Marsupial Anti-Müllerian Hormone Gene Structure, Regulatory Elements, and Expression1

Abstract

During male sexual development in reptiles, birds, and mammals, anti-Müllerian hormone (AMH) induces the regression of the Müllerian ducts that normally form the primordia of the female reproductive tract. Whereas Müllerian duct regression occurs during fetal development in eutherian mammals, in marsupial mammals this process occurs after birth. To investigate AMH in a marsupial, we isolated an orthologue from the tammar wallaby (Macropus eugenii) and characterized its expression in the testes and ovaries during development. The wallaby AMH gene is highly conserved with the eutherian orthologues that have been studied, particularly within the encoded C-terminal mature domain. The N-terminus of marsupial AMH is divergent and larger than that of eutherian species. It is located on chromosome 3/4, consistent with its autosomal localization in other species. The wallaby 5' regulatory region, like eutherian AMH genes, contains binding sites for SF1, SOX9, and GATA factors but also contains a putative SRY-binding site. AMH expression in the developing testis begins at the time of seminiferous cord formation at 2 days post partum, and Müllerian duct regression begins shortly afterward. In the developing testis, AMH is localized in the cytoplasm of the Sertoli cells but is lost by adulthood. In the developing ovary, there is no detectable AMH expression, but in adults it is produced by the granulosa cells of primary and secondary follicles. It is not detectable in atretic follicles. Collectively, these studies suggest that AMH expression has been conserved during mammalian evolution and is intimately linked to upstream sex determination mechanisms.

Anti-Müllerian hormone is a gonadal cytokine with two circulating forms and cryptic actions

“…AMH is synthesised in the gonads of all vertebrate species examined to date, including fish (Western et al 1999, Halm et al 2007, amphibians (Kodama et al 2015), birds (Smith et al 1999, Nishikimi et al 2000, reptiles (Western et al 1999, Shoemaker et al 2007, marsupials (Juengel et al 2002, Pask et al 2004 and eutherian mammals (Josso 1973, Meyers-Wallen et al 1987, Kuroda et al 1990. In fish that do not have Müllerian ducts, AMH regulates the proliferation of germ cells in both sexes (Morinaga et al 2007).…”

A novel marsupial pri-miRNA transcript has a putative role in gamete maintenance and defines a vertebrate miRNA cluster paralogous to the miR-15a/miR-16-1 cluster

“…In marsupials, the molecular aspects of follicle maintenance and development are less well understood and limited to AMH (Juengel et al 2002), LIF (Cui & Selwood 2000), KIT (Greenwood et al 1996, Eckery et al 2002a, GDF9 and BMP15 (Eckery et al 2002b) in Trichosurus vulpecula and AMH in Macropus eugenii (Pask et al 2004). These genes show similar ovarian expression patterns in marsupials and eutherians, suggestive of conserved roles.…”

Prostaglandin D₂ Regulates SOX9 Nuclear Translocation during Gonadal Sex Determination in Tammar Wallaby, <b><i>Macropus eugenii</i></b>

“…The expression patterns and localizations of these genes are similar to those of eutherian mammals during gonadal differentiation. In males, SOX9 is expressed in Sertoli cells [Pask et al, 2002], where it stimulates AMH secretion to regress the müllerian ducts [Hutson et al, 1988;Pask et al, 2004]. In females, in the absence of SRY , the female sex-determining genes, such as WNT4 and FOXL2, appear to regulate normal ovarian differentiation [Yu et al, 2006;.…”