Jo Hyung Ah, Kim Joo-Young, Yang Seung Hee, Han Seung Seok, Joo Kwon Wook, Kim Yon Su, Kim Dong Ki
Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea.
Kidney Research Institute, Seoul National University, Seoul, Korea.
Kidney Res Clin Pract. 2016 Dec;35(4):212-218. doi: 10.1016/j.krcp.2016.09.003. Epub 2016 Sep 17.
Interleukin-6 (IL6) is an important regulator of cellular hypertrophy through the gp130/Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathway. We tested the hypothesis that IL6 and its downstream gp130/JAK2/STAT3 pathway participated in high glucose (HG)-induced podocyte hypertrophy.
IL6 levels in the media and lysates of podocytes were measured by enzyme-linked immunosorbent assay. Western blots were performed to determine the protein expression levels of gp130/JAK2/STAT3 among podocytes cultured with normal glucose (NG), NG + mannitol, NG + recombinant IL6, HG, and HG + IL6-neutralizing antibodies (IL6NAb). Immunoprecipitation was examined to determine whether gp130 interacted with JAK2 in response to HG or IL6. Podocyte hypertrophy was verified using protein/cell counts and flow cytometry.
IL6 levels were significantly increased in the media and lysates of podocytes cultured in HG compared with the NG groups. The nuclear phospho-STAT3/STAT3 ratio was increased by HG and NG + IL6 and was attenuated in the HG + IL6NAb groups, indicating that nuclear STAT3 was activated following JAK2 and cytosolic STAT3 activation in response to IL6 secreted by HG-stimulated podocytes. Immunoprecipitation showed increased phospho-JAK2 recruitment to gp130 in the HG and NG + IL6 groups, and the addition of IL6NAb in the HG group significantly abrogated these increases. Podocyte hypertrophy was significantly increased in the HG and NG + IL6 compared with the NG condition and was diminished by the addition of IL6NAbs to the HG group.
IL6 might play a prominent role in the local activation of JAK2/STAT3 in podocyte hypertrophy under HG conditions. studies examining this pathway are warranted.
白细胞介素-6（IL6）是通过gp130/Janus激酶2（JAK2）/信号转导和转录激活因子3（STAT3）途径调节细胞肥大的重要因子。我们检验了IL6及其下游gp130/JAK2/STAT3途径参与高糖（HG）诱导的足细胞肥大的假说。
采用酶联免疫吸附测定法检测足细胞培养基和裂解物中的IL6水平。进行蛋白质印迹法以确定在正常葡萄糖（NG）、NG+甘露醇、NG+重组IL6、HG以及HG+IL6中和抗体（IL6NAb）培养的足细胞中gp130/JAK2/STAT3的蛋白表达水平。通过免疫沉淀法检测在HG或IL6刺激下gp130是否与JAK2相互作用。使用蛋白质/细胞计数和流式细胞术验证足细胞肥大。
与NG组相比，HG培养的足细胞培养基和裂解物中的IL6水平显著升高。HG和NG+IL6组中核磷酸化STAT3/STAT3比值升高，而HG+IL6NAb组中该比值降低，这表明在HG刺激的足细胞分泌IL6后，JAK2和胞质STAT3激活后核STAT3被激活。免疫沉淀显示HG组和NG+IL6组中磷酸化JAK2与gp130的结合增加，HG组中添加IL6NAb可显著消除这些增加。与NG条件相比，HG组和NG+IL6组中足细胞肥大显著增加，而HG组中添加IL6NAb可减轻足细胞肥大。
在HG条件下，IL6可能在足细胞肥大中JAK2/STAT3的局部激活中起重要作用。有必要对该途径进行研究。
