Kalamidas S A, Kotoulas O B, Hann A C
Department of Anatomy, Histology and Embryology, Medical School, University of Ioannina, Ioannina, Greece.
Microsc Res Tech. 2002 Jun 15;57(6):507-11. doi: 10.1002/jemt.10104.
The effects of agents that could manipulate the lysosomal calcium such as phorbol myristate acetate, ionophore A23187, and phentolamine on the lysosomal glycogen degradation were studied by electron microscopy, morphometric analysis, and biochemical assays in newborn rat hepatocytes. Phorbol myristate acetate, which promotes the input of calcium to lysosomes, increased the total volume of autophagic vacuoles and the activity of lysosomal glycogen-hydrolyzing acid alpha 1,4 glucosidase and decreased the fractional volume of undigested glycogen inside the autophagic vacuoles and also decreased the activity of acid mannose 6-phosphatase. Ionophore A23187, which releases lysosomal calcium, produced opposite results in these enzyme activities. Phentolamine, an alpha-adrenergic blocking agent which interferes with the generation of phosphoinositides and may activate the lysosomal calcium uptake pump, increased the total volume of autophagic vacuoles and the activity of lysosomal glycogen-hydrolyzing acid glucosidase and decreased the fractional volume of undigested glycogen inside the autophagic vacuoles. The results of this study constitute evidence that changes in lysosomal calcium may influence certain aspects of autophagy, including the degradation of glycogen inside the autophagic vacuoles. They also support our previous postulate [Kalamidas and Kotoulas (2000a,b) Histol Histopathol 15:29-35, 1011-1018] that stimulation of autophagic mechanisms in newborn rat hepatocytes may be associated with acid mannose 6-phosphatase activity-deficient lysosomes.
通过电子显微镜、形态计量分析和生化检测，研究了佛波酯、离子载体A23187和酚妥拉明等能够调控溶酶体钙的试剂对新生大鼠肝细胞溶酶体糖原降解的影响。促进钙进入溶酶体的佛波酯增加了自噬泡的总体积以及溶酶体糖原水解性酸性α-1,4-葡萄糖苷酶的活性，降低了自噬泡内未消化糖原的体积分数，还降低了酸性甘露糖6-磷酸酶的活性。释放溶酶体钙的离子载体A23187在这些酶活性方面产生了相反的结果。酚妥拉明是一种α-肾上腺素能阻滞剂，它干扰磷酸肌醇的生成并可能激活溶酶体钙摄取泵，增加了自噬泡的总体积以及溶酶体糖原水解性酸性葡萄糖苷酶的活性，降低了自噬泡内未消化糖原的体积分数。本研究结果证明溶酶体钙的变化可能影响自噬的某些方面，包括自噬泡内糖原的降解。它们还支持我们之前的假设[Kalamidas和Kotoulas（2000a，b）《组织学与组织病理学》15:29 - 35，1011 - 1018]，即新生大鼠肝细胞自噬机制的刺激可能与酸性甘露糖6-磷酸酶活性缺陷的溶酶体有关。
