Houri J J, Ogier-Denis E, De Stefanis D, Bauvy C, Baccino F M, Isidoro C, Codogno P
INSERM U410 Neuroendocrinologie et Biologie Cellulaire Digestives, Faculté de Médecine Xavier Bichat, Paris, France.
Biochem J. 1995 Jul 15;309 ( Pt 2)(Pt 2):521-7. doi: 10.1042/bj3090521.
Our previous results have demonstrated that, in undifferentiated human colon cancer HT-29 cells, a pool of glycoproteins bearing high-mannose oligosaccharides rapidly escapes the exocytic pathway to be degraded in the lysosomal compartment [Trugnan, Ogier-Denis, Sapin, Darmoul, Bauvy, Aubery and Codogno (1991) J. Biol. Chem. 266, 20849-20855]. We report here on the mechanism that governs this degradative pathway. Using pulse-chase experiments in combination with subcellular fractionation, we have observed that the sequestration of high-mannose glycoproteins in lysosomes was impaired by drugs which interfere with the autophagic-lysosomal pathway. The accumulation of high-mannose glycoproteins in the lysosomal fraction was shown to be part of the general autophagic pathway constitutively expressed in undifferentiated cells, as independently measured by the sequestration of the cytosolic enzyme lactate dehydrogenase and electroloaded raffinose. Furthermore, when HT-29 cells were cultured under differentiation-permissive conditions, the decreased accumulation of high-mannose glycoproteins in the lysosomal compartment was correlated with the decrease in autophagy.
我们之前的研究结果表明，在未分化的人结肠癌HT-29细胞中，一群带有高甘露糖寡糖的糖蛋白迅速逃离胞吐途径，在溶酶体区室中被降解[特吕尼昂、奥吉尔 - 德尼、萨潘、达穆尔、鲍维、奥贝里和科多尼奥（1991年）《生物化学杂志》266卷，20849 - 20855页]。我们在此报告控制这一降解途径的机制。通过脉冲追踪实验结合亚细胞分级分离，我们观察到，干扰自噬 - 溶酶体途径的药物会损害溶酶体中高甘露糖糖蛋白的隔离。溶酶体部分中高甘露糖糖蛋白的积累被证明是未分化细胞中组成型表达的一般自噬途径的一部分，这可通过胞质酶乳酸脱氢酶的隔离和电加载棉子糖独立测量得到。此外，当HT-29细胞在允许分化的条件下培养时，溶酶体区室中高甘露糖糖蛋白积累的减少与自噬的减少相关。
