Abstract:
:The "pocket" proteins pRb, p107, and p130 are a family of negative growth regulators. Previous studies have demonstrated that overexpression of pRb can repress transcription by RNA polymerase (Pol) I. To assess whether pRb performs this role under physiological conditions, we have examined pre-rRNA levels in cells from mice lacking either pRb alone or combinations of the three pocket proteins. Pol I transcription was unaffected in pRb-knockout fibroblasts, but specific disruption of the entire pRb family deregulated rRNA synthesis. Further analysis showed that p130 shares with pRb the ability to repress Pol I transcription, whereas p107 is ineffective in this system. Production of rRNA is abnormally elevated in Rb(-/-) p130(-/-) fibroblasts. Furthermore, overexpression of p130 can inhibit an rRNA promoter both in vitro and in vivo. This reflects an ability of p130 to bind and inactivate the upstream binding factor, UBF. The data imply that rRNA synthesis in living cells is subject to redundant control by endogenous pRb and p130.
journal_name
Mol Cell Bioljournal_title
Molecular and cellular biologyauthors
Ciarmatori S,Scott PH,Sutcliffe JE,McLees A,Alzuherri HM,Dannenberg JH,te Riele H,Grummt I,Voit R,White RJdoi
10.1128/mcb.21.17.5806-5814.2001subject
Has Abstractpub_date
2001-09-01 00:00:00pages
5806-14issue
17eissn
0270-7306issn
1098-5549journal_volume
21pub_type
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