title: Cell cycle-dependent modulations of fenestrin expression in Tetrahymena pyriformis.
abstract: In Tetrahymena, besides apparent cell polarity generated by specialized cortical structures, several proteins display a specific asymmetric distribution suggesting their involvement in the generation and the maintenance of cell polarization. One of these proteins, a membrane skeleton protein called fenestrin, forms an antero-posterior gradient, and is accepted as a marker of cell polarity during different cellular processes, such as cell division or oral replacement. In conjugating cells, fenestrin forms an intracytoplasmic net which participates in pronuclear exchange. The function of fenestrin is still unknown. To better understand the role of fenestrin we characterized this protein in an amicronuclear Tetrahymena pyriformis. We show that in this ciliate not only does fenestrin localization change in a cell division-dependent manner, but its mRNA and protein level is also cell cycle-regulated. We determine that the two available anti-fenestrin antibodies, 3A7 and 9A7, recognize different pools of fenestrin isoforms, and that 9A7 is the more general. In addition, our results indicate that fenestrin is a phosphoprotein. We also show that the level of fenestrin in the amicronuclear T. pyriformis and the amicronuclear BI3840 strain of T. thermophila is several times lower than in micronuclear T. thermophila.
authors.affiliation: Department of Animal Physiology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland; Department of Cell Biology, Nencki Institute of Experimental Biology PAS, 3 Pasteur Street, 02-093 Warsaw, Poland. Electronic address: ejoachimiak@biol.uw.edu.pl.
authors.forename: Ewa
authors.initials: E
authors.lastname: Joachimiak
authors.forename: Mauryla
authors.initials: M
authors.lastname: Kiersnowska
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Jedynak
authors.forename: Magdalena
authors.initials: M
authors.lastname: Majewska
authors.forename: Hanna
authors.initials: H
authors.lastname: Fabczak
authors.forename: Stanisław
authors.initials: S
authors.lastname: Fabczak
mesh_terms: D000595:Amino Acid Sequence; D002453:Cell Cycle / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000235:genetics*; D016415:Sequence Alignment; D013769:Tetrahymena pyriformis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D008565:Membrane Proteins; D015800:Protozoan Proteins
keywords: Cytoskeleton; Epiplasm; Fenestrin; Tetrahymena