Understanding how the assembly of nascent mRNA into a ribonucleoprotein (mRNP) influences R-loop homeostasis is crucial for gaining insight into the cellular mechanisms that prevent genome instability. Here, we identify three RNA-binding proteins, Rie1, Rim4 and She2, whose stoichiometry is important to limit R-loop accumulation and, thus, to prevent DNA damage. Interestingly, Rim4 and She2 are overrepresented in mRNPs assembled in the absence of THO. In addition, we found that an excess of Dis3 impairs exosome function, promoting R-loops, particularly from non-coding RNAs, which cause genomic instability. Our results indicate that mRNP assembly is a precise process that, when perturbed by changes in the availability of different RBPs or RNAs, causes R-loop-mediated DNA damage in the cell. These results may help to understand the mechanism that promotes cancer, as several RBPs are overexpressed in different types of tumors.