Watanabe Y, Kashihara N, Makino H, Kanwar Y S
Department of Pathology, Northwestern University Medical School, Chicago, Illinois.
Kidney Int. 1992 May;41(5):1262-73. doi: 10.1038/ki.1992.188.
Effect of insulin-like growth factor-1 (IGF) on the synthesis of glomerular proteoglycans (PGs) in an ex vivo recirculating organ perfusion system was investigated. Kidneys were perfused with a medium (approximately 80 ml) containing [35S]-sulfate (250 microCi/ml) and IGF (62.5 to 625 ng/ml). After radiolabeling, a small cortical piece was saved for tissue autoradiography, and the remaining kidney and the perfusion medium were utilized for biochemical studies. The glomeruli were isolated; their PGs extracted and characterized. A two- to threefold increase of the total radioactivities in tissue and media fractions was observed with the exposure to IGF. By Sepharose CL-6B chromatography, the tissue PGs eluted as two peaks (A and B) with Kav = 0.24 and 0.48, and the majority of the radioactivity was confined to peak A. This peak contained intact PGs while peak B included glycosaminoglycan (GAG) chains. Elution profiles of the glomerular PGs were similar in the control and IGF groups. However, there was a disproportionate increase of chondroitin/dermatan sulfate in the IGF group. The media fractions also had two peaks, and most of the radioactivity was associated with peak B containing GAG chains. A remarkable accentuation of peak B along with significant increase in the chondroitin/dermatan sulfate were observed in the IGF group. By DEAE-Sephacel chromatography, the PGs/GAGs of IGF group eluted at a relatively lower salt concentration as compared to the control. Autoradiography revealed a relatively high concentration of radioactivity over the mesangium as compared to the other cell types of the glomerulus. [35S]-methionine studies revealed a generalized increase of protein synthesis in the IGF group, but comparatively much less than that of PGs/GAGs. These results indicate that IGF enhances the biosynthesis of PGs/GAGs by various cell types of the renal glomerulus, especially that of the mesangial cell, as reflected by the selective increase of chondroitin/dermatan sulfate.
研究了胰岛素样生长因子-1（IGF）对离体循环器官灌注系统中肾小球蛋白聚糖（PGs）合成的影响。用含有[35S] - 硫酸盐（250微居里/毫升）和IGF（62.5至625纳克/毫升）的培养基（约80毫升）灌注肾脏。放射性标记后，保留一小片皮质用于组织放射自显影，其余肾脏和灌注培养基用于生化研究。分离出肾小球；提取并鉴定其PGs。暴露于IGF后，组织和培养基组分中的总放射性增加了两到三倍。通过琼脂糖CL-6B色谱法，组织PGs以两个峰（A和B）洗脱，Kav分别为0.24和0.48，大部分放射性集中在峰A。该峰包含完整的PGs，而峰B包含糖胺聚糖（GAG）链。对照组和IGF组中肾小球PGs的洗脱曲线相似。然而，IGF组中硫酸软骨素/硫酸皮肤素的增加不成比例。培养基组分也有两个峰，大部分放射性与含有GAG链的峰B相关。在IGF组中观察到峰B明显增强，同时硫酸软骨素/硫酸皮肤素显著增加。通过DEAE - 琼脂糖凝胶色谱法，与对照组相比，IGF组的PGs/GAGs在相对较低的盐浓度下洗脱。放射自显影显示，与肾小球的其他细胞类型相比，系膜区的放射性浓度相对较高。[35S] - 甲硫氨酸研究表明，IGF组中蛋白质合成普遍增加，但比PGs/GAGs的增加相对少得多。这些结果表明，IGF增强了肾小球各种细胞类型，尤其是系膜细胞的PGs/GAGs生物合成，硫酸软骨素/硫酸皮肤素的选择性增加反映了这一点。
