External suppression causes the low expression of the Cosmc gene in IgA nephropathy
External suppression causes the low expression of the Cosmc gene in IgA nephropathy
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DOI：
10.1093/ndt/gfm781
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发表时间：
2008-05-01
影响因子：
6.1
通讯作者：
Ma, Xing Yi
中科院分区：
文献类型：
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作者：
Qin, Wei;Zhong, Xiang;Ma, Xing Yi
目标。IgA(1)异常o糖基化是IgA肾病（IgAN）的主要发病机制之一，IgAN患者核心I β 3- gal - t特异性分子伴侣（Cosmc） mRNA表达显著降低。本研究试图阐明这种下调是遗传疾病还是外部抑制的结果。IgAN患者65例，非IgAN肾小球肾炎患者23例，正常对照21例。提取基因组DNA， PCR扩增Cosmc基因并直接测序。分离IgAN患者和正常对照的外周血B淋巴细胞，分别用RPMI-1640或脂多糖（LPS）培养72 h，采用实时荧光定量pcr法（real-time rt - pcr）检测基线、RPMI培养或RPMI + LPS处理后的Cosmc mRNA表达水平。(1) Cosmc基因的整个编码框区域被成功扩增并直接测序。在2例IgAN患者中检测到4个单核苷酸多态性。两个是错义突变，其他是沉默突变。然而，它们彼此不同，与表达水平无关；(2) IgAN患者Cosmc mRNA的基线表达量显著低于正常对照组（Ct(Cosmc /GAPDH) 1.29 +/- 0.08 vs 1.20 +/- 0.01，为正常对照组的31%）；(3) RPMI培养后IgAN患者的Cosmc mRNA表达水平显著升高（1.22 +/- 0.12 vs 1.29 +/- 0.08，为基线水平的219%），而正常对照组无显著升高；(4)LPS （RPMI + LPS培养）能强烈抑制Cosmc mRNA表达（1.25 +/- 0.01 vs 1.22 +/- 0.12，为RPMI治疗组的61%）。未检测到常见的Cosmc基因突变。在无血浆培养中，Cosmc mRNA表达显著升高，而LPS能显著抑制其表达，提示IgAN中Cosmc mRNA低表达可能不是遗传疾病所致，而是外部抑制所致。
Objective. IgA(1) aberrant O-glycosylation is one of the main pathogeneses of IgA nephropathy (IgAN), and the core I beta 3-Gal-T-specific molecular chaperone (Cosmc) mRNA expression of IgAN patients was significantly decreased. This study tried to clarify whether the down-regulation was a result of genetic disorders or external suppressions.Method. Sixty-five IgAN patients, 23 non-IgAN glomerulonephritis patients and 21 normal controls were recruited. Genomic DNA was extracted and the Cosmc gene was PCR amplified and directly sequenced. Peripheral B lymphocytes of IgAN patients and normal controls were isolated, and cultured with RPMI-1640 alone or with lipopolysaccharide (LPS) for 72 h. The Cosmc mRNA expression levels at baseline, after RPMI culture or RPMI + LPS treatment were measured by real-time RT-PCR.Results. (1) The whole coding frame region of the Cosmc gene was successfully amplified and directly sequenced. Four single nucleotide polymorphisms were detected in two IgAN patients. Two were missense mutations and the others were silent mutations. However, they are different from each other, and unrelated to expression levels; (2) the baseline Cosmc mRNA expression in IgAN patients was significantly lower than normal controls (Ct(COSMC/GAPDH) 1.29 +/- 0.08 versus 1.20 +/- 0.01, 31% of normal controls); (3) the Cosmc mRNA expression level of IgAN patients was remarkably increased after the RPMI culture (1.22 +/- 0.12 versus 1.29 +/- 0.08, 219% of the baseline level), while not in normal controls and (4) treatment with LPS (culture with RPMI + LPS) could strongly inhibit the expression of Cosmc mRNA (1.25 +/- 0.01 versus 1.22 +/- 0.12, 61% of the RPMI treatment group).Conclusion. No common Cosmc gene mutation was detected. Significantly increased Cosmc expression was observed in plasma-free culture, while LPS could significantly inhibit it, which suggested that it might not be genetic disorders but external suppression that causes the low Cosmc mRNA expression in IgAN.