Hydrogen Peroxide Alters Splicing of Soluble Guanylyl Cyclase and Selectively Modulates Expression of Splicing Regulators in Human Cancer Cells

Background: Soluble guanylyl cyclase (sGC) plays a central role in nitric oxide (NO)-mediated signal transduction in the cardiovascular, nervous and gastrointestinal systems. Alternative RNA splicing has emerged as a potential mechanism to modulate sGC expression and activity. C-alpha 1 sGC is an alternative splice form that is resistant to oxidation-induced protein degradation and demonstrates preferential subcellular distribution to the oxidized environment of endoplasmic reticulum (ER). Methodology/Principal Findings: Here we report that splicing of C-alpha 1 sGC can be modulated by H2O2 treatment in BE2 neuroblastoma and MDA-MD-468 adenocarcinoma human cells. In addition, we show that the H2O2 treatment of MDA-MD-468 cells selectively decreases protein levels of PTBP1 and hnRNP A2/B1 splice factors identified as potential alpha 1 gene splicing regulators by in silico analysis. We further demonstrate that down-regulation of PTBP1 by H2O2 occurs at the protein level with variable regulation observed in different breast cancer cells. Conclusions/Significance: Our data demonstrate that H2O2 regulates RNA splicing to induce expression of the oxidation-resistant C-alpha 1 sGC subunit. We also report that H2O2 treatment selectively alters the expression of key splicing regulators. This process might play an important role in regulation of cellular adaptation to conditions of oxidative stress.