Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture and Rural Affairs, Fisheries College, Jimei University, 185 Yinjiang Road, Jimei District, Xiamen 361021, China; School of Life Sciences, Ningde Normal University, 1 College Road, Dongqiao Economic and Technological Development Zone, Ningde 352100, China.
Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture and Rural Affairs, Fisheries College, Jimei University, 185 Yinjiang Road, Jimei District, Xiamen 361021, China.
Comp Biochem Physiol Part D Genomics Proteomics. 2021 Jun;38:100801. doi: 10.1016/j.cbd.2021.100801. Epub 2021 Feb 27.
Large lipid transfer proteins (LLTPs) are extensively involved in various physiological processes. In the present study, five LLTP sequences encoding apolipocrustacein 1 (apoCr 1), apoCr 2, precursor of the large discoidal lipoprotein (dLp) and high density lipoprotein/β-glucan binding protein (HDL-BGBP) (dLp-BGBP), microsomal triglyceride transfer protein (MTP) and clotting protein (CP) were identified in the hepatopancreas of Scylla paramamosain. Of these, apoCr 2, dLp-BGBP, and MTP were newly identified in this species, and the former two proteins were classified into the APO family while the later into the MTP family in phylogenetic trees. The apoCr 1 expression level was dramatically increased in the hepatopancreas towards ovarian maturation, which was extremely greater than that in the ovaries concurrently, likely to meet the considerable requirements of yolk protein and lipids for embryo development. The dLp-BGBP expression level in male crabs was comparable to that in female crabs, supporting HDL-BGBP acts as a major circulatory lipid carrier. The close phylogenetic relationship between dLp-BGBP and the scaffolding protein of lipid transfer particle implied dLp might facilitate lipid transfer between the hepatopancreas and HDL-BGBP-containing lipoproteins. The MTP expression level was positively related to ovarian development in both the hepatopancreas and ovaries, indicating MTP may be involved in lipoprotein assembly in the hepatopancreas and lipid droplet maturation in the ovaries. CP may play a crucial role in embryo development based on high expression level observed in the testes of mature crabs. Our findings provide novel insights into LLTP superfamily members and their functions in decapods.
大型脂质转运蛋白（LLTP）广泛参与各种生理过程。本研究在锯缘青蟹（Scylla paramamosain）肝胰腺中鉴定了 5 种编码载脂蛋白 1（apoCr 1）、载脂蛋白 2（apoCr 2）、大圆盘脂蛋白（dLp）和高密度脂蛋白/β-葡聚糖结合蛋白（HDL-BGBP）前体（dLp-BGBP）、微粒体甘油三酯转移蛋白（MTP）和凝血蛋白（CP）的 LLTP 序列。其中，apoCr 2 和 dLp-BGBP 是本研究新发现的，这两种蛋白在系统发育树中分别归类为 APO 家族和 MTP 家族。apoCr 1 在肝胰腺中的表达水平随着卵巢的成熟而显著增加，远远高于同时期卵巢中的表达水平，可能满足胚胎发育对卵黄蛋白和脂质的大量需求。雄性蟹肝胰腺中 dLp-BGBP 的表达水平与雌性蟹相当，支持 HDL-BGBP 作为主要的循环脂质载体。dLp-BGBP 与脂质转运颗粒的支架蛋白在系统发育上的密切关系暗示 dLp 可能有助于肝胰腺和含 HDL-BGBP 的脂蛋白之间的脂质转运。MTP 在肝胰腺和卵巢中的表达水平与卵巢发育呈正相关，表明 MTP 可能参与肝胰腺中脂蛋白的组装和卵巢中脂质滴的成熟。CP 在成熟蟹的精巢中观察到高表达，可能在胚胎发育中发挥关键作用。本研究结果为十足目动物 LLTP 超家族成员及其功能提供了新的见解。
