Ravichandran, P. | bioRxiv Science

bioRxiv2023

Integrated single cell and unsupervised spatial transcriptomic analysis defines molecular anatomy of the human dorsolateral prefrontal cortex

The molecular organization of the human neocortex has been historically studied in the context of its histological layers. However, emerging spatial transcriptomic technologies have enabled unbiased identification of transcriptionally-defined spatial domains that move beyond classic cytoarchitecture. Here we used the Visium spatial gene expression platform to generate a data-driven molecular neuroanatomical atlas across the anterior-posterior axis of the human dorsolateral prefrontal cortex (DLPFC). Integration with paired single nucleus RNA-sequencing data revealed distinct cell type compositions and cell-cell interactions across spatial domains. Using PsychENCODE and publicly available data, we map the enrichment of cell types and genes associated with neuropsychiatric disorders to discrete spatial domains. Finally, we provide resources for the scientific community to explore these integrated spatial and single cell datasets at research.libd.org/spatialDLPFC/. SummaryGeneration of a molecular neuroanatomical map of the human prefrontal cortex reveals novel spatial domains and cell-cell interactions relevant for psychiatric disease.

neuroscience↗

bioRxiv2021

Dual avatars of E. coli grxB encoded Glutaredoxin 2 perform ascorbate recycling and ion channel activities

Glutaredoxins (Grxs) are single-domain redox enzymes of the thioredoxin superfamily, and primarily function as glutathione (GSH) dependent disulphide reductases. Whereas, the E. coli Glutaredoxin 2 (EcGrx2) encoded by grxB has two conserved GST-fold domains, it still lacks a classical Grx-like functions. In this study, we show for the first time, that EcGrx2 exists in both soluble and membrane integrated forms. The soluble form associates with a previously unidentified GSH dependent dehydroascrobate (DHA) reductase, and the membrane integrated form possesses ion channel activities. Using enzyme kinetic data and structural data we unequivocally demonstrate that EcGrx2 recycles ascorbate (AsA) from DHA. This ability to recycle AsA is inhibited by Zinc (Zn2+). We also show that both wildtype and the E. coli grxB deletion mutant can be rescued from H2O2-induced oxidative stress using ascorbate as an antioxidant, which otherwise is only known as a carbon source in bacteria. Moreover, the grxB- mutant is susceptible to intracellular killing by ROS producing macrophages. We further discovered that EcGrx2 integrates into the native E. coli membrane and show that the purified soluble protein readily inserts into artificial lipid bilayer membrane and conducts ions in vitro. Our data demonstrates a highly conserved functional similarity among EcGrx2-orthologs and highlights that the utilization and subsequent recycling of ascorbate as an antioxidant by grxB harbouring gram-negative bacteria, including human pathogens, may provide a survival advantage under hostile oxidative environments.

biochemistry↗