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Somaiya RD, Stebbins K, Gingrich EC, Xie H, Campbell JN, Garcia ADR, Fox MA. Sonic hedgehog-dependent recruitment of GABAergic interneurons into the developing visual thalamus. eLife 2022; 11:e79833. [PMID: 36342840 PMCID: PMC9640189 DOI: 10.7554/elife.79833] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 10/10/2022] [Indexed: 11/09/2022] Open
Abstract
Axons of retinal ganglion cells (RGCs) play critical roles in the development of inhibitory circuits in visual thalamus. We previously reported that RGC axons signal astrocytes to induce the expression of fibroblast growth factor 15 (FGF15), a motogen required for GABAergic interneuron migration into visual thalamus. However, how retinal axons induce thalamic astrocytes to generate Fgf15 and influence interneuron migration remains unknown. Here, we demonstrate that impairing RGC activity had little impact on interneuron recruitment into mouse visual thalamus. Instead, our data show that retinal-derived sonic hedgehog (SHH) is essential for interneuron recruitment. Specifically, we show that thalamus-projecting RGCs express SHH and thalamic astrocytes generate downstream components of SHH signaling. Deletion of RGC-derived SHH leads to a significant decrease in Fgf15 expression, as well as in the percentage of interneurons recruited into visual thalamus. Overall, our findings identify a morphogen-dependent neuron-astrocyte signaling mechanism essential for the migration of thalamic interneurons.
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Affiliation(s)
- Rachana Deven Somaiya
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech CarilionRoanokeUnited States
- Graduate Program in Translational Biology, Medicine, and Health, Virginia TechBlacksburgUnited States
| | - Katelyn Stebbins
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech CarilionRoanokeUnited States
- Graduate Program in Translational Biology, Medicine, and Health, Virginia TechBlacksburgUnited States
- Virginia Tech Carilion School of MedicineRoanokeUnited States
| | - Ellen C Gingrich
- Department of Biology, Drexel UniversityPhiladelphiaUnited States
- Department of Neurobiology and Anatomy, Drexel University College of MedicinePhiladelphiaUnited States
| | - Hehuang Xie
- Fralin Life Sciences Institute at Virginia TechBlacksburgUnited States
- School of Neuroscience, College of Science, Virginia TechBlacksburgUnited States
- Genetics, Bioinformatics and Computational Biology Program, Virginia TechBlacksburgUnited States
- Department of Biomedical Sciences and Pathobiology, Virginia–Maryland College of Veterinary MedicineBlacksburgUnited States
| | - John N Campbell
- Department of Biology, University of VirginiaCharlottesvilleUnited States
- Neuroscience Graduate Program, University of VirginiaCharlottesvilleUnited States
| | - A Denise R Garcia
- Department of Biology, Drexel UniversityPhiladelphiaUnited States
- Department of Neurobiology and Anatomy, Drexel University College of MedicinePhiladelphiaUnited States
| | - Michael A Fox
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech CarilionRoanokeUnited States
- School of Neuroscience, College of Science, Virginia TechBlacksburgUnited States
- Department of Biological Sciences, College of Science, Virginia TechBlacksburgUnited States
- Department of Pediatrics, Virginia Tech Carilion School of MedicineRoanokeUnited States
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Sabbagh U, Govindaiah G, Somaiya RD, Ha RV, Wei JC, Guido W, Fox MA. Diverse GABAergic neurons organize into subtype-specific sublaminae in the ventral lateral geniculate nucleus. J Neurochem 2021; 159:479-497. [PMID: 32497303 PMCID: PMC8210463 DOI: 10.1111/jnc.15101] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 05/14/2020] [Accepted: 05/19/2020] [Indexed: 12/16/2022]
Abstract
In the visual system, retinal axons convey visual information from the outside world to dozens of distinct retinorecipient brain regions and organize that information at several levels, including either at the level of retinal afferents, cytoarchitecture of intrinsic retinorecipient neurons, or a combination of the two. Two major retinorecipient nuclei which are densely innervated by retinal axons are the dorsal lateral geniculate nucleus, which is important for classical image-forming vision, and ventral LGN (vLGN), which is associated with non-image-forming vision. The neurochemistry, cytoarchitecture, and retinothalamic connectivity in vLGN remain unresolved, raising fundamental questions of how it receives and processes visual information. To shed light on these important questions, used in situ hybridization, immunohistochemistry, and genetic reporter lines to identify and characterize novel neuronal cell types in mouse vLGN. Not only were a high percentage of these cells GABAergic, we discovered transcriptomically distinct GABAergic cell types reside in the two major laminae of vLGN, the retinorecipient, external vLGN (vLGNe) and the non-retinorecipient, internal vLGN (vLGNi). Furthermore, within vLGNe, we identified transcriptionally distinct subtypes of GABAergic cells that are distributed into four adjacent sublaminae. Using trans-synaptic viral tracing and in vitro electrophysiology, we found cells in each these vLGNe sublaminae receive monosynaptic inputs from retina. These results not only identify novel subtypes of GABAergic cells in vLGN, they suggest the subtype-specific laminar distribution of retinorecipient cells in vLGNe may be important for receiving, processing, and transmitting light-derived signals in parallel channels of the subcortical visual system.
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Affiliation(s)
- Ubadah Sabbagh
- Center for Neurobiology ResearchFralin Biomedical Research Institute at Virginia Tech CarilionRoanokeVAUSA
- Graduate Program in Translational Biology, Medicine, and HealthVirginia TechBlacksburgVAUSA
| | - Gubbi Govindaiah
- Department of Anatomical Sciences and NeurobiologyUniversity of Louisville School of MedicineLouisvilleKYUSA
| | - Rachana D. Somaiya
- Center for Neurobiology ResearchFralin Biomedical Research Institute at Virginia Tech CarilionRoanokeVAUSA
- Graduate Program in Translational Biology, Medicine, and HealthVirginia TechBlacksburgVAUSA
| | - Ryan V. Ha
- School of NeuroscienceVirginia TechBlacksburgVAUSA
| | - Jessica C. Wei
- NeuroSURFFralin Biomedical Research Institute at Virginia Tech CarilionRoanokeVAUSA
| | - William Guido
- Department of Anatomical Sciences and NeurobiologyUniversity of Louisville School of MedicineLouisvilleKYUSA
| | - Michael A. Fox
- Center for Neurobiology ResearchFralin Biomedical Research Institute at Virginia Tech CarilionRoanokeVAUSA
- School of NeuroscienceVirginia TechBlacksburgVAUSA
- Department of Biological SciencesVirginia TechBlacksburgVAUSA
- Department of PediatricsVirginia Tech Carilion School of MedicineRoanokeVAUSA
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Yin L, Banerjee S, Fan J, He J, Lu X, Xie H. Epigenetic regulation of neuronal cell specification inferred with single cell "Omics" data. Comput Struct Biotechnol J 2020; 18:942-952. [PMID: 32368329 PMCID: PMC7184133 DOI: 10.1016/j.csbj.2020.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 04/04/2020] [Accepted: 04/05/2020] [Indexed: 12/19/2022] Open
Abstract
The brain is a highly complex organ consisting of numerous types of cells with ample diversity at the epigenetic level to achieve distinct gene expression profiles. During neuronal cell specification, transcription factors (TFs) form regulatory modules with chromatin remodeling proteins to initiate the cascade of epigenetic changes. Currently, little is known about brain epigenetic regulatory modules and how they regulate gene expression in a cell-type specific manner. To infer TFs involved in neuronal specification, we applied a recursive motif search approach on the differentially methylated regions identified from single-cell methylomes. The epigenetic transcription regulatory modules (ETRM), including EGR1 and MEF2C, were predicted and the co-expression of TFs in ETRMs were examined with RNA-seq data from single or sorted brain cells using a conditional probability matrix. Lastly, computational predications were validated with EGR1 ChIP-seq data. In addition, methylome and RNA-seq data generated from Egr1 knockout mice supported the essential role of EGR1 in brain epigenome programming, in particular for excitatory neurons. In summary, we demonstrated that brain single cell methylome and RNA-seq data can be integrated to gain a better understanding of how ETRMs control cell specification. The analytical pipeline implemented in this study is freely accessible in the Github repository (https://github.com/Gavin-Yinld/brain_TF).
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Affiliation(s)
- Liduo Yin
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China.,Kunming College of Life Science, University of Chinese Academy of Sciences, Beijing 100101, China.,Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming 650223, China
| | - Sharmi Banerjee
- Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, VA 24061, USA.,Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA 24061, USA
| | - Jiayi Fan
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA 24061, USA
| | - Jianlin He
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA 24061, USA
| | - Xuemei Lu
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China.,Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming 650223, China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing 100101, China
| | - Hehuang Xie
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA 24061, USA.,Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Blacksburg, VA, 24061, USA.,School of Neuroscience, Blacksburg, VA, 24061, USA
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Su J, Charalambakis NE, Sabbagh U, Somaiya RD, Monavarfeshani A, Guido W, Fox MA. Retinal inputs signal astrocytes to recruit interneurons into visual thalamus. Proc Natl Acad Sci U S A 2020; 117:2671-2682. [PMID: 31964831 PMCID: PMC7007527 DOI: 10.1073/pnas.1913053117] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Inhibitory interneurons comprise a fraction of the total neurons in the visual thalamus but are essential for sharpening receptive field properties and improving contrast-gain of retinogeniculate transmission. During early development, these interneurons undergo long-range migration from germinal zones, a process regulated by the innervation of the visual thalamus by retinal ganglion cells. Here, using transcriptomic approaches, we identified a motogenic cue, fibroblast growth factor 15 (FGF15), whose expression in the visual thalamus is regulated by retinal input. Targeted deletion of functional FGF15 in mice led to a reduction in thalamic GABAergic interneurons similar to that observed in the absence of retinal input. This loss may be attributed, at least in part, to misrouting of interneurons into nonvisual thalamic nuclei. Unexpectedly, expression analysis revealed that FGF15 is generated by thalamic astrocytes and not retino-recipient neurons. Thus, these data show that retinal inputs signal through astrocytes to direct the long-range recruitment of interneurons into the visual thalamus.
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Affiliation(s)
- Jianmin Su
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA 24016
| | - Naomi E Charalambakis
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, KY 40202
| | - Ubadah Sabbagh
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA 24016
- Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, VA 24061
| | - Rachana D Somaiya
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA 24016
- Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, VA 24061
| | - Aboozar Monavarfeshani
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA 24016
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061
| | - William Guido
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, KY 40202;
| | - Michael A Fox
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA 24016;
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061
- Department of Pediatrics, Virginia Tech Carilion School of Medicine, Roanoke, VA 24016
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