Institute for Synaptic Plasticity, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
National Health, Lung and Blood Institute (NIH), Bethesda, MD, USA.
Nat Commun. 2020 Oct 8;11(1):5083. doi: 10.1038/s41467-020-18889-5.
In hippocampal pyramidal cells, a small subset of dendritic spines contain endoplasmic reticulum (ER). In large spines, ER frequently forms a spine apparatus, while smaller spines contain just a single tubule of smooth ER. Here we show that the ER visits dendritic spines in a non-random manner, targeting spines during periods of high synaptic activity. When we blocked ER motility using a dominant negative approach against myosin V, spine synapses became stronger compared to controls. We were not able to further potentiate these maxed-out synapses, but long-term depression (LTD) was readily induced by low-frequency stimulation. We conclude that the brief ER visits to active spines have the important function of preventing runaway potentiation of individual spine synapses, keeping most of them at an intermediate strength level from which both long-term potentiation (LTP) and LTD are possible.
在海马锥体神经元中，一小部分树突棘包含内质网（ER）。在大的树突棘中，内质网经常形成一个棘器，而较小的树突棘只包含一个光滑内质网的小管。在这里，我们表明 ER 以非随机的方式访问树突棘，在突触活动高的时期靶向树突棘。当我们使用针对肌球蛋白 V 的显性负性方法阻断 ER 运动时，与对照组相比，棘突触变得更强。我们无法进一步增强这些达到最大值的突触，但低频刺激很容易诱导长时程压抑（LTD）。我们的结论是，ER 短暂访问活跃的树突棘具有重要的功能，可以防止单个棘突触的失控增强，使它们中的大多数处于中间强度水平，从而使长时程增强（LTP）和 LTD 都成为可能。
