地塞米松和过氧化氢对合浦珠母贝珍珠层结构及基质蛋白表达的影响

Effects of Dexamethasone and peroxide on the nacre structure and expression level of matrix protein in Pinctada fucata

分别用地塞米松(Dexamethasone,DEX)和过氧化氢(H2O2)处理合浦珠母贝(Pinctada fucata),研究其对贝珍珠层和基质蛋白表达的影响。扫描电镜观察显示,DEX可促进珍珠层生长,H2O2则抑制珍珠层生长。体外碳酸钙结晶实验表明,DEX处理组间液蛋白调控文石生成的趋势加强,并加速碳酸钙结晶速率;H2O2处理组相反。实时定量PCR实验显示,DEX处理组TGFβ和NF-кB信号通路关键因子pf-smad3、pf-rel等和基质蛋白Nacrein等基因表达水平明显降低,H2O2作用组则显著上升。由上述结果推测,DEX和H2O2可通过抑制或激活合浦珠母贝的TGFβ和NF-кB信号通路,从而调控与珍珠层形成相关的基质蛋白的表达,并影响珍珠层的结构;同时暗示贝的免疫体系和矿化系统可能存在协同作用,该作用机制具有生物进化学意义,并对养殖珍珠的培育具有借鉴作用。

Signaling pathways are thought to play critical roles in biomineralization, however, not much evidence has been revealed in Pinctada fucata so far. Herein, we have studied the relevance between these signaling path- ways and the matrix proteins through inhibiting and activating TGFβ and NF-KB signaling pathways by using dexamethasone and peroxide. Results show that TGFβ and NF-KB signaling pathways had negative correlation with the growth of nacre, and they contributed to the regulation of crystal form and the crystallization rate of calcium carbonate. The expression levels of pf-smad3, pf-rel and Nacrein decreased synchronously after DEX treatment, while increased synchronously after H2O2 treatment. The results indicate that DEX and H2O2 might regulate the matrix proteins and affect nacre structure by inhibiting and activating TGFβ and NF-KB signaling pathways. The results also suggest that there might be cross-coupling between immune system and biomineralization system in Pinctadafucata, and the two systems might share the same signaling pathways like TGFβ and NF-KB pathways.