Zhang Xiaoli, Shi Kun, Li Yi, Zhang Haiyu, Hao Jing
Key Laboratory of the Ministry of Education for Experimental Teratology, Department of Histology and Embryology, School of Medicine, Shandong University, Jinan 250012, PR China.
Obstetric Genetic Disease Laboratory, Maternal and Child Health Hospital of Zibo City, Zibo 255029, PR China.
Reprod Toxicol. 2014 Jun;45:87-93. doi: 10.1016/j.reprotox.2014.01.009. Epub 2014 Feb 4.
Lipopolysaccharide (LPS) can reduce sperm count and sperm quality. The molecular mechanisms underlying this process are not fully understood. In this report, we investigated the effects of LPS-treated Sertoli cells on self-renewal and differentiation of spermatogoinial stem cells (SSCs). Sertoli cell cultures were established and incubated with LPS (10μg/ml) for 1, 2 or 3 days, respectively. The culture media were collected and used as conditioned media (CM) to culture SSCs. The expression of glial cell-derived neurotrophic factor (GDNF), stem cell factor (SCF) and bone morphogenetic protein 4 (BMP4) in Sertoli cells treated with LPS was analyzed by RT-PCR and Western blotting. The results showed that the expression of SSC differentiation markers, c-kit and Sohlh2, was increased, while the expression of SSC self-renewal markers, plzf, oct4, and PCNA, was repressed when cultured in CM from LPS-treated Sertoli cells. GDNF levels in Sertoli cells and CM reduced dramatically after LPS treatments, while SCF and BMP4 levels did not show any significant changes. Moreover, correlated with the GDNF levels in CM, GDNF target genes, Bcl6b and Etv5, were reduced markedly in SSCs. Our results suggest that LPS inhibits the expression of GDNF in Sertoli cells, and might prevent the SSC self-renewal via down-regulation of GDNF target genes.
脂多糖（LPS）可降低精子数量和精子质量。这一过程背后的分子机制尚未完全明确。在本报告中，我们研究了经LPS处理的支持细胞对精原干细胞（SSCs）自我更新和分化的影响。建立支持细胞培养体系，并分别用LPS（10μg/ml）处理1、2或3天。收集培养基并用作条件培养基（CM）来培养SSCs。通过RT-PCR和蛋白质免疫印迹法分析经LPS处理的支持细胞中胶质细胞源性神经营养因子（GDNF）、干细胞因子（SCF）和骨形态发生蛋白4（BMP4）的表达。结果显示，当在经LPS处理的支持细胞的条件培养基中培养时，SSC分化标志物c-kit和Sohlh2的表达增加，而SSC自我更新标志物plzf、oct4和增殖细胞核抗原（PCNA）的表达受到抑制。LPS处理后，支持细胞和条件培养基中的GDNF水平显著降低，而SCF和BMP4水平未显示任何显著变化。此外，与条件培养基中的GDNF水平相关，SSCs中GDNF靶基因Bcl6b和Etv5明显减少。我们的结果表明，LPS抑制支持细胞中GDNF的表达，并可能通过下调GDNF靶基因来阻止SSC的自我更新。
