Detection of alternative splicing of fibronectin mRNA in a single cell.

Pre-fibronectin mRNA is subject to alternative splicing at three sites, EDA, EDB and IIICS. We analyzed the alternative splicing of fibronectin mRNA in a single cell. Reverse transcription-polymerase chain reaction analyses showed cells that produced a single form of mRNA at each one of these sites as well as cells that produced multiple forms at a given site: for example, some cells produced either the EDA(+) or EDA(-) form of the mRNA and other cells produced both forms. About 80% of the cells produced both (+) and (-) forms of the mRNA at the EDA and EDB sites, and the remaining cells contained either the (+) or (-) form. Five forms of fibronectin mRNA can result from alternative splicing at the IIICS site. Complex combinations of alternative splicing products were observed among the individual cells: there were ten different combinations of mRNA isoforms with respect to the IIICS site. Statistically significant changes in alternative splicing at the IIICS site were observed during cellular senescence.