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306 results on '"Kamasawa, Naomi"'

4. LRIT1 Modulates Adaptive Changes in Synaptic Communication of Cone Photoreceptors

Author

Sarria, Ignacio, Cao, Yan, Wang, Yuchen, Ingram, Norianne T, Orlandi, Cesare, Kamasawa, Naomi, Kolesnikov, Alexander V, Pahlberg, Johan, Kefalov, Vladimir J, Sampath, Alapakkam P, and Martemyanov, Kirill A

Subjects
Neurosciences, Eye Disease and Disorders of Vision, Aetiology, 2.1 Biological and endogenous factors, Eye, Animals, Cell Line, HEK293 Cells, Humans, Membrane Glycoproteins, Mice, Mouse Embryonic Stem Cells, Receptors, Metabotropic Glutamate, Retinal Cone Photoreceptor Cells, Synapses, G protein coupled receptors, ON-bipolar neurons, cone photoreceptors, leucine-rich repeat proteins, synaptic transmission, Biochemistry and Cell Biology, Medical Physiology
Abstract

Cone photoreceptors scale dynamically the sensitivity of responses to maintain responsiveness across wide range of changes in luminance. Synaptic changes contribute to this adaptation, but how this process is coordinated at the molecular level is poorly understood. Here, we report that a cell adhesion-like molecule, LRIT1, is enriched selectively at cone photoreceptor synapses where it engages in a trans-synaptic interaction with mGluR6, the principal receptor in postsynaptic ON-bipolar cells. The levels of LRIT1 are regulated by the neurotransmitter release apparatus that controls photoreceptor output. Knockout of LRIT1 in mice increases the sensitivity of cone synaptic signaling while impairing its ability to adapt to background light without overtly influencing the morphology or molecular composition of photoreceptor synapses. Accordingly, mice lacking LRIT1 show visual deficits under conditions requiring temporally challenging discrimination of visual signals in steady background light. These observations reveal molecular mechanisms involved in scaling synaptic communication in the retina.

Published
2018

6. The Auxiliary Calcium Channel Subunit α2δ4 Is Required for Axonal Elaboration, Synaptic Transmission, and Wiring of Rod Photoreceptors.

Author

Wang, Yuchen, Fehlhaber, Katherine E, Sarria, Ignacio, Cao, Yan, Ingram, Norianne T, Guerrero-Given, Debbie, Throesch, Ben, Baldwin, Kristin, Kamasawa, Naomi, Ohtsuka, Toshihisa, Sampath, Alapakkam P, and Martemyanov, Kirill A

Subjects
Axons, Synapses, Cells, Cultured, Animals, Mice, Knockout, Humans, Mice, Mice, Mutant Strains, Calcium Channels, Calcium Channels, L-Type, Receptors, Metabotropic Glutamate, Nerve Tissue Proteins, Synaptic Transmission, Female, Male, Retinal Bipolar Cells, Retinal Rod Photoreceptor Cells, Retinal Cone Photoreceptor Cells, calcium channels, cell adhesion, circuit formation, retina, ribbon synapse, synaptic transmission, synaptogenesis, trans-synaptic interactions, vision, wiring, Cells, Cultured, Knockout, Mutant Strains, L-Type, Receptors, Metabotropic Glutamate, Neurology & Neurosurgery, Neurosciences, Cognitive Sciences, Psychology
Abstract

Neural circuit wiring relies on selective synapse formation whereby a presynaptic release apparatus is matched with its cognate postsynaptic machinery. At metabotropic synapses, the molecular mechanisms underlying this process are poorly understood. In the mammalian retina, rod photoreceptors form selective contacts with rod ON-bipolar cells by aligning the presynaptic voltage-gated Ca2+ channel directing glutamate release (CaV1.4) with postsynaptic mGluR6 receptors. We show this coordination requires an extracellular protein, α2δ4, which complexes with CaV1.4 and the rod synaptogenic mediator, ELFN1, for trans-synaptic alignment with mGluR6. Eliminating α2δ4 in mice abolishes rod synaptogenesis and synaptic transmission to rod ON-bipolar cells, and disrupts postsynaptic mGluR6 clustering. We further find that in rods, α2δ4 is crucial for organizing synaptic ribbons and setting CaV1.4 voltage sensitivity. In cones, α2δ4 is essential for CaV1.4 function, but is not required for ribbon organization, synaptogenesis, or synaptic transmission. These findings offer insights into retinal pathologies associated with α2δ4 dysfunction.

Published
2017

14. Mechanism for Selective Synaptic Wiring of Rod Photoreceptors into the Retinal Circuitry and Its Role in Vision

Author

Cao, Yan, Sarria, Ignacio, Fehlhaber, Katherine E, Kamasawa, Naomi, Orlandi, Cesare, James, Kiely N, Hazen, Jennifer L, Gardner, Matthew R, Farzan, Michael, Lee, Amy, Baker, Sheila, Baldwin, Kristin, Sampath, Alapakkam P, and Martemyanov, Kirill A

Subjects
Neurosciences, Eye Disease and Disorders of Vision, Underpinning research, 1.1 Normal biological development and functioning, Neurological, Eye, Animals, HEK293 Cells, Humans, Mice, Mice, Knockout, Nerve Net, Photic Stimulation, Rats, Retina, Retinal Rod Photoreceptor Cells, Synapses, Vision, Ocular, Psychology, Cognitive Sciences, Neurology & Neurosurgery
Abstract

In the retina, rod and cone photoreceptors form distinct connections with different classes of downstream bipolar cells. However, the molecular mechanisms responsible for their selective connectivity are unknown. Here we identify a cell-adhesion protein, ELFN1, to be essential for the formation of synapses between rods and rod ON-bipolar cells in the primary rod pathway. ELFN1 is expressed selectively in rods where it is targeted to the axonal terminals by the synaptic release machinery. At the synapse, ELFN1 binds in trans to mGluR6, the postsynaptic receptor on rod ON-bipolar cells. Elimination of ELFN1 in mice prevents the formation of synaptic contacts involving rods, but not cones, allowing a dissection of the contributions of primary and secondary rod pathways to retinal circuit function and vision. We conclude that ELFN1 is necessary for the selective wiring of rods into the primary rod pathway and is required for high sensitivity of vision.

Published
2015

18. ESTABLISHMENT AND APPLICATION OF WORKFLOWS FOR STRUCTURE-FUNCTION ANALYSIS OF SYNAPTIC COMPONENTS

Author

Thomas, Connon I. (author), Kamasawa, Naomi (Thesis advisor), Murphey, Rodney (Thesis advisor), Florida Atlantic University (Degree grantor), Department of Biological Sciences, Charles E. Schmidt College of Science, Thomas, Connon I. (author), Kamasawa, Naomi (Thesis advisor), Murphey, Rodney (Thesis advisor), Florida Atlantic University (Degree grantor), Department of Biological Sciences, and Charles E. Schmidt College of Science

Abstract

At the site of neuronal communication, multiple interacting components drive synapse structure and function. Synaptic vesicle pools, membrane proteins, mitochondria, and perisynaptic astrocyte processes (PAPs) are all structures that can be altered through naturally occurring plasticity mechanisms to modulate neurotransmission, and disruption of these structures can result in synapse dysfunction and disease. Due to the minute size of the synapse, electron microscopy (EM) remains the gold standard for ultrastructural characterization; however, due to the complexity of EM datasets, extraction of information has become a bottleneck which places limits on the amount of data that can be collected and analyzed. A need exists for easy-to-use workflows that automate and enhance analysis throughput, to keep up with the streams of image data that are able to be produced. Here, I develop the use of AI algorithms, correlative microscopy techniques, and novel structural analysis methods to characterize postsynaptic mitochondria, PAPs, synaptic vesicles, and integral membrane proteins and their impact on synapse structure and function. I show that both postsynaptic mitochondria and PAPs in the visual cortex are positioned to support synapse structure and function; cleavage of a synaptic adhesion molecule affects synaptic vesicle accumulation in the amygdala; and presynaptic voltage gated calcium channels aggregate near active zone machinery in the brainstem. In addition, I highlight the use of virtual reality as a fast and intuitive tool for the identification and isolation of individual neurites in 3D EM. Thus, my work establishes novel technical approaches for EM and advances our understanding of neuronal communication through original research of several synaptic components., 2023, Includes bibliography., Degree granted: Dissertation (PhD)--Florida Atlantic University, 2023., Collection: FAU Electronic Theses and Dissertations Collection

Published
2023

25. Presynaptic Rac1 controls synaptic strength through the regulation of synaptic vesicle priming

Author

Keine, Christian, Al-Yaari, Mohammed, Radulovic, Tamara, Thomas, Connon I., Valino Ramos, Paula, Guerrero-Given, Debbie, Ranjan, Mrinalini, Taschenberger, Holger, Kamasawa, Naomi, Young Jr., Samuel M., Keine, Christian, Al-Yaari, Mohammed, Radulovic, Tamara, Thomas, Connon I., Valino Ramos, Paula, Guerrero-Given, Debbie, Ranjan, Mrinalini, Taschenberger, Holger, Kamasawa, Naomi, and Young Jr., Samuel M.

Abstract

Synapses contain a limited number of synaptic vesicles (SVs) that are released in response to action potentials (APs). Therefore, sustaining synaptic transmission over a wide range of AP firing rates and timescales depends on SV release and replenishment. Although actin dynamics impact synaptic transmission, how presynaptic regulators of actin signaling cascades control SV release and replenishment remains unresolved. Rac1, a Rho GTPase, regulates actin signaling cascades that control synaptogenesis, neuronal development, and postsynaptic function. However, the presynaptic role of Rac1 in regulating synaptic transmission is unclear. To unravel Rac1’s roles in controlling transmitter release, we performed selective presynaptic ablation of Rac1 at the mature mouse calyx of Held synapse. Loss of Rac1 increased synaptic strength, accelerated EPSC recovery after conditioning stimulus trains, and augmented spontaneous SV release with no change in presynaptic morphology or AZ ultrastructure. Analyses with constrained short-term plasticity models revealed faster SV priming kinetics and, depending on model assumptions, elevated SV release probability or higher abundance of tightly docked fusion-competent SVs in Rac1-deficient synapses. We conclude that presynaptic Rac1 is a key regulator of synaptic transmission and plasticity mainly by regulating the dynamics of SV priming and potentially SV release probability.

Published
2022

33. Adhesion GPCR Latrophilin 3 regulates synaptic function of cone photoreceptors in a trans-synaptic manner

Author

Wang, Yuchen, primary, Cao, Yan, additional, Hays, Cassandra L., additional, Laboute, Thibaut, additional, Ray, Thomas A., additional, Guerrero-Given, Debbie, additional, Ahuja, Abhimanyu S., additional, Patil, Dipak, additional, Rivero, Olga, additional, Kamasawa, Naomi, additional, Kay, Jeremy N., additional, Thoreson, Wallace B., additional, and Martemyanov, Kirill A., additional

Published
2021
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38. IgSF11 homophilic adhesion proteins promote layer-specific synaptic assembly of the cortical interneuron subtype

Author

Hayano, Yasufumi, primary, Ishino, Yugo, additional, Hyun, Jung Ho, additional, Orozco, Carlos G., additional, Steinecke, André, additional, Potts, Elizabeth, additional, Oisi, Yasuhiro, additional, Thomas, Connon I., additional, Guerrero-Given, Debbie, additional, Kim, Eunjoon, additional, Kwon, Hyung-Bae, additional, Kamasawa, Naomi, additional, and Taniguchi, Hiroki, additional

Published
2021
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50. Presynaptic development is controlled by the core active zone proteins CAST/ELKS

Author

Radulovic, Tamara, primary, Dong, Wei, additional, Goral, R. Oliver, additional, Thomas, Connon I., additional, Veeraraghavan, Priyadharishini, additional, Montesinos, Monica Suarez, additional, Guerrero‐Given, Debbie, additional, Goff, Kevin, additional, Lübbert, Matthias, additional, Kamasawa, Naomi, additional, Ohtsuka, Toshihisa, additional, and Young, Samuel M., additional

Published
2020
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