The splicing activator DAZAP1 integrates splicing control into MEK/Erk-regulated cell proliferation and migration

Abstract

Alternative splicing of pre-mRNA is a critical stage of gene regulation in response to environmental stimuli. Here we show that DAZAP1, an RNA binding protein involved in mammalian development and spermatogenesis, promotes inclusion of weak exons through specific recognition of diverse cis-elements. The C-terminal proline-rich domain of DAZAP1 interacts with and neutralizes general splicing inhibitors, and is sufficient to activate splicing when recruited to pre-mRNA. This domain is phosphorylated by the MEK/Erk pathway and this modification is essential for the splicing regulatory activity and the nuclear/cytoplasmic translocation of DAZAP1. Using mRNA-seq we identify endogenous splicing events regulated by DAZAP1, many of which are involved in maintaining cell growth. Knockdown or over-expression of DAZAP1 causes a cell proliferation defect. Taken together, these studies reveal a molecular mechanism that integrates splicing control into MEK/Erk regulated cell proliferation.

The Splicing Factor RBM4 Controls Apoptosis, Proliferation, and Migration to Suppress Tumor Progression

“…These results suggest that RBM4 functions as a general splicing inhibitor to specifically suppress splicing from both exonic and intronic contexts. Such activities are in contrast to DAZAP1, a splicing factor that recognizes the same GTAACG site but functions as a splicing activator (Choudhury et al, 2014). Interestingly, DAZAP1 does not affect splicing of exons containing a nearby CGGCGG site (Figure S1A and S1B), suggesting a partial overlap of binding specificity and an incomplete functional competition between RBM4 and DAZAP1.…”

“…These results present an unusual regulatory mode compared to typical splicing factors. Many splicing factors, like SR proteins, hnRNP A1, and DAZAP1, contain a separate RNA binding module to recognize targets and an independent functional module to control splicing (Choudhury et al, 2014; Del Gatto-Konczak et al, 1999; Graveley and Maniatis, 1998). RBM4 may represent another class in which both fragments can inhibit splicing but the entire protein harbors a stronger activity, indicating that the two fragments cooperatively control splicing rather than function in a modular fashion.…”

Efficient backsplicing produces translatable circular mRNAs

“…4B). Both RBM4 and DAZAP1 were found to recognize ESS1 but had opposite activities in controlling exon inclusion in canonical splicing (Choudhury et al 2014;Wang et al 2014b). Consistently they showed opposite effects on the backsplicing of circRNA from ESS1-containing exon, although they also affected backsplicing of other minigenes in a sequence independent fashion (Fig.…”

Transcriptome-wide identification and study of cancer-specific splicing events across multiple tumors

“…The same splicing factor may either activate or inhibit splicing by binding to its cognate SREs in different pre-mRNA regions, which is commonly referred to as context dependent activity [12–14]. Various cellular signaling pathways, such as the MEK/ERK or c-Myc pathway [15–17], were found to control the expression level and activity of splicing factors, which in turn determine different splicing patterns in distinct tissues (reviewed in [10, 18]). Many splicing factors are involved in cancer pathogenesis through mediating AS of hundreds of genes [4].…”