Department of Anatomy, Ivanovo State Medical Academy, Ivanovo, Russia.
Department of Anatomy, Saint Petersburg State Paediatric Medical University, St. Petersburg, Russia.
Histochem Cell Biol. 2020 Jun;153(6):413-429. doi: 10.1007/s00418-020-01851-3. Epub 2020 Mar 11.
In spite of tremendous progress in deciphering the molecular mechanisms involved in intracellular transport in cell culture and in the test tube, many aspects of this process in situ remain unclear. Here, we examined lipid transcytosis in enterocytes in adult rats. Apical clathrin-coated buds and the ER exit sites were not found. After starvation, the Golgi complex was in a non-transporting state and contained many vesicles, but no intercisternal connections and typical the cis-most and the trans-most cisternae. Following the addition of the lipids in the form of chyme, pre-chylomicrons (pre-ChMs) were initially found in the tubules of the smooth SER attached to the basolateral plasmalemma below the belt composed of adhesive junctions (AJ) and always connected with other cisternae. However, the ER exit sites were still absent. Pre-ChMs moved into the cis-most cisterna and were concentrated in cisternal distensions at the trans-side of the Golgi complex. This induced attachment of the cis-most and the trans-most cisternae to the Golgi complex. Post-Golgi carriers fused with the basolateral plasmalemma and delivered ChMs outside. Overloading of enterocytes with lipids resulted in an accumulation of lipid droplets, an increase of the diameter of ChMs, and shift of the Golgi complex to the transporting state with the formation of intercisternal connections, attachment of the cis-most and the trans-most cisternae and disappearance of vesicles. These data are discussed from the functional point of view. In spite of tremendous progress in deciphering the molecular mechanisms involved in intracellular transport in cell culture and in the test tube, many aspects of this process in situ remain unclear. Here, we examined lipid transcytosis in enterocytes in adult rats. Apical clathrin-coated buds and the ER exit sites were not found. After starvation, the Golgi complex was in a non-transporting state and contained many vesicles, but no intercisternal connections and typical the cis-most and the trans-most cisternae. Following the addition of the lipids in the form of chyme, pre-chylomicrons (pre-ChMs) were initially found in the tubules of the smooth SER attached to the basolateral plasmalemma below the belt composed of adhesive junctions (AJ) and always connected with other cisternae. However, the ER exit sites were still absent. Pre-ChMs moved into the cis-most cisterna and were concentrated in cisternal distensions at the trans-side of the Golgi complex. This induced attachment of the cis-most and the trans-most cisternae to the Golgi complex. Post-Golgi carriers fused with the basolateral plasmalemma and delivered ChMs outside. Overloading of enterocytes with lipids resulted in an accumulation of lipid droplets, an increase of the diameter of ChMs, and shift of the Golgi complex to the transporting state with the formation of intercisternal connections, attachment of the cis-most and the trans-most cisternae and disappearance of vesicles. These data are discussed from the functional point of view.
尽管在细胞培养和试管中阐明细胞内运输所涉及的分子机制方面取得了巨大进展，但该过程在原位的许多方面仍不清楚。在这里，我们研究了成年大鼠肠上皮细胞中的脂质胞吞作用。未发现顶端网格蛋白包被的芽和内质网出口部位。饥饿后，高尔基复合体处于非运输状态，含有许多囊泡，但没有内质网内腔连接和典型的最靠近 cis 腔和最靠近 trans 腔。在用食糜的形式添加脂质后，最初在附着于由粘着连接（AJ）组成的腰带下方的基底外侧质膜的光滑 SER 的小管中发现了前乳糜微粒（pre-ChMs），并且始终与其他腔室相连。然而，内质网出口部位仍然不存在。Pre-ChMs 进入最靠近 cis 的腔室，并在高尔基复合体的 trans 侧的腔室扩张中浓缩。这诱导了最靠近 cis 的和最靠近 trans 的腔室与高尔基复合体的附着。高尔基复合体后载体与基底外侧质膜融合，并将 ChMs 运出细胞外。肠上皮细胞脂质超载会导致脂滴积累、ChMs 直径增加以及高尔基复合体向具有内质网内腔连接形成、最靠近 cis 的和最靠近 trans 的腔室附着以及囊泡消失的运输状态转变。这些数据从功能角度进行了讨论。尽管在细胞培养和试管中阐明细胞内运输所涉及的分子机制方面取得了巨大进展，但该过程在原位的许多方面仍不清楚。在这里，我们研究了成年大鼠肠上皮细胞中的脂质胞吞作用。未发现顶端网格蛋白包被的芽和内质网出口部位。饥饿后，高尔基复合体处于非运输状态，含有许多囊泡，但没有内质网内腔连接和典型的最靠近 cis 腔和最靠近 trans 腔。在用食糜的形式添加脂质后，最初在附着于由粘着连接（AJ）组成的腰带下方的基底外侧质膜的光滑 SER 的小管中发现了前乳糜微粒（pre-ChMs），并且始终与其他腔室相连。然而，内质网出口部位仍然不存在。Pre-ChMs 进入最靠近 cis 的腔室，并在高尔基复合体的 trans 侧的腔室扩张中浓缩。这诱导了最靠近 cis 的和最靠近 trans 的腔室与高尔基复合体的附着。高尔基复合体后载体与基底外侧质膜融合，并将 ChMs 运出细胞外。肠上皮细胞脂质超载会导致脂滴积累、ChMs 直径增加以及高尔基复合体向具有内质网内腔连接形成、最靠近 cis 的和最靠近 trans 的腔室附着以及囊泡消失的运输状态转变。这些数据从功能角度进行了讨论。
