Human Arrest Defective 1 Acetylates and Activates β-Catenin, Promoting Lung Cancer Cell Proliferation

Abstract

Arrest defective 1 (ARD1), an acetyltransferase, is essential for the yeast life cycle. Although its human homologue (hARD1) has been identified, its biological functions in human cells remain unclear. In the present study, we examined the biological function of hARD1. In H1299 and A549 lung cancer cells, hARD1-silencing RNA inhibited cell proliferation and induced G 1 arrest. Cyclin D1 was also found to be downregulated in these growth-arrested cells, and the ectopic expression of cyclin D1 rescued cell growth. hARD1 knockdown repressed the promoter activity of the cyclin D1 gene, which inhibited the transcription of cyclin D1. Moreover, hARD1 knockdown reduced the binding of B-catenin/TCF4 transcription factor to cyclin D1 promoter and repressed its transcriptional activity. Inversely, hARD1 expression increased the transcriptional activity of B-catenin. Both endogenous and ectopically expressed hARD1 was coimmunoprecipitated with B-catenin. hARD1 knockdown did not affect B-catenin expression or degradation but noticeably reduced acetylated B-catenin. The B-catenin binding and acetylation by hARD1 were observed in vitro. Therefore, it is suggested that hARD1 participates in proliferation of lung cancer cells via the activation of

NAA10 controls osteoblast differentiation and bone formation as a feedback regulator of Runx2

“…A growing body of evidence has suggested that NAA10 has diverse functions beyond the cotranslational modification. NAA10 can catalyse amino-terminal a-acetylation or lysine e-acetylation in many proteins as post-translational modification [17][18][19]30 , and our results provide additional support for this role of NAA10. Moreover, given our result showing that recombinant NAA10 catalyses lysyl acetylation without auxiliary partners, NAA10 is likely to have its enzymatic activity as a monomer.…”

“…A polyclonal antibody against NAA10 was raised in rats against full-length human NAA10 (ref. 17). Mouse NAA10 and b-tubulin primary antibodies and horseradish peroxidase-conjugated secondary antibodies were purchased from Santa Cruz Biotechnology (Santa Cruz, CA); anti-Runx2 from MBL (Nagoya, Japan); Acetylated-Lysine antibody from Cell Signaling Technologies (Billerical, MA); anti-a-Myc-tag and Flag-tag antibody from Sigma-Aldrich.…”

“…Site-specific mutations of Runx2 were performed using PCR-based mutagenesis (Stratagene; Cedar Creek, TX). The NAA10 plasmid was constructed as previously described 17 . For transient transfection with plasmids or siRNAs, cells at B40% density were transfected with plasmids or siRNAs using calcium phosphate or Lipofectamine reagent (Invitrogen).…”

“…Besides BMP signalling pathways, the Wnt/b-catenin signalling pathway has been reported to play a role in osteoblast differentiation and maturation 20 . Further, NAA10 has been reported to acetylate and activate b-catenin in lung cancer cell lines 17 . In the present study, however, NAA10 does not regulate Wnt3a-stimulated osteoblast differentiation ( Supplementary Fig.…”

“…Its orthologs have been identified in mouse and human cells, and participate in cell growth and proliferation, as shown in yeasts 15 . Functionally, NAA10 catalyses the amino-terminal a-acetylation of proteins in yeast and mammalian cells 16 , and it is also known to induce the lysine e-acetylation of several proteins, including b-catenin, myosin light-chain kinase and androgen receptor [17][18][19] . Because NAA10 is ubiquitously expressed in many human cells, it is expected to have diverse functions in addition to cell cycle regulation.…”