Promoter CpG methylation of Hox-a10 and Hox-a11 in mouse uterus not altered upon neonatal diethylstilbestrol exposure.
Mouse abdominal B-like Hoxa genes are expressed and functionally required in the developing reproductive tracts. Mice lacking either Hoxa-10 or Hoxa-11, two of the AbdB Hoxa genes, exhibit abnormal uterine development similar to that induced by in utero diethylstilbestrol (DES) exposure. Indeed, uterine Hoxa-10 and Hoxa-11 expression is potently repressed by perinatal DES exposure, providing a potential molecular mechanism for DES-induced reproductive tract malformations. We have shown previously that DES can permanently alter uterine lactoferrin gene expression through modulation of the lactoferrin promoter methylation pattern. Here we ask whether a similar mechanism also functions to deregulate uterine Hoxa-10 or Hoxa-11 expression during neonatal DES exposure. We mapped the Hoxa-10 promoter by cloning a 1.485 kb DNA fragment 5' of the Hoxa-10 exon1a. A 5' rapid amplification of cDNA ends (RACE) experiment revealed a transcription start site for the a10-1 transcript. Functional analysis of the proximal 200-bp sequences demonstrated significant promoter activity, confirming the location of the Hoxa-10 promoter. Moreover, methylation assays performed on eight CpGs in Hoxa-10 and 19 CpGs in Hoxa-11 proximal promoters demonstrated that all these CpGs were highly unmethylated in both control and DES-dosed mice from postnatal day 5 to day 30. Significant methylation around Hoxa-10 and Hoxa-11 promoters was only observed in DES-induced uterine carcinomas in 18-mo-old mice. Our results suggest that DES-induced downregulations of Hoxa-10 or Hoxa-11 gene expression are not associated with methylation changes in their proximal promoters and that gene imprinting by developmental DES exposure may be a gene-specific phenomenon.
Li
S
S
Laboratory of Biosystems and Cancer, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
Ma
L
L
Chiang
T
T
Burow
M
M
Newbold
R R
RR
Negishi
M
M
Barrett
J C
JC
McLachlan
J A
JA
D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D019175:DNA Methylation / Q000187:drug effects*; D004268:DNA-Binding Proteins / Q000235:genetics*; D004054:Diethylstilbestrol / Q000494:pharmacology*; D004968:Estrogens, Non-Steroidal / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D000080905:Homeobox A10 Proteins; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D014599:Uterus / Q000502:physiology*
D004268:DNA-Binding Proteins; D004968:Estrogens, Non-Steroidal; C484298:HOXA11 protein, human; D000080905:Homeobox A10 Proteins; D018398:Homeodomain Proteins; C094041:Hoxa11 protein, mouse; C092119:Hoxa10 protein, mouse; D004054:Diethylstilbestrol