title: Exonucleolytic degradation of RNA by p53 protein in cytoplasm.
abstract: p53 in cytoplasm displays an intrinsic 3'-->5' exonuclease activity. To understand the significance of p53 exonuclease activity in cytoplasm, cytoplasmic extracts of various cell lines were examined for exonuclease activity with different single-stranded RNA (ssRNA) substrates. Using an in vitro RNA degradation assay, we observed in cytoplasmic extracts of LCC2 cells, expressing high levels of endogenous wtp53, an efficient 3'-->5' exonuclease activity with RNA substrates, removing the 3'-terminal nucleotides. Interestingly, RNA containing AU-rich sequences (ARE) is the permissive substrate for exonucleolytic degradation. Evidence that exonuclease function with RNA detected in cytoplasmic extracts is attributed to the p53 is supported by several facts: (1) this activity closely parallels with status and levels of endogenous cytoplasmic p53; (2) the endogenous exonuclease exerts identical RNA substrate specificity and excision profile characteristic for purified baculovirus-or bacterially-expressed wtp53s; (3) the exonuclease activity with ARE RNA is competed out by the presence of ss or double-stranded DNA substrate utilized by p53 protein in cytoplasm; (4) immunoprecipitation by specific anti-p53 antibodies markedly reduced the exonuclease activity with both RNA and DNA substrates; and (5) transfection of the wtp53, but not exonuclease-deficient mutant p53-R175H, into p53-null H1299 or HCT116 cells induced high levels of exonuclease activity with ARE RNA substrate in cytoplasm with characteristic excision profile. The efficient ARE RNA degradation correlates with the efficient binding of p53 to ARE RNA in cytoplasm. The possible role of p53 exonuclease activity in ARE-mRNA destabilization in cytoplasm, which may be important for expression of proteins that control cell growth and/or apoptosis is discussed.
authors: Infectious Diseases Unit, Sheba Medical Center, Tel Hashomer, Israel. bakhanus@yahoo.com
authors: Mary
authors: M
authors: Bakhanashvili
authors: Rachel
authors: R
authors: Gedelovich
authors: Shai
authors: S
authors: Grinberg
authors: Galia
authors: G
authors: Rahav
mesh_terms: D001483:Base Sequence; D003593:Cytoplasm / Q000737:chemistry; D005092:Exonucleases / Q000378:metabolism*; D006801:Humans; D012313:RNA / Q000378:metabolism*; D020871:RNA Stability; D013379:Substrate Specificity; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D016159:Tumor Suppressor Protein p53; D012313:RNA; D005092:Exonucleases
references: EMBO J. 1995 Sep 15;14(18):4442-9
references: 7556087
references: EMBO J. 2001 Feb 15;20(4):914-23
references: 11179235
references: Oncogene. 2000 Aug 17;19(35):4042-9
references: 10962561
references: EMBO J. 1993 Jun;12(6):2389-96
references: 7685274
references: Oncogene. 2001 Nov 15;20(52):7635-44
references: 11753641
references: Growth Factors. 1996;13(1-2):99-110
references: 8804994
references: Oncogene. 2004 Sep 9;23(41):6890-9
references: 15286711
references: Eur J Biochem. 2001 Apr;268(7):2047-54
references: 11277927
references: J Biol Chem. 2002 Dec 13;277(50):48558-64
references: 12324455
references: Biochemistry. 1992 Oct 6;31(39):9393-8
references: 1382590
references: Oncogene. 1998 Jul 23;17(3):261-70
references: 9690508
references: FEBS Lett. 1999 May 7;450(3):197-204
references: 10359074
references: Nature. 1992 Jul 2;358(6381):15-6
references: 1614522
references: Oncogene. 2004 May 27;23(25):4371-9
references: 15064727
references: Oncogene. 2003 Jun 5;22(23):3554-61
references: 12789264
references: J Biol Chem. 2000 May 26;275(21):16202-12
references: 10821866
references: Oncogene. 2003 Jan 16;22(2):233-45
references: 12527892
references: Int J Radiat Biol. 1998 Dec;74(6):729-37
references: 9881718
references: EMBO J. 2002 Jan 15;21(1-2):165-74
references: 11782436
references: Biochem Soc Trans. 2002 Nov;30(Pt 6):952-8
references: 12440953
references: Nucleic Acids Res. 1991 May 11;19(9):2499
references: 2041787
references: J Biol Chem. 2005 Jun 10;280(23):22406-17
references: 15809297
references: Proc Natl Acad Sci U S A. 1999 Jan 19;96(2):424-8
references: 9892649
references: Nucleic Acids Res. 2002 Apr 1;30(7):1493-9
references: 11917009
references: Oncogene. 2000 Jul 6;19(29):3321-9
references: 10918588
references: Mol Cell Biol. 2000 Nov;20(22):8420-31
references: 11046139
references: Mol Cell Biol. 1994 Nov;14 (11):7414-20
references: 7935455
references: Trends Biochem Sci. 1995 Nov;20(11):465-70
references: 8578590
references: Antimicrob Agents Chemother. 2005 Apr;49(4):1576-9
references: 15793143
references: Oncogene. 1993 May;8(5):1183-93
references: 8479742
references: Mol Cell Biol. 1995 Apr;15(4):2219-30
references: 7891716
references: Cancer Invest. 2002;20(4):509-17
references: 12094546
references: J Pathol. 1999 Jan;187(1):112-26
references: 10341712
references: Oncogene. 1994 Jul;9(7):1925-9
references: 8208539
references: Cell. 1996 Jun 28;85(7):1089-99
references: 8674115
references: Oncogene. 1999 Dec 13;18(53):7706-17
references: 10618711
references: Mol Cell Biol. 1992 Nov;12(11):5145-51
references: 1406686
references: Mol Cell Biol. 1996 Apr;16(4):1490-9
references: 8657122