Thermogenetic neurostimulation with single-cell resolution

AbstractThermogenetics is a promising innovative neurostimulation technique, which enables robust activation of neurons using thermosensitive transient receptor potential (TRP) cation channels. Broader application of this approach in neuroscience is, however, hindered by a limited variety of suitable ion channels, and by low spatial and temporal resolution of neuronal activation when TRP channels are activated by ambient temperature variations or chemical agonists. Here, we demonstrate rapid, robust and reproducible repeated activation of snake TRPA1 channels heterologously expressed in non-neuronal cells, mouse neurons and zebrafish neurons in vivo by infrared (IR) laser radiation. A fibre-optic probe that integrates a nitrogen−vacancy (NV) diamond quantum sensor with optical and microwave waveguide delivery enables thermometry with single-cell resolution, allowing neurons to be activated by exceptionally mild heating, thus preventing the damaging effects of excessive heat. The neuronal responses to the activation by IR laser radiation are fully characterized using Ca2+ imaging and electrophysiology, providing, for the first time, a complete framework for a thermogenetic manipulation of individual neurons using IR light.</jats:p

Novel bimodal TRBD1-TRBD2 rearrangements with dual or absent D-region contribute to TRB V-(D)-J combinatorial diversity

T-cell receptor (TR) diversity of the variable domains is generated by recombination of both the alpha (TRA) and beta (TRB) chains. The textbook process of TRB chain production starts with TRBD and TRBJ gene rearrangement, followed by the rearrangement of a TRBV gene to the partially rearranged D-J gene. Unsuccessful V-D-J TRB rearrangements lead to apoptosis of the cell. Here, we performed deep sequencing of the poorly explored pool of partial TRBD1-TRBD2 rearrangements in T-cell genomic DNA. We reconstructed full repertoires of human partial TRBD1-TRBD2 rearrangements using novel sequencing and validated them by detecting V-D-J recombination-specific byproducts: excision circles containing the recombination signal (RS) joint 5’D2-RS – 3’D1-RS. Identified rearrangements were in compliance with the classical 12/23 rule, common for humans, rats, and mice and contained typical V-D-J recombination footprints. Interestingly, we detected a bimodal distribution of D-D junctions indicating two active recombination sites producing long and short D-D rearrangements. Long TRB D-D rearrangements with two D-regions are coding joints D1-D2 remaining classically on the chromosome. The short TRB D-D rearrangements with no D-region are signal joints, the coding joint D1-D2 being excised from the chromosome. They both contribute to the TRB V-(D)-J combinatorial diversity. Indeed, short D-D rearrangements may be followed by direct V-J2 recombination. Long D-D rearrangements may recombine further with J2 and V genes forming partial D1-D2-J2 and then complete V-D1-D2-J2 rearrangement. Productive TRB V-D1-D2-J2 chains are present and expressed in thousands of clones of human antigen-experienced memory T cells proving their capacity for antigen recognition and actual participation in the immune response

ECG recordings of cardiac pacing in mice carriyng TRPV1

The data are ECG recordings acquired from mice whose cardiac muscle tissue carries the human TRPV1 channel. ECG was recorded with standard procedure on the limbs with disposable electrodes, with one or two electrodes. Myocardial stimulation was applied with an IR laser. Each archive contains the result of an ECG recording of one animal. Initial recordings are cut so that the unsuccessful recordings are excluded. File name Recording date Vector type Vector Amount No1 2022 06 22 AAV488 6x10-11 No2 2022 06 16 AAV479 6x10-12 No3 2022 06 22 AAV488 6x10-11 No4 2021 10 1

The mammalian pannexin family is homologous to the invertebrate innexin gap junction proteins

We have cloned the genes PANX1, PANX2 and PANX3, encoding putative gap junction proteins homologous to invertebrate innexins, which constitute a new family of mammalian proteins called pannexins. Phylogenetic analysis revealed that pannexins are highly conserved in worms, mollusks, insects and mammals, pointing to their important function. Both innexins and pannexins are predicted to have four transmembrane regions, two extracellular loops, one intracellular loop and intracellular N and C termini. Both the human and mouse genomes contain three pannexin-encoding genes. Mammalian pannexins PANX1 and PANX3 are closely related, with PANX2 more distant. The human and mouse pannexin-1 mRNAs are ubiquitously, although disproportionately, expressed in normal tissues. Human PANX2 is a brain-specific gene; its mouse orthologue, Panx2, is also expressed in certain cell types in developing brain. In silico evaluation of Panx3 expression predicts gene expression in osteoblasts and synovial fibroblasts. The apparent conservation of pannexins between species merits further investigation

In vivo dynamics of acidosis and oxidative stress in the acute phase of an ischemic stroke in a rodent model

Ischemic cerebral stroke is one of the leading causes of death and disability in humans. However, molecular processes underlying the development of this pathology remain poorly understood. There are major gaps in our understanding of metabolic changes that occur in the brain tissue during the early stages of ischemia and reperfusion. In particular, it is generally accepted that both ischemia (I) and reperfusion (R) generate reactive oxygen species (ROS) that cause oxidative stress which is one of the main drivers of the pathology, although ROS generation during I/R was never demonstrated in vivo due to the lack of suitable methods. In the present study, we record for the first time the dynamics of intracellular pH and H2O2 during I/R in cultured neurons and during experimental stroke in rats using the latest generation of genetically encoded biosensors SypHer3s and HyPer7. We detect a buildup of powerful acidosis in the brain tissue that overlaps with the ischemic core from the first seconds of pathogenesis. At the same time, no significant H2O2 generation was found in the acute phase of ischemia/reperfusion. HyPer7 oxidation in the brain was detected only 24 h later. Comparison of in vivo experiments with studies on cultured neurons under I/R demonstrates that the dynamics of metabolic processes in these models significantly differ, suggesting that a cell culture is a poor predictor of metabolic events in vivo