Bagshaw Richard D, Mahuran Don J, Callahan John W
Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Canada.
Mol Neurobiol. 2005 Aug;32(1):27-41. doi: 10.1385/MN:32:1:027.
This review focuses on events involved in the biogenesis of the lysosome. This organelle contains a diverse array of soluble, luminal proteins capable of digesting all the macromolecules in the cell. Altered function of lysosomes or its constituent enzymes has been implicated in a host of human pathologies, including storage diseases, cancer, and infectious and neurodegenerative diseases. Luminal enzymes are well-characterized, and aspects of how they are incorporated into lysosomes are known. However, little is known about the composition of the membrane surrounding the organelle or how the membrane is assembled. Our starting point to study lysosome biogenesis is to define the composition of the membrane by the use of proven methods for purification of lysosomes to near homogeneity and then to characterize membrane-associated and integral lysosomal membrane proteins. This has been achieved using advanced proteomics (electrophoretic or chromatographic separations of proteins followed by time-of-flight mass spectrometric identification of peptide sequences). To date, we have identified 55 proteins in the membrane-associated fraction and 215 proteins in the integral membrane. By applying these methods to mouse models of lysosome dysgenesis (such as BEIGE, Pale Ear, PEARL) that are related to human diseases such as Chediak-Higashi and Hermansky-Pudlak syndromes, it may be possible to define the membrane protein composition of lysosomes in each of these mutants and to determine how they differ from normal. Identifying proteins affected in the respective mutants may provide hints about how they are targeted to the lysosomal membrane and how failure to target them leads to disease; these features are pivotal to understanding lysosome biogenesis and have the potential to implicate lysosomes in a broad range of human pathologies.
本综述聚焦于溶酶体生物发生过程中涉及的事件。这种细胞器含有一系列多样的可溶性腔蛋白，能够消化细胞内的所有大分子。溶酶体或其组成酶的功能改变与许多人类疾病有关，包括贮积病、癌症、感染性疾病和神经退行性疾病。腔内酶已得到充分表征，并且已知它们如何被纳入溶酶体的一些方面。然而，对于围绕该细胞器的膜的组成或膜是如何组装的却知之甚少。我们研究溶酶体生物发生的出发点是通过使用经过验证的方法将溶酶体纯化至接近均一性来确定膜的组成，然后对膜相关和整合的溶酶体膜蛋白进行表征。这已通过先进的蛋白质组学技术（蛋白质的电泳或色谱分离，随后通过飞行时间质谱鉴定肽序列）得以实现。迄今为止，我们已经在膜相关部分鉴定出55种蛋白质，在整合膜中鉴定出215种蛋白质。通过将这些方法应用于与人类疾病如切-东综合征和赫曼斯基-普德拉克综合征相关的溶酶体发育异常的小鼠模型（如米色、淡耳、珍珠），有可能确定每个这些突变体中溶酶体的膜蛋白组成，并确定它们与正常情况有何不同。鉴定在各个突变体中受影响的蛋白质可能会提供有关它们如何靶向溶酶体膜以及未能靶向它们如何导致疾病的线索；这些特征对于理解溶酶体生物发生至关重要，并且有可能将溶酶体与广泛的人类疾病联系起来。
