Department of Chemistry, FFCLRP-USP, University of São Paulo, Ribeirão Preto, SP, Brazil.
Department of Epidemiology and Prevention, IRCCS NEUROMED, Pozzilli, IS, Italy.
Biochim Biophys Acta Gen Subj. 2020 Aug;1864(8):129629. doi: 10.1016/j.bbagen.2020.129629. Epub 2020 Apr 29.
Vascular smooth muscle cells (VSMCs) transdifferentiated ectopically trigger vascular calcifications, contributing to clinical cardiovascular disease in the aging population. AnxA5 and TNAP play a crucial role in (patho)physiological mineralization.
We performed affinity studies between DPPC and 9:1 DPPC:DPPS-proteoliposomes carrying AnxA5 and/or TNAP and different types of collagen matrix: type I, II, I + III and native collagenous extracellular matrix (ECM) produced from VSMCs with or without differentiation, to simulate ectopic calcification conditions.
AnxA5-proteoliposomes had the highest affinity for collagens, specially for type II. TNAP-proteoliposomes bound poorly and the simultaneous presence of TNAP in the AnxA5-proteoliposomes disturbed interactions between AnxA5 and collagen. DPPC AnxA5-proteoliposomes affinities for ECM from transdifferentiating cells went up 2-fold compared to that from native VSMCs. The affinities of DPPC:DPPS-proteoliposomes were high for ECM from VSMCs with or without differentiation, underscoring a synergistic effect between AnxA5 and DPPS. Co-localization studies uncovered binding of proteoliposomes harboring AnxA5 or TNAP+AnxA5 to various regions of the ECM, not limited to type II collagen.
AnxA5-proteoliposomes showed the highest affinities for type II collagen, deposited during chondrocyte mineralization in joint cartilage. TNAP in the lipid/protein microenvironment disturbs interactions between AnxA5 and collagen. These findings support the hypothesis that TNAP is cleaved from the MVs membrane just before ECM binding, such facilitating MV anchoring to ECM via AnxA5 interaction.
Proteoliposomes as MV biomimetics are useful in the understanding of mechanisms that regulate the mineralization process and may be essential for the development of novel therapeutic strategies to prevent or inhibit ectopic mineralization.
异位转分化的血管平滑肌细胞（VSMCs）触发血管钙化，导致老龄化人群中的临床心血管疾病。AnxA5 和 TNAP 在（病理）生理矿化中发挥关键作用。
我们在 DPPC 和载有 AnxA5 和/或 TNAP 的 9:1 DPPC:DPPS 脂蛋白与不同类型的胶原基质（I 型、II 型、I+III 型和源自未分化和分化的 VSMCs 的天然胶原细胞外基质（ECM））之间进行了亲和研究，以模拟异位钙化条件。
AnxA5 脂蛋白对胶原具有最高的亲和力，特别是对 II 型胶原。TNAP 脂蛋白结合不良，同时存在于 AnxA5 脂蛋白中的 TNAP 会干扰 AnxA5 与胶原之间的相互作用。与源自天然 VSMCs 的 ECM 相比，DPPC AnxA5 脂蛋白对转化细胞 ECM 的亲和力增加了 2 倍。DPPC:DPPS 脂蛋白对有或无分化的 VSMCs 的 ECM 的亲和力很高，强调了 AnxA5 和 DPPS 之间的协同作用。共定位研究揭示了携带 AnxA5 或 TNAP+AnxA5 的脂蛋白与 ECM 的各个区域结合，不仅限于 II 型胶原。
AnxA5 脂蛋白对软骨关节中软骨细胞矿化过程中沉积的 II 型胶原具有最高的亲和力。脂质/蛋白质微环境中的 TNAP 会干扰 AnxA5 与胶原之间的相互作用。这些发现支持这样的假设，即 TNAP 在 ECM 结合之前从 MV 膜上被切割，从而通过 AnxA5 相互作用促进 MV 锚定到 ECM。
作为 MV 仿生物的脂蛋白有助于理解调节矿化过程的机制，对于开发预防或抑制异位矿化的新型治疗策略可能是必不可少的。
