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Updated: Jul 4, 2026

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Imaging Dendritic Spines in Caenorhabditis elegans
Published on: September 27, 2021
単一のデンドリティック脊椎の活性化によって誘発されるRas活動の拡散
Christopher D Harvey1, Ryohei Yasuda, Haining Zhong
1Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA.
まとめ
単一デンドリット状の棘におけるNMDA受容体活性化からのカルシウム信号は,局所的に拡散する. このRasシグナリングカスケードは,近隣のシナプスを結合して,長期増強 (LTP) の値に影響を与えます.
科学分野:
- 神経科学は神経科学である.
- 細胞生物学 細胞生物学
- 分子シグナリング
背景:
- 個々のデンドリット状の棘は,NMDA受容体の活性化によるカルシウム (Ca2+) の流入を区分する.
- この区画化による下流信号伝達の影響は,完全に理解されていません.
研究 の 目的:
- 個々のデンドリット状の脊椎にCa2+の流入を下流のシグナルイベントの空間的な範囲を調査する.
- 重要なシグナル伝達分子であるRas GTPaseの活性化が,活性化された脊椎を超えて広がっているかどうかを判断する.
主な方法:
- 2フォトンの光成像と2フォトンのグルタミン酸解封を用いた.
- NMDA受容体の活性化後の単一脊椎レベルでの Ras GTPaseの活性をモニターした.
主要な成果:
- 長期増強 (LTP) 誘導中のNMDA受容体の活性化により,単一の脊椎内でのCa2+依存Ras活性化が生じました.
- Rasの活性化は,約5分以内に衰退したが, dendriteに沿って約10μmに広がり,隣接する棘を侵略した.
- このRas依存のシグナリングの広がりは,LTP誘導の局所的値の調節に不可欠でした.
結論:
- シナプスCa2+信号は,個々の脊椎に厳格に限定されていません.
- Rasのような下流信号分子は,隣接する脊椎に拡散し,複数のシナプスを機能的に結合することができます.
- この脊髄間のコミュニケーションは,シナプス性可塑性において重要な役割を果たします.
関連する概念動画
The Ras Gene
The Ras-gene-encoded proteins are regulators of signaling pathways controlling cell proliferation, differentiation, or cell survival. The Ras-gene family in humans constitutes three primary members—the HRas, NRas, and KRas. These genes code for four functionally distinct yet closely related proteins—the HRas, NRas, KRas4A, and KRas4B. The involvement of mutant Ras genes in human cancer was first discovered in 1982 and is among the most common causes of human tumorigenesis.
Ras is a superfamily...
Ras is a superfamily...
MAPK Signaling Cascades
Mitogen-activated protein kinase, or MAPK pathway, activates three sequential kinases to regulate cellular responses such as proliferation, differentiation, survival, and apoptosis. The canonical MAPK pathway starts with a mitogen or growth factor binding to an RTK. The activated RTKs stimulate Ras, which recruits Raf or MAP3 Kinase (MAPKKK), the first kinase of the MAPK signaling cascade. Raf further phosphorylates and activates MEK or MAP2 Kinases (MAPKK), which in turn phosphorylates MAP...
Action Potential
Neurons communicate by firing action potentials—the electrochemical signal that is propagated along the axon. The signal results in the release of neurotransmitters at axon terminals, thereby transmitting information to the nervous system. An action potential is a specific "all-or-none" change in membrane potential that results in a rapid spike in voltage.
Membrane potential in neurons
Neurons typically have a resting membrane potential of about -70 millivolts (mV). When they receive...
Membrane potential in neurons
Neurons typically have a resting membrane potential of about -70 millivolts (mV). When they receive...
Intracellular Signaling Cascades
Once a ligand binds to a receptor, the signal is transmitted through the membrane and into the cytoplasm. The continuation of a signal in this manner is called signal transduction. Signal transduction only occurs with cell-surface receptors, which cannot interact with most components of the cell, such as DNA. Only internal receptors can interact directly with DNA in the nucleus to initiate protein synthesis. When a ligand binds to its receptor, conformational changes occur that affect the...
Rab Cascades
Rab GTPases act in a regulated cascade during membrane fusion, helping the lipid bilayers mix. The Rab family of proteins are active when bound to GTP, and inactive when bound to GDP. Hence, they act as guanine nucleotide-dependent molecular switches. Rab-GTP recognizes and binds to long or short-range tethering proteins to capture the target vesicle. These tethers coordinate with SNAREs on the vesicle and the target membrane to assemble the trans SNARE complex that locks the mixing bilayers.
Integration of Synaptic Events
Synaptic integration mainly includes the summation of graded potentials. Graded potentials, regardless of their type, cause subtle alterations in membrane voltage, resulting in either depolarization or hyperpolarization. These incremental changes, when combined or summed, can propel the neuron toward its threshold. Consider, for example, a membrane experiencing a +15 mV shift, causing it to depolarize from -70 mV to -55 mV. In this scenario, graded potentials govern the membrane's ability to...

