GDNF and insulin cooperate to enhance the proliferation and differentiation of enteric crest-derived cells
GDNF and insulin cooperate to enhance the proliferation and differentiation of enteric crest-derived cells
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DOI：
10.1002/neu.10204
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发表时间：
2003-05-01
期刊：
影响因子：
--
通讯作者：
Epstein, ML
中科院分区：
文献类型：
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作者：
Focke, PJ;Swetlik, AR;Epstein, ML
在此之前，我们已经证明，胶质源性神经营养因子(GDNF)可以刺激禽肠上皮源性细胞的增殖，也可以促进底物Akt(Akt-P)下游的磷脂酰肌醇3-激酶(PI3K)的磷酸化。在目前的研究中，我们测试了GDNF非依赖性的PI3K激活增加是否足以支持增殖。我们发现，胰岛素可诱导禽肠冠源性细胞Akt的磷酸化水平显著增加，并能启动DNA合成，但通过BrdU掺入法检测，胰岛素不能在培养中保持随时间的增殖。GDNF也可以启动DNA合成，但它也不能在培养的肠嵴来源的细胞中维持BrdU的掺入。在培养16-48小时后，BrdU的持续掺入依赖于GDNF和胰岛素的组合。使用磷酸化特异性抗体，我们发现Akt-P水平在增殖期(BrdU掺入在培养16-48小时内保持)和非增殖期相似，表明Akt-P水平并不是唯一控制BrdU掺入程度的因素。然而，最低水平的PI3K激活是必需的，正如PI3K抑制剂LY-294002对增殖的剂量依赖性抑制所表明的那样。我们的结论是，PI3K通路的完整性对于肠道CREST来源的细胞的增殖是必不可少的，但Akt-P的绝对水平并不决定增殖的程度。在同时含有GDNF和胰岛素的培养物中的增殖促进表明，还涉及其他途径，包括PI3K下游效应分子而不是Akt在调节禽肠冠源性细胞增殖中发挥重要作用的可能性。(C)2003年威利期刊公司。
Previously we have shown that glial derived neurotrophic factor (GDNF) stimulates modest increases in the proliferation of avian enteric crest-derived cells and similar increases in the phosphorylation of the phosphoinositide 3-kinase (PI3K) downstream substrate Akt (Akt-P). In the present study we tested whether GDNF-independent increases in PI3K activation would be sufficient to support proliferation. We found that insulin induces a large increase in the phosphorylation of Akt and can initiate DNA synthesis in avian enteric crest-derived cells, but is unable to maintain proliferation over time in culture, measured by BrdU incorporation. GDNF can also initiate DNA synthesis, but it too is unable to maintain BrdU incorporation in cultured enteric crest-derived cells. Sustained incorporation of BrdU after 16-48 h in culture is shown to be dependent on a combination of GDNF and insulin. Using a phospho-specific antibody, we found Akt-P levels to be similar in the proliferating (BrdU incorporation maintained from 16-48 h in culture) and nonproliferating populations, suggesting that Akt-P levels were not solely controlling the extent of BrdU incorporation. A minimum level of PI3K activation, however, is required, as shown by the dose-dependent reduction in proliferation with the PI3K inhibitor LY-294002. We conclude that the integrity of the PI3K pathway is essential for enteric crest-derived cell proliferation, but that the absolute levels of Akt-P do not determine the extent of proliferation. The enhanced proliferation in cultures containing both GDNF and insulin suggests that other pathways are involved, including the possibility that PI3K downstream effectors other than Akt are important in the regulation of avian enteric crest-derived cell proliferation. (C) 2003 Wiley Periodicals, Inc.