Lichter-Konecki U, Moter S E, Krawisz B R, Schlotter M, Hipke C, Konecki D S
Molecular and Cellular Biology Laboratory, Marshfield Medical Research Foundation, Marshfield Clinic, WI 54449, USA.
Differentiation. 1999 Jul;65(1):43-58. doi: 10.1046/j.1432-0436.1999.6510043.x.
We report the isolation and characterization of the murine homologues to human and chicken lysosome-associated membrane protein (Lamp)-2 transcripts and their prevalent expression patterns during development. Lamp-2 transcripts code for proteins predominant in and specific for the lysosomal membrane. The function of these proteins is still under investigation. Other than in the lysosomal membrane, Lamp-2 proteins have been detected at the plasma membrane of cells in a differentiation dependent and activation dependent manner. They were also observed at the plasma membrane of cells, which secrete lysosomal hydrolases. Involvement of Lamp-2 in cell adhesion during such events has been proposed. A study of the developmental expression patterns of m-Lamp-2 transcripts was undertaken to help elucidate possible functions of their respective proteins. The m-Lamp-2b transcript was prevalent in neural crest derived ganglia. The m-Lamp-2a and -2c transcripts were similarly expressed in structures containing neural crest derived tissue with the strongest signals detected in thymus. However, m-Lamp-2a and -2c transcript expression differed in mesoderm or endoderm derived mesenchymal and epithelial tissues. M-Lamp-2c expression was pronounced in mesenchyme early in development, in limb connective tissue, and in lung parenchyma, whereas m-Lamp-2a was prevalent in the liver, the pancreas, and in differentiating kidney epithelium, and became increasingly prominent in the epithelial lining of the digestive and the respiratory tract during development. These results correlated with the detection of m-Lamp-2 protein in these tissues. In conclusion, all m-Lamp-2 transcripts were detected in tissues undergoing apoptosis during development requiring phagolysosome involvement. In addition, m-Lamp-2a and m-Lamp-2c transcripts were observed in epithelium and mesenchyme during the time of epithelial-mesenchymal interaction, mesenchymal-epithelial transformation, and branching. Their expression pattern became more tissue and cell type specific as differentiation progressed. These patterns indicate a possible involvement of m-Lamp-2 proteins in cell/cell or cell/extracellular matrix interaction, and appear to reflect tissue and cell type specific roles of lysosomes during morphogenesis.
我们报告了小鼠与人及鸡溶酶体相关膜蛋白（Lamp）-2转录本的同源物的分离与鉴定，以及它们在发育过程中的普遍表达模式。Lamp-2转录本编码主要存在于溶酶体膜且对其具有特异性的蛋白质。这些蛋白质的功能仍在研究中。除了在溶酶体膜中，Lamp-2蛋白还以分化依赖和激活依赖的方式在细胞膜上被检测到。它们也在分泌溶酶体水解酶的细胞的细胞膜上被观察到。有人提出Lamp-2在此类事件中参与细胞黏附。对m-Lamp-2转录本的发育表达模式进行了研究，以帮助阐明其各自蛋白质的可能功能。m-Lamp-2b转录本在神经嵴衍生的神经节中普遍存在。m-Lamp-2a和-2c转录本在含有神经嵴衍生组织的结构中表达相似，在胸腺中检测到最强信号。然而，m-Lamp-2a和-2c转录本在中胚层或内胚层衍生的间充质和上皮组织中的表达有所不同。m-Lamp-2c在发育早期的间充质、肢体结缔组织和肺实质中表达明显，而m-Lamp-2a在肝脏、胰腺和分化中的肾上皮中普遍存在，并在发育过程中在消化道和呼吸道的上皮衬里中变得越来越突出。这些结果与在这些组织中检测到的m-Lamp-2蛋白相关。总之，在发育过程中经历需要吞噬溶酶体参与的凋亡的组织中检测到了所有m-Lamp-2转录本。此外，在上皮-间充质相互作用、间充质-上皮转化和分支期间，在上皮和间充质中观察到了m-Lamp-2a和m-Lamp-2c转录本。随着分化的进行，它们的表达模式变得更加组织和细胞类型特异性。这些模式表明m-Lamp-2蛋白可能参与细胞/细胞或细胞/细胞外基质相互作用，并且似乎反映了溶酶体在形态发生过程中的组织和细胞类型特异性作用。
