The DNA Damage Response Pathway Regulates the Alternative Splicing of the Apoptotic Mediator Bcl-x

Abstract

Alternative splicing often produces effectors with opposite functions in apoptosis. Splicing decisions must therefore be tightly connected to stresses, stimuli, and pathways that control cell survival and cell growth. We have shown previously that PKC signaling prevents the production of proapoptotic Bcl-x S to favor the accumulation of the larger antiapoptotic Bcl-x L splice variant in 293 cells. Here we show that the genotoxic stress induced by oxaliplatin elicits an ATM-, CHK2-, and p53-dependent splicing switch that favors the production of the proapoptotic Bcl-x S variant. This DNA damage-induced splicing shift requires the activity of protein-tyrosine phosphatases. Interestingly, the ATM/CHK2/p53/tyrosine phosphatases pathway activated by oxaliplatin regulates Bcl-x splicing through the same regulatory sequence element (SB1) that receives signals from the PKC pathway. Convergence of the PKC and DNA damage signaling routes may control the abundance of a key splicing repressor because SB1-mediated repression is lost when protein synthesis is impaired but is rescued by blocking proteasome-mediated protein degradation. The SB1 splicing regulatory module therefore receives antagonistic signals from the PKC and the p53-dependent DNA damage response pathways to control the balance of pro-and antiapoptotic Bcl-x splice variants.

TCERG1 Regulates Alternative Splicing of the Bcl-x Gene by Modulating the Rate of RNA Polymerase II Transcription

“…The CMV-X2, HIV-X2, and HIV-X2. 13 reporter minigenes have been previously described (20,59). Bcl-x inserts of plasmids X2 and X2.13 were produced by PCR amplification using plasmids CMV-X2 and CMV-X2.13 (27) as templates, the PfuTurbo polymerase,and primers AscI-X-Fwd and X-Age-Rev.…”

The emerging role of pre-messenger RNA splicing in stress responses: Sending alternative messages and silent messengers

“…23 Likewise, Drosophila TAF1 splicing regulation by ionizing radiation and CPT are mediated by ATM/CHK2 and ATR/CHK1 pathways, respectively. 42 With respect to the role of p53, AS regulation by genotoxic agents can be either p53-dependent (e.g., Bcl-x regulation by oxaliplatin), 23 p53-independent (e.g., MDM2 regulation by various agents and caspase 9 regulation by UV), 21,[35][36][37] or dependent on p53 inactivation (e.g., Fas regulation by mitomycin C). 26 The cases of Bcl-x and MDM2 regulations, in particular, …”

“…20,22 Cyclophosphamide, oxaliplatin and UV favor the production of the pro-apoptotic Bcl-x S isoform and decrease the anti-apoptotic Bcl-x L isoform, through the regulation of alternative 5' splice sites in exon 2. 20,21,23 Thus, genotoxic agents induce the pro-apoptotic splice isoforms of several genes.…”

Modification of Akt by SUMO conjugation regulates alternative splicing and cell cycle

“…Thus, deciphering the splicing regulators and the signal transduction pathways controlling these alternative splicing events may have important implications for cancer pathophysiology, and, as such, it has been the focus of different laboratories. 42,[46][47][48][49][50][51] Here, we determined that Akt is involved in the regulation of Bcl-x pre-mRNA splicing. In agreement with the prosurvival role of Akt, its activation favors the production of the pro-survival mRNA isoform of Bcl-x, and it does so in a SUMOylation-dependent manner.…”