CryoET shows cofilactin filaments inside the microtubule lumen.
CryoET shows cofilactin filaments inside the microtubule lumen.
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CryoET 显示微管腔内的 cofilactin 丝。
DOI：
10.1101/2023.03.31.535077
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Carter,AndrewP
中科院分区：
文献类型：
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作者：
Santos,CamillaVentura;Rogers,StephenL;Carter,AndrewP
细胞质微管是管状聚合物，可以在其管腔内容纳小蛋白质或细丝。这些物体的身份及其积累机制尚未最终确定。在这里，我们使用低温电子断层扫描的果蝇S2细胞突起，并发现细丝内的微管内腔，这类似于最近报道的人类HAP 1细胞。这些丝的频率增加后，抑制肌/内质网Ca 2 + ATP酶的小分子药物毒胡萝卜素。亚断层平均显示，管腔细丝采用螺旋结构，让人想起cofilin结合的肌动蛋白（cofilactin）。与此一致，我们观察到cofilin去磷酸化，一种激活修饰，在细胞中在相同的条件下，增加管腔细丝的出现。此外，RNA干扰敲除cofilin降低了具有cofilactin形态的腔丝的频率。这些结果表明，cofilin激活刺激其积累的肌动蛋白丝内微管内腔。
Cytoplasmic microtubules are tubular polymers that can harbor small proteins or filaments inside their lumen. The identities of these objects and mechanisms for their accumulation have not been conclusively established. Here, we used cryogenic electron tomography ofDrosophilaS2 cell protrusions and found filaments inside the microtubule lumen, which resemble those reported recently in human HAP1 cells. The frequency of these filaments increased upon inhibition of the sarco/endoplasmic reticulum Ca2+ATPase with the small molecule drug thapsigargin. Subtomogram averaging showed that the luminal filaments adopt a helical structure reminiscent of cofilin‐bound actin (cofilactin). Consistent with this, we observed cofilin dephosphorylation, an activating modification, in cells under the same conditions that increased luminal filament occurrence. Furthermore, RNA interference knock‐down of cofilin reduced the frequency of luminal filaments with cofilactin morphology. These results suggest that cofilin activation stimulates its accumulation on actin filaments inside the microtubule lumen.