title: Nse1 and Nse4, subunits of the Smc5-Smc6 complex, are involved in Dictyostelium development upon starvation.
abstract: The Smc5-Smc6 complex contains a heterodimeric core of two SMC proteins and non-Smc elements (Nse1-6), and plays an important role in DNA repair. We investigated the functional roles of Nse4 and Nse1 in Dictyostelium discoideum. Nse4 and Nse3 expressed as Flag-tagged fusion proteins were highly enriched in nuclei, while Nse1 was localized in whole cells. Using yeast two-hybrid assays, only the interaction between Nse3 and Nse1 was detected among the combinations. However, all of the interactions among these three proteins were recognized by co-immunoprecipitation assay using cell lysates prepared from the cells expressing green fluorescent protein (GFP)- or Flag-tagged fusion proteins. GFP-tagged Nse1, which localized in whole cells, was translocated to nuclei when co-expressed with Flag-tagged Nse3 or Nse4. RNAi-mediated Nse1 and Nse4 knockdown cells (Nse1 KD and Nse4 KD cells) were generated and found to be more sensitive to UV-induced cell death than control cells. Upon starvation, Nse1 and Nse4 KD cells had increases in the number of smaller fruiting bodies that formed on non-nutrient agar plates or aggregates that formed under submerged culture. We found a reduction in the mRNA level of pdsA, in vegetative and 8 h-starved Nse4 KD cells, and pdsA knockdown cells displayed effects similar to Nse4 KD cells. Our results suggest that Nse4 and Nse1 are involved in not only the cellular DNA damage response but also cellular development in D. discoideum.
authors.affiliation: Laboratory of Neurochemistry, College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Taniura
authors.affiliation: Laboratory of Neurochemistry, College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Tanabe
authors.affiliation: Laboratory of Neurochemistry, College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Bando
authors.affiliation: Laboratory of Neurochemistry, College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan.
authors.forename: Natsumi
authors.initials: N
authors.lastname: Arai
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology*; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000502:physiology*; D003470:Culture Media / Q000494:pharmacology; D004023:Dictyostelium / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D055785:Gene Knockdown Techniques; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits; D015800:Protozoan Proteins / Q000235:genetics / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D013217:Starvation / Q000235:genetics
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D003470:Culture Media; D046912:Multiprotein Complexes; D021122:Protein Subunits; D015800:Protozoan Proteins
keywords: Dictyostelium discoideum; Nse1; Nse3; Nse4; Smc5-Smc6 complex; cellular development; pdsA