Disulfide isomerase glucose-regulated protein 58 is required for the nuclear localization and degradation of retinoic acid receptor alpha.
Retinoic acid receptor alpha (RARA) is critical for spermatogenesis, as shown by a sterility phenotype observed in Rara knockout mice. RARA is important in both Sertoli and germ cells of the testis. Here, we demonstrate that a disulfide isomerase glucose-regulated protein 58 (GRp58) participates in the nuclear import and degradation of RARA in Sertoli cells. GRp58 interacted with RARA in the presence of all-trans retinoic acid (ATRA) ligand and, as a complex, it was translocated from the cytoplasm to the nucleus and, then with time, GRp58 dissociated from RARA and was found in the cytoplasm. The GRp58 RNAi treatment disrupted ATRA-dependent RARA nuclear localization, indicating the requirement of GRp58 for RARA nuclear localization. Moreover, treatment with sulfhydryl-modifying agents that oxidize SH-groups of cysteine residues to disulfide bonds abolished ATRA-mediated RARA nuclear localization, suggesting that the thiol oxidoreductase activity of GRp58 may be required for RARA nuclear import. Additionally, the proteasome inhibitor treatment resulted in the co-localization of GRp58 and RARA at the endoplasmic reticulum (ER), suggesting that GRp58 may bring RARA to the ER for the ER-associated degradation (ERAD) of RARA before it is de-coupled from RARA for recycling. In this regard, proteasome inhibitor treatment also increased the interaction of RARA with UBE2J2, an ERAD-associated ubiquitin E2 enzyme. Collectively, the results indicate that GRp58 may act as a molecular chaperone that alters the protein conformation of RARA for its delivery to the nucleus and, then with time, accompanies RARA to the ER for RARA ubiquitination and proteasome-mediated ERAD.
Zhu
Li
L
School of Molecular Biosciences, Center for Reproductive Biology, Washington State University, Pullman, Washington 99164-4234, USA.
Santos
Nadine C
NC
Kim
Kwan Hee
KH
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D008297:Male; D008954:Models, Biological; D008969:Molecular Sequence Data; D019704:Protein Disulfide-Isomerases / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018168:Receptors, Retinoic Acid / Q000378:metabolism*; D000072482:Retinoic Acid Receptor alpha; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution / Q000187:drug effects
D034741:RNA, Small Interfering; C000607072:Rara protein, mouse; C000607073:Rara protein, rat; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; C513196:PDIA3 protein, rat; D019704:Protein Disulfide-Isomerases