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. hp VHL-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.
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Kroll, S. L., Paulding, W. R., Schnell, P. O., Barton, M. C., Conaway, J. W., Conaway, R. C., & Czyzyk-Krzeska, M. F. (1999). von Hippel-Lindau protein induces hypoxia-regulated arrest of tyrosine hydroxylase transcript elongation in pheochromocytoma cells. Journal of Biological Chemistry, 274(42), 30109–30114. https://doi.org/10.1074/jbc.274.42.30109