GCUNC-45 is a novel regulator for the progesterone receptor/hsp90 chaperoning pathway.
The hsp90 chaperoning pathway is a multiprotein system that is required for the production or activation of many cell regulatory proteins, including the progesterone receptor (PR). We report here the identity of GCUNC-45 as a novel modulator of PR chaperoning by hsp90. GCUNC-45, previously implicated in the activities of myosins, can interact in vivo and in vitro with both PR-A and PR-B and with hsp90. Overexpression and knockdown experiments show GCUNC-45 to be a positive factor in promoting PR function in the cell. GCUNC-45 binds to the ATP-binding domain of hsp90 to prevent the activation of its ATPase activity by the cochaperone Aha1. This effect limits PR chaperoning by hsp90, but this can be reversed by FKBP52, a cochaperone that is thought to act later in the pathway. These findings reveal a new cochaperone binding site near the N terminus of hsp90, add insight on the role of FKBP52, and identify GCUNC-45 as a novel regulator of the PR signaling pathway.
Department of Biochemistry and Molecular Biology, Mayo Clinic, 200 First St. Southwest, Rochester, MN 55905, USA.
Ahmed
A
Chadli
J Dinny
JD
Graham
M Greg
MG
Abel
Twila A
TA
Jackson
David F
DF
Gordon
William M
WM
Wood
Sara J
SJ
Felts
Kathryn B
KB
Horwitz
David
D
Toft
D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D011980:Receptors, Progesterone / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D022021:Tacrolimus Binding Proteins / Q000378:metabolism
D033942:Adaptor Proteins, Vesicular Transport; D018841:HSP90 Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D018832:Molecular Chaperones; D011980:Receptors, Progesterone; C475144:TTC1 protein, human; C509158:UNC45A protein, human; D020962:Heterotrimeric GTP-Binding Proteins; D022021:Tacrolimus Binding Proteins; C403485:tacrolimus binding protein 4