| 研究実績の概要 |
The appearance of the nervous system was an evolutionary event that allowed animals to control their behavior, physiology, and development. In the nervous system, chemical signaling occurs either via non-synaptic volume transmission mainly by neuropeptides or synaptic (wired) transmission by classical neurotransmitters. During the early evolution of animals, the diffusion-driven volume transmission was the common mode of communication even in organisms without a nervous system. Later in the evolution, a faster and more targeted synaptic signaling was needed as animal bodies and behaviors increased in complexity. But how did peptidergic signaling networks evolve into synapse-centric neural networks? One crucial event was the establishment of cell-to-cell contacts to maintain and stabilize connectivity patterns. Here, I show that Neurexin (Nrxn), a core presynaptic adhesion molecule that has critical roles in bilaterian chemical synapse, is already present and functional in the ancestral nervous system. Cell-type expression data suggests that the ancestral Nrxn has a classic morphogenesis-related adhesive role in basal metazoans. In Cnidaria, the closest outgroup to Bilateria, Nrxns diversified with most homologs became fully integrated into a subset of neurons. Results from the functional analysis neuronal Nrxns experimental suggest the likely functional importance of a presynaptic adhesion molecule in maintaining synapse connectivity within a relatively simple ancient animal.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
In FY 2020, I found that in the cnidarian model organism, Nematostella vectensis, delta form neurexins are expressed in neuron cell clusters that exhibit both peptidergic and neurotransmitter signaling ability. I performed functional analysis to investigate the function of neuronal Nrxns in the sea anemone. Knockdown of NvNrxns did not affect animal and neuron survival but affected some synaptic proteins. Knockdown animals displayed behavior abnormalities, but neuropeptide development was undisturbed. This experimental evidence suggests the likely functonal importance of a presynaptic adhesion molecule in maintaining neuronal communication within a simple nervous system.
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