Professor Chihiro Hama

Area and Subject Taught Brain Development
Research Theme(s) Regulatory Mechanisms for the Formation of Neural Circuits
Academic Degrees Doctor of Science, University of Tokyo
Keywords for Research Field Genetic Program, Neural Circuit, Synapse, Axon, Mutation, Drosophila
Office Phone Number 81-75-705-3120

Research Overview

How the brain exhibits a variety of function still remains enigmatic. We study molecular mechanisms underlying specific neuronal events during development and also try to understand the genetic program that globally governs the circuit formation in the brain.
To approach these problems, we employ a small brain of Drosophila comprising only 105 neurons, a millionth the size of the human brain. Our research, based on analysis of the mutants that show either behavioral or morphological phenotypes, is focused on two themes concerning neural circuit formation.

  1. A role for Hig protein in synapses. The hig (hikaru geneki) gene, identified by a mutant phenotype of reduced locomotor activity, encodes a secretory protein localized to the synaptic clefts in the brain. The goal of this project is to reveal a role for Hig and Hig-associated protein complexes in the synaptic clefts. In addition, the absence of one of the human proteins resembling to Hig is known to cause epilepsy, mental retardation or brain malformation. Thus, we are also interested in the functional relationships between Hig and the human protein.
  2. Analysis of the mutants showing abnormal axonal projection of olfactory receptor neurons (ORNs). We have isolated several mutants in which ORN axons exhibit abnormal projection patterns in the first-order olfactory center in the brain. The purpose of this project is to reveal the molecular mechanisms underlying the precise axonal projection of ORNs.

Notable Publications and Works in the Last Three Years

  1. Nakayama, M. and Hama, C. Modulation of neurotransmitter receptors and synaptic differentiation by proteins containing complement-related domains. Neuroscience Research 69, 87-92 (2011).
  2. Sakurai, M., Aoki, T., Yoshikawa, S., Santschi, L.A., Saito, H., Endo, K., Ishikawa, K.,Kimura, K-i., Ito, K., Thomas, J.B. and Hama, C. Differentially expressed Drl and Drl-2 play opposing roles in Wnt5 signaling during Drosophila olfactory system development. The Journal of Neuroscience 29, 4972-4980 (2009).