不同来源的人血清白蛋白对1-磷酸鞘氨醇的结合运载作用研究

Binding and carrying role of human serum albumin from various sources to sphingosine-1-phosphate

目的研究不同来源的人血清白蛋白(human serum albumin,HSA)对1-磷酸鞘氨醇(sphingosine-1-phosphate,S1P)的结合运载作用。方法以人血浆来源HSA(plasma derived HSA,pHSA)和基因重组HSA(recombinant HSA,rHSA)样本为研究对象,首先利用LC-MS/MS技术,比较分析上述样本中S1P含量的差异;其次,在生理浓度条件下,向HSA样本中直接添加S1P进行负载处理,比较不同来源的HSA对S1P结合作用;在无血清培养条件下,将不同来源HSA样本与HUVEC细胞进行共培养,分析不同处理组的细胞培养上清中S1P含量的变化,比较不同来源的HSA对细胞中S1P的运载作用。利用表面等离子体共振SPR技术分析不同来源HSA与S1P分子的相互作用情况并计算其亲和力大小。利用AutoDock Vina软件和Molprophet平台,对HSA和S1P进行分子对接分析,并预测HSA中S1P的关键结合口袋域。结果S1P含量检测结果显示,所有pHSA样本中均含有一定水平的S1P(3.31±0.03~30.35±0.07)μg/L,且不同厂家生产的pHSA样本中的S1P含量差异显著(P<0.001);然而所有rHSA样本中均未检测出S1P。负载处理结果显示,不同来源HSA对S1P的结合作用存在显著差异(P<0.001),且rHSA对S1P平均负载量约为pHSA的2倍(ΔC_(rHSA)=801.75±142.45μg/L vsΔC_(pHSA)=461.94±85.73μg/L;P<0.001,t=5.006)。共培养处理结果显示,所有HSA样本处理组与HUVEC细胞共培养处理6h后上清中的S1P浓度均明显升高,而空白对照组上清中S1P浓度无变化;处理6 h、12 h和24 h后各处理组间上清中S1P浓度均存在显著差异(P<0.001)。SPR分析结果显示,与rHSA相比,pHSA与S1P之间的亲和力更高(KD_(pHSA-S1P):2.38E-06,KD_(rHSA-S1P):3.72E-06)。分子对接分析和结合口袋预测发现,HSA与S1P的关键结合口袋可能位于HSA分子的IB亚结构域。结论不同来源的HSA对S1P均具有一定的结合运载作用,但这种作用差异具有统计学意义,与HSA分子的IB亚结构域存在关联。

Objective To investigate the binding and carrying effects of human serum albumin(HSA)from various sources on sphingosine-1-phosphate(S1P).Methods Utilizing human plasma-derived HSA(pHSA)and recombinant HSA(rHSA)samples as the focal points of our investigation,LC-MS/MS technology was employed to meticulously compare and analyze the disparities in S1P content among the aforementioned samples.Subsequently,under physiological concentration conditions,S1P was directly introduced to HSA samples for loading processing,facilitating a comprehensive comparison of the binding efficacy of HSA from different sources to S1P.Within a serum-free culture setting,HSA samples from various sources were co-cultured with HUVEC cells.The alterations in S1P content within the cell culture supernatant across different treatment groups were meticulously analyzed,allowing for a nuanced comparison of the S1P carry effects exerted by HSA from different sources on cells.The interaction between HSA and S1P molecules from different sources was analyzed and their affinity was calculated using surface plasmon resonance(SPR)technology.Furthermore,leveraging AutoDock Vina software and the Molprophet platform,the molecular docking analysis of HSA and S1P was conducted,aiming to predict the key binding pocket domain of S1P within HSA.Results All pHSA samples exhibited detectable levels of S1P(ranging from 3.31±0.03 to 30.35±0.07μg/L),with significant variations observed among pHSA samples from different manufacturers(P<0.001).Conversely,S1P was undetectable in all rHSA samples.Upon load treatment,the binding affinity of HSA from diverse sources to S1P demonstrated significant discrepancies(P<0.001),with rHSA exhibiting approximately double the average S1P loading compared to pHSA(ΔCrHSA=801.75±142.45μg/L vsΔCpHSA=461.94±85.73μg/L;P<0.001,t=5.006).Co-culture treatment outcomes revealed a significant elevation in S1P concentration within the supernatant after 6 hours of co-culture across all HSA sample processing groups with HUVEC cells,while no changes were observed in the supernatant of the blank control group.Notably,significant differences in supernatant S1P concentration were observed among treatment groups at 6 h,12 h,and 24 h(P<0.001).SPR analysis unveiled a stronger affinity of pHSA for S1P compared to rHSA(KD_(pHSA-S1P):2.38E-06,KD_(rHSA-S1P):3.72E-06).Molecular docking analysis and binding pocket prediction suggested that the key binding pocket of HSA and S1P may reside in the IB subdomain of the HSA molecule.Conclusion HSA from various sources exhibits distinct binding and carrying effects on S1P,which appear to be closely associated with the IB subdomain of the HSA molecule.