Antonini Dario, Rossi Barbara, Han Rong, Minichiello Annunziata, Di Palma Tina, Corrado Marcella, Banfi Sandro, Zannini Mariastella, Brissette Janice L, Missero Caterina
Telethon Institute of Genetics and Medicine, Via Pietro Castellino 111, 80131 Naples, Italy.
Mol Cell Biol. 2006 Apr;26(8):3308-18. doi: 10.1128/MCB.26.8.3308-3318.2006.
p63, a p53 family member, is essential for the development of various stratified epithelia and is one of the earliest markers of many ectodermal structures, including the epidermis, oral mucosa, apical ectodermal ridge, and mammary gland. Genetic regulatory mechanisms controlling p63 spatial expression during development have not yet been defined. Using a genomic approach, we identified an evolutionarily conserved cis-regulatory element, located 160 kb downstream of the first p63 exon, which functions as a keratinocyte-specific enhancer and is sufficient to recapitulate expression of the endogenous gene during mouse embryogenesis. Dissection of the p63 enhancer activity revealed a positive autoregulatory loop in which the p63 proteins directly bind to and are essential regulators of the enhancer. Accordingly, transactivating p63 isoforms induce endogenous p63 expression in cells that do not normally express this gene, whereas dominant negative isoforms suppress p63 expression in keratinocytes. In addition the transcription factor AP-2 also binds to the enhancer and cooperates with p63 to induce its activity. These results demonstrate that a long-range autoregulatory loop is involved in the regulation of p63 expression during embryonic development and in adult cells.
p63是p53家族成员之一，对各种复层上皮的发育至关重要，并且是许多外胚层结构（包括表皮、口腔黏膜、顶端外胚层嵴和乳腺）最早的标志物之一。尚未明确在发育过程中控制p63空间表达的遗传调控机制。我们采用基因组学方法，鉴定出一个进化上保守的顺式调控元件，位于p63第一个外显子下游160 kb处，其作为角质形成细胞特异性增强子，足以在小鼠胚胎发育过程中重现内源性基因的表达。对p63增强子活性的剖析揭示了一个正向自调控环，其中p63蛋白直接结合到增强子上，并且是增强子的必需调控因子。因此，反式激活p63异构体可在通常不表达该基因的细胞中诱导内源性p63表达，而显性负性异构体则抑制角质形成细胞中的p63表达。此外，转录因子AP-2也结合到增强子上，并与p63协同诱导其活性。这些结果表明，一个长程自调控环参与了胚胎发育过程中和成年细胞中p63表达的调控。
