Biochemistry Department, University of Geneva, Geneva, Switzerland.
Traffic. 2020 Jan;21(1):76-93. doi: 10.1111/tra.12715.
The late endosomes/endo-lysosomes of vertebrates contain an atypical phospholipid, lysobisphosphatidic acid (LBPA) (also termed bis[monoacylglycero]phosphate [BMP]), which is not detected elsewhere in the cell. LBPA is abundant in the membrane system present in the lumen of this compartment, including intralumenal vesicles (ILVs). In this review, the current knowledge on LBPA and LBPA-containing membranes will be summarized, and their role in the control of endosomal cholesterol will be outlined. Some speculations will also be made on how this system may be overwhelmed in the cholesterol storage disorder Niemann-Pick C. Then, the roles of intralumenal membranes in endo-lysosomal dynamics and functions will be discussed in broader terms. Likewise, the mechanisms that drive the biogenesis of intralumenal membranes, including ESCRTs, will also be discussed, as well as their diverse composition and fate, including degradation in lysosomes and secretion as exosomes. This review will also discuss how intralumenal membranes are hijacked by pathogenic agents during intoxication and infection, and what is the biochemical composition and function of the intra-endosomal lumenal milieu. Finally, this review will allude to the size limitations imposed on intralumenal vesicle functions and speculate on the possible role of LBPA as calcium chelator in the acidic calcium stores of endo-lysosomes.
脊椎动物的晚期内体/内溶酶体含有一种非典型的磷脂，溶血磷脂酸（LBPA）（也称为双[单酰基甘油]磷酸酯[BMP]），在细胞的其他部位检测不到。LBPA 在该隔室腔中的膜系统中含量丰富，包括腔内囊泡（ILVs）。在这篇综述中，将总结 LBPA 和含有 LBPA 的膜的当前知识，并概述它们在控制内体胆固醇中的作用。还将对该系统如何在胆固醇贮积病 Niemann-Pick C 中被压倒进行一些推测。然后，将更广泛地讨论腔内膜在内溶酶体动力学和功能中的作用。同样，还将讨论驱动腔内膜生物发生的机制，包括 ESCRTs，以及它们的多种组成和命运，包括在溶酶体中降解和作为外泌体分泌。这篇综述还将讨论腔内膜如何在中毒和感染期间被病原体劫持，以及内体腔内环境的生化组成和功能是什么。最后，这篇综述将暗示腔内囊泡功能所受到的大小限制，并推测 LBPA 作为内溶酶体酸性钙库中的钙螯合剂的可能作用。
