Secalonic acid D blocks embryonic palatal mesenchymal cell-cycle by altering the activity of CDK2 and the expression of p21 and cyclin E.
Secalonic acid D blocks embryonic palatal mesenchymal cell-cycle by altering the activity of CDK2 and the expression of p21 and cyclin E.
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DOI：
10.1002/bdrb.20043
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发表时间：
2005-06
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影响因子：
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通讯作者：
V. Dhulipala;K. K. Maddali-K.;W. Welshons;C. Reddy
中科院分区：
文献类型：
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作者：
V. Dhulipala;K. K. Maddali-K.;W. Welshons;C. Reddy
背景真菌毒素-secalonic acid D（SAD）是一种已知的动物和潜在的人类腭裂（CP）诱导剂，由玉米中的青霉菌产生。SAD选择性抑制鼠胚胎腭间充质（MEPM）细胞的增殖，导致细胞数量减少。这些效应可以解释架子大小的减少和SAD暴露小鼠后代中观察到的CP。SAD对人胚腭间充质细胞（HEPM）的增殖有明显的抑制作用，并能阻断细胞周期从G1期向S期的进程，提示SAD对人具有潜在的CP诱导作用。方法采用妊娠12天（GD）小鼠胚胎和HEPM细胞，检测SAD对人胚腭间充质细胞增殖的抑制作用。SAD诱导的周期阻滞是由于体内和体外阶段特异性调节组分的破坏。SAD对各种细胞周期蛋白依赖性激酶（CDK）的活性和各种阳性（细胞周期蛋白和CDK）和阴性（CDK抑制剂p15，16，18，19，21，27，57）细胞周期调节剂的水平的影响进行了评估，分别进行激酶测定和免疫印迹。结果：SAD可特异性抑制小鼠胚胎腭G1/S期特异性CDK 2活性，降低细胞周期蛋白E水平，并有增加CIP/kip CDK抑制剂p21水平的趋势。在HEPM细胞培养物中，暴露于SAD的IC 50显著影响所有上述靶标。此外，还观察到CDK 4/6的水平/活性降低，细胞周期蛋白D1、D2、D3、E、A和所有INK 4家族蛋白的水平降低，以及CIP/kip CDK抑制剂p57的水平增加。结论S期特异性细胞周期蛋白CDK 2、cyclin E和p21可能是SAD的共同靶点，可能与SAD诱导的CP的发病机制有关。
BACKGROUND The mycotoxin, secalonic acid D (SAD), a known animal and potential human cleft palate (CP)-inducing agent, is produced by Pencillium oxalicum in corn. SAD selectively inhibits proliferation of murine embryonic palatal mesenchymal (MEPM) cells leading to a reduction in cell numbers. These effects can explain the reduction in shelf size and the resulting CP seen in the offspring of SAD-exposed mice. Ability of SAD to inhibit proliferation as well as to block the progression of cells from G1- to S-phase of the cell-cycle were also shown in the human embryonic palatal mesenchymal (HEPM) cells suggesting the potential CP-inducing effect of SAD in human beings METHODS Gestation day (GD) 12 mouse embryos and HEPM cells were used to test the hypothesis that the cell-cycle block induced by SAD results from a disruption of stage-specific regulatory components both in vivo and in vitro. The effects of SAD on the activity of various cyclin dependent kinases (CDK) and on the levels of various positive (cyclins and CDK) and negative (CDK inhibitors p15, 16, 18, 19, 21, 27, 57) cell-cycle regulators were assessed by performing kinase assays and immunoblots, respectively. RESULTS In the murine embryonic palates, SAD specifically inhibited G1/S-phase-specific CDK2 activity, reduced the level of cyclin E and tended to increase the level of the CIP/kip CDK inhibitor, p21. In the HEPM cell cultures, exposure to IC50 of SAD significantly affected all of the above targets. In addition, a reduction in the levels/activity of CDK 4/6, a reduction in the levels of cyclins D1, D2, D3, E, A, and all INK4 family proteins, and an increase in the level of the CIP/kip CDK inhibitor, p57, were also seen. CONCLUSIONS These results suggest that the S-phase-specific cell-cycle proteins CDK2, cyclin E and possibly p21 are the common targets of SAD in murine palatal shelves in vivo and in human embryonic palatal mesenchymal cells in vitro and may be relevant to the pathogenesis of SAD-induced CP.