Multiple in vivo footprints are specific to the active allele of the X-linked human hypoxanthine phosphoribosyltransferase gene 5' region: implications for X chromosome inactivation.
Multiple in vivo footprints are specific to the active allele of the X-linked human hypoxanthine phosphoribosyltransferase gene 5' region: implications for X chromosome inactivation.
复制标题
多个体内足迹特异于 X 连锁人次黄嘌呤磷酸核糖转移酶基因 5 区域的活性等位基因：对 X 染色体失活的影响。
DOI：
10.1128/mcb.12.12.5345-5354.1992
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发表时间：
1992
影响因子：
5.3
通讯作者：
Yang,TP
中科院分区：
文献类型：
--
作者：
Hornstra,IK;Yang,TP
雄性和雌性哺乳动物中X连锁基因的剂量补偿是通过每个雌性体细胞中一条X染色体的随机失活来实现的。因此，大多数X连锁基因的转录活性等位基因和转录非活性等位基因位于每个雌性细胞核内。为了研究维持这种独特的差异基因表达系统的机制，我们分析了调节蛋白与活性和非活性X染色体上人类次黄嘌呤磷酸核糖基转移酶（HPRT）基因5′区域的差异结合。与转录活性和非活性HPRT等位基因相关的DNA-蛋白质相互作用的研究在完整的培养细胞中通过使用连接介导的聚合酶链反应和硫酸二甲酯通过体内足迹法进行。对活性等位基因的分析表明至少有六个足迹区域，而在非活性等位基因上没有检测到足迹。在活跃等位基因上的足迹中，至少有四个出现在典型的GC盒或Sp1共有结合位点上，一个与潜在的AP-2结合位点相关，另一个与先前未报道的与序列特异性DNA结合因子相互作用的DNA序列相关。虽然在失活的X染色体上没有观察到HPRT基因的足迹，但用5-氮杂胞苷处理的失活等位基因的再活化恢复了在活性等位基因上发现的体内足迹模式。这些实验的结果，结合最近的研究X-连锁的人类PGK-1基因，承担的X染色体失活模型的影响。
Dosage compensation of X-linked genes in male and female mammals is accomplished by random inactivation of one X chromosome in each female somatic cell. As a result, a transcriptionally active allele and a transcriptionally inactive allele of most X-linked genes reside within each female nucleus. To examine the mechanism responsible for maintaining this unique system of differential gene expression, we have analyzed the differential binding of regulatory proteins to the 5′ region of the human hypoxanthine phosphoribosyltransferase (HPRT) gene on the active and inactive X chromosomes. Studies of DNA-protein interactions associated with the transcriptionally active and inactive HPRT alleles were carried out in intact cultured cells by in vivo footprinting by using ligation-mediated polymerase chain reaction and dimethyl sulfate. Analysis of the active allele demonstrates at least six footprinted regions, whereas no footprints were detected on the inactive allele. Of the footprints on the active allele, at least four occur over canonical GC boxes or Sp1 consensus binding sites, one is associated with a potential AP-2 binding site, and another is associated with a DNA sequence not previously reported to interact with a sequence-specific DNA-binding factor. While no footprints were observed for the HPRT gene on the inactive X chromosome, reactivation of the inactive allele with 5-azacytidine treatment restored the in vivo footprint pattern found on the active allele. Results of these experiments, in conjunction with recent studies on the X-linked human PGK-1 gene, bear implications for models of X chromosome inactivation.