Molecular cloning and characterization of chicken orphan nuclear receptor cTR2.
Orphan nuclear receptors belong to the nuclear receptor superfamily of liganded transcription factors, whose ligands either do not exist or remain to be identified. We report here the cloning and characterization of the chicken orphan nuclear receptor, cTR2 (chicken testicular receptor 2). The cTR2 gene encodes a protein of 569 amino acids which shows approximately 72% overall identity with TR2 (NR2C1) and 95% identity in the DNA-binding domain (DBD). The cTR2 gene is expressed in almost all adult tissues and embryonic stages examined unlike its mammalian relative TR2, which is specifically expressed in testis. Electrophoretic mobility shift assays demonstrate that cTR2 binds the canonical direct repeat DNA recognition sequences spaced by one, four, and five nucleotides (DR1, DR4, and DR5), and in consistence with the results with canonical DNA-binding sequences, cTR2 forms specific DNA-protein complex with chicken phenobarbital response elements containing DR4 motifs. Both in vitro and in vivo interaction studies demonstrate that cTR2 forms homodimer. Moreover, transient transfection studies reveal its capability to transactivate canonical DR1, DR4, and DR5 sequences and the constitutive activity of cTR2 is mapped to the N-terminal region of this orphan receptor. Finally, cTR2 represses transactivation of estrogen receptor in a dose-dependent manner.
Sanyal
Sabyasachi
S
Hormone Research Center, Chonnam National University, 500-757 Kwangju, Republic of Korea.
Handschin
Chirstoph
C
Podvinec
Michael
M
Song
Kwang-Hoon
KH
Kim
Han-Jong
HJ
Kim
Joon-Young
JY
Seo
Young-Woo
YW
Kim
Sung-A
SA
Kwon
Hyuk-Bang
HB
Lee
Keesook
K
Kim
Won-Sun
WS
Meyer
Urs A
UA
Choi
Hueng-Sik
HS
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo; D002645:Chickens / Q000235:genetics* / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D008969:Molecular Sequence Data; D057107:Nuclear Receptor Subfamily 2, Group C, Member 1; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism; D011987:Receptors, Steroid / Q000235:genetics* / Q000378:metabolism; D011988:Receptors, Thyroid Hormone / Q000235:genetics* / Q000378:metabolism; D014018:Tissue Distribution; D015533:Transcriptional Activation
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D057107:Nuclear Receptor Subfamily 2, Group C, Member 1; D011960:Receptors, Estrogen; D011987:Receptors, Steroid; D011988:Receptors, Thyroid Hormone