HoxA10-like proteins in the reproductive tract of the viviparous lizard Eulamprus tympanum and the oviparous lizard Lampropholis guichenoti

Abstract: The gene HoxA10 and its protein product are essential for the formation of the extensions of the plasma membrane called uterodomes or pinopods in mammalian uterine epithelia. In mice, the presence of the HoxA10 protein and uterodomes is needed for uterine receptivity to blastocyst implantation. The viviparous lizard Eulamprus tympanum displays uterodomes whereas the oviparous lizard Lampropholis guichenoti does not. To explore the theory that HoxA10 is involved in the formation of uterodomes we investigated whether HoxA10 immunoreactive proteins were present in both species during their reproductive cycles. Oviduct proteins from vitellogenic, gravid or non-reproductive L. guichenoti (n =19) and E. tympanum (n =28) were separated by electrophoresis and analysed by Western blot and specific antibodies to HoxA10. E. tympanum displayed HoxA10 immunoreactive bands at 59 and 63 kDa in 20 out of the 28 samples. All of the L. guichenoti samples displayed HoxA10 immunoreactive bands, 18 had bands at 59 and 64 kDa and 1 animal had a single band at 59 kDa. There were no significant differences in the level of HoxA10 immunoreactivity between the different stages of reproductive cycle in either species. The different molecular mass of the larger band in L. guichenoti (64 kDa) compared to E. tympanum (63 kDa) indicates that the two lizards express different isoforms of the HoxA10-like proteins and it will be interesting in future studies to determine whether there are differences in the biological activity of the proteins that regulate different physiological functions in the uterus of viviparous and oviparous lizards. [Copyright &y& Elsevier]