Liaoning Key Laboratory of Marine Animal Immunology, Dalian Ocean University, Dalian 116023, China; Dalian Key Laboratory of Aquatic Animal Disease Prevention and Control, Dalian Ocean University, Dalian 116023, China; Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian 116023, China.
Liaoning Key Laboratory of Marine Animal Immunology, Dalian Ocean University, Dalian 116023, China; Dalian Key Laboratory of Aquatic Animal Disease Prevention and Control, Dalian Ocean University, Dalian 116023, China; Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian 116023, China; Southern Laboratory of Ocean Science and Engineering, Guangdong, Zhuhai 519000, China.
Gene. 2023 Oct 30;884:147687. doi: 10.1016/j.gene.2023.147687. Epub 2023 Aug 2.
Bone morphogenetic proteins (BMPs) are key factors controlling osteoblast differentiation, which have been proved to be involved in the hard tissue formation of marine mollusks. In the present study, a member of BMPs gene (CgBMP7) was identified from Pacific oyster Crassostrea gigas (C. gigas) with the aim to understand its possible role in the regulation of shell formation under ocean acidification (OA) conditions. The open reading frame (ORF) of CgBMP7 was of 1254 bp encoding a polypeptide of 417 amino acids. The deduced amino acid sequence of CgBMP7 was comprised of one signal peptide, one prodomain and one TGF-β domain, which shared 21.69%-61.10% identities with those from other species. The mRNA transcript of CgBMP7 was ubiquitously expressed in all the tested tissues of adult oysters with a higher expression level in mantle, notably highest in the middle fold (MF) of the three folds of mantle. The expression level of bone morphogenetic protein type I receptor (CgBMPR1B) mRNA was also highest in the MF and up-regulated dramatically post recombinant BMP7 protein (rCgBMP7) stimulation. After the blockage of BMPR1B with inhibitor LDN193189 (LDN), the mRNA expression level and phosphorylation level of CgSmad1/5/8 in mantle were decreased, and the mRNA expression levels of CgCaM and Cgengrailed-1 were down-regulated significantly. During the oysters were exposed to acidified seawater for weeks, the expression levels of CgBMP7, CgBMPR1B and CgSmad1/5/8 in the MF decreased significantly (p < 0.01) at the 4 week, and CgCaM and Cgengrailed-1 also exhibited the same variable expression patterns as CgBMP7. In addition, the growth of shell in the treatment group (pH 7.8) was slower than that in the control group (pH 8.1). These results collectively indicated that BMP7 was able to trigger the BMPR-Smad signaling pathway and involved in controlling the formation of oyster calcified shell under OA conditions.
骨形态发生蛋白（BMPs）是控制成骨细胞分化的关键因子，已被证明参与海洋贝类的硬组织形成。本研究从太平洋牡蛎（Crassostrea gigas）中鉴定出一个 BMPs 基因（CgBMP7），旨在了解其在海洋酸化（OA）条件下贝壳形成调控中的可能作用。CgBMP7 的开放阅读框（ORF）为 1254bp，编码一个 417 个氨基酸的多肽。CgBMP7 的推导氨基酸序列包含一个信号肽、一个前肽和一个 TGF-β 结构域，与其他物种的同源性为 21.69%-61.10%。CgBMP7 的 mRNA 转录本在成年牡蛎所有检测组织中均广泛表达，在套膜中表达水平较高，特别是在套膜的三个褶皱中的中褶（MF）最高。骨形态发生蛋白 I 型受体（CgBMPR1B）mRNA 的表达水平也在 MF 中最高，并且在重组 BMP7 蛋白（rCgBMP7）刺激后显著上调。用抑制剂 LDN193189（LDN）阻断 BMPR1B 后，套膜中 CgSmad1/5/8 的 mRNA 表达水平和磷酸化水平降低，CgCaM 和 Cgengrailed-1 的 mRNA 表达水平也显著下调。在牡蛎暴露于酸化海水数周后，MF 中 CgBMP7、CgBMPR1B 和 CgSmad1/5/8 的表达水平在第 4 周显著降低（p<0.01），CgCaM 和 Cgengrailed-1 也表现出与 CgBMP7 相同的可变表达模式。此外，处理组（pH 7.8）的壳生长速度比对照组（pH 8.1）慢。这些结果共同表明，BMP7 能够触发 BMPR-Smad 信号通路，并参与 OA 条件下牡蛎钙化壳的形成调控。
