Abstract P5-06-09: Cyclin d1 binding to chromatin and the induction of chromosomal instability requires the fuzzy domain

Abstract

Abstract The cyclin D1 gene encodes the regulatory subunit of a holoenzyme that phosphorylates and inactivates the retinoblastoma (Rb) and the nuclear respiratory factor 1 (NRF1) proteins to regulate nuclear DNA synthesis and mitochondrial biogenesis. Cyclin D1 is required for oncogene-dependent growth and genetic ablation of the murine cyclin D1 gene resulted in resistance to Ras or ErbB2-induced mammary tumorigenesis and APC-induced gastrointestinal tumorigenesis. Cyclin D1 overexpression occurs in human breast, prostate, lung, and gastrointestinal malignancies and its abundance is induced at the level of transcription, translation and through post-translational modifications. Cyclin D1 plays a key role in transcriptional regulation inducing gene expression governing chromosomal instability (CIN) and cell-cycle progression. Cyclin D1 is also known to bind TF regulatory regions in chromatin immuno-precipitation (ChIP) assays. Genome wide analysis of cyclin D1 occupancy using ChIP-Seq identified binding sites including both the coding and non-coding genome with enrichment for genes regulating CIN and the G2/M phase (Top2A, AurkB, Cenpp, Mlf1ip, Zw10, Ckap2) consistent with enrichment of cyclin D1 at G2/M and the finding that cyclin D1 induces CIN. We sought to identify the molecular mechanisms governing the recruitment of cyclin D1 in the context of local chromatin to promote CIN. In order to define the domain of cyclin D1 involved in aneuploidy and tumorigenesis, we transduced and assessed the induction of aneuploidy in MEF cells using cyclin D1 wt (wt), cyclin D1 C-terminus domain (C4), cyclin D1 mutant lacking of the E-box motif (ΔE) or ctrl. We also searched for potential histone protein interaction motifs in cyclin D1 and determined the epigenetic motif recognized by cyclin D1 using a histone peptide array. The recognition of an epigenetic code by cyclin D1 may facilitate genome wide expression changes during cell-cycle progression and tumorigenesis. We finally identified a “fuzzy” domain of cyclin D1 which is required to local chromatin access for regulatory promoter regions governing and promoting CIN. Citation Format: Pestell RG, Di Sante G, Di Rocco A, Pupo C, Crosariol M, Tompa P, Tantos A, Wang C, Yu Z, Vadlamudi R, Mann M, Casimiro MC. Cyclin d1 binding to chromatin and the induction of chromosomal instability requires the fuzzy domain [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-06-09.