Protein Science Laboratory of the Ministry of Education, School of Life Science, Tsinghua University, Beijing, China.
Department of Biotechnology and Biomedicine, Yangtze Delta Region Institute of Tsinghua University, Jiaxing, China.
Acta Biochim Biophys Sin (Shanghai). 2019 May 23;51(5):484-491. doi: 10.1093/abbs/gmz031.
Molluscan shell is a biomineral that consists of a highly organized calcium carbonate composite. Organisms mainly use matrix proteins to elaborately control the biomineralization process, but knowledge of their regulatory mechanisms is limited. The transcription factor Pf-Rel, which belongs to the Rel/nuclear factor-κB family, was shown to regulate transcription at the Nacrein promoter in the pearl oyster Pinctada fucata. Here, we further explored the transcriptional regulation mechanisms of Pf-Rel on the matrix proteins Prismalin-14 and MSI60. The relative expression levels of Prismalin-14 and MSI60 were high in the mantle edge and mantle pallial tissues of P. fucata. These three genes were significantly up-regulated after shell notching, suggesting that they might play important roles during shell formation. Importantly, Pf-Rel gene knockdown by RNA interference led to down-regulation of Prismalin-14 and MSI60 expression. In transient co-transfection assays, Pf-Rel significantly up-regulated the promoter activities of the Prismalin-14 and MSI60 genes in a dose-dependent manner. Furthermore, the promoter regions of Prismalin-14 (-1794 to -1599 bp) and MSI60 (-2244 to -1141 bp) were required for the activation by Pf-Rel. Altogether, these results suggest that the transcription factor Pf-Rel can up-regulate the expression of the matrix protein genes Prismalin-14 and MSI60 during shell formation in P. fucata, which improves our understanding of transcription regulation at the molecular level during molluscan shell development.
软体动物壳是一种由高度组织化的碳酸钙复合材料组成的生物矿物。生物主要利用基质蛋白来精细地控制生物矿化过程，但对其调控机制的了解有限。转录因子 Pf-Rel 属于 Rel/nuclear factor-κB 家族，被证明可调节珍珠贝 Pinctada fucata 中珠母贝蛋白基因的转录。在这里，我们进一步探讨了 Pf-Rel 对基质蛋白 Prismalin-14 和 MSI60 的转录调控机制。Prismalin-14 和 MSI60 的相对表达水平在珍珠贝的边缘组织和套膜组织中较高。这三个基因在壳切开后显著上调，表明它们可能在壳形成过程中发挥重要作用。重要的是，RNA 干扰导致 Pf-Rel 基因敲低后，Prismalin-14 和 MSI60 的表达下调。在瞬时共转染实验中，Pf-Rel 以剂量依赖性方式显著上调 Prismalin-14 和 MSI60 基因的启动子活性。此外，Prismalin-14（-1794 至-1599bp）和 MSI60（-2244 至-1141bp）的启动子区域对于 Pf-Rel 的激活是必需的。总之，这些结果表明，转录因子 Pf-Rel 可以在珍珠贝的壳形成过程中上调基质蛋白基因 Prismalin-14 和 MSI60 的表达，这提高了我们对软体动物壳发育过程中分子水平转录调控的理解。
