Monash Institute of Medical Research, Faculty of Medicine, Nursing, and Health Sciences, Monash University, Melbourne, Australia.
PLoS Genet. 2012;8(12):e1003070. doi: 10.1371/journal.pgen.1003070. Epub 2012 Dec 20.
Bladder exstrophy epispadias complex (BEEC) is a severe congenital anomaly; however, the genetic and molecular mechanisms underlying the formation of BEEC remain unclear. TP63, a member of TP53 tumor suppressor gene family, is expressed in bladder urothelium and skin over the external genitalia during mammalian development. It plays a role in bladder development. We have previously shown that p63(-/-) mouse embryos developed a bladder exstrophy phenotype identical to human BEEC. We hypothesised that TP63 is involved in human BEEC pathogenesis. RNA was extracted from BEEC foreskin specimens and, as in mice, ΔNp63 was the predominant p63 isoform. ΔNp63 expression in the foreskin and bladder epithelium of BEEC patients was reduced. DNA was sequenced from 163 BEEC patients and 285 ethnicity-matched controls. No exon mutations were detected. Sequencing of the ΔNp63 promoter showed 7 single nucleotide polymorphisms and 4 insertion/deletion (indel) polymorphisms. Indel polymorphisms were associated with an increased risk of BEEC. Significantly the sites of indel polymorphisms differed between Caucasian and non-Caucasian populations. A 12-base-pair deletion was associated with an increased risk with only Caucasian patients (p = 0.0052 Odds Ratio (OR) = 18.33), whereas a 4-base-pair insertion was only associated with non-Caucasian patients (p = 0.0259 OR = 4.583). We found a consistent and statistically significant reduction in transcriptional efficiencies of the promoter sequences containing indel polymorphisms in luciferase assays. These findings suggest that indel polymorphisms of the ΔNp63 promoter lead to a reduction in p63 expression, which could lead to BEEC.
膀胱外翻-尿道上裂复合畸形（BEEC）是一种严重的先天性异常；然而，BEEC 形成的遗传和分子机制尚不清楚。TP63 是 TP53 肿瘤抑制基因家族的成员，在哺乳动物发育过程中表达于膀胱尿路上皮和外生殖器皮肤。它在膀胱发育中起作用。我们之前已经表明，p63（-/-）小鼠胚胎发育出与人类 BEEC 相同的膀胱外翻表型。我们假设 TP63 参与了人类 BEEC 的发病机制。从 BEEC 包皮标本中提取 RNA，与在小鼠中一样，ΔNp63 是主要的 p63 同工型。BEEC 患者包皮和膀胱上皮的 ΔNp63 表达减少。对 163 名 BEEC 患者和 285 名种族匹配的对照者的 DNA 进行测序。未检测到外显子突变。对 ΔNp63 启动子进行测序显示了 7 个单核苷酸多态性和 4 个插入/缺失（indel）多态性。indel 多态性与 BEEC 的风险增加有关。重要的是，indel 多态性在白人和非白人人群中的位点不同。12 个碱基对的缺失与仅白人患者的风险增加相关（p=0.0052 优势比（OR）=18.33），而 4 个碱基对的插入仅与非白人患者相关（p=0.0259 OR=4.583）。我们在荧光素酶检测中发现，含有 indel 多态性的启动子序列的转录效率有一致的和统计学上显著的降低。这些发现表明，ΔNp63 启动子的 indel 多态性导致 p63 表达减少，这可能导致 BEEC。
