Susumu Tomita PhD

Associate Professor of Cellular and Molecular Physiology

Research Interests

Synaptic transmission; Brain; Biochemistry; Molecular biology; Immunocytochemistry; Gene-targeted animals; Electrophysiology


Research Summary

My laboratory's approach to understand the brain is to reduce the brain to various components and ultimately molecules. Temporally, neurotransmission by a major excitatory neurotransmitter, glutamate, is very quick and is clearly essential for brain function; however, the modulation of brain function underlying learning,
memory, emotion, cognition, etc., happens on a different time scale than that of neurotransmission. Our broad goal is to understand how basic synaptic
transmission can be modulated over seconds to hours, thereby supporting complex brain functions. The efficacy of synaptic transmission is determined
by glutamate concentration at the synaptic cleft and by the number and channel properties of the glutamate receptors, which can be modulated by neuronal activation (synaptic plasticity). We have uncovered a network of modulatory proteins for glutamate receptors to control their number and properties. By understanding the machinery that controls the number and channel properties of
glutamate receptors, we hope to reveal the principal rules governing synaptic transmission and synaptic plasticity.

Extensive Research Description

My laboratory’s approach to understand brain is to reduce brain to various components and ultimately molecules. The primary functional component of brain is the neural circuit, which are comprised of anatomical neuronal wiring and synaptic transmission. Temporally, neurotransmission by a major excitatory neurotransmitter in brain, glutamate, is very quick and is clearly essential for brain function; however, the modulation of brain function underlying learning, memory, emotion, cognition, etc., happens on a different time scale than that of neurotransmission. Our broad goal is to understand how basic synaptic transmission can be modulated over seconds to hours, thereby supporting complex brain functions.The efficacy of synaptic transmission is determined by glutamate concentration at the synaptic cleft and by the number and channel properties of the glutamate receptors, which can be modulated by neuronal activation (synaptic plasticity).

It is therefore important to determine how many receptors are at synapses and how strongly these receptors are activated upon glutamate releases. We have uncovered a network of modulatory proteins for glutamate receptors to control their number and properties. By understanding the machinery that controls the number and channel properties of glutamate receptors, we hope to reveal the principal rules governing synaptic transmission and synaptic plasticity. Combined with neuronal wiring mapping, this should help us understand a big picture of neural circuits and the momentary changes that occur in neural circuits to control animal behavior.


Selected Publications

  • Yan D, Yamasaki M, Straub C, Watanabe M, and Tomita S. Homeostatic control of synaptic transmission by distinct glutamate receptors. Neuron, 78:687-399, 2013
  • Brockie PJ, Jensen M, Mellem JE, Jensen E, Yamasaki T, Wang R, Maxfield D, Thacker C, Hoerndli F, Dunn PJ, Tomita S, Madsen DM, Maricq AV. Cornichons control ER export of AMPA receptors to regulate synaptic excitability. Neuron, 80:129-142, 2013
  • Sumioka A, Brown T, Kato AS, Bredt DS, Kauer JA, and Tomita S. PDZ binding of TARP?-8 controls synaptic transmission, but not synaptic plasticity. Nature Neurosci., 14:1410-1412, 2011
  • Straub C, Hunt DL, Yamasaki M, Kim KS, Watanabe M, Castillo PE, and Tomita S. Unique functions of kainate receptors in the brain are determined by the auxiliary subunit Neto1. Nature Neurosci., 14, 866-873, 2011
  • Kato AS, Gill MB, Ho MT, Yu H, Tu Y, Siuda ER, Wang H, Qian YW, Nisenbaum ES, Tomita S, and Bredt DS. Hippocampal AMPA receptor gating controlled by both TARP and cornichon proteins. Neuron, 68, 1082-1096, 2010
  • Sumioka A, Yan D, Tomita S. TARP phosphorylation regulates synaptic AMPA receptors through lipid bilayers. Neuron, 66:755-67, 2010.
  • Zhang W, St-Gelais F, Grabner CP, Trinidad JC, Sumioka A, Morimoto-Tomita M, Kim KS, Straub C, Burlingame AL, Howe JR, Tomita S. Novel transmembrane accessory subunit modulates kainate-type glutamate receptors. Neuron, 61:385-96, 2009.
  • Morimoto-Tomita M, Zhang W, Straub C, Cho CH, Kim KS, Howe JR, Tomita S. Auto-inactivation of neuronal AMPA receptors via glutamate-regulated TARP interaction. Neuron, 61:101-12, 2009.
  • Cho CH, St-Gelais F, Zhang W, Tomita S, Howe JR. Two families of TARP isoforms that have distinct effects on the kinetic properties of AMPA receptors and synaptic currents. Neuron, 55:890-904, 2007.

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