Acetylation by p300 Regulates Nuclear Localization and Function of the Transcriptional Corepressor CtBP2

Abstract

CtBP family members, CtBP1 and CtBP2, are unique transcriptional regulators that adapt a metabolic enzyme fold, and their activities are regulated by NAD(H)-binding. CtBP1 is both cytoplasmic and nuclear, and its subcellular localization is regulated by sumoylation, phosphorylation, and binding to a PDZ protein. In contrast, we showed that CtBP2 is exclusively nuclear. CtBP1 and CtBP2 are highly similar, but differ at the N-terminal 20 amino acid region. Substitution of the N-terminal domain of CtBP1 with the corresponding CtBP2 domain confers a dominant nuclear localization pattern to CtBP1. The N-terminal domain of CtBP2 contains three Lys residues. Our results show that these Lys residues are acetylated by the nuclear acetylase p300. Although all three Lys residues of CtBP2 (Lys-6, Lys-8, and Lys-10) appear to be acetylated, acetylation of Lys-10 is critical for nuclear localization. CtBP2 with a single amino acid substitution at Lys-10 (K10R) is predominantly localized in the cytoplasm. The cytoplasmic localization of the K10R mutant is correlated with enhanced nuclear export that is inhibited by leptomycin B. Furthermore, lack of acetylation at Lys-10 renders CtBP2 to be more efficient in repression of the E-cadherin promoter. Our studies have revealed the important roles of acetylation in regulating subcellular localization and transcriptional activity of CtBP2.

Developmental expression and phylogenetic conservation of alternatively spliced forms of the C-terminal binding protein corepressor

“…CtBP1 is phosphorylated at serine158, a modification that induces nuclear to cytoplasmic translocation (Barnes et al, 2003). CtBP2 has a unique N-terminus that is acetylated, which facilitates nuclear retention of the protein (Zhao et al, 2006). Whether these differences play a role directly in transcription is unclear; both proteins may function similarly when recruited to promoters.…”

Histone deacetylase inhibitors: molecular mechanisms of action

“…This suggests that the primary activity of HDACs may be directed against non-histone substrates. At least 50 non-histone proteins of known biological function have been identified, which may be acetylated and substrates of HDACs (Table 1) (Glozak et al, 2005;Marks and Dokmanovic, 2005;Rosato and Grant, 2005;Bolden et al, 2006;Minucci and Pelicci, 2006;Zhao et al, 2006). In addition, two recent proteomic studies identified many lysine-acetylated substrates (Iwabata et al, 2005;Kim et al, 2006).…”

Changes in C-terminal Binding Protein 2 (CtBP2) Corepressor Complex Induced by E1A and Modulation of E1A Transcriptional Activity by CtBP2

“…The PCR-amplified DNA was digested with NcoI/SalI and ligated to the SalI/BamHI fragment of pFH-CtBP2 (40) and the NcoI/ BamHI fragment of the pET-11c vector (Novagen) to generate the pH6-CtBP2 expression construct. pH6 -3KR-CtBP2 was constructed by the same approach using pFH-3KR-CtBP2 (40) as the template for PCR. Plasmids pH6-⌬N-CtBP2 and pH6-A58E-CtBP2 were constructed by substituting the XhoI/ BamHI fragment of pFH-⌬N-CtBP2 and pFH-A58E-CtBP2 (40) for the same fragment of pH6-CtBP2.…”

“…pH6 -3KR-CtBP2 was constructed by the same approach using pFH-3KR-CtBP2 (40) as the template for PCR. Plasmids pH6-⌬N-CtBP2 and pH6-A58E-CtBP2 were constructed by substituting the XhoI/ BamHI fragment of pFH-⌬N-CtBP2 and pFH-A58E-CtBP2 (40) for the same fragment of pH6-CtBP2. pH6-CtBP1-L and pH6-CtBP1-S were constructed by substituting the XhoI/BglII fragment of pFH-CtBP1 and pFH-CtBP1-S (40) for the XhoI/ BamHI fragment of pH6-CtBP2.…”

“…Despite extensive sequence similarities, the vertebrate CtBPs differ in the N-terminal 20-amino acid region. CtBP2 contains a unique 19-amino acid Lys/Arg-rich N-terminal domain, which is modified by acetylation by p300 and is required for nuclear localization of CtBP2 (40). The two isoforms of CtBP1 vary by the presence of a 13-amino acid N-terminal domain in CtBP1-L or by the absence of this domain in CtBP1-S (reviewed in Ref.…”