title: Identification of a novel PNMA-MS1 gene in marsupials suggests the LTR retrotransposon-derived PNMA genes evolved differently in marsupials and eutherians.
abstract: Two major gene families derived from Ty3/Gypsy long terminal repeat (LTR) retrotransposons were recently identified in mammals. The sushi-ichi retrotransposon homologue (SIRH) family comprises 12 genes: 11 in eutherians including Peg10 and Peg11/Rtl1 that have essential roles in the eutherian placenta and 1 that is marsupial specific. Fifteen and 12 genes were reported in the second gene family, para-neoplastic antigen MA (PNMA), in humans and mice, respectively, although their biological functions and evolutionary history remain largely unknown. Here, we identified two novel candidate PNMA genes, PNMA-MS1 and -MS2 in marsupials. Like all eutherian-specific PNMA genes, they exhibit the highest homology to a Gypsy12_DR (DR, Danio rerio) Gag protein. PNMA-MS1 is conserved in both Australian and South American marsupial species, the tammar wallaby and grey short-tailed opossum. However, no PNMA-MS1 orthologue was found in eutherians, monotremes or non-mammalian vertebrates. PNMA-MS1 was expressed in the ovary, mammary gland and brain during development and growth in the tammar, suggesting that PNMA-MS1 may have acquired a marsupial-specific function. However, PNMA-MS2 seems to be a pseudogene. The absence of marsupial orthologues of eutherian PNMA genes suggests that the retrotransposition events of the Gypsy12_DR-related retrotransposons that gave rise to the PNMA family occurred after the divergence of marsupials and eutherians.
authors.affiliation: 1Department of Epigenetics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
authors.forename: Sawa
authors.initials: S
authors.lastname: Iwasaki
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Suzuki
authors.forename: Matthew
authors.initials: M
authors.lastname: Pelekanos
authors.forename: Helen
authors.initials: H
authors.lastname: Clark
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Ono
authors.forename: Geoff
authors.initials: G
authors.lastname: Shaw
authors.forename: Marilyn B
authors.initials: MB
authors.lastname: Renfree
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kaneko-Ishino
authors.forename: Fumitoshi
authors.initials: F
authors.lastname: Ishino
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D006801:Humans; D008394:Marsupialia; D051379:Mice; D008969:Molecular Sequence Data; D018626:Retroelements; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D020080:Tandem Repeat Sequences
chemical_list: D017931:DNA Primers; D018626:Retroelements
keywords: LTR retrotransposons; PNMA family; mammalian evolution; marsupial-specific genes