The sterol carrier protein 2/3-oxoacyl-CoA thiolase (SCPx) is involved in cholesterol uptake in the midgut of Spodoptera litura: gene cloning, expression, localization and functional analyses.
The sterol carrier protein 2/3-oxoacyl-CoA thiolase (SCPx) is involved in cholesterol uptake in the midgut of Spodoptera litura: gene cloning, expression, localization and functional analyses.
复制标题
甾醇载体蛋白 2/3-氧代酰基-CoA 硫解酶 (SCPx) 参与斜纹夜蛾中肠的胆固醇摄取：基因克隆、表达、定位和功能分析
DOI：
10.1186/1471-2199-10-102
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发表时间：
2009-11-13
影响因子：
--
通讯作者：
Feng QL
中科院分区：
文献类型：
--
作者：
Guo XR;Zheng SC;Liu L;Feng QL
背景
固醇载体蛋白2/3-氧代酰基-CoA硫解酶（SCPx）基因被认为参与胆固醇的吸收和转运。胆固醇是一种膜组分，是蜕皮甾类的前体，但不能在昆虫中从头合成。然而，SCPx基因的表达，胆固醇的吸收和鳞翅目昆虫的发展之间的直接关联仍有待实验证明。
结果
从斜纹夜蛾（Spodoptera litura）中克隆了一个SCPx cDNA（S1 SCPx）。Sl SCPx cDNA编码由3-氧代酰基-CoA硫解酶（SCPx-t）结构域和SCP-2（SCPx-2）结构域组成的535个氨基酸的蛋白质。S1 SCPx mRNA主要在中肠中表达，S1 SCPx-2 mRNA在中肠、脂肪体和表皮中均有表达，而S1 SCPx-t mRNA在中肠、脂肪体和表皮中均未检测到。用抗S1 SCPx-t抗体进行蛋白质印迹分析时，在6龄幼虫中肠中检测到58 kDa的全长SCPx蛋白和44 kDa的SCPx-t蛋白;用抗S1 SCPx-2抗体检测到16 kDa的SCP-2蛋白。Sl SCPx蛋白在切割后切割成两种较小的蛋白，SCPx-t和SCPx-2。该基因似乎表达为两种形式的mRNA转录本，分别翻译为两种蛋白质。S1 SCPx-t和S1 SCPx-2蛋白在六龄幼虫中肠中具有明显不同的定位。S1 SCPx和S1 SCPx-t蛋白主要在细胞质中检测到，而S1 SCPx-2蛋白在Spli-221细胞的细胞质和细胞核中检测到。S1 SCPx和S1 SCPx-2蛋白的过表达增强了Spli-221细胞的胆固醇摄取。通过dsRNA干扰敲低S1 SCPx转录物导致血淋巴中胆固醇水平降低，并延迟幼虫到蛹的转变。
结论
S1 SCPx基因在家蚕幼虫发育过程中的时空表达模式。斜纹夜蛾在取食期与中肠有特异的联系。该基因的过度表达增加了胆固醇的吸收和干扰其转录降低胆固醇的吸收和延迟幼虫蛹变态。所有这些结果综合起来表明，该中肠特异性S1 SCPx基因对于S.斜纹。
Background
Sterol carrier protein-2/3-oxoacyl-CoA thiolase (SCPx) gene has been suggested to be involved in absorption and transport of cholesterol. Cholesterol is a membrane component and is a precursor of ecdysteroids, but cannot be synthesized de novo in insects. However, a direct association between SCPx gene expression, cholesterol absorption and development in lepidopteran insects remains to be experimentally demonstrated.
Results
An SCPx cDNA (Sl SCPx) cloned from the common cutworm, Spodoptera litura, was characterized. The Sl SCPx cDNA encoded a 535-amino acid protein consisting of a 3-oxoacyl-CoA thiolase (SCPx-t) domain and a SCP-2 (SCPx-2) domain. Sl SCPx mRNA was expressed predominately in the midgut, while Sl SCPx-2 mRNA was detected in the midgut, fat body and epidermis and no Sl SCPx-t mRNA was detected. A 58-kDa full-length SCPx protein and a 44-kDa SCPx-t protein were detected in the midgut of sixth instar larvae when the anti-Sl SCPx-t antibody was used in western blotting analysis; a 16-kDa SCP-2 protein was detected when anti-Sl SCPx-2 antibody was used. Sl SCPx protein was post-translationally cleaved into two smaller proteins, SCPx-t and SCPx-2. The gene appeared to be expressed into two forms of mRNA transcripts, which were translated into the two proteins, respectively. Sl SCPx-t and Sl SCPx-2 proteins have distinct and different locations in the midgut of sixth instar larvae. Sl SCPx and Sl SCPx-t proteins were detected predominately in the cytoplasm, whereas Sl SCPx-2 protein was detected in the cytoplasm and nuclei in the Spli-221 cells. Over-expression of Sl SCPx and Sl SCPx-2 proteins enhanced cholesterol uptake into the Spli-221 cells. Knocking-down Sl SCPx transcripts by dsRNA interference resulted in a decrease in cholesterol level in the hemolymph and delayed the larval to pupal transition.
Conclusion
Spatial and temporal expression pattern of this Sl SCPx gene during the larval developmental stages of S. litura showed its specific association with the midgut at the feeding stage. Over-expression of this gene increased cholesterol uptake and interference of its transcript decreased cholesterol uptake and delayed the larval to pupal metamorphosis. All of these results taken together suggest that this midgut-specific Sl SCPx gene is important for cholesterol uptake and normal development in S. litura.
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影响因子：
4.8
作者：
Frolov, A;Cho, TH;Schroeder, F
通讯作者：
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影响因子：
2.6
作者：
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通讯作者：
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DOI：
10.1016/0010-406x(64)90001-5
发表时间：
1964-01-01
期刊：
COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY
影响因子：
--
作者：
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通讯作者：
SMITH, DA
DOI：
10.1046/j.1440-169x.1996.t01-3-00005.x
发表时间：
1996-08-01
影响因子：
2.5
作者：
Kitamura, T;Kobayashi, S;Okada, M
通讯作者：
Okada, M
DOI：
10.1080/10425170600886706
发表时间：
2006-10-01
期刊：
DNA SEQUENCE
影响因子：
--
作者：
Gong, Jing;Hou, Yong;Xia, Qing-You
通讯作者：
Xia, Qing-You