Investigation of the role of the histone modifying enzyme peptidyl arginine deiminase 4 (PAD4) in breast cancer progression

• Applicant: Dr. Sonja Christa Stadler
• Subject Area: Cell Biology
• Term: from 2010 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 169659824

• Final Report Year: 2012

Final Report Abstract

Peptidylarginine deiminase 4 (PAD4) is a Ca2+ -dependent enzyme that converts arginine and methylarginine residues to citrulline, with histone proteins being among the better-described substrates to date. However, the biological function of this post-translational modification in histones, as well as in non-histone proteins, is poorly understood. Our study showed that PAD4 recognizes, binds, and citrullinates glycogen synthase kinase-3 beta (GSK3β), both in vitro and in vivo. GSK3β is known to be a key regulator of transcription factors involved in tumor progression, and its decreased expression or loss of enzymatic activity has been associated with human cancers. We demonstrated that silencing of PAD4 in breast cancer cells leads to a striking reduction of nuclear GSK3β protein levels, activation of TGFβ signaling, induction of epithelial-to-mesenchymal transition (EMT), and production of invasive tumors in xenograft assays. Moreover, in breast cancer patients, reduction of PAD4 and nuclear GSK3β is associated with increased tumor invasiveness. We propose that PAD4 citrullination of GSK3β is a novel post-translational modification that regulates its nuclear localization and thereby plays a critical, role in maintaining the epithelial phenotype.

Publications

• Daxx is an H3.3-specific histone chaperone and cooperates with ATRX in replication-independent chromatin assembly at telomeres. Proc Natl Acad Sci USA. 2010;107:14075-80
  Lewis PW, Elsaesser SJ, Noh KM, Stadler SC, Allis CD
  
• Distinct factors control histone variant H3.3 localization at specific genomic regions. Cell. 2010; 140:678-91
  Goldberg AD, Banaszynski LA, Noh KM, Lewis PW, Elsaesser SJ, Stadler SC, et al.
  
• Genome-wide analysis reveals PADI4 cooperates with Elk-1 to activate c-Fos expression in breast cancer cells. PLoS Genet. 2011;7:e1002112
  Zhang X, Gamble MJ, Stadler S, Cherrington BD, Causey CP, Thompson PR, et al.
  
• Multiple interactions recruit MLL1 and MLL1 fusion proteins to the HOXA9 locus in leukemogenesis. Mol Cell. 2011;38:853-63
  Milne TA, Kim J, Wang GG, Stadler SC, Basrur V, Whitcomb SJ, et al.