Impact of sphingomyelin acyl chain heterogeneity upon properties of raft-like membranes
Impact of sphingomyelin acyl chain heterogeneity upon properties of raft-like membranes
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DOI：
10.1016/j.bbamem.2022.184036
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发表时间：
2022-09-02
影响因子：
3.4
通讯作者：
Matsumori，Nobuaki
中科院分区：
文献类型：
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作者：
Hirano，Kana;Kinoshita，Masanao;Matsumori，Nobuaki
鞘磷脂（SM）是脂筏的主要成分，具有丰富的长且饱和的酰基链的特征。最近，我们报道了荧光标记的脂质（包括 C16:0 和 C18:0SM）保留了固有脂质的膜行为。在这里，我们新制备了具有较长酰基链的荧光 SM，C22:0 和 C24:1，用于观察它们在 SM/胆固醇 (chol)/二油酰磷脂酰胆碱 (DOPC) 双层中的分配和扩散。尽管荧光 C24:1SM 在有序 (Lo) 相和无序 (Ld) 相之间均匀分布，但其他具有饱和酰基链的荧光 SM 优先分布在 Lo 相中。有趣的是，当荧光SM和膜SM的酰基链不同时，与酰基链相同时相比，荧光SM向Lo相的分布减少。 C16:0SM/C22:0SM/chol/DOPC 四元双层也观察到这种趋势，其中次要 SM 比主要 SM 更多地被排除在 Lo 相之外。我们还发现，SM 的共存会导致 SM 从 Lo 相流出，同时 DOPC 流入 Lo 相，从而减少两相之间的流动性差异。这些结果表明脂筏的理化性质受到 SM 酰基链异质性的调节。
Sphingomyelin (SM) is a main component of lipid rafts and characteristic of abundance of long and saturated acyl chains. Recently, we reported that fluorescence-labeled lipids including C16:0 and C18:0SMs retained membrane behaviors of inherent lipids. Here, we newly prepared fluorescent SMs with longer acyl chains, C22:0 and C24:1, for observing their partition and diffusion in SM/cholesterol (chol)/dioleoylphosphatidylcholine (DOPC) bilayers. Although fluorescent C24:1SM underwent a uniform distribution between ordered (Lo) and disordered (Ld) phases, other fluorescent SMs with saturated acyl chains were preferentially distributed in the Lo phase. Interestingly, when the acyl chains of fluorescent and membrane SMs are different, distribution of fluorescent SM to the Lo phase was reduced compared to when the acyl chains are the same. This tendency was also observed for C16:0SM/C22:0SM/chol/DOPC quaternary bilayers, where the minor SM was more excluded out of the Lo phase than the major SM. We also found that the coexistence of SMs induces SM efflux out of the Lo phase and simultaneous DOPC influx to the Lo phase, consequently reducing the difference in fluidity between the two phases. These results suggest that physicochemical properties of lipid rafts are regulated by the acyl chain heterogeneity of SMs.