von Hippel-Lindau protein induces hypoxia-regulated arrest of tyrosine hydroxylase transcript elongation in pheochromocytoma cells.
Rat pheochromocytoma (PC12) cells were stably transfected with either wild type or mutated human von Hippel-Lindau tumor suppressor protein (hpVHL). These proteins have opposing effects on regulating expression of the gene encoding tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine synthesis. Whereas wild type hpVHL represses levels of TH mRNA and protein 5-fold, a truncated pVHL mutant, pVHL(1-115), induces accumulation of TH mRNA and protein 3-fold. hpVHL-induced inhibition of TH gene expression does not involve either a decrease in TH mRNA stability or repression of TH promoter activity. However, repression results from inhibition of RNA elongation at a downstream region of the TH gene. This elongation pause is accompanied by hpVHL sequestration in the nuclear extracts of elongins B and C, regulatory components of the transcription elongation heterotrimer SIII (elongin A/B/C). Hypoxia, a physiological stimulus for TH gene expression, alleviates the elongation block. A truncated pVHL mutant, pVHL(1-115), stimulates TH gene expression by increasing the efficiency of TH transcript elongation. This is the first report showing pVHL-dependent regulation of specific transcript elongation in vivo, as well as dominant negative activity of pVHL mutants in pheochromocytoma cells.
Kroll
S L
SL
Department of Molecular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0576, USA.
Paulding
W R
WR
Schnell
P O
PO
Barton
M C
MC
Conaway
J W
JW
Conaway
R C
RC
Czyzyk-Krzeska
M F
MF
D000818:Animals; D015687:Cell Hypoxia; D015536:Down-Regulation; D000075065:Elongin; D005786:Gene Expression Regulation / Q000235:genetics; D016147:Genes, Tumor Suppressor; D006801:Humans; D008025:Ligases; D016716:PC12 Cells; D011506:Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D025521:Tumor Suppressor Proteins; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics*; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein
C000616397:ELOA protein, human; C000616404:Eloa protein, rat; D000075065:Elongin; D011506:Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D014446:Tyrosine 3-Monooxygenase; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D008025:Ligases; C497446:VHL protein, human