Latest Publications
Nanoscale synchrotron x-ray analysis of intranuclear iron in melanised neurons of Parkinson’s substantia nigra
Jake Brooks, James Everett, Emily Hill, Kharmen Billimoria, Christopher M. Morris, Peter J. Sadler, Neil Telling & Joanna F. Collingwood
Neuromelanin-pigmented neurons of the substantia nigra are selectively lost during the progression of Parkinson’s disease. These neurons accumulate iron in the disease state, and iron-mediated neuron damage is implicated in cell death. Here, scanning transmission x-ray microscopy (STXM) is used to probe iron foci in relation to the surrounding ultrastructure in melanised neurons of human substantia nigra from a confirmed Parkinson’s case. The findings show that STXM is a powerful label-free tool for the in situ, nanoscale chemical characterisation of both organic and inorganic intracellular components. Future applications are likely to shed new light on incompletely understood biochemical mechanisms, such as metal dysregulation and morphological changes to cell nucleoli, that are important in understanding the pathogenesis of Parkinson’s.
Structure of the MlaC-MlaD complex reveals molecular basis of periplasmic phospholipid transport
Peter Wotherspoon, Hannah Johnston, David J. Hardy, Rachel Holyfield, Soi Bui, Giedrė Ratkevičiūtė, Pooja Sridhar, Jonathan Colburn, Charlotte B. Wilson, Adam Colyer, Benjamin F. Cooper, Jack A. Bryant, Gareth W. Hughes, Phillip J. Stansfeld, Julien R. C. Bergeron & Timothy J. Knowles
The Maintenance of Lipid Asymmetry (Mla) pathway is a multicomponent system found in all gram-negative bacteria that contributes to virulence, vesicle blebbing and preservation of the outer membrane barrier function. Here, we report the structure of E. coli MlaC in complex with the MlaD hexamer in two distinct stoichiometries. Utilising in vivo complementation assays, an in vitro fluorescence-based transport assay, and molecular dynamics simulations, we confirm key residues, identifying the MlaD β6-β7 loop as essential for MlaCD function. We also provide evidence that phospholipids pass between the C-terminal helices of the MlaD hexamer to reach the central pore, providing insight into the trajectory of GPL transfer between MlaC and MlaD.
Direct water-soluble molecules transfer from transplanted bone marrow mononuclear cell to hippocampal neural stem cells
Okinaka Y, Maeda M, Kataoka Y, Nakagomi T, Doi A, Boltze J, Claussen C, Gul S, Taguchi A
Intravascularly transplanted bone marrow cells, including bone marrow mononuclear cells (BM-MNC) and mesenchymal stem cells, transfer water-soluble molecules to cerebral endothelial cells via gap junctions. Following transplantation of BM-MNC, this fosters hippocampal neurogenesis and enhancement of neuronal function. Herein, we report the impact of transplanted BM-MNC on neural stem cells (NSC) in the brain. Surprisingly, direct transfer of water-soluble molecules from transplanted BM-MNC and peripheral mononuclear cells to NSC in the hippocampus was observed already 10 minutes after cell transplantation, and transfer from BM-MNC to GFAP-positive cortical astrocytes was also observed. In-vitro investigations revealed that BM-MNC abolish the expression of HIF1α in astrocytes. We suggest that the transient and direct transfer of water-soluble molecules between cells in circulation and NSC in the brain may be one of the biological mechanisms underlying repair of brain function.
Adenosine signalling to astrocytes coordinates brain metabolism and function
Shefeeq M. Theparambil, Olga Kopach, Alice Braga, Shereen Nizari, Patrick S. Hosford, Virag Sagi-Kiss, Anna Hadjihambi, Christos Konstantinou, Noemi Esteras, Ana Gutierrez Del Arroyo, Gareth L. Ackland, Anja G. Teschemacher, Nicholas Dale, Tobias Eckle, Petros Andrikopoulos, Dmitri A. Rusakov, Sergey Kasparov & Alexander V. Gourine
Brain computation performed by billions of nerve cells relies on a sufficient and uninterrupted nutrient and oxygen supply. Astrocytes, the ubiquitous glial neighbours of neurons, govern brain glucose uptake and metabolism, but the exact mechanisms of metabolic coupling between neurons and astrocytes that ensure on-demand support of neuronal energy needs are not fully understood. Here we show, using experimental in vitro and in vivo animal models, that neuronal activity-dependent metabolic activation of astrocytes is mediated by neuromodulator adenosine acting on astrocytic A2B receptors. The data identifies the adenosine A2B receptor as an astrocytic sensor of neuronal activity and show that cAMP signalling in astrocytes tunes brain energy metabolism to support its fundamental functions such as sleep and memory.
Johannes Boltze publications
Perioperative stroke deteriorates white matter integrity by enhancing cytotoxic CD8 + T‐cell activation
Yuxi Zhou, Xin Wang, Wen Yin, Yan Li, Yunlu Guo, Chen Chen, Johannes Boltze, Arthur Liesz, Tim Sparwasser, Daxiang Wen, Weifeng Yu, and Peiying Li
Here we explore the regulatory mechanisms of microglia‐mediated cytotoxic CD8+ T‐cell infiltration in the white matter injury of perioperative stroke (PIS). We found surgery aggravated white matter injury and deteriorated sensorimotor deficits up to 28 days following PIS. The PIS mice exhibited significantly increased activation of peripheral and central CD8+ T cells, while significantly reduced numbers of mature oligodendrocytes compared to IS mice. Neutralizing CD8+ T cells partly reversed the aggravated demyelination following PIS. Pharmacological blockage or genetic deletion of receptor‐interacting protein kinase 1 (RIPK1) activity could alleviate CD8+ T‐cell infiltration and demyelination in PIS mice. Surgery exacerbates demyelination and worsens neurological function by promoting infiltration of CD8+ T cells and microglia necroptosis, suggesting that modulating interactions of CD8+ T cells and microglia could be a novel therapeutic target of long‐term neurological deficits of PIS.. CNS Neuroscience and Therapeutics. July 2024
The association between air pollutant exposure and cerebral small vessel disease imaging markers with modifying effects of PRS-defined genetic susceptibility
Studies have highlighted a possible link between air pollution and cerebral small vessel disease (CSVD) imaging markers. However, the exact association and effects of polygenic risk score (PRS) defined genetic susceptibility remains unclear. This cross-sectional study used data from the UK Biobank. Participants aged 40–69 years were recruited between the year 2006 and 2010. The annual average concentrations of NOX, NO2, PM2.5, PM2.5–10, PM2.5 absorbance, and PM10, were estimated, and joint exposure to multiple air pollutants was reflected in the air pollution index (APEX). Air pollutant exposure was classified into the low (T1), intermediate (T2), and high (T3) tertiles.. Our study demonstrated that air pollutant exposure may be associated with CSVD imaging markers, with females being more susceptible, and that PRS-defined genetic susceptibility may modify the associations of air pollutants.
Structures of wild-type and a constitutively closed mutant of connexin26 shed light on channel regulation by CO2
Deborah H. Brotherton, Sarbjit Nijjar, Christos G. Savva, Nicholas Dale, Alexander D. Cameron
Connexins allow intercellular communication by forming gap junction channels (GJCs) between juxtaposed cells. Connexin26 (Cx26) can be regulated directly by CO2. This is proposed to be mediated through carbamylation of K125. We show that mutating K125 to glutamate, mimicking the negative charge of carbamylation, causes Cx26 GJCs to be constitutively closed. Through cryo-EM we observe that the K125E mutation pushes a conformational equilibrium towards the channel having a constricted pore entrance, similar to effects seen on raising the partial pressure of CO2. In previous structures of connexins, the cytoplasmic loop, important in regulation and where K125 is located, is disordered. Through further cryo-EM studies we trap distinct states of Cx26 and observe density for the cytoplasmic loop. The interplay between the position of this loop, the conformations of the transmembrane helices and the position of the N-terminal helix, which controls the aperture to the pore, provides a mechanism for regulation.