RNA and DNA polymerases are key molecular motors playing central roles in fundamental biological processes like transcription and replication. Recent experimental evidence suggest they may also play an important role in architecturing the genome inside cell nuclei. I’ll present our current effort to characterize the biophysics of the coupling between the translocating activity of these motors and their capacity to self-interact and how such a coupling may shape the spatio-temporal dynamics of chromosomes. Combining analysis of experimental data and polymer modeling, I’ll illustrate how RNA Pol II transcription acts on gene organization through micro-compartmentalization and how DNA Pol replication shapes chromosomes in S-phase through a loop extrusion process.