A Functional Screen for Regulators of CKDN2A Reveals MEOX2 as a Transcriptional Activator of INK4a
A Functional Screen for Regulators of CKDN2A Reveals MEOX2 as a Transcriptional Activator of INK4a
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DOI：
10.1371/journal.pone.0005067
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发表时间：
2009-04-02
期刊：
影响因子：
3.7
通讯作者：
Chanda, Sumit K.
中科院分区：
文献类型：
--
作者：
Irelan, Jeffrey T.;del Arroyo, Ana Gutierrez;Chanda, Sumit K.
CDKN2A 基因座编码两种重要的肿瘤抑制因子 INK4a 和 ARF，它们通过诱导细胞衰老来响应致癌应激。我们使用含有 INK4a 调控序列的报告基因进行了基因组规模的 cDNA 过表达筛选，以鉴定该位点的新型转录激活因子。该筛选揭示了 285 个 cDNA，推测它们调节 INK4a 的转录激活。其中，56 个被注释为转录因子，包括两个先前报道的基因座激活子 ETS2 和 JUNB。进一步验证了十四个基因的活性和特异性，包括几种同源域蛋白。我们发现其中一种同源结构域蛋白 MEOX2 (GAX) 的转录在诱导衰老过程中在原代细胞中增强，并且该蛋白的强制表达导致诱导过早衰老。我们进一步证明 MEOX2 诱导的衰老依赖于 INK4a 活性，染色质免疫沉淀研究表明 MEOX2 直接结合 INK4a 启动子。这些结果支持了这种同源域蛋白作为人类细胞中 INK4a 转录和衰老的直接调节因子的作用。
The CDKN2A locus encodes two important tumor suppressors, INK4a and ARF, which respond to oncogenic stresses by inducing cellular senescence. We conducted a genome-scale cDNA overexpression screen using a reporter containing INK4a regulatory sequences to identify novel transcriptional activators of this locus. This screen revealed 285 cDNAs that putatively regulate the transcriptional activation of INK4a. Of these, 56 are annotated as transcription factors, including two previously reported activators of the locus, ETS2 and JUNB. Fourteen genes were further validated for activity and specificity, including several homeodomain proteins. We found that the transcription of one of these, the homeodomain protein MEOX2 ( GAX) is enhanced in primary cells during the induction of senescence, and forced expression of this protein results in the induction of premature senescence. We further demonstrate that MEOX2-induced senescence is dependent upon INK4a activity, and chromatin immunoprecipitation studies indicate that MEOX2 directly binds the INK4a promoter. These results support a role for this homeodomain protein as a direct regulator of INK4a transcription and senescence in human cells.