DYRK1A protein kinase promotes quiescence and senescence through DREAM complex assembly

Abstract

In the absence of growth signals, cells exit the cell cycle and enter into G0 or quiescence. Alternatively, cells enter senescence in response to inappropriate growth signals such as oncogene expression. The molecular mechanisms required for cell cycle exit into quiescence or senescence are poorly understood. The DREAM (DP, RB [retinoblastoma] , E2F, and MuvB) complex represses cell cycle-dependent genes during quiescence. DREAM contains p130, E2F4, DP1, and a stable core complex of five MuvB-like proteins: LIN9, LIN37, LIN52, LIN54, and RBBP4. In mammalian cells, the MuvB core dissociates from p130 upon entry into the cell cycle and binds to BMYB during S phase to activate the transcription of genes expressed late in the cell cycle. We used mass spectroscopic analysis to identify phosphorylation sites that regulate the switch of the MuvB core from BMYB to DREAM. Here we report that DYRK1A can specifically phosphorylate LIN52 on serine residue 28, and that this phosphorylation is required for DREAM assembly. Inhibiting DYRK1A activity or point mutation of LIN52 disrupts DREAM assembly and reduces the ability of cells to enter quiescence or undergo Ras-induced senescence. These data reveal an important role for DYRK1A in the regulation of DREAM activity and entry into quiescence.

The Hippo pathway kinase Lats2 prevents DNA damage-induced apoptosis through inhibition of the tyrosine kinase c-Abl

“…Recent studies have shown links between the Hippo pathway and the pRB (retinoblastoma) pathway in the context of cellular senescence. [44][45][46][47] The latter studies show a role for Lats2 in mediating repression of E2F target genes by pRB in senescence. These studies induced senescence through oncogene expression or serum withdrawal.…”

E2F4 (E2F transcription factor 4, p107/p130-binding)

“…Indeed, E2F4 protein levels are not significantly modulated during cell cycle progression; however, its nuclear localization is tightly regulated (Lindeman et al, 1997;Verona et al, 1997;Deschenes et al, 2004) (see below). Furthermore, many studies have reported E2F4 phosphorylation but only a few have associated these phosphorylation events with a specific function (Beijersbergen et al, 1994;Ginsberg et al, 1994;Vairo et al, 1995;Gaubatz et al, 2001;Popov et al, 2005;Araki et al, 2008;Scime et al, 2008;Van Hoof et al, 2009;Litovchick et al, 2011). For example, Araki et al, 2008 showed that E2F4 phosphorylation by IKKα and/or IKKβ leads to increased binding of the E2F4/p130 complex to DNA in TIG-3 human primary fibroblasts.…”

“…E2F4 is the only E2F possessing a stretch of 13 consecutive serine residues in its transactivation domain (Sardet et al, 1995). Numerous publications infer that E2F4 is a phosphorylated protein (Beijersbergen et al, 1994;Ginsberg et al, 1994;Vairo et al, 1995;Gaubatz et al, 2001;Popov et al, 2005;Scime et al, 2008) although only a few have identified specific phosphorylation sites: T14 and S16 are phosphorylated residues (Van Hoof et al, 2009); S281 and S285 are phosphorylated by IKKα and IKKβ and enhance E2F4 nuclear localization and DNA-binding of the E2F4/p130 complex in human primary fibroblasts (Araki et al, 2008); S384 is phosphorylated in the DREAM or MMB complexes (Litovchick et al, 2011). Thereafter, genes required for DNA synthesis and cell cycle progression are induced, allowing cells to enter S-phase and pursue their cell cycle (Cobrinik, 2005;Malumbres and Barbacid, 2009). In addition to pocket protein-mediated regulation, E2F4 is also controlled by other mechanisms such as phosphorylation, antisenses (Yochum et al, 2007), reactive oxygen species (Kim and Lee, 2010), cofactors and mainly by its subcellular localization.…”

“…Indeed, E2F4 binds various genes having functions in mitochondrial biogenesis, metabolism, cytoskeleton and mRNA processing (Cam et al, 2004). Moreover, E2F4 is thought to regulate the expression of certain miRNAs (Lee et al, 2011), control DNA repair (Ren et al, 2002;DuPree et al, 2004;Bindra and Glazer, 2007;Crosby et al, 2007;Dominguez-Brauer et al, 2009;Hegan et al, 2010;Lee et al, 2011), control survival in certain specific cell contexts (Chang et al, 2000;Wang et al, 2000;Ebelt et al, 2005;Garneau et al, 2007;Yang et al, 2008;Lee et al, 2011) as well as regulate aging and senescence (Iakova et al, 2003;Litovchick et al, 2011;Martin et al, 2011). Lastly, although the majority of E2F4 binding sites are located near transcription start sites and contribute to direct activation or repression of transcription (Lee et al, 2011;Lo et al, 2011), many sites are frequently localized more than 20 kb away from any annotated transcription start sites, suggesting that E2F4 can also act as a long-range transcriptional regulator (Lee et al, 2011).…”

“…However, E2F4 migrates as an heterogeneous set of bands between 57-64 kDa which are associated with extensive phosphorylations (Beijersbergen et al, 1994;Ginsberg et al, 1994;Vairo et al, 1995;Gaubatz et al, 2001;Popov et al, 2005;Araki et al, 2008;Scime et al, 2008;Van Hoof et al, 2009;Litovchick et al, 2011). Unlike E2F1, E2F2 and E2F3, which exhibit a cyclin A binding domain at their N-terminus, E2F4 has a truncated N-terminus and therefore does not harbor this domain (Beijersbergen et al, 1994;Sardet et al, 1995).…”