclein aggregates, and the combined data are used to present a comprehensive mechanism of the folding of α-synuclein on lipid membranes

Weak long-range correlated motions in a surface patch of ubiquitin involved in molecular recognition.

[Image: see text] Long-range correlated motions in proteins are candidate mechanisms for processes that require information transfer across protein structures, such as allostery and signal transduction. However, the observation of backbone correlations between distant residues has remained elusive, and only local correlations have been revealed using residual dipolar couplings measured by NMR spectroscopy. In this work, we experimentally identified and characterized collective motions spanning four β-strands separated by up to 15 Å in ubiquitin. The observed correlations link molecular recognition sites and result from concerted conformational changes that are in part mediated by the hydrogen-bonding network