A unique cytoplasmic localization of retinoic acid receptor-gamma and its regulations.
Recent evidence suggests that extranuclear action of retinoid receptors is involved in mediating the pleiotropic effects of retinoids. However, whether they reside in the cytoplasm remains elusive. Here, we showed that retinoic acid receptor-gamma (RARgamma) was cytoplasmic in confluent cells, or when cells were released from serum depletion or treated with growth factors. In studying the regulation of RARgamma subcellular localization, we observed that ectopically overexpressed RARgamma was mainly cytoplasmic irrespective of serum concentration and cell density. The cytoplasmic retention of RARgamma was inhibited by ligand retinoic acid (RA). In addition, coexpression of retinoid X receptor-alpha (RXRalpha) resulted in nuclear localization of RARgamma through their heterodimerization. Mutagenesis studies revealed that a C-terminal fragment of RXRalpha potently prevents RA-induced RARgamma nuclear localization and transcriptional function. Furthermore, our results showed that the cytoplasmic retention of RARgamma was due to the presence of its unique N-terminal A/B domain, which was subject to regulation by p38 MAPK-mediated phosphorylation. Deletion or mutation of the N-terminal A/B domain largely impaired its cytoplasmic localization. Together, our data demonstrate that the subcellular localization of RARgamma is regulated by complex interactions among ligand binding, receptor phosphorylation, and receptor dimerizations.
Han
Young-Hoon
YH
Burnham Institute for Medical Research, Cancer Center, La Jolla, California 92037, USA. yhhan@kcch.re.kr
Zhou
Hu
H
Kim
Jin-Hee
JH
Yan
Ting-dong
TD
Lee
Kee-Ho
KH
Wu
Hua
H
Lin
Feng
F
Lu
Na
N
Liu
Jie
J
Zeng
Jin-zhang
JZ
Zhang
Xiao-kun
XK
D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D001798:Blood Proteins / Q000494:pharmacology; D002452:Cell Count; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D003470:Culture Media / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D019281:Dimerization; D006367:HeLa Cells; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology; D007668:Kidney / Q000166:cytology; D016296:Mutagenesis; D010766:Phosphorylation / Q000502:physiology; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology*; D018168:Receptors, Retinoic Acid / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D047490:Retinoid X Receptor alpha / Q000378:metabolism; D013329:Structure-Activity Relationship; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D000097768:Retinoic Acid Receptor gamma
D001798:Blood Proteins; D003470:Culture Media; D036341:Intercellular Signaling Peptides and Proteins; D018168:Receptors, Retinoic Acid; D047490:Retinoid X Receptor alpha; D048051:p38 Mitogen-Activated Protein Kinases; D000097768:Retinoic Acid Receptor gamma