Yokota S, Nishimura Y, Kato K
Department of Anatomy, Yamanashi Medical School, Japan.
Histochemistry. 1988;90(4):277-83. doi: 10.1007/BF00495971.
Localization of cathepsin L in rat kidney was investigated by immunocytochemical techniques. Kidneys were fixed by perfusion and embedded in Epon or Lowicryl K4M without postosmication. For light microscopy (LM), semi-thin sections of the Epon-embedded material were stained by the immunoenzyme technique after removal of epoxy resin. For electron microscopy (EM), ultra-thin sections of Lowicryl K4M-embedded material were stained by the protein A-gold technique. By LM, reaction deposits for cathepsin L were present in the cytoplasmic granules of proximal tubule cells, but little or no reaction product was noted in distal tubule, collecting tubule, and most of urinary tubules in the medulla. By EM, heavy gold label for cathepsin L was confined exclusively to lysosomes of the proximal tubule cells, but little or no label to those of the other segments. In immunocytochemical control sections, no reaction was observed. These results indicate that a main container of cathepsin L is lysosomes of the proximal tubule and suggest that the enzyme plays a role in the degradation of endocytosed proteins.
采用免疫细胞化学技术研究了大鼠肾脏中组织蛋白酶L的定位。通过灌注固定肾脏，并将其包埋在Epon或Lowicryl K4M中，无需后固定。对于光学显微镜（LM），在去除环氧树脂后，用免疫酶技术对Epon包埋材料的半薄切片进行染色。对于电子显微镜（EM），用蛋白A-金技术对Lowicryl K4M包埋材料的超薄切片进行染色。通过LM观察，组织蛋白酶L的反应沉积物存在于近端小管细胞的细胞质颗粒中，但在远端小管、集合小管以及髓质中的大多数泌尿小管中几乎没有或没有观察到反应产物。通过EM观察，组织蛋白酶L的重金标记仅局限于近端小管细胞的溶酶体中，而其他节段的溶酶体几乎没有或没有标记。在免疫细胞化学对照切片中，未观察到反应。这些结果表明，组织蛋白酶L的主要储存部位是近端小管的溶酶体，并提示该酶在胞吞蛋白质降解中起作用。
