1 8 polarity site-to-nucleus communication 1 9 2 0 2 1 2 Abstract (175 words). 1 Permanently polarized cells have developed transduction mechanisms linking 2 polarity-sites with gene regulation in the nucleus. In neurons, one mechanism is 3 based on long-distance retrograde migration of transcription factors (TFs). 4 Aspergillus nidulans FlbB is the only known fungal TF shown to migrate 5 retrogradely to nuclei from the polarized region of fungal cells known as hyphae. 6 There, FlbB controls developmental transitions by triggering the production of 7 asexual multicellular structures. FlbB dynamics in hyphae is orchestrated by 8 regulators FlbE and FlbD. At least three FlbE domains are involved in the 9 acropetal transport of FlbB, with a final MyoE/actin filament-dependent step from 1 0 the subapex to the apex. Experiments employing a T2A viral peptide-containing 1 1 chimera (FlbE::mRFP::T2A::FlbB::GFP) suggest that apical FlbB/FlbE 1 2 interaction is inhibited in order to initiate a dynein-dependent FlbB transport to 1 3 nuclei. FlbD controls the nuclear accumulation of FlbB through a cMyb domain 1 4 and a C-terminal LxxLL motif. Overall, results elucidate a highly dynamic pattern 1 5 of FlbB interactions, which enable timely developmental induction. Furthermore, 1 6 this system establishes a reference for TF-based long-distance signaling in 1 7 permanently polarized cells.