Dimethyl Sulfoxide Affects the Selection of Splice Sites

Abstract

Depending on the cell lines and cell types, dimethyl sulfoxide (Me 2 SO) can induce or block cell differentiation and apoptosis. Although Me 2 SO treatment alters many levels of gene expression, the molecular processes that are directly affected by Me 2 SO have not been clearly identified. Here, we report that Me 2 SO affects splice site selection on model pre-mRNAs incubated in a nuclear extract prepared from HeLa cells. A shift toward the proximal pair of splice sites was observed on pre-mRNAs carrying competing 5-splice sites or competing 3-splice sites. Because the activity of recombinant hnRNP A1 protein was similar when added to extracts containing or lacking Me 2 SO, the activity of endogenous A1 proteins is probably not affected by Me 2 SO. Notably, in a manner reminiscent of SR proteins, Me 2 SO activated splicing in a HeLa S100 extract. Moreover, the activity of recombinant SR proteins in splice site selection in vitro was improved by Me 2 SO. Polar solvents like DMF and formamide similarly modulated splice site selection in vitro but formamide did not activate a HeLa S100 extract. We propose that Me 2 SO improves ionic interactions between splicing factors that contain RS-domains. The direct impact of Me 2 SO on alternative splicing may explain, at least in part, the different and sometimes opposite effects of Me 2 SO on cell differentiation and apoptosis.Me 2 SO 1 is a polar solvent used to promote cell differentiation of tumor cell lines. For example, the treatment of mouse erythroleukemic and neuroblastoma cells with 2% Me 2 SO induces morphological changes and differentiation in red blood cells and neurons, respectively (e.g. see Refs. 1, 2). Me 2 SO also induces differentiation of the human U937 monoblast leukemia cell line into monocyte/macrophage (3) and stimulates the differentiation of a human ovarian adenocarcinoma cell line (4). Paradoxically, Me 2 SO prevents the terminal differentiation of myoblasts (5, 6), inhibits the differentiation of adipocytes (7), blocks the differentiation of antibody-producing plasma cells (8), and interferes with the differentiation of chick embryo chondrocytes (9). Whereas Me 2 SO has been used to induce apoptosis in some cell lines (10, 11), it inhibits cell density-dependent apoptosis of CHO cells (6). Thus, depending on the cell line, Me 2 SO can have completely different effects on differentiation and apoptosis.The cellular mechanisms that are affected by Me 2 SO remain unclear. Because Me 2 SO facilitates DNA uptake during transfection procedures (e.g. see Ref. 12), Me 2 SO has been proposed to affect the integrity of cell membranes. Because Me 2 SO alters protein kinase C activity and the expression of integrin complexes (6, 13), Me 2 SO may alter intracellular signaling processes, which in turn may have a broad impact on many aspects of gene expression. Me 2 SO treatment promotes changes in the abundance of certain mRNAs and in the ratio of spliced isoforms (14 -17). Among the genes reported to be affected in their alternative splicing is the NCAM pre-mR...

Dimethyl Sulfoxide Exposure Facilitates Phospholipid Biosynthesis and Cellular Membrane Proliferation in Yeast Cells

“…It has been reported that Me 2 SO affects the selection of splice sites and causes a shift toward the proximal pair of splice sites on pre-mRNAs carrying competing 5Ј-splice sites or competing 3Ј-splice sites (19). We did not observe any morphological changes when budding S. cerevisiae cells were treated with 10% Me 2 SO (Fig.…”

“…Thus, the effect of Me 2 SO varies depending on the cell line and cell type. At the molecular level Me 2 SO is known to affect RNA splicing and causes a shift toward the proximal pair of splice sites on pre-mRNAs carrying competing 5Ј-splice sites or competing 3Ј-splice sites (19).…”

Spi-1/PU.1 but not Fli-1 inhibits erythroid-specific alternative splicing of 4.1R pre-mRNA in murine erythroleukemia cells

“…A recent work has shown that DMSO can alter premRNA splicing by interfering with the recruitment of splicing factors (Bolduc et al, 2001). This observation led us to ask whether exon 16 inclusion in mature 4.1R Spi-1/PU.1 regulates erythroid pre-mRNA splicing O Théoleyre et al mRNA in DMSO-treated MEL cells could reflect such a direct effect of DMSO.…”

“…Whether these effects result from a direct interference of DMSO with one step or the other of mRNA metabolism is an issue that has just begun to be addressed. Hence, it has recently been shown that DMSO activates splice site selection and enhances SR protein activity in HeLa extracts (Bolduc et al, 2001 Erythroid-specific splicing of 4.1R pre-mRNA is affected by Spi-1/PU.1, but not by Fli-1…”

“…DMSO is a polar solvent that induces or blocks differentiation and apoptosis of a variety of cell lines. It can also affect different aspects of mRNA metabolism, including transcription, maturation, translation and stability, leading to quantitative and structural (alternative splicing) changes of a variety of transcripts (Bolduc et al, 2001, and references therein). Whether these effects result from a direct interference of DMSO with one step or the other of mRNA metabolism is an issue that has just begun to be addressed.…”