Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100039, China.
Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
Fish Shellfish Immunol. 2017 Nov;70:30-39. doi: 10.1016/j.fsi.2017.08.043. Epub 2017 Sep 1.
Aldehyde dehydrogenases (ALDHs) belong to a super-family of detoxifying proteins and perform a significant role in developing epithelial homeostasis, protecting cells from toxic aldehydes and drug resistance. However, the activity and function of these detoxifying proteins remain unknown, especially in fish. In our research, we aimed to study functions of aldehyde dehydrogenase 7A1 (ALDH7A1) in Atlantic salmon infected by Aeromonas salmonicida. Recombinant ALDH7A1 (rALDH7A1) was verified by SDS-PAGE and western blot. The molecular mass of the deduced amino acid sequence of rALDH7A1 is 58.9 kDa with an estimated pI of 7.09. Only a low complexity region (yvegvgevqeyvdv) without a signal peptide existed in rALDH7A1. Results of ELISA indicated that rALDH7A1 exhibited apparent binding activities with A. salmonicida and its expression was highest in fish kidney. A Real-Time PCR (qRT-PCR) assay in kidneys confirmed that fish in this experiment were authentically infected and bacterial loads in rALDH7A1-adminsitered fish were significantly reduced at an early stage of infection. Meanwhile, we found the mRNA expression of NF-kβ, P-38 MAPK, caspase-3 and TNF-α were mainly up-regulated at 72 h in the kidneys and livers of highly infected fish injected with rALDH7A1, and the same variation trend existed in fish spleens at 12 h. Consistent with these observations, neutralization experiments in vivo indicated that rALDH7A1 could obviously reduce the death rate compared to the BSA and control group. Taken together, we concluded that rALDH7A1 could act in host immune defense against bacterial infection and decrease the mortality rate of Atlantic salmon at early stages of infection with A. salmonicida.
醛脱氢酶（ALDHs）属于解毒蛋白超家族，在维持上皮细胞稳态、保护细胞免受毒性醛类和耐药性方面发挥着重要作用。然而，这些解毒蛋白的活性和功能仍不清楚，特别是在鱼类中。在我们的研究中，我们旨在研究醛脱氢酶 7A1（ALDH7A1）在感染鲑鱼气单胞菌的大西洋鲑中的功能。通过 SDS-PAGE 和 Western blot 验证了重组 ALDH7A1（rALDH7A1）。rALDH7A1 的推导氨基酸序列的分子质量为 58.9 kDa，估计等电点为 7.09。rALDH7A1 中仅存在一个低复杂度区域（yvegvgevqeyvdv），没有信号肽。ELISA 结果表明，rALDH7A1 与 A. salmonicida 具有明显的结合活性，在鱼肾中表达量最高。肾脏中的 Real-Time PCR（qRT-PCR）检测证实，本实验中的鱼确实被感染了，并且在感染早期 rALDH7A1 给药组鱼的细菌负荷明显降低。同时，我们发现，在感染严重的鱼的肾脏和肝脏中，NF-kβ、P-38 MAPK、caspase-3 和 TNF-α 的 mRNA 表达在 72 h 时主要上调，而在鱼脾脏中则在 12 h 时存在相同的变化趋势。与这些观察结果一致，体内中和实验表明，与 BSA 和对照组相比，rALDH7A1 可明显降低死亡率。综上所述，我们得出结论，rALDH7A1 可在宿主免疫防御中发挥作用，抵抗细菌感染，并降低感染鲑鱼气单胞菌的大西洋鲑在感染早期的死亡率。
