title: Phtf1 is an integral membrane protein localized in an endoplasmic reticulum domain in maturing male germ cells.
abstract: Phtf1 is a gene evolutionarily conserved from Drosophila to human that is abundantly expressed in testis. In adult rat, transcripts were abundant in germinal meiotic and postmeiotic cells. Phtf1-specific antibodies revealed weak activity in a juxtanuclear region of early pachytene spermatocytes. Labeling progressively extended to the entire cytoplasm of step 2-3 spermatids, became intense from step 4, and persisted until the end of spermiogenesis, when it was eliminated in the residual bodies. Phtf1 displayed the properties of an integral membrane protein. In transfected cells and haploid cells of rat seminiferous epithelium, it colocalized with ER markers (calnexin and calmegin, respectively). By using both ER and Golgi markers (TGN-38, p58), we were able to show that, in pachytene spermatocytes and in Golgi phase spermatids, phtf1 labeled a region neighboring the cis-Golgi that probably corresponded to the peripheral Golgi region. Phtf1 staining was not related to beta-COP, AP1, or AP2 aptamers, indicating that it was not transported between Golgi saccules or between the Golgi complex and plasma membrane. However, aptamer labeling showed that chlatrin vesicles could be engaged in a new traffic route, raising the possibility of a meiotic proacrosomal vesicle origin. Colocalization between phtf1 and calmegin decreased during the acrosomal phase. During the maturation phase, phtf1 was able to identify different ER domains, as described previously for the peripheral Golgi region. Phtf1 provides a potential new marker for Golgi modifications as well as for many of the obscure transformations undergone by the endoplasmic reticulum. It could help to elucidate the morphogenic events connected with the transformation of spermatogenic cells.
authors.affiliation: INSERM U.567 CNRS-UMR 8104, Institut Cochin, Departement d'Hematologie, Maternité de Port-Royal, Université Rene Descartes, 75014 Paris, France.
authors.forename: J
authors.initials: J
authors.lastname: Oyhenart
authors.forename: R
authors.initials: R
authors.lastname: Le Goffic
authors.forename: M
authors.initials: M
authors.lastname: Samson
authors.forename: B
authors.initials: B
authors.lastname: Jégou
authors.forename: N
authors.initials: N
authors.lastname: Raich
mesh_terms: D016475:3T3 Cells; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002135:Calcium-Binding Proteins; D037281:Calnexin / Q000378:metabolism; D002522:Chlorocebus aethiops; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005854:Germ Cells / Q000378:metabolism*; D006023:Glycoproteins; D006056:Golgi Apparatus / Q000502:physiology*; D018398:Homeodomain Proteins / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D037241:Mannose-Binding Lectins / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018832:Molecular Chaperones; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013737:Testis / Q000378:metabolism*; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D014162:Transfection
chemical_list: D002135:Calcium-Binding Proteins; D006023:Glycoproteins; D018398:Homeodomain Proteins; C084004:LMAN1 protein, human; C501458:Lman1 protein, rat; D037241:Mannose-Binding Lectins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; C120706:PHTF1 protein, human; C485642:Phtf1 protein, mouse; C485643:Phtf1 protein, rat; D012333:RNA, Messenger; C072237:TGOLN2 protein, human; C513047:Tgoln1 protein, mouse; C513046:Tgoln2 protein, mouse; C513045:Tgoln2 protein, rat; D014157:Transcription Factors; D037281:Calnexin; C087341:calmegin