Regulation of prohormone convertase 1 (PC1) by thyroid hormone.
The prohormone convertases (PCs) PC1 and PC2 are key enzymes capable of processing a variety of prohormones to their bioactive forms. In this study, we demonstrated that 6-n-propyl-2-thiouracil (PTU)-induced hypothyroidism stimulated, whereas triido-L-thyronine (T(3))-induced hyperthyroidism suppressed, PC1 mRNA levels in the rat anterior pituitary. Using 5' deletions of the human PC1 (hPC1) promoter transiently transfected into GH3 (a somatotroph cell line) cells, we found that T(3) negatively regulated hPC1 promoter activity and that this regulation required the region from -82 to +19 bp relative to the transcription start site. Electrophoretic mobility shift assays (EMSAs) using purified thyroid hormone receptor-alpha1 (TR alpha 1) and retinoid X receptor-beta (RXRbeta) proteins and GH3 nuclear extracts demonstrated that the region from -10 to +19 bp of the hPC1 promoter bound TR alpha 1 as both a monomer and a homodimer and bound TR alpha 1/RXR beta as a heterodimer and multimer. EMSAs with oligonucleotides containing point mutations of the putative negative thyroid response elements (TREs) exhibited diminished homodimer and loss of multimer binding. We conclude that there are multiple novel TRE-like sequences in the hPC1 promoter located from -10 to +19 bp.
Li
Q L
QL
Division of Endocrinology, Department of Medicine, Cedars-Sinai Research Institute--University of California at Los Angeles School of Medicine, Los Angeles, 90048, USA.
Jansen
E
E
Brent
G A
GA
Friedman
T C
TC
D000077556:Alitretinoin; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D016282:Aspartic Acid Endopeptidases / Q000235:genetics* / Q000378:metabolism*; D002478:Cells, Cultured; D017353:Gene Deletion; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology; D017930:Genes, Reporter; D007037:Hypothyroidism / Q000139:chemically induced / Q000378:metabolism*; D008156:Luciferases / Q000235:genetics; D008297:Male; D016254:Mutagenesis, Insertional / Q000502:physiology; D009841:Oligonucleotides / Q000235:genetics / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000502:physiology; D043484:Proprotein Convertases; D011499:Protein Processing, Post-Translational / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D047488:Retinoid X Receptors; D014157:Transcription Factors / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology; D014284:Triiodothyronine / Q000378:metabolism*; D014498:Uracil / Q000031:analogs & derivatives*
D000970:Antineoplastic Agents; D009841:Oligonucleotides; D010446:Peptide Fragments; D012333:RNA, Messenger; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D014157:Transcription Factors; D014284:Triiodothyronine; C056698:6-n-propyluracil; D000077556:Alitretinoin; D014212:Tretinoin; D014498:Uracil; D008156:Luciferases; D043484:Proprotein Convertases; D016282:Aspartic Acid Endopeptidases