Comparative analysis of the mammalian WNT4 promoter

We have defined a highly conserved 89 bp minimal promoter region in human WNT4 by comparative analysis with the tammar wallaby. There are many conserved transcription factor binding sites in the proximal promoter region, including SP1, MyoD, NFκB and AP2, as well as highly conserved CpG islands within the human, mouse and marsupial promoters, suggesting that DNA methylation may play an important role in WNT4 transcriptional regulation.Using a marsupial model, we have been able to provide new information on the transcriptional regulators in the promoter of this essential mammalian developmental gene, WNT4. These transcription factor binding sites and CpG islands are highly conserved in two disparate mammals, and are likely key controlling elements in the regulation of this essential developmental gene.Wingless-type MMTV integration site family, member 4 (WNT4) is a locally acting signalling molecule, regulating cell-cell interactions, proliferation, differentiation, migration, and gene activation [1-10]. It is a highly conserved gene within mammals and has multiple roles in organogenesis and homeostasis and is of special interest in the sexual differentiation of the ovary [11-24]. While it can elicit its effects through the "canonical" WNT/β-catenin signalling pathway [5], it mainly acts through "non-canonical" signalling pathways. The WNT4 signalling pathway is mediated by the factor c-Jun N-terminal Kinase (JNK) in both the frog eye and human kidney development [16,25,26]. While WNT4 function is well defined, the underlying mechanisms that regulate its expression are still largely unknown.Marsupials are mammals that diverged from the eutherian mammal lineage around 130 million years ago. Marsupials differ from other mammals in subtle ways especially in their mode of reproduction [27]. We use the tammar wallaby as the model marsupial because most sexual differentiation occurs after birth, unlike in eutherian mammals where differentiation of the testis and ovary occu