Identification and characterization of proteins involved in nuclear organization using Drosophila GFP protein trap lines.
BACKGROUND
Strains from a collection of Drosophila GFP protein trap lines express GFP in the normal tissues where the endogenous protein is present. This collection can be used to screen for proteins distributed in the nucleus in a non-uniform pattern.


RESULTS
We analyzed four lines that show peripheral or punctate nuclear staining. One of these lines affects an uncharacterized gene named CG11138. The CG11138 protein shows a punctate distribution in the nuclear periphery similar to that of Drosophila insulator proteins but does not co-localize with known insulators. Interestingly, mutations in Lamin proteins result in alterations in CG11138 localization, suggesting that this protein may be a novel component of the nuclear lamina. A second line affects the Decondensation factor 31 (Df31) gene, which encodes a protein with a unique nuclear distribution that appears to segment the nucleus into four different compartments. The X-chromosome of males is confined to one of these compartments. We also find that Drosophila Nucleoplasmin (dNlp) is present in regions of active transcription. Heat shock leads to loss of dNlp from previously transcribed regions of polytene chromosome without redistribution to the heat shock genes. Analysis of Stonewall (Stwl), a protein previously found to be necessary for the maintenance of germline stem cells, shows that Stwl is present in a punctate pattern in the nucleus that partially overlaps with that of known insulator proteins. Finally we show that Stwl, dNlp, and Df31 form part of a highly interactive network. The properties of other components of this network may help understand the role of these proteins in nuclear biology.


CONCLUSIONS
These results establish screening of GFP protein trap alleles as a strategy to identify factors with novel cellular functions. Information gained from the analysis of CG11138 Stwl, dNlp, and Df31 sets the stage for future studies of these proteins.
Department of Biology, Emory University, Atlanta, GA, USA.
Margaret
M
Rohrbaugh
Alyssia
A
Clore
Julia
J
Davis
Sharonta
S
Johnson
Brian
B
Jones
Keith
K
Jones
Joanne
J
Kim
Bramwel
B
Kithuka
Krystal
K
Lunsford
Joy
J
Mitchell
Brian
B
Mott
Edward
E
Ramos
Maza R
MR
Tchedou
Gilbert
G
Acosta
Mark
M
Araujo
Stuart
S
Cushing
Gabriel
G
Duffy
Felicia
F
Graves
Kyler
K
Griffin
B V
BV
Gurudatta
Deaundra
D
Jackson
Denis
D
Jaimes
Kendall
K
Jamison
Khali
K
Jones
Dhaujee
D
Kelley
Marquita
M
Kilgore
Derica
D
Laramore
Thuy
T
Le
Bakhtawar
B
Mazhar
Muhammad M
MM
Mazhar
Britney
B
McCrary
Teanndras
T
Miller
Celethia
C
Moreland
Alex
A
Mullins
Elyas
E
Munye
Sheila
S
Okoorie
Elisha
E
Pittman
Nikkita
N
Roberts
De'Warren
D
Rose
Alex
A
Rowland
Anwar
A
Shagarabi
Jamela
J
Smith
Tayler
T
Stallworth
Nicole
N
Stroud
Elizabeth
E
Sung
Kai
K
Sung
Naomi
N
Takenaka
Eduardo
E
Torre
Jarvis
J
Veira
Kim
K
Vu
William
W
Wagstaff
Ashley M
AM
Wood
Karen
K
Wu
Jingping
J
Yang
Victor G
VG
Corces
D000818:Animals; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000378:metabolism*; D004171:Diploidy; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D005854:Germ Cells / Q000166:cytology / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism*; D018869:Heat-Shock Response; D034904:Lamin Type A / Q000378:metabolism; D008297:Male; D008954:Models, Biological; D034881:Nuclear Lamina / Q000201:enzymology; D056489:Nucleoplasmins; D059007:Polytene Chromosomes / Q000378:metabolism; D060066:Protein Interaction Maps; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
D029721:Drosophila Proteins; D034904:Lamin Type A; D056489:Nucleoplasmins; C440308:lamin C; D049452:Green Fluorescent Proteins; D044767:Ubiquitin-Protein Ligases