title: Is prnt a pseudogene? Identification of ram Prt in testis and ejaculated spermatozoa.
abstract: A hallmark of prion diseases or transmissible spongiform encephalopaties is the conversion of the cellular prion protein (PrP(C)), expressed by the prion gene (prnp), into an abnormally folded isoform (PrP(Sc)) with amyloid-like features that causes scrapie in sheep among other diseases. prnp together with prnd (which encodes a prion-like protein designated as Doppel), and prnt (that encodes the prion protein testis specific--Prt) with sprn (shadow of prion protein gene, that encodes Shadoo or Sho) genes, constitute the "prion gene complex". Whereas a role for prnd in the proper functioning of male reproductive system has been confirmed, the function of prnt, a recently discovered prion family gene, comprises a conundrum leading to the assumption that ruminant prnt is a pseudogene with no protein expression. The main objective of the present study was to identify Prt localization in the ram reproductive system and simultaneously to elucidate if ovine prnt gene is transcribed into protein-coding RNA. Moreover, as Prt is a prnp-related protein, the amyloid propensity was also tested for ovine and caprine Prt. Recombinant Prt was used to immunize BALB/c mice, and the anti-Prt polyclonal antibody (APPA) immune response was evaluated by ELISA and Western Blot. When tested by indirect immunofluorescence, APPA showed high avidity to the ram sperm head apical ridge subdomain, before and after induced capacitation, but did not show the same behavior against goat spermatozoa, suggesting high antibody specificity against ovine-Prt. Prt was also found in the testis when assayed by immunohistochemistry during ram spermatogenesis, where spermatogonia, spermatocytes, spermatids and spermatozoa, stained positive. These observations strongly suggest ovine prnt to be a translated protein-coding gene, pointing to a role for Prt protein in the ram reproductive physiology. Besides, caprine Prt appears to exhibit a higher amyloid propensity than ovine Prt, mostly associated with its phenylalanine residue.
authors.affiliation: Unidade de Recursos Genéticos, Reprodução e Melhoramento Animal, Instituto Nacional dos Recursos Biológicos L-INIA Santarém, Quinta da Fonte Boa, Vale de Santarém, Portugal.
authors.forename: Jorge
authors.initials: J
authors.lastname: Pimenta
authors.forename: Ana
authors.initials: A
authors.lastname: Domingos
authors.forename: Pedro
authors.initials: P
authors.lastname: Santos
authors.forename: Carla C
authors.initials: CC
authors.lastname: Marques
authors.forename: Cátia
authors.initials: C
authors.lastname: Cantante
authors.forename: Ana
authors.initials: A
authors.lastname: Santos
authors.forename: João P
authors.initials: JP
authors.lastname: Barbas
authors.forename: Maria C
authors.initials: MC
authors.lastname: Baptista
authors.forename: António E M
authors.initials: AE
authors.lastname: Horta
authors.forename: Aldino
authors.initials: A
authors.lastname: Viegas
authors.forename: Patrícia
authors.initials: P
authors.lastname: Mesquita
authors.forename: João
authors.initials: J
authors.lastname: Gonçalves
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Fontes
authors.forename: José A M
authors.initials: JA
authors.lastname: Prates
authors.forename: Rosa M L N
authors.initials: RM
authors.lastname: Pereira
mesh_terms: D000818:Animals; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D006041:Goats; D008297:Male; D051379:Mice; D011328:Prions / Q000235:genetics / Q000378:metabolism*; D011544:Pseudogenes / Q000235:genetics*; D013094:Spermatozoa / Q000378:metabolism*; D013737:Testis / Q000378:metabolism*
chemical_list: D011328:Prions