Genetic selection for modulators of a retinoic-acid-responsive reporter in human cells.
We used a genetic screening methodology, a human cell line bearing a retinoic-acid-responsive enhanced GFP reporter, and a flow sorter to recover dominant modulators of reporter expression. Four inducers and three suppressors that were fused to the C terminus of a protein scaffold for stability were isolated and their mechanisms of action studied. Mutagenesis experiments indicated that six of these dominant agents exerted their effects at the protein level. The single cDNA coding fragment that was isolated comprised the central 64-amino-acid section of human cyclophilin B, which contained its peptidyl-prolyl isomerase domain; this cyclophilin fragment repressed expression of the retinoic-acid-responsive reporter. The remaining clones encoded peptides shorter than 30 amino acids unrelated to known gene open reading frames. Genetic epistasis studies between the strongest inducer, R3, and a dominant-negative mutant of RARalpha suggest that the two factors function in the same pathway. Transcript microarray analyses suggest that R3 induced a subset of the retinoid-responsive genes in melanoma cells. Finally, yeast two-hybrid assays and co-immunoprecipitation studies of human cell extracts identified PAT1 as a protein that interacts with R3.
Richards
Burt
B
Deltagen Proteomics, Salt Lake City, Utah 84108, USA.
Karpilow
Jon
J
Dunn
Christine
C
Peterson
Isaac
I
Maxfield
Andrew
A
Zharkikh
Ludmilla
L
Abedi
Majid
M
Hurlburt
Anthony
A
Hardman
Joshua
J
Hsu
Forrest
F
Li
Wenhua
W
Rebentisch
Matthew
M
Sandrock
Robert
R
Sandrock
Tanya
T
Kamb
Alexander
A
Teng
David H-F
DH
D020121:5' Untranslated Regions / Q000235:genetics; D000595:Amino Acid Sequence; D001483:Base Sequence; D002460:Cell Line; D021983:Cyclophilins / Q000737:chemistry / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics; D015723:Gene Library; D017930:Genes, Reporter; D005820:Genetic Testing / Q000379:methods*; D006801:Humans; D008969:Molecular Sequence Data; D019696:Peptidylprolyl Isomerase; D018168:Receptors, Retinoic Acid / Q000235:genetics*; D015183:Restriction Mapping; D012641:Selection, Genetic; D014162:Transfection
D020121:5' Untranslated Regions; D018076:DNA, Complementary; D004272:DNA, Mitochondrial; D018168:Receptors, Retinoic Acid; C081786:cyclophilin B; D021983:Cyclophilins; D019696:Peptidylprolyl Isomerase