TY - GEN AB - The development, evolution, and function of the vertebrate central nervous system (CNS) can be best studied using diverse model organisms. Amphibians, with their unique phylogenetic position at the transition between aquatic and terrestrial lifestyles, are valuable for understanding the origin and evolution of the tetrapod brain and spinal cord. Their metamorphic developmental transitions and unique regenerative abilities also facilitate the discovery of mechanisms for neural circuit remodeling and replacement. The genetic toolkit for amphibians, however, remains limited, with only a few species having sequenced genomes and a small number of transgenic lines available. In mammals, recombinant adeno-associated viral vectors (AAVs) have become a powerful alternative to genome modification for visualizing and perturbing the nervous system. AAVs are DNA viruses that enable neuronal transduction in both developing and adult animals with low toxicity and spatial, temporal, and cell-type specificity. However, AAVs have never been shown to transduce amphibian cells efficiently. To bridge this gap, we established a simple, scalable, and robust strategy to screen AAV serotypes in three distantly-related amphibian species: the frogs Xenopus laevis and Pelophylax bedriagae, and the salamander Pleurodeles waltl, in both developing larval tadpoles and post-metamorphic animals. For each species, we successfully identified at least two AAV serotypes capable of infecting the CNS; however, no pan-amphibian serotype was identified, indicating rapid evolution of AAV tropism. In addition, we developed an AAV-based strategy that targets isochronic cohorts of developing neurons – a critical tool for parsing neural circuit assembly. Finally, to enable visualization and manipulation of neural circuits, we identified AAV variants for retrograde tracing of neuronal projections in adult animals. Our findings expand the toolkit for amphibians to include AAVs, establish a generalizable workflow for AAV screening in non-canonical research organisms, generate testable hypotheses for the evolution of AAV tropism, and lay the foundation for modern cross-species comparisons of vertebrate CNS development, function, and evolution. AU - Jaeger, Eliza C.B. AU - Vijatovic, David AU - Deryckere, Astrid AU - Zorin, Nikol AU - Nguyen, Akemi L. AU - Ivanian, Georgiy AU - Woych, Jamie AU - Arnold, Rebecca C AU - Ortega Gurrola, Alonso AU - Shvartsman, Arik AU - Barbieri, Francesca AU - Toma, Florina-Alexandra AU - Gorbsky, Gary J. AU - Horb, Marko E. AU - Cline, Hollis T. AU - Shay, Timothy F. AU - Kelley, Darcy B. AU - Yamaguchi, Ayako AU - Shein-Idelson, Mark AU - Tosches, Maria Antonietta AU - Sweeney, Lora Beatrice Jaeger ID - 15016 T2 - bioRxiv TI - Adeno-associated viral tools to trace neural development and connectivity across amphibians ER - TY - JOUR AB - Vertebrate movement is orchestrated by spinal inter- and motor neurons that, together with sensory and cognitive input, produce dynamic motor behaviors. These behaviors vary from the simple undulatory swimming of fish and larval aquatic species to the highly coordinated running, reaching and grasping of mice, humans and other mammals. This variation raises the fundamental question of how spinal circuits have changed in register with motor behavior. In simple, undulatory fish, exemplified by the lamprey, two broad classes of interneurons shape motor neuron output: ipsilateral-projecting excitatory neurons, and commissural-projecting inhibitory neurons. An additional class of ipsilateral inhibitory neurons is required to generate escape swim behavior in larval zebrafish and tadpoles. In limbed vertebrates, a more complex spinal neuron composition is observed. In this review, we provide evidence that movement elaboration correlates with an increase and specialization of these three basic interneuron types into molecularly, anatomically, and functionally distinct subpopulations. We summarize recent work linking neuron types to movement-pattern generation across fish, amphibians, reptiles, birds and mammals. AU - Wilson, Alexia C AU - Sweeney, Lora Beatrice Jaeger ID - 13097 JF - Frontiers in Neural Circuits SN - 1662-5110 TI - Spinal cords: Symphonies of interneurons across species VL - 17 ER - TY - JOUR AB - Cellular metabolism must adapt to changing demands to enable homeostasis. During immune responses or cancer metastasis, cells leading migration into challenging environments require an energy boost, but what controls this capacity is unclear. Here, we study a previously uncharacterized nuclear protein, Atossa (encoded by CG9005), which supports macrophage invasion into the germband of Drosophila by controlling cellular metabolism. First, nuclear Atossa increases mRNA levels of Porthos, a DEAD-box protein, and of two metabolic enzymes, lysine-α-ketoglutarate reductase (LKR/SDH) and NADPH glyoxylate reductase (GR/HPR), thus enhancing mitochondrial bioenergetics. Then Porthos supports ribosome assembly and thereby raises the translational efficiency of a subset of mRNAs, including those affecting mitochondrial functions, the electron transport chain, and metabolism. Mitochondrial respiration measurements, metabolomics, and live imaging indicate that Atossa and Porthos power up OxPhos and energy production to promote the forging of a path into tissues by leading macrophages. Since many crucial physiological responses require increases in mitochondrial energy output, this previously undescribed genetic program may modulate a wide range of cellular behaviors. AU - Emtenani, Shamsi AU - Martin, Elliot T AU - György, Attila AU - Bicher, Julia AU - Genger, Jakob-Wendelin AU - Köcher, Thomas AU - Akhmanova, Maria AU - Pereira Guarda, Mariana AU - Roblek, Marko AU - Bergthaler, Andreas AU - Hurd, Thomas R AU - Rangan, Prashanth AU - Siekhaus, Daria E ID - 10918 JF - The Embo Journal TI - Macrophage mitochondrial bioenergetics and tissue invasion are boosted by an Atossa-Porthos axis in Drosophila VL - 41 ER - TY - JOUR AB - Optogenetics has been harnessed to shed new mechanistic light on current and future therapeutic strategies. This has been to date achieved by the regulation of ion flow and electrical signals in neuronal cells and neural circuits that are known to be affected by disease. In contrast, the optogenetic delivery of trophic biochemical signals, which support cell survival and are implicated in degenerative disorders, has never been demonstrated in an animal model of disease. Here, we reengineered the human and Drosophila melanogaster REarranged during Transfection (hRET and dRET) receptors to be activated by light, creating one-component optogenetic tools termed Opto-hRET and Opto-dRET. Upon blue light stimulation, these receptors robustly induced the MAPK/ERK proliferative signaling pathway in cultured cells. In PINK1B9 flies that exhibit loss of PTEN-induced putative kinase 1 (PINK1), a kinase associated with familial Parkinson’s disease (PD), light activation of Opto-dRET suppressed mitochondrial defects, tissue degeneration and behavioral deficits. In human cells with PINK1 loss-of-function, mitochondrial fragmentation was rescued using Opto-dRET via the PI3K/NF-кB pathway. Our results demonstrate that a light-activated receptor can ameliorate disease hallmarks in a genetic model of PD. The optogenetic delivery of trophic signals is cell type-specific and reversible and thus has the potential to inspire novel strategies towards a spatio-temporal regulation of tissue repair. AU - Inglés Prieto, Álvaro AU - Furthmann, Nikolas AU - Crossman, Samuel H. AU - Tichy, Alexandra Madelaine AU - Hoyer, Nina AU - Petersen, Meike AU - Zheden, Vanessa AU - Bicher, Julia AU - Gschaider-Reichhart, Eva AU - György, Attila AU - Siekhaus, Daria E AU - Soba, Peter AU - Winklhofer, Konstanze F. AU - Janovjak, Harald L ID - 9363 IS - 4 JF - PLoS genetics TI - Optogenetic delivery of trophic signals in a genetic model of Parkinson's disease VL - 17 ER - TY - JOUR AB - Mosaic analysis with double markers (MADM) offers one approach to visualize and concomitantly manipulate genetically defined cells in mice with single-cell resolution. MADM applications include the analysis of lineage, single-cell morphology and physiology, genomic imprinting phenotypes, and dissection of cell-autonomous gene functions in vivo in health and disease. Yet, MADM can only be applied to <25% of all mouse genes on select chromosomes to date. To overcome this limitation, we generate transgenic mice with knocked-in MADM cassettes near the centromeres of all 19 autosomes and validate their use across organs. With this resource, >96% of the entire mouse genome can now be subjected to single-cell genetic mosaic analysis. Beyond a proof of principle, we apply our MADM library to systematically trace sister chromatid segregation in distinct mitotic cell lineages. We find striking chromosome-specific biases in segregation patterns, reflecting a putative mechanism for the asymmetric segregation of genetic determinants in somatic stem cell division. AU - Contreras, Ximena AU - Amberg, Nicole AU - Davaatseren, Amarbayasgalan AU - Hansen, Andi H AU - Sonntag, Johanna AU - Andersen, Lill AU - Bernthaler, Tina AU - Streicher, Carmen AU - Heger, Anna-Magdalena AU - Johnson, Randy L. AU - Schwarz, Lindsay A. AU - Luo, Liqun AU - Rülicke, Thomas AU - Hippenmeyer, Simon ID - 9603 IS - 12 JF - Cell Reports TI - A genome-wide library of MADM mice for single-cell genetic mosaic analysis VL - 35 ER - TY - JOUR AB - Amyotrophic lateral sclerosis (ALS) leads to a loss of specific motor neuron populations in the spinal cord and cortex. Emerging evidence suggests that interneurons may also be affected, but a detailed characterization of interneuron loss and its potential impacts on motor neuron loss and disease progression is lacking. To examine this issue, the fate of V1 inhibitory neurons during ALS was assessed in the ventral spinal cord using the SODG93A mouse model. The V1 population makes up ∼30% of all ventral inhibitory neurons, ∼50% of direct inhibitory synaptic contacts onto motor neuron cell bodies, and is thought to play a key role in modulating motor output, in part through recurrent and reciprocal inhibitory circuits. We find that approximately half of V1 inhibitory neurons are lost in SODG93A mice at late disease stages, but that this loss is delayed relative to the loss of motor neurons and V2a excitatory neurons. We further identify V1 subpopulations based on transcription factor expression that are differentially susceptible to degeneration in SODG93A mice. At an early disease stage, we show that V1 synaptic contacts with motor neuron cell bodies increase, suggesting an upregulation of inhibition before V1 neurons are lost in substantial numbers. These data support a model in which progressive changes in V1 synaptic contacts early in disease, and in select V1 subpopulations at later stages, represent a compensatory upregulation and then deleterious breakdown of specific interneuron circuits within the spinal cord. AU - Salamatina, Alina AU - Yang, Jerry H AU - Brenner-Morton, Susan AU - Bikoff, Jay B AU - Fang, Linjing AU - Kintner, Christopher R AU - Jessell, Thomas M AU - Sweeney, Lora Beatrice Jaeger ID - 8914 JF - Neuroscience SN - 0306-4522 TI - Differential loss of spinal interneurons in a mouse model of ALS VL - 450 ER -