Cao Zhe, Fung Chun Wing, Mak Ho Yi
Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China.
Front Cell Dev Biol. 2022 Apr 4;10:856474. doi: 10.3389/fcell.2022.856474. eCollection 2022.
In addition to coordinating the storage and mobilization of neutral fat, lipid droplets (LDs) are conserved organelles that can accommodate additional cargos in order to support animal development. However, it is unclear if each type of cargo is matched with a specific subset of LDs. Here, we report that SEIP-1/seipin defines a subset of oocyte LDs that are required for proper eggshell formation in . Using a photoconvertible fluorescent protein-based imaging assay, we found that SEIP-1 positive LDs were selectively depleted after fertilization, coincident of the formation of a lipid-rich permeability barrier of the eggshell. Loss of SEIP-1 function caused impenetrant embryonic arrest, which could be worsened by FAT-3/fatty acyl-CoA desaturase deficiency or suppressed by PLIN-1/Perilipin deficiency. The embryonic development of mutant in turn depended on the recruitment of RAB-18/Rab18 to LDs, which was not observed in wild type embryos. We propose that SEIP-1 dependent and independent mechanisms act in parallel to ensure the packaging and export of lipid-rich permeability barrier constituents, which involve LDs. The identity of these LDs, as defined by their associated proteins, exhibits unexpected plasticity that ultimately ensures the survival of embryos .
除了协调中性脂肪的储存和动员外，脂滴（LDs）是保守的细胞器，能够容纳额外的货物以支持动物发育。然而，目前尚不清楚每种类型的货物是否与特定的脂滴亚群相匹配。在这里，我们报告SEIP-1/ seipin定义了一个卵母细胞脂滴亚群，该亚群是秀丽隐杆线虫正常卵壳形成所必需的。使用基于光转换荧光蛋白的成像分析，我们发现受精后SEIP-1阳性脂滴被选择性消耗，这与富含脂质的卵壳通透性屏障的形成同时发生。SEIP-1功能丧失导致胚胎发育停滞，FAT-3/脂肪酸辅酶A去饱和酶缺乏会加剧这种情况，而PLIN-1/围脂滴蛋白缺乏则会抑制这种情况。反过来，突变体的胚胎发育依赖于RAB-18/Rab18募集到脂滴，而在野生型胚胎中未观察到这种情况。我们提出，SEIP-1依赖和独立的机制并行发挥作用，以确保富含脂质的通透性屏障成分的包装和输出，这涉及脂滴。由其相关蛋白定义的这些脂滴的特性表现出意想不到的可塑性，最终确保胚胎的存活。
